Category Archives: Application Mgmt

December 10, 2009

REST in practice for IT and Cloud management (part 3: wrap-up)

[Preface: a few months ago I shared some thoughts about how REST was (or could) be applied to IT and Cloud management. Part 1 was a comparison of the RESTful aspects of four well-known IaaS Cloud APIs and part 2 was an analysis of how REST applies to configuration management. Both of these entries received well-informed reader comments BTW, so if you read the posts but didn’t come back for the comments you really owe it to yourself to do so now. At the time, I jotted down thoughts for subsequent entries in this series, but I never got around to posting them. Since the topic seems to be getting a lot of attention these days (especially in DMTF) I decided to go back to these notes and see if I could extract a few practical recommendations in the form of a wrap-up.]

The findings listed below should be relevant whether your protocol is trying to be truly RESTful, just HTTP-centric or even zen-SOAPy. Many of the issues that arise when creating a protocol that maps well to IT management use cases should transcend these variations and that’s what I try to cover.

Finding #1: Relationships (links) are first-class entities (a.k.a. “hypermedia”)

The clear conclusion of both part 1 and part 2 was that the most relevant part of REST for IT and Cloud management is the use of hypermedia. IT management enjoys a head start on this compared to other domains, because its models are already rich in explicit relationships (e.g. CIM associations), as opposed to other business domains in which relationships are more implicit (to the end user at least). But REST teaches us that just having relationships in your model is not enough. They need to be exposed in a way that maps directly to the protocol, so that following a relationship is an infrastructure-level task, not an application-level task: passing an ID as a parameter for some domain-specific function is not it.

This doesn’t violate the rule to not mix the protocol and the model because the alignment should take place in the metamodel. XML is famously weak in that respect, but that’s where Atom steps in, handling relationships in a generic way. Similarly, support for references is, in addition to its accolade to Schematron, one of the main benefits of SML (extra kudos for apparently dropping the “EPR” reference scheme between submission and standardization, in favor of just the “URI” scheme). Not to mention RDFa and friends. Or HTTP Link headers (explained) for link-challenged types.

Finding #2: Put IDs on steroids

There is little to argue about the value of clearly identifying things of interest and we didn’t wait for the Web to realize this. But it is also one of the most vexing and complex problems in many areas of computing (including IT management). Some of the long-standing questions include:

  • Use an opaque ID (some random-looking string a characters) or an ID grounded in “unique” properties of the resource (if you can find any)?
  • At what point does a thing stop being the same (typical example: if I replace each hardware component of a server one after the other, at which point is it not the same server anymore? Does it make sense for the IT guys to slap an “asset id” sticker on the plastic box around it?)
  • How do you deal with reconciling two resources (with their own IDs) when you realize they represent the same thing?

REST guidelines don’t help with these questions. There often is an assumption, which is true for many web apps, that the application “owns” the resource. My “inbox” only exists as a resource within the mail server application (e.g. Gmail or an Exchange server). Whatever URI GMail assigns for it is the URI for my inbox, period. Things are not as simple when the resources exist outside of any specific application: take a server, for example: the board management controller (or the hypervisor in the case of a VM), the OS management layer and the management agent installed on the machine all have claims to report on the machine (and therefore a need to identify it).

To some extent, Cloud computing simplifies many of these issues by providing controllers that “own” infrastructure resources and can authoritatively identify them. But it really is only pushing the problem to the next level of the stack.

Making the ID a URI doesn’t magically answer these questions. Though it helps in that it lets you leverage reconciliation mechanisms developed around URIs (such as <atom:link rel=”alternate”> or owl:sameAs). What REST does is add another constraint to this ID mechanism: Make the IDs dereferenceable URLs rather than just URIs.

I buy into this. A simple GET on a resource URI doesn’t solve everything but it has so many advantages that it should be attempted in all cases. And make this HTTP GET please (see finding #6).

In this adoption of GET, we just have to deal with small details such as:

  • What URL do I use for resources that have more than one agent/controller?
  • How close to the resource do I point this URL? If it’s too close to it then it may change as the resource evolves (e.g. network changes) or be affected by the resource performance (e.g. a crashed machine or application that does not respond to its management API). If it’s removed from the resource, then I introduce a scope (e.g. one controller) within which the resource has to remain, which may cause scalability concerns (how many VMs can/should one controller handle, what if I want to migrate a VM across the ocean…).

These are somewhat corner cases (and the more automation and virtualization you get, the fewer possible controllers you have per resource). While they need to be addressed, they don’t come close to negating the value of dereferenceable IDs. In addition, there are plenty of mechanisms to help with the issues above, from links in the representations (obviously) to RDDL-style lightweight directory to a last resort “give Saint Peter a call” mechanism (the original WSRF proposal had a sub-specification called WS-RenewableReferences that would let you ask for a new version of an expired EPR but it was never published — WS-Naming in then-GGF also touched on that with its reference resolvers — showing once again that the base challenges don’t change as fast as technology flavors).

Implicit in this is the fact that URIs are vastly superior to EPRs. The latter were only just a band-aid on a broken system (which may have started back when WSDL 1.1 decided to define “ports” as message aggregators that can have only one URL) and it’s been more debilitating to SOAP than any other interoperability issue. Web services containers internalized this assumption to the point of providing a stunted dispatch mechanism that made it very hard to assign distinct URLs to resources.

Finding #3: If REST told you to jump off a bridge, would you do it?

Adherence to REST is not required to get the benefits I describe in this series. There is a lot to be inspired by in REST, but it shouldn’t be a religion. Sure, if you squint hard enough (and poke it here and there) you can call your interface RESTful, but why bother with the contortions if some parts are not so. As long as they don’t detract from the value of REST in the other parts. As in all conversions, the most fervent adepts of RPC will likely be tempted to become its most violent denunciators once they’re born again. This is a tired scenario that we don’t need to repeat. Don’t think of it as a conversion but as a new perspective.

Look at the “RESTful with many parameters?” comment thread on Stefan Tilkov’s excellent InfoQ introduction to REST. It starts with some shared distaste for parameter-laden URIs and a search for a more RESTful approach. This gets suggested:

You could do a post on some URI like ./query/product_dep which would create a query resource. Now you “add” products to the query either by sending a product uri list with the initial post or by calling post on ./query/product_dep/{id}. With every post to the query resource the get on the query resource would change.

Yeah, you could. But how about an RPC-like query operation rather than having yet another resource lifecycle to manage just for the sake of being REST-compliant? And BTW, how do you think any sane consumer of your API is going to handle this? You guessed it, by packaging the POST/POST/GET/DELETE in one convenient client-side library function called “query”. As much as I criticize RPC-centric toolkits (see finding #5 below), it would be justified in this case.

Either you understand why/how REST principles benefit you or you don’t. If you do, then use this understanding to interpret the REST principles to best fit your needs. If you don’t, then no amount of CONTENT-TYPE-pixie-dust-spreading, GET-PUT-POST-DELETE-golden-rule-following and HATEOAS-magical-incantation-reciting will help you. That’s the whole point, for me at least, of this tree-part investigation. Stefan says essential the same, but in a converse way, in his article: “there are often reasons why one would violate a REST constraint, simply because every constraint induces some trade-off that might not be acceptable in a particular situation. But often, REST constraints are violated due to a simple lack of understanding of their benefits.” He says “understand why you violate” and I say “understand why you obey”. It is essentially the same (if you’re into stereotypes you can attribute the difference to his Germanic heritage and my Gallic blood).

Even worse than bending your interface to appear RESTful, don’t cherry-pick your use cases to only keep those that you feel you can properly address via REST, leaving the others aside. Conversely, don’t add requirements just because REST makes them easy to support (interesting how quickly “why do you force me to manage the lifecycle of yet another resource just to run a query” turns into “isn’t this great, you can share queries among users and you can handle long-running queries, I am sure we need this”).

This is not to say that you should not create a fully RESTful system. Just that you don’t necessarily have to and you can still get many benefits as long as you open your eyes to the cost/benefits trade-off involved.

Finding #4: Learn humility from REST

Beyond the technology, there is a vibe behind REST design. You can copy the technology and still miss it. I described it in 2005 as Humble Architecture, and applied to SOA at the time. But it describes REST just as well:

More practically, this means that the key things to keep in mind when creating a service, is that you are not at the center of the universe, that you don’t know who is going to consume your service, that you don’t know what they are going to do with it, that you are not necessarily the one who can make the best use of the information you have access to and that you should be willing to share it with others openly…

The SOA Manifesto recently called this “intrinsic interoperability”.

In IT management terms, it means that you can RESTify your CMDB and your event console and your asset management software and your automation engine all you want, if you see your code as the ultimate consumer and the one that knows best, as the UI that users have to go through, the “ultimate source of truth” and the “manager of managers” then it doesn’t matter how well you use HTTP.

Finding #5: Beware of tools bearing gifts

To a large extent, the great thing about REST is how few tools there are to take it away from you. So you’re pretty much forced to understand what is going on in your contract as opposed to being kept ignorant by a wsdl2java type of toolkit. Sure, Java (and .NET) have improved in that regard, but really the cultural damage is done and the expectations have been set. Contrast this to “the ‘router’ is just a big case statement over URI-matching regexps”, from Tim Bray’s post on the Sun Cloud API, one of my main inspirations for this investigation.

REST is not inherently immune to the tool-controlling-the-hand syndrome. It’s just a matter of time until such tools try to make REST “accessible” to the “normal” developer (who can supposedly prevent thread deadlocks but not parse XML). Joe Gregorio warns about this in the context of WADL (to summarize: WADL brings XSD which leads to code generation). Keep this in mind next time someone states that REST is more “loosely coupled” than SOAP. It’s how you use it that matters.

Finding #6: Use screws, not glue, so we can peer inside and then close the lid again

The “view source” option is how I and many others learned HTML. It unfortunately created a generation of HTML monsters who never went past version 3.2 (the marbled background makes me feel young again). But it also fueled the explosion of the Web. On-the-wire inspection through soapUI is what allowed me to perform this investigation and report on it (WMI has allowed this for years, but WS-Management is what made it accessible and usable for anyone on any platform). This was, of course, in the context of SOAP which is also inspectable. Still, in that respect nothing beats plain HTTP which is why I recommend HTTP GET in finding #2 (make IDs dereferenceable) even though I don’t expect that the one-page-per-resource view is going to be the only way to access it in the finished product.

These (HTML source, on-the-wire XML and resource-description pages) rarely hit the human eye and yet their presence enables the development of the more commonly used views. Making it as easy as possible to see what is going on under the covers helps with learning, with debugging, with extending and with innovating. In the same way that 99% of web users don’t look at the HTML source (and 99.99% of them don’t see the HTTP requests) but the Web would not be what it is to them if this inspectability wasn’t been there to fuel its development.

Along the same line, make as few assumptions as possible about the consumers in your interfaces. Which, in practice, often means document what goes on the wire. WSDL/WADL can be used as a format, but they are at most one small component. Human-readable semantics are much more important.

Finding #7: Nothing is free

Part of what was so attractive about SOAP is everything you were going to get “for free” by using it. Message-level security (for all these use cases where your messages starts over HTTP, then hops onto a train, then get delivered by a carrier pigeon). Reliable messaging. Transactionality. Intermediaries (they were going to be a big deal in SOAP, as you can see in vestigial form today in the Nodes/Roles left in the spec – also, do you remember WS-Routing? I do.)

And it’s true that by now there is a body of specifications that support this as composable SOAP headers. But the lack of usage of these features contrasts with how often they were bandied in the early days of SOAP.

Well, I am detecting some of the same in the REST camp. How often have you heard about how REST enables caching? Or about how content types allows an ISP to compress images on the fly to speed up delivery over dial-up? Like in the SOAP case, these are real features and sometimes useful. It doesn’t mean that they are valuable to you. And if they are not, then don’t let them be used as justifications. Especially since they are not free. If caching doesn’t help me (because of low volume, because security considerations prevent a shared cache, etc) then its presence actually adds a cost to me, since I now have to worry whether something is cached or not and deal with ETags. Or I have to consistently remember to request the cache to be bypassed.

Finding #8: Starting by sweeping you front door.

Before you agonize about how RESTful your back-end management protocol is, how about you make sure that your management application (the user front-end) is a decent Web application? One with cool URIs , where the back button works, where bookmarks work, where the data is not hidden in some over-encompassing Flash/Silverlight thingy. Just saying.

***

Now for some questions still unanswered.

Question #1: Is this a flee market?

I am highly dubious of content negotiation and yet I can see many advantages to it. Mostly along the lines of finding #6: make it easy for people to look under the hood and get hold of the data. If you let them specify how they want to see the data, it’s obviously easier.

But there is no free lunch. Even if your infrastructure takes care of generating these different views for you (“no coding, just check the box”), you are expanding the surface of your contract. This means more documentation, more testing, more interoperability problems and more friction when time comes to modify the interface.

I don’t have enough experience with format negotiation to define the sweetspot of this practice. Is it one XML representation and one HTML, period (everything else get produced by the client by transforming the XML)? But is the XML Atom-wrapped or not? What about RDF? What about JSON? Not to forget that SOAP wrapper, how hard can it be to add. But soon enough we are in legacy hell.

Question #2: Mime-types?

The second part of Joe Gregorio’s WADL entry is all about Mime types and I have a harder time following him there. For one thing, I am a bit puzzled by the different directions in which Mime types go at the same time. For example, we have image formats (e.g. “image/png”), packaging/compression formats (e.g. “application/zip”) and application formats (e.g. “application/vnd.oasis.opendocument.text” or “application/msword”). But what if I have a zip full of PNG images? And aren’t modern word processing formats basically a zip of XML files? If I don’t have the appropriate viewer, maybe I’d like them to be at least recognized as ZIP files. I don’t see support for such composition and taxonomy in these types.

And even within one type, things seem a bit messy in practice. Looking at the registered applications in the “options” menu of my Firefox browser, I see plenty of duplication:

  • application/zip vs. application/x-zip-compressed
  • application/ms-powerpoint vs. application/vnd.ms-powerpoint
  • application/sdp vs. application/x-sdp
  • audio/mpeg vs. audio/x-mpeg
  • video/x-ms-asf vs. video/x-ms-asf-plugin

I also wonder at what level of depth I want to take my Mime types. Sure I can use Atom as a package but if the items I am passing around happen to be CIM classes (serialized to XML), doesn’t it make sense to advertise this? And within these classes, can I let you know which domain (e.g. which namespace) my resources are in (virtual machines versus support tickets)?

These questions may simply be a reflection of my lack of maturity in the fine art of using Mime types as part of protocol design. My experience with them is more of the “find the type that works through trial and error and then leave it alone” kind.

[Side note: the first time I had to pay attention to Mime types was back in 1995/1996, playing with non-parsed headers and the multipart/x-mixed-replace type to bring some dynamism to web pages (that was before JavaScript or even animated GIFs). The site is still up, but the admins have messed up the Apache config so that the CGIs aren’t executed anymore but return the Python code. So, here are some early Python experiments from yours truly: this script was a “pushed” countdown and this one was a “pushed” image animation. Cool stuff at the time, though not in a “get a date” kind of way.]

On the other hand, I very much agree with Joe’s point that “less is more”, i.e. that by not dictating how the semantics of a Mime type are defined the system forces you to think about the proper way to define them (e.g. an English-language RFC). As opposed to WSDL/XSD which gives the impression that once your XML validator turns green you’re done describing your interface. These syntactic validations are a complement at best, and usually not a very useful one (see “fat-bottomed specs”).

In comments on previous posts, Stu Charlton also emphasizes the value that Mime types bring. “Hypermedia advocates exposing a variety of links for such state-transitions, along with potentially unique media types to describe interfaces to those transitions.” I get the hypermedia concept, the HATEOAS approach and its very practical benefits. But I am still dubious about the role of Mime types in achieving them and I am not the only one with such qualms. I have too much respect for Joe and Stu to dismiss it entirely, but until I get an example that makes it “click” in practice for me I won’t sweat about Mime types too much.

Question #3: Riding the Zeitgeist?

That’s a practical question rather than a technical one, but as a protocol creator/promoter you are going to have to decide whether you market it as “RESTful”. If I have learned one thing in my past involvement with standards it is that marketing/positioning/impressions matter for standards as much as for products. To a large extent, for Clouds, Linked Data is a more appropriate label. But that provides little marketing/credibility humph with CIOs compared to REST (and less buzzword-compliance for the tech press). So maybe you want to write your spec based on Linked Data and then market it with a REST ribbon (the two are very compatible anyway). Just keep in mind that REST is the obvious choice for protocols in 2009 in the same way that SOAP was a few years ago.

Of course this is not an issue if you specification is truly RESTful. But none of the current Cloud “RESTful” APIs is, and I don’t expect this to change. At least if you go by Roy Fielding’s definition (or Paul’s handy summary):

A REST API must not define fixed resource names or hierarchies (an obvious coupling of client and server). Servers must have the freedom to control their own namespace. Instead, allow servers to instruct clients on how to construct appropriate URIs, such as is done in HTML forms and URI templates, by defining those instructions within media types and link relations. [Failure here implies that clients are assuming a resource structure due to out-of band information, such as a domain-specific standard, which is the data-oriented equivalent to RPC’s functional coupling].

And (in a comment) Mark Baker adds:

I’ve reviewed lots of “REST APIs”, many of them privately for clients, and a common theme I’ve noticed is that most folks coming from a CORBA/DCE/DCOM/WS-* background, despite all the REST knowledge I’ve implanted into their heads, still cannot get away from the need to “specify the interface”. Sometimes this manifests itself through predefined relationships between resources, specifying URI structure, or listing the possible response codes received from different resources in response to the standard 4 methods (usually a combination of all those). I expect it’s just habit. But a second round of harping on the uniform interface – that every service has the same interface and so any service-specific interface specification only serves to increase coupling – sets them straight.

So the question of whether you want to market yourself as RESTful (rather than just as “inspired by the proper use of HTTP illustrated by REST”) is relevant, if only because you may find the father of REST throwing (POSTing?) tomatoes at you. There is always a risk in wearing clothes that look good but don’t quite fit you. The worst time for your pants to fall off is when you suddenly have to start running.

For more on this, refer to Ted Neward’s excellent Roy decoder ring where he not only explains what Roy means but more importantly clarifies that “if you’re not doing REST, it doesn’t mean that your API sucks” (to which I’d add that it is actually more likely to suck if you try to ape REST than if you allow yourself to be loosely inspired by it).

***

Wrapping up the wrap-up

There is one key topic that I had originally included in this wrap-up but decided to remove: extensibility. Mark Hapner brings it up in a comment on a previous post:

It is interesting to note that HTML does not provide namespaces but this hasn’t limited its capabilities. The reason is that links are a very effective mechanism for composing resources. Rather than composition via complicated ‘embedding’ mechanisms such as namespaces, the web composes resources via links. If HTML hadn’t provided open-ended, embeddable links there would be no web.

I am the kind of guy who would have namespace-qualified his children when naming them (had my wife not stepped in) so I don’t necessarily see “extension via links” as a negation of the need for namespaces (best example: RDF). The whole topic of embedding versus linking is a great one but this post doesn’t need another thousand words and the “REST in practice” umbrella is not necessarily the best one for this discussion. So I hereby conclude my “REST in practice for IT and Cloud management” series, with the intent to eventually start a “Linked Data in practice for IT and Cloud management” series in which extensibility will be properly handled. And we can also talk about querying (conspicuously absent from Cloud APIs, unless CMDBf is now a Cloud API) and versioning. As a teaser for the application of Linked Data to IT/Cloud, I will leave you with what Vint Cerf has to say.

[UPDATED 2010/1/27: I still haven’t written the promised “Linked Data in practice for IT and Cloud management” post, but this explanation of the usage of Linked Data for data.gov.uk pretty much says it all. I may still write a post describing how what Jeni says about government data applies to Cloud management APIs, but it’s almost too obvious to bother. Actually, there may be reasons why Cloud management benefits even more from Linked Data than UK government data, so it may still be worth a post. At some point. When I convince myself that it may influence things rather than be background noise.]

15 Comments

Filed under API, Application Mgmt, Automation, Cloud Computing, Everything, IT Systems Mgmt, Manageability, Mgmt integration, Modeling, Protocols, REST, Semantic tech, SOA, SOAP, Specs, Utility computing

December 4, 2009

Can I get a price check on this AMI?

I almost titled this entry “Cloud + Tivoli = $” in reference to the previous one (“Cloud + proprietary software = ♥”). In that earlier entry, I described the opportunity for Cloud providers to benefit themselves, their customers and software vendors by drastically reducing the frictions involved in using proprietary software (rather than open source software). The example I used was Windows EC2 instances. But it’s not the best example because there is a very tight relationship between Amazon and Microsoft on this. In many ways, these Windows instances are “hard-coded” in EC2: they have a special credential retrieval mechanism, their price appears in the main EC2 price list, etc. This cannot scale as a generic Amazon-mediated payment service for many software vendors.

Rather than the special case of Windows instances, the more interesting situation to look at is the availability of vendor-provided EC2 instances at a higher price. So I went to look a bit more into this, and I came out… very confused and $20 poorer.

Earlier in the week, I had noticed an announcement of IBM Tivoli on EC2 that explained that “the hourly price for Tivoli on EC2 includes an IBM license”. This seemed like a perfect place for me to start. My first question was “how much does it cost”? The blog entry doesn’t say. It links to a Tivoli on EC2 FAQ on the IBM site, which doesn’t say either (apparently IBM’s target customers work in recession-proof industries and do not “frequently ask” about prices). I then followed the link to the overall IBM and AWS FAQ but it just states that “charges will be announced by Amazon Web Services in the coming months”. Both FAQs explain how to use your traditional IBM license on EC2, but that’s not what I am after. At this point, I feel like a third-world tourist who entered a high-end jewelry store in Paris where no price is displayed. Call me plebeian, but I am more accustomed to Target-like stores with price-check scanners in the aisles…

I hypothesized that the AWS console might show me the price when I select the Tivoli AMIs. But no such luck. Tired of searching, and since I was already in the console, I figured I’d just launch an instance and see the hourly cost in my account usage. Since it comes in three versions (depending on how many targets you want Tivoli to manage), I launched one of each. Additionally, for one of them I launched instances of two different sizes so I can verify that the price difference is equal to the base EC2 price difference between such instance sizes. Here is what I got:

ec2-tivoli-bill

Of course, by the time my account usage page was updated (it took a few hours) I had found the price list which in retrospect wasn’t that hard to find (from Amazon, not IBM).

So maybe I am not the brightest droplet in the cloud, but for 20 bucks I consider that at least I bought the right to make a point: these prices should not be just on some web page. They should be accessible at the time of launch, in the console. And also in the EC2 API, so that the various EC2 tools can retrieve them. Whether it’s just for human display or to use as part of some automation logic, this should be available in an authoritative manner, without the need to scrape a page.

The other thing that bothers me is the need to decide upfront whether I want to launch a Tivoli instance to manage 50 virtual cores, 200 virtual cores or 600 virtual cores. That feels very inelastic for an EC2 deployment. I want to be charged for the actual number of virtual cores I am managing at any point in time. I realize the difficulty in metering this way (the need for Tivoli to report this to AWS, the issue of trust…) but hopefully it will eventually get there.

While I am talking about future improvements, another limitation is that there can currently only be one vendor per AMI. What if someone wants to write an application that runs on top of Oracle Middleware and package this as a paid AMI? It would be nice if Amazon eventually allowed the price of the instance to be split three-ways (Amazon, Oracle, application vendor).

In any case, now you know why this investigation left me poorer. The confused part comes from the fact that I had earlier experimented with Amazon Paid AMIs and it was an entirely different experience. Better in some ways: you get a clear price list upfront such as this.

ec2-paid-ami-price

But not as good in other ways: you have to purchase the paid AMI in a way that it is somewhat disconnected from the launch of the instance. And for some reason you paid for this directly out of your credit card as opposed to it going to your AWS usage account along with all your other charges. I would expect that many customers will use these paid AMIs are part of a larger EC2 deployment and as such it seems awkward to have it billed separately.

But overall, it’s the disconnect between the two that the confuses me. Are there two different types of paid AMIs (three if you include the Windows EC2 instances)? What am I missing?

The next step in my investigation should probably be to create an AMI and set a price on it, so I get the vendor’s view in addition to the consumer’s view. And maybe I can earn my $20 back in the process…

7 Comments

Filed under Amazon, Application Mgmt, Business, Cloud Computing, Everything, IBM, IT Systems Mgmt, Utility computing

December 2, 2009

Cloud + proprietary software = ♥

When I left HP for Oracle, in the summer of 2007, a friend made the argument that Cloud Computing (I think we were still saying “Utility Computing” at the time) would be the death of proprietary software.

There was a lot to support this view. EC2 was one year old and its usage was overwhelmingly based on open source software (OSS). For proprietary software, there was no clear understanding of how licensing terms applied to Cloud deployments. Not only would most sales reps not know the answer, back then they probably wouldn’t have comprehended the question.

Two and a half years later… well it doesn’t look all that different at first blush. EC2 seems to still be a largely OSS-dominated playground. Especially since the most obvious (though not necessarily the most accurate) measure is to peruse the description/content of public AMIs. They are (predictably since you can’t generally redistribute proprietary software) almost entirely OSS-based, with the exception of the public AMIs provided by software vendors themselves (Oracle, IBM…).

And yet the situation has improved for usage of proprietary software in the Cloud. Most software vendors have embraced Cloud deployments and clarified licensing issues (taking the example of Oracle, here is its Cloud Computing Center page, an overview of the licensing policy for Cloud deployments and the AWS/Oracle partnership page to encourage the use of Oracle software on EC2; none of this existed in 2007).

But these can be called reactive adaptations. At best (depending on the variability of your load and whether you use an Unlimited License Agreement), these moves have brought the “proprietary vs. OSS” debate in the Cloud back to the same parameters as for on-premise deployments. They have simply corrected the initial challenge of not even knowing how to license proprietary software for Cloud deployments.

But it’s not stopping here. What we are seeing is some of the parameters for the “proprietary vs. OSS” debate become more friendly towards proprietary software in the Cloud than on-premise. I am referring to the emergence of EC2 instances for which the software licenses are included in the per-hour rate for server instances. This pretty much removes license management as a concern altogether. The main example is Windows EC2 instances. As a user, you don’t have to deal with any Windows license consideration. You just request a machine and use it. Which of course doesn’t mean you are not paying for Windows. These Windows instances are more expensive than comparable Linux instances (e.g. $0.34 versus $0.48 per hour in the case of a “standard/large” instance) and Amazon takes care of paying Microsoft.

The removal of license management as a concern may not make a big difference to large corporations that have an Unlimited License Agreement, but for smaller companies it may take a chunk out of the reasons to use open source software. Not only do you not have to track license usage (and renewal), you never have to spend time with a sales rep. You don’t have to ask yourself at what point in your beta program you’ve moved from a legitimate use of the (often free) development license to a situation in which you need a production license. Including the software license directly in the cost of the base Cloud resource (e.g. the virtual machine instance) makes planning (and auto-scaling) easier: you use the same algorithm as in the “free license” situation, just with a different per hour cost. The trade-off becomes quantitative rather than qualitative. You can trade a given software stack against a faster CPU or more memory or more storage, depending on which combination serves your needs better. It doesn’t matter if the value you get from the instance comes from the software in the image or the hardware. This moves IaaS closer to PaaS (force.com doesn’t itemize your bill between hardware cost and software cost). Anything that makes IaaS more like PaaS is good for IaaS.

From an earlier post, about virtual appliances:

As with all things computer-related, the issue is going to get blurrier and then irrelevant . The great thing about software is that there is no solid line. In this case, we will eventually get more customized appliances (via appliance builders or model-driven appliance generation) blurring the line between installed software and appliance-based software.

I was referring to a blurring line in terms of how software is managed, but it’s also true in terms of how it is licensed.

There are of course many other reasons (than license management) why people use open source software rather than proprietary. The most obvious being the cost of the license (which, as we have seen, doesn’t go away but just gets incorporated in the base Cloud instance rate). Or they may simply prefer a given open source product independently of any licensing aspect. Some need access to the underlying code, to customize/improve it for their purpose. Or they may be leery of depending on one entity for the long-term viability of their platform. There may even be some who suspect any software that they don’t examine/compile themselves to contain backdoors (though these people are presumably not candidates for Cloud deployments in he first place). Etc. These reasons remain pretty much unchanged in the Cloud. But, anecdotally at least, removing license management concerns from both manual and automated tasks is a big improvement.

If Cloud providers get it right (which would require being smarter than wireless service providers, a low bar) and software vendors play ball, the “proprietary vs. OSS” debate may become more favorable to proprietary software in the Cloud than it is on-premise. For the benefit of customers, software vendors and Cloud providers. Hopefully Amazon will succeed where telcos mostly failed, in providing a convenient application metering/billing service for 3rd-party software offered on top of their infrastructural services (without otherwise getting in the way). Anybody remembers the Minitel? Today we’d call that a “Terminal as a Service” offering and if it did one thing well (beyond displaying green characters) it was billing. Which reminds me, I probably still have one in my parent’s basement.

[Note: every page of this blog mentions, at the bottom, that “the statements and opinions expressed here are my own and do not necessarily represent those of Oracle Corporation” but in this case I will repeat it here, in the body of the post.]

[UPDATED 2009/12/29: The Register seems to agree. In fact, they come close to paraphrasing this blog entry:

“It’s proprietary applications offered by enterprise mainstays such as Oracle, IBM, and other big vendors that may turn out to be the big winners. The big vendors simply manipulated and corrected their licensing strategies to offer their applications in an on-demand or subscription manner.

Amazonian middlemen

AWS, for example, now offers EC2 instances for which the software licenses are included in the per-hour rate for server instances. This means that users who want to run Windows applications don’t have to deal with dreaded Windows licensing – instead, they simply request a machine and use it while Amazon deals with paying Microsoft.”]

[UPDATED 2010/1/25: I think this “Cloud as Monetization Strategy for Open Source” post by Geva Perry (based on an earlier post by Savio Rodrigues ) confirms that in the Cloud the line between open source and proprietary software is thinning.]

[UPDATED 2010/11/12: Related and interesting post on the AWS blog: Cloud Licensing Models That Exist Today]

6 Comments

Filed under Amazon, Application Mgmt, Automation, Business, Cloud Computing, Everything, Open source, Oracle, Utility computing, Virtual appliance

December 1, 2009

Oracle Real User Experience Insight 6.0

Oracle just released version 6.0 of Real User Experience Insight (friends call it RUEI), which is part of the Enterprise Manager portfolio. As the name indicates, it captures and presents in great details the experience of actual users interacting with your application. This is real traffic, not synthetic probes. It’s is a mature product, which originally came from the Moniforce acquisition two years ago.

One way to classify the improvements in this version is to sort them based on who they are exciting for:

Exciting for techies

The ability to link in context from RUEI to diagnostic tools in Enterprise Manager. For example, going from a slow JSP in RUEI to a view of its role in the overall composite application. Or to a deep-dive in Java diagnostic.

Exciting for Oracle applications administrators

Many improvements (in the form of updated “Accelerators”) for using RUEI to manage Oracle EBS, PeopleSoft, Siebel and JD Edwards. Including EBS Forms support in socket mode without Chronos (those who know what this means rejoice, others can safely ignore).

Exciting for business and marketing people

The full capture and replay of user sessions. The ease of reproducing errors and seeing exactly what your users do and experience. Terrifyingly edifying at times.

1 Comment

Filed under Application Mgmt, Everything, IT Systems Mgmt, Oracle

November 25, 2009

Can your hypervisor radio for air support?

As I was reading about Microsoft Azure recently, a military analogy came to my mind. Hypervisors are tanks. Application development and runtime platforms compose the air force.

Tanks (and more generally the mechanization of ground forces) transformed war in the 20th century. They multiplied the fighting capabilities of individuals and changed the way war was fought. A traditional army didn’t stand a chance against a mechanized one. More importantly, a mechanized army that used the new tools with the old mindset didn’t stand a chance against a similarly equipped army that had rethought its strategy to take advantage of the new capabilities. Consider France at the beginning of WWII, where tanks were just canons on wheels, spread evenly along the front line to support ground troops. Contrast this with how Germany, as part of the Blitzkrieg, used tanks and radios to create highly mobile – and yet coordinated – units that caused havoc in the linear French defense.

Exercise for the reader who wants to push the analogy further:

  • Describe how Blitzkrieg-style mobility of troops (based on tanks and motorized troop transports) compares to Live Migration of virtual machines.
  • Describe how the use of radios by these troops compares to the use of monitoring and control protocols to frame IT management actions.

Tanks (hypervisor) were a game-changer in a world of foot soldiers (dedicated servers).

But no matter how good your tanks are, you are at a disadvantage if the other party achieves air superiority. A less sophisticated/numerous ground force that benefits from strong air support is likely to prevail over a stronger ground force with no such support. That’s what came to my mind as I read about how Azure plans to cover the IaaS layer, but in the context of an application-and-data-centric approach. Where hypervisors are not left to fend for themselves based on the limited view of the horizion from the periscope of their turrets but rather orchestrated, supported (and even deployed) from the air, from the application platform.

C-130 tank airdrop

(Yes, I am referring to the Azure vision as it was presented at PDC09, not necessarily the currently available bits.)

Does your Cloud vendor/provider need an air force?

Exercise for the reader who wants to push the analogy to the stratosphere:

  • Describe how business logic/process, business transaction management and business intelligence are equivalent to satellites, surveying the battlefield and providing actionable intelligence.

The new Cloud stack (“military-cloud complex” version):

cloud-military-stack

[Note: I have no expertise in military history (or strategy) beyond high school classes about WWI and WWII, plus a couple of history books and a few war movies. My goal here is less to be accurate on military concerns (though I hope to be) than to draw an analogy which may be meaningful to fellow IT management geeks who share my level of (in)expertise in military matters. This is just yet another way in which I try to explain that, for Clouds as for plain old IT management, “it’s the application, stupid”.]

1 Comment

Filed under Application Mgmt, Azure, Cloud Computing, Everything, IT Systems Mgmt, Mgmt integration, Utility computing, Virtualization

November 10, 2009

Desirable technical characteristics of PaaS

PaaS can most dramatically improve the IT experience in four areas:

  • Hosting/operations efficiency
  • Application-centric management
  • Development productivity
  • Security

To do so, there are technical characteristics that PaaS frameworks should eventually exhibit. These are not technical characteristics of a given PaaS container, they are shared characteristics that go across all container types, no matter what the operational capabilities of the containers are.

Here is a rough and unorganized list of the desirable characteristics (meta-capabilities) of PaaS Cloud containers:

  • An application component model that supports deployment/configuration across all PaaS container types.
  • Explicit interactions/invocations between application components (resilient connections between component: infrastructure-level retry/reroute)
  • Uniform and consistent request tracking across all components. Ability to intercept component-to-component communication.
  • Short-term (or externally persisted) state so that all instances can be quickly redirected out of any one node.
  • Subset of platform management interface exposed to consumer, along with out of the box application management. Application metrics consolidated at application level rather than node level.
  • Consistent, model-based application management interface across all container types. Hooks for component code to provide its manageability in the same framework.
  • Minimal footprint of any container node for limited patching requirements.
  • Assistance for debugging platform-hosted code (see this entry).
  • No encroachment of container technology on application contract (e.g. no forced URL structure).
  • Application uniformly scalable to the limit of the underlying hardware (no imposed partitioning).
  • Shared authentication / authorization / auditing across containers.
  • Minimum contract/interface exposed by each container.
  • Governance of application services, aligned (in model/protocols) with the container management interfaces.
  • [UPDATE: need to add metering+billing as William Louth pointed out in a comment]

This applies across the board to public, private and hybrid PaaS. The distinctions between these delivery models are real but at a different level. The important thing is that the PaaS administrator is different from the application administrator in all cases. On the other hand, most of these technical characteristics are not achievable for lower-level Cloud resources (like virtual hosts and low-level storage) which is why the IaaS form of Cloud leaves the Cloud promise only partially fulfilled.

4 Comments

Filed under Application Mgmt, Cloud Computing, Everything, IT Systems Mgmt, Manageability, Mgmt integration, Middleware, PaaS, Utility computing

November 9, 2009

Enumeration of PaaS container types

What do we need from an on-demand application platform for enterprise software? Here is a proposed classification of container types on which you can create/scale/manage applications. Your application is made of modules that run on these containers (e.g. one app may have two “synchronous web request” modules, one “structured data service” module and one “scheduled job” module). All tied together using an application component model that dovetails with the capabilities of the different containers. The proposed containers map to the following capabilities:

  • Synchronous web request processing
  • Long-lived (persisted) process execution with introspectable/declarative flow
  • Event processing
  • Persistence (a few different types: structured vs. buckets/files vs. object cache)
  • Batch/background/scheduled/queued processing
  • Possibly some advanced Web/mobile UI (portals, human task flows…)
  • User management (self-contained or as an abstraction layer for other systems)
  • [UPDATED 2009/11/19: I should have included pluggable protocol/format adapters.]

While new applications may be built to run purely on such a platform, you will not be able to run your IT solely on it anytime in the foreseeable future. So if you are thinking about it from the perspective of the entire universe of virtualization containers needed to support your IT system, you’ll need to add lower-level container types, such as:

  • Guest hosts (typically from hypervisors)
  • Low-level (e.g. block) storage
  • Networking between them

Another way to think about it is that Cloud/Utility computing is about having pools of resources dynamically allocated. There needs to be few enough pools that each pool is large enough and used across enough consumers to derive efficiencies from the act of sharing. But there needs to be enough pool types that applications have a complete infrastructure to run on that lets them abstracts away what is not business logic. This list is an attempt at this middle ground.

This is a classification of containers, not a description. There are many different ways to realize each of them. The synchronous  web request processing could look like a servlet engine, a Python handler or a PHP page. The persisted execution could be a BPEL engine or some other state machine definition/execution engine. The structured data interface could look like SQL, XQuery or SPARQL, etc… In addition, more specialized application infrastructure elements (e.g. video streaming, analytics) might enter the picture for some applications.

I hope to see the discussion move beyond “IaaS vs. PaaS” towards talking about more specific container types that are needed/supported by the different virtualization stacks. My application doesn’t care if the file container is considered IaaS or PaaS.

The next post will list desired characteristics of the PaaS environment (meta-capabilities that go across all the container types in the first list but may not be available from the lower-level containers in the second list).

7 Comments

Filed under Application Mgmt, Cloud Computing, Everything, Middleware, PaaS, Utility computing

November 2, 2009

Would you like some management with that appliance?

Andi Mann recently wrote an interesting post about virtual appliances . He uses the domain name pleasediscuss.com for his blog so I figured I’d do just that. More specifically, I have three comments on his article.

Opaque or transparent appliance

Andi’s concerns about the security and management problems posed by virtual appliances are real, but he seems to assume that the content of the appliance is necessarily opaque to the customer and under the responsibility of the appliance provider. Why can’t a virtual appliance be transparent in the sense that the customer is able to efficiently manage at least some aspects of the software installed on it? “You can’t put agents on most virtual appliances, they don’t come with WMI, and most have only a GUI for management” says Andi. Why can’t an appliance come with an agent (especially in these days of consolidation where many vendors provide many layers of the stack – hypervisor / OS / application container / application / management tools – including their agent)? Why can’t it implement a standard management API (most servers nowadays implement WBEM, WS-Management and/or IPMI pre-boot – on the motherboard – which is a lot more challenging to do than supporting a similar protocol in a virtual appliance). Andi is really criticizing the current offering more than the virtual appliance model per se and in this I can join him.

Let me put it differently, since this is probably just a question of definition: what would Andi call a virtual appliance that does expose management APIs for its infrastructure (e.g. WS-Management for the OS, JMX for the java stack) or that comes with an agent (HP, IBM, BMC, Oracle…) installed on it?

Such an appliance (let’s call it a “transparent virtual appliance” for now) doesn’t provide all the commonly claimed benefits of an appliance (zero config/admin) but as Andi points out these benefits come with major intrinsic drawbacks. A transparent virtual appliance still drastically simplifies installation (especially useful for test/dev/demo/POC). It doesn’t entirely free you of monitoring and configuration but at least it provides you with a very consistent and controlled starting point, manageable from the start (no need to subsequently install an agent). In addition, it can be made “just enough” (just enough OS, just enough app server…) to require a lot less maintenance than an application stack that you assemble yourself out of generic parts. We’ll always have trade offs between how optimized/customized it is versus how uniform your overall environment can be, but I don’t see the use of an appliance as a delivery mechanism as necessarily cornering you into a completely opaque situation, from a management perspective.

Those who attended Oracle Open World a few weeks ago were treated to an example of such an appliance, if they attended any of the sessions that covered Oracle’s Appliance Builder (the main one was, I believe, Virtualizing Oracle Fusion Middleware in the Modern Data Center, in case you have access to the Open World On Demand replay and slides). I believe it’s probably the same content that @jayfry3 was shown when he tweeted about “Oracle is demoing their private cloud self-service app”. These appliances are not at all opaque from a management perspective. To the contrary, they are highly manageable, coming with an Enterprise Manager agent installed that can manage everything in the appliance (and when that “everything” doesn’t include the OS, it’s because there isn’t one thanks to JRockit Virtual Edition, making things slimmer, faster, safer and more manageable). And of course the OVM-based environment in which you deploy these appliances is also managed by Enterprise Manager. OK, my point here wasn’t to go into marketing mode, but this is cool stuff and an example of what virtual appliances should be. BTW, this was also demonstrated during Hasan Rizvi’s keynote at OpenWorld, including the management of these systems through Enterprise Manager.

In the long run it’s irrelevant

As with all things computer-related, the issue is going to get blurrier and then irrelevant . The great thing about software is that there is no solid line. In this case, we will eventually get more customized appliances (via appliance builders or model-driven appliance generation) blurring the line between installed software and appliance-based software.

Waiting for PaaS

Towards the end of his post, Andi paints an optimistic vision of the future: “I also think that virtual appliances have a bright future – but in some ways I continue to see them as a beta version of what could (or should) come next.  By adding in capabilities for responsible and accountable management, they could form the basis of more fully-functional virtual service management containers. These in turn could form the basis of elastic, mobile, network-deployed, responsible cloud appliances that deliver complete end-to-end service management without regard to physical location or domain of control.”

I mostly agree with this vision, though when I describe it it is in the guise of a PaaS platform. Where your appliance (which today goes from the OS all the way to the app) has shrunk to an application template that you deploy in the PaaS environment (rather than in a hypervisor). If/when the underlying PaaS environment has reached the right level of management automation you get all the benefits of an appliance while maintaining the consistency of your environment and its adherence to your management policies (because the environment is the PaaS platform and its management is driven from your policies).

[As is often the case, this started as a comment (on Andi’s blog) and quickly outgrew that environment, leading to this new post. Plus, Andi’s blog is brand new and seems to be well worth spreading the word about (Andi himself is under-marketing it).]

3 Comments

Filed under Application Mgmt, Automation, Desired State, Everything, IT Systems Mgmt, Manageability, Oracle, Oracle Open World, OVM, PaaS, Virtual appliance, WS-Management

October 28, 2009

OWL news you can use

The W3C released OWL 2 today. Most readers of this blog are IT management people (whether they call it “cloud computing” or “boring old system management”) and don’t follow RDF, OWL, SPARQL etc too closely (if at all). Yet there is a lot of potential value in using these technologies for IT management, so I thought it might be helpful to provide some practical resources on the topic. I have selected articles that cover the special (some may say “twisted”) approach of using OWL and its friends for validation rather than just inference, as this use case is very relevant to IT management.

Of course you can also go to the W3C standard itself, starting with the overview of OWL 2.

Just so you don’t feel lonely if you decide to explore this path, have a look at Elastra’s sexy technology stack. ECML, EDML and EMML are all defined as OWL ontologies.

Comments Off on OWL news you can use

Filed under Application Mgmt, Everything, IT Systems Mgmt, Mgmt integration, Modeling, OWL, RDF, Semantic tech, Specs, Standards

October 27, 2009

Yes you can read the OSGi specification

You know what I like the best about OSGi? That it doesn’t put the bar too high for architects. At first I was a bit intimidated by the size  (338 pages for the “core specification”, 862 pages for the “service compendium”) and the fact that I had to look up “compendium”. But then they put me right at ease:

“Architects should focus on the introduction of each subject. This introduction contains a general overview of the subject, the requirements that influenced its design, and a short description of its operation as well as the entities that are used. The introductory sections require knowledge of Java concepts like classes and interfaces, but should not require coding experience.”

I am like so totally overqualified for my job. Hell, I even know what packages are.

(from the recently released OSGi version 4.2.)

3 Comments

Filed under Application Mgmt, Everything, Off-topic, OSGi

October 15, 2009

Cloud platform patching conundrum: PaaS has it much worse than IaaS and SaaS

The potential user impact of changes (e.g. patches or config changes) made on the Cloud infrastructure (by the Cloud provider) is a sore point in the Cloud value proposition (see Hoff’s take for example). You have no control over patching/config actions taken by the provider, any of which could potentially affect you. In a traditional data center, you can test the various changes on specific applications; you don’t have to apply them at the same time on all servers; and you can even decide to skip some infrastructure patches not relevant to your application (“if it aint’ broken…”). Not so in a Cloud environment, where you may not even know about a change until after the fact. And you have no control over the timing and the roll-out of the patch, so that some of your instances may be running on patched nodes and others may not (good luck with troubleshooting that).

Unfortunately, this is even worse for PaaS than IaaS. Simply because you seat on a lot more infrastructure that is opaque to you. In a IaaS environment, the only thing that can change is the hardware (rarely a cause of problem) and the hypervisor (or equivalent Cloud OS). In a PaaS environment, it’s all that plus whatever flavor of OS and application container is used. Depending on how streamlined this all is (just enough OS/AS versus a traditional deployment), that’s potentially a lot of code and configuration. Troubleshooting is also somewhat easier in a IaaS setup because the error logs are localized (or localizable) to a specific instance. Not necessarily so with PaaS (and even if you could localize the error, you couldn’t guarantee that your troubleshooting test runs on the same node anyway).

In a way, PaaS is squeezed between IaaS and SaaS on this. IaaS gets away with a manageable problem because the opaque infrastructure is not too thick. For SaaS it’s manageable too because the consumer is typically either a human (who is a lot more resilient to change) or a very simple and well-understood interface (e.g. IMAP or some Web services). Contrast this with PaaS where the contract is that of an application container (e.g. JEE, RoR, Django).There are all kinds of subtle behaviors (e.g, timing/ordering issues) that are not part of the contract and can surface after a patch: for example, a bug in the application that was never found because before the patch things always happened in a certain order that the application implicitly – and erroneously – relied on. That’s exactly why you always test your key applications today even if the OS/AS patch should, in theory, not change anything for the application. And it’s not just patches that can do that. For example, network upgrades can introduce timing changes that surface new issues in the application.

And it goes both ways. Just like you can be hurt by the Cloud provider patching things, you can be hurt by them not patching things. What if there is an obscure bug in their infrastructure that only affects your application. First you have to convince them to troubleshoot with you. Then you have to convince them to produce (or get their software vendor to produce) and deploy a patch.

So what are the solutions? Is PaaS doomed to never go beyond hobbyists? Of course not. The possible solutions are:

  • Write a bug-free and high-performance PaaS infrastructure from the start, one that never needs to be changed in any way. How hard could it be? ;-)
  • More realistically, narrowly define container types to reduce both the contract and the size of the underlying implementation of each instance. For example, rather than deploying a full JEE+SOA container componentize the application so that each component can deploy in a small container (e.g. a servlet engine, a process management engine, a rule engine, etc). As a result, the interface exposed by each container type can be more easily and fully tested. And because each instance is slimmer, it requires fewer patches over time.
  • PaaS providers may give their users some amount of visibility and control over this. For example, by announcing upgrades ahead of time, providing updated nodes to test on early and allowing users to specify “freeze” periods where nothing changes (unless an urgent security patch is needed, presumably). Time for a Cloud “refresh” in ITIL/ITSM-land?
  • The PaaS providers may also be able to facilitate debugging of infrastructure-related problem. For example by stamping the logs with a version ID for the infrastructure on the node that generated the log entry. And the ability to request that a test runs on a node with the same version. Keeping in mind that in a SOA / Composite world, the root cause of a problem found on one node may be a configuration change on a different node…

Some closing notes:

  • Another incarnation of this problem is likely to show up in the form of PaaS certification. We should not assume that just because you use a PaaS you are the developer of the application. Why can’t I license an ISV app that runs on GAE? But then, what does the ISV certify against? A given PaaS provider, e.g. Google? A given version of the PaaS infrastructure (if there is such a thing… Google advertises versions of the GAE SDK, but not of the actual GAE runtime)? Or maybe a given PaaS software stack, e.g. the Oracle/Microsoft/IBM/VMWare/JBoss/etc, meaning that any Cloud provider who uses this software stack is certified?
  • I have only discussed here changes to the underlying platform that do not change the contract (or at least only introduce backward-compatible changes, i.e. add APIs but don’t remove any). The matter of non-compatible platform updates (and version coexistence) is also a whole other ball of wax, one that comes with echoes of SOA governance discussions (because in PaaS we are talking about pure software contracts, not hardware or hardware-like contracts). Another area in which PaaS has larger challenges than IaaS.
  • Finally, for an illustration of how a highly focused and specialized container cuts down on the need for config changes, look at this photo from earlier today during the presentation of JRockit Virtual Edition at Oracle Open World. This slide shows (in font size 3, don’t worry you’re not supposed to be able to read), the list of configuration files present on a normal Linux instance, versus a stripped-down (“JeOS”) Linux, versus JRockit VE.


By the way, JRockit VE is very interesting and the environment today is much more favorable than when BEA first did it, but that’s a topic for another post.

[UPDATED 2009/10/22: For more on this (in an EC2-centric context) see section 4 (“service problem resolution”) of this IBM paper. It ends with “another possible direction is to develop new mechanisms or APIs to enable cloud users to directly and automatically query and correlate application level events with lower level hardware information to better identify the root cause of the problem”.]

[UPDATES 2012/4/1: An example of a PaaS platform update which didn’t go well.]

9 Comments

Filed under Application Mgmt, Cloud Computing, Everything, Google App Engine, Governance, ITIL, Manageability, Mgmt integration, PaaS, SaaS, Utility computing, Virtualization

September 24, 2009

The future (2006 version), has arrived

Remember 2006? Things were starting to fall into place for IT management integration and automation:

  • SDD was already on its way to cleanly describe/package/manage the lifecycle of simple and composite applications alike,
  • the first version of SML came out to capture all the relevant constraints of complex and composite systems and open the door to “desired-state management”,
  • the CMDBf effort was started to seamlessly integrate all sources of configuration and provide a bird-eye view of your entire IT infrastructure, and
  • the WSDM/WS-Management convergence/reconciliation was announced and promised to free management consoles from supporting many resource discovery, collection and control mechanisms and from having platform/library dependencies between the manager and its targets.

It looked like we were a year or two from standardization on all these and another year or two from shipping implementations. Things were looking good.

Good news: the schedule was respected. SDD, SML and CMDBf are now all standards (at OASIS, W3C and DMTF respectively). And today the Eclipse COSMOS project announced the release of COSMOS 1.1 which implements them all. The WSDM/WS-Management convergence is the only one that didn’t quite go according to the plan but it is about to come out as a standard too (in a pared-down form).

Bad news: nobody cares. We’ve moved on to “private clouds”.

Having been involved with these specifications in various degrees (a little bit on SDD, a fair amount on SML and a lot on CMDBf and WSDM/WS-Management) I am not as detached as my sarcastic tone may suggest. But as they say in action movies, “don’t let sentiments get in the way of the mission”.

There is still a chance to reuse parts of this stack (e.g. the CMDBf query language) and there are lessons to learn from our errors. The over-promising, the technical misjudgments, the political bickering, the lack of concrete customer validation, etc. To some extent this work was also victim of collateral damages from the excesses of WS-* (I am looking at you WS-Addressing). We also failed to notice the rise of the hypervisor in our peripheral vision.

I tried to capture some important lessons in this post-mortem. For the edification of the cloud generation. I also see a pendulum in action. Where we over-engineered I now see some under-engineering (overly granular interaction models, overemphasis on the virtual machine as the unit of everything, simplistic constraint models, underestimation of config/patching issues…). Things will come around and may eventually look familiar (suggested exercise: compare PubSubHubBub with WS-Notification).

As long as each iteration gets us closer to the goal things are good.

See you in 2012. Same place, same day, same time.

3 Comments

Filed under Application Mgmt, Automation, Cloud Computing, CMDB, CMDB Federation, CMDBf, Desired State, Everything, IT Systems Mgmt, Manageability, Mgmt integration, Modeling, Protocols, SML, Specs, Standards, Utility computing, WS-Management

September 22, 2009

Thoughts on the “Simple Cloud API”

PHP developers with Cloud aspirations rejoice! Zend has announced a PHP toolkit (called the Simple Cloud API project) to abstract and access application-level Cloud services. This is not just YACA (yet another Cloud API), as there are interesting differences between this and all the other Cloud toolkits out there.

First it’s PHP, which was not covered by the existing toolkits. Considering how many web applications are written in PHP (including the one that serves this very blog) this may seem strange, until you realize that most Cloud toolkits out there are focused on provisioning/managing low-level compute resources of the IaaS kind. Something that is far out of PHP’s sweetspot and much more practically handled with Java, Python, Ruby or some .NET language accessible via PowerShell.

Which takes us to the second, and arguably most interesting, characteristic of this toolkit: it is focused on application-level Cloud services (files, documents and queues for now) rather than infrastructure-level. In other word, it’s the first (to my knowledge) PaaS toolkit.

I also notice that Zend has gotten endorsements from IBM, Microsoft, Nirvanix, Rackspace and GoGrid. The first two especially seem to have impressed InfoWorld. Let’s keep in mind that at this point all we are talking about are canned quotes in a press release. Which rank only above politician campaign promises as predictor of behavior. In any case that can’t be the full extent of IBM and Microsoft’s response to the VMWare/Cisco push on IaaS standards. But it may suggest that their response will move the battlefield to include PaaS, which would be a smart move.

Now for a few more acerbic comments:

  • It has “simple” in its name, like SOAP (as Pete Lacey famously lampooned). In the long term this tends to negatively correlate with simplicity, just like the presence of “democratic” in the official name of a country does not bode well for actual democracy.
  • Please, don’t shorten “Simple Cloud API” to SCA which is already claimed in a (potentially) closely related field.
  • Reuven Cohen is technically correct to see it as “a way to create other higher level programmatic API interfaces such as REST or SOAP using an easy, yet portable PHP programming environment”. But pay attention to how many turtles are on this pile: the native provider API, the adapter to the “simple cloud API”, the SOAP or REST remote API and the consuming application’s native API. How much real isolation are you getting when you build your house on such a wobbly foundation

[UPDATE: Comments from someone in the know:  a programmer working on adding Azure support for this Simple Cloud API project.]

2 Comments

Filed under Application Mgmt, Cloud Computing, Everything, IBM, Manageability, Mgmt integration, Microsoft, Middleware, Open source, Portability, Utility computing

September 21, 2009

Look Ma, no hypervisor!

Encouraged by hypervisor vendors, the confusion between virtualization and Cloud Computing is rampant. In the industry, the term “virtualization” (and its corollary, “virtual machine”) is used in so many different ways that it has lost all usefulness. For a recent example, read the introduction of this SNIA/OGF white paper (on Cloud Storage) which asserts that “the new technology underlying this is the system virtual machine that allows multiple instances of an operating system and associated applications to run on single physical machine. Delivering this over the network, on demand, is termed Infrastructure as a Service (IaaS)”.

In fact, even IaaS-type Cloud services don’t imply the use of hypervisors.

We need to decouple the Cloud interface/contract (e.g. “what are the types of resources that can I provision on demand? hosts, app servers, storage capacity, app services…”) from the underlying implementation (e.g. “are hypervisors used by the Cloud provider?”). At the risk of spelling out things that may be obvious to many readers of this blog, here is a simplified matrix of Cloud Computing systems, designed to illustrate that all combinations of interface and implementation are possible and in many cases even reasonable.

IaaS interface PaaS interface
Hypervisor used Yes! (see #1) Yes! (see #2)
Hypervisor not used Yes! (see #3) Yes! (see #4)

#1: IaaS interface, hypervisor-based implementation

This is a very common approach these days, both in public Clouds (EC2, Rackspace and presumably at some point the VMWare vCloud Express service providers) and private Clouds (Citrix, Sun, Oracle, Eucalyptus, VMWare…). Basically, you take a bunch of servers, put hypervisors on all of them and make VMs running on these hypervisors available to the Cloud customers.

But despite its predominance, this is not the only path to a Cloud, not even to an IaaS (e.g. “x86 hosts on demand”) Cloud. The following three other scenarios are all valid too.

#2: PaaS interface, hypervisor-based implementation

This is the road SpringSource has been on, first with Cloud Foundry (using AWS EC2 which is based on the Xen hypervisor) and presumably soon on top of VMWare.

#3: IaaS interface, no hypervisor in the implementation

Let’s remember that the utility computing vision (before the term fell in desuetude in favor of “cloud”) has been around before x86 hypervisors were so common. Take Loudcloud as an illustration. They were building what is now called a “public Cloud” starting back in 1999 and not using any hypervisor. Just bare metal provisioning and advanced provisioning automation software. Then they sold the hosting part to EDS (now HP) and only kept the software, under the name Opsware (now HP too, incidentally). That software was meant to create what we now call a “private Cloud”. See this old DCML announcement as one example of the Opsware vision. And no hypervisor was harmed in the making of this movie.

At the current point in time, the hardware (e.g. multiple cores, shared memory) and software (hypervisors, legacy apps) environment is such that hypervisor-based solutions seem to have an edge over those based on automated provisioning/configuration alone. But these things tend to change quickly in our industry… Especially if you factor in non-technical considerations like compliance, fear of data leakage and the risk of having the hardware underlying your application seized because of an investigation involving another tenant…

And this is not going into finner techno-philosophical points about the different types of hypervisors. Not to mention mainframe LPARs… One could build a hypervisor-free IaaS solution on these.

To some extent, you may even put the “pwned” machines (in a botnet) in this “IaaS with no hypervisor” category (with the small difference that what’s being made available is an x86 with an OS, typically Windows, already installed). If you factor out externalities (like the FBI breaking down your front door at 6:00AM) this approach has claims as the most cost-effective form of Cloud computing available today… Solaris zones are another example of possible foundation for a hypervisor-free IaaS-like offering (here too, with an OS rather than a “raw host” as the interface).

#4: PaaS interface, no hypervisor in the implementation

In the public sphere, this corresponds to Google App Engine.

In the private sphere, several companies have built it themselves on top of WebLogic, by adding some level of “on-demand” application provisioning in order to streamline the relationship between the IT group running the servers and the business groups who want to deploy applications on them. Something that one should ideally be able to buy rather than build.

Waiting for the question to become irrelevant

Like most deeply-ingrained confusions, the conflation of virtualization and Cloud Computing won’t be dispelled as much as made irrelevant. The four categories enumerated in this post are a point-in-time view of a continuously evolving system. What may start today as a bundle of a hypervisor, an OS and an app server may become a somewhat monolithic “PaaS engine” over time as the components are more tightly integrated. That “engine” may have memory isolation mechanisms that look a lot like a hypervisor. But it may not be able to host a generic OS. In the same way that whales don’t have fingers and toes and yet they are still very much apparent in their skeleton.

[UPDATED 2009/10/8: A real-life example of #3! On-demand servers via bare metal provisioning (via Sam). No hypervisor in the picture. See also here.]

[UPDATED 2009/12/29: Another non-hypervisor Cloud provider! NewServers. Here is their API. And a Q&A.]

3 Comments

Filed under Application Mgmt, Cloud Computing, Everything, Google App Engine, Implementation, IT Systems Mgmt, Middleware, Utility computing, Virtualization, VMware, XenSource

September 2, 2009

VMWare publishes (and submits) vCloud API

VMWare published its vCloud API yesterday (it was previously only available to a few partners) and submitted it to the DMTF, as had been previously announced. So much for my speculations involving IBM.

It may be time to update the Cloud API comparison. After a very quick first pass, vCloud looks quite similar to the Sun Cloud API (that’s a compliment). For example, they both handle long-lived operations via a “202 Accepted” complemented by a resource that represents the progress (“status” for Sun, “task” for vCloud). A very visible (but not critical) difference is the use of JSON (Sun) versus XML (vCloud).

As expected, OVF/OVA is central to vCloud. More once I have read the whole specification.

In any case, things are going to get interesting in the DMTF Cloud incubator. I there a path to adoption?Assuming that Amazon keeps sitting it out, what will the other Cloud vendors with an API (Rackspace, GoGrid, Sun…) do? I doubt they ever had plans/aspirations to own or even drive the standard, but how much are they willing to let VMWare do it? How much does Citrix/Xen want to steer standards versus simply implement them in the context of the Xen Cloud project? What about OGF/OCCI with which the DMTF is supposedly collaborating?How much support is VMWare going to receive from its service provider partners? How much traction does VMWare have with Cisco, HP (server division) and IBM on this? What are the plans at Oracle and Microsoft? Speaking of Microsoft, maybe it will at some point want its standard strategy playbook back. At least when VMWare is done using it.

5 Comments

Filed under API, Application Mgmt, Automation, Cloud Computing, DMTF, Everything, IT Systems Mgmt, Mgmt integration, Protocols, REST, Specs, Standards, Utility computing, Virtualization, VMware

August 26, 2009

Thoughts on VMWare, SpringSource and PaaS

I am late to the party for  commenting on the upstream and downstream acquisitions involving SpringSource. I was away on vacations, but Rod Johnson obviously didn’t have too many holiday plans of his own in August.

First came the acquisition by VMWare. Then the acquisition of Cloud Foundry and the launch of its SpringSource reincarnation.

You’ve all read a lot about this already, so I’ll limit myself to a few bullet-point comments.

  • I was wrong to think at the time of the Hyperic acquisition that SpringSource would focus on app-centric management, BTM and transaction tracing more than Cloud computing and automation.
  • This move by VMWare helps me make some of the points I have been trying to make internally about Cloud computing.
  • This is a step in the progress from “fake machines” to true “virtual machines” (note to self: I may have to stop referring to “fake machines” as “VMWare-style virtual machines”).
  • Savio Rodrigues makes some interesting points, especially on the difference between a framework and a runtime.
  • Many people have hypervisors, a management console and middleware bits. If you are industry-darlings VMWare/SpringSource people seem more willing to assume that you can put them all in a bag, shake it and out comes a PaaS platform than if you are boring old Oracle, Microsoft or IBM. Fine. But let’s see how the (very real) potential gets delivered. Kudos to Adrian Colyer for taking a shot at describing it in a reasonable way, though there is still a fair amount of hand-waving… and already a drift towards the “I don’t need no cluster, I have a hypervisor and everything is a VM” reflex.
  • The “what does it mean for RedHat” angle seems to miss the point to me and be a byproduct of over-focusing on the “open source” aspect which is not all that relevant. This is more about Oracle, Microsoft and IBM than RedHat in my view.
  • Won’t it be fun when Cisco, VMWare and BMC are all one company and little SpringSource calls the shots from within (I have seen this happen more than once during my days at HP Software)?
  • I have no opinion on the question of whether VMWare over-paid or not. I’ll tell you in two years… :-)

Comments Off on Thoughts on VMWare, SpringSource and PaaS

Filed under Application Mgmt, Cloud Computing, Everything, Middleware, Spring, Utility computing, Virtualization, VMware

July 28, 2009

REST in practice for IT and Cloud management (part 2: configuration management)

What benefits does REST provide for configuration management (in traditional data centers and in Clouds)?

Part 1 of the “REST in practice for IT and Cloud management” investigation looked at Cloud APIs from leading IaaS providers. It examined how RESTful they are and what concrete benefits derive from their RESTfulness. In part 2 we will now look at the configuration management domain. Even though it’s less trendy, it is just as useful, if not more, in understanding the practical value of REST for IT management. Plus, as long as Cloud deployments are mainly of the IaaS kind, you are still left with the problem of managing the configuration of everything that runs of top the virtual machines (OS, middleware, DB, applications…). Or, if you are a glass-half-full person, here is another way to look at it: the great thing about IaaS (and host virtualization in general) is that you can choose to keep your existing infrastructure, applications and management tools (including configuration management) largely unchanged.

At first blush, REST is ideally suited to configuration management.

The RESTful Cloud APIs have no problem retrieving resource descriptions, but they seem somewhat hesitant in the way they deal with resource-specific actions. Tim Bray described one of the challenges in his well-considered Slow REST post. And indeed, applying REST to these “do something that may take some time and not result exactly in what was requested” scenarios is a lot less straightforward than when you’re just doing document/data retrieval. In contrast you’d think that applying REST to the task of retrieving configuration data from a CMDB or other configuration store would be a no-brainer. Especially in the IT management world, where we already have explicit resource models and a rich set of relationships defined. Let’s give each resource a URI that responds to HTTP GET requests, let’s turn the associations into hyperlinks in the resource presentation, let’s mint a MIME type to represent this format and we are out of the office in time for a 4:00PM tennis game when all the courts are available (hopefully our tennis partners are as bright as us and can get out early too). This “work smarter not harder” approach would allow us to present this list of benefits in our weekly progress report:

-1- A URI-based scheme makes the protocol independent of the resource topology, unlike today’s data stores that usually struggle to represent relationships between stores.

-2- It is simpler to code against than CIM-over-HTTP or WS-Management. It is cross-platform, unlike WMI or JMX.

-3- It makes it trivial to browse the configuration data from a Web browser (the resources themselves could provide an HTML representation based on content-type negotiation, or a simple transformation could generate it for the Web browser).

-4- You get REST-induced caching and scalability.

In the shower after the tennis game, it becomes apparent that benefit #4 is largely irrelevant for IT management use cases. That the browser in #3 would not be all that useful beyond simple use cases. That #2 is good for karma but developers will demand a library that hides this benefit anyway. And that the boss is going to say that he doesn’t care about #1either because his product is “the single source of truth” so it needs to import from the other configuration store, not reference them.

Even if we ignore the boss (once again) it only  leaves #1 as a practical benefit. Surprise, that’s also the aspect that came out on top of the analysis in part 1 (see “the API doesn’t constrain the design of the URI space” highlight, reinforced by Mark’s excellent comment on the role of hypertext). Clearly, there is something useful for IT management in this “hypermedia” thing. This will largely be the topic of part 3.

There are also quite a few things that this RESTification of the configuration management store doesn’t solve:

-1- The ability to query: “show me all the WebLogic instances that run on a Windows host and don’t have patch xyz applied”. You don’t have much of a CMDB if you can’t answer this. For an analogy, remember (or imagine) a pre-1995 Web with no search engine, where you can only navigate by starting from your browser home page and clicking through static links step by step, or through bookmarks.

-2- The ability to retrieve the configuration change history and to compare configurations across resources (or to a reference configuration).

This is not to say that these two features cannot be built on top of a RESTful IT resource model. Just that they are the real meat of configuration management (rather than a simple resource-by-resource configuration browser) and that your brilliant re-architecture hasn’t really helped in addressing them. Does a RESTful foundation make these features harder to build? Not necessarily, but there are some tricky aspects to take care of:

-1- In hypermedia systems, the links are usually part of the resource representation, not resources of their own. In IT management, relationships/associations can have their own lifecycle and configuration properties.

-2- Be careful that you can really maintain the address of a resource. It’s one thing to make sure that a UUID gets maintained as a resource configuration changes, it’s another to ensure that a dereferenceable URI remains unchanged. For example, the admin server of a cluster may move over time from one node to another.

More fundamentally, the ability to deal with multiple resources at the same time and/or to use the model at different levels of granularity is often a challenge. Either you make your protocol more complex to account for this or your pollute your resource model (with a bunch of arbitrary “groups”, implicit or explicit).

We saw this in the Cloud APIs too. It typically goes something like this: you can address an individual server (called “foo”) by sending requests to http://Cloudprovider.com/server/foo. Drop the “foo” part of the URL and now you can address all the servers, for example to retrieve their configuration or possibly to reboot them. This gives me a way of dealing with multiple resources at time, but only along the lines pre-defined by the API. What if I want to deal only with the servers that host nodes of a given cluster. Sorry, not possible. What if the servers have different hosts in their URIs (remember, “the API doesn’t constrain the design of the URI space”)? Oops.

WS-Management, in the SOAP world, takes this one step further with Selectors, through which you can embed some kind of query, the result of which is what you are addressing in your message. Or, if all you want to do is GET, you can model you entire datacenter as one giant virtual XML doc (a document which is never assembled in practice) and use WSRF/WSDM’s “QueryExpression” or WS-Management’s “FragmentTransfer” to the same effect. BTW, I have issues with the details of how these mechanisms work (and I have described an alternative under the motto “if you are going to suffer with WS-Addressing, at least get some value out of it”).

These are all non-RESTful atrocities to a RESTafarian, but in my mind the Cloud REST API reviewed in part 1 have open Pandora’s box by allowing less-qualified URIs to address all instances of a class. I expect you’ll soon see more precise query parameters in these URIs and they’ll look a lot like WS-Management Selectors (e.g. http://Cloudprovider.com/server?OS=Linux&CPUType=X86). Want to take bets about when a Cloud API URI format with an embedded regex first arrives?

When you need this, my gut feeling is that you are better off not worrying too much about trying to look RESTful. There is no shame to using an RPC pattern in the right circumstances. Don’t be the stupid skier who ends up crashing in a tree because he is just too cool for the using snowplow position.

One of the most common reasons to deal with multiple resources together is to run queries such as the “show me all the WebLogic instances that run on a Windows host and don’t have patch xyz applied” example above. Such a query mechanism recently became a DMTF standard, it’s called CMDBf. It is SOAP-based and doesn’t attempt to have anything to do with REST. Not that it didn’t cross the mind of a bunch of people, lead by Michael Coté when CMDBf first emerged (read the comments too). But as James Governor rightly predicted in the first comment, Coté heard “dick” from us on this (I represented HP in CMDBf and ended up being an editor of the specification, focusing on the “query” part). I don’t remember reading the entry back then but I must have since I have been a long time Coté fan. I must have dismissed the idea so quickly that it didn’t even register with my memory. Well, it’s 2009 now, CMDBf v1 is a DMTF standard and guess what? I, and many other SOAP-the-world-till-it-shines alumni, are looking a lot more seriously into what’s in this REST thing (thus this series of posts for me). BTW in this piece Coté also correctly predicted that CMDBf would be “more about CMDB interoperation than federation” but that didn’t take as much foresight (it was pretty obvious to me from the start).

Frankly I am still not sure that there is much benefit from REST in what CMDBf does, which is mostly a query interface. Yes the CMDBf query and its response go over SOAP. Yes in this case SOAP is mostly a useless wrapper since none of the implementations will likely support any WS-* SOAP header (other than paying the WS-Addressing tax). Sure we could remove it and send plain XML over HTTP. Or replace the SOAP wrapper with an Atom wrapper. Would it be anymore RESTful? Not one bit.

And I don’t see how to make it more RESTful. There are plenty of things in the periphery the query operation that can be made RESTful, along the lines of what I described above. REST could make the discovery/reconciliation tasks of the CMDB more efficient. The CMDBf query result format could be improved so that from the returned elements I can navigate my way among resources by following hyperlinks. But the query operation itself looks fundamentally RPCish to me, just like my interaction with the Google search page is really an RPC call that happens to return a Web page full of hyperlinks. In a way, this query (whether Google or CMDBf) can at best be the transition point from RPC to REST. It can return results that open a world of RESTful requests to you, but the query invocation itself is not RESTful. And that’s OK.

In part 3 (now available), I will try to synthesize the lessons from the Cloud APIs (part 1) and configuration management (this post) and extract specific guidance to get the best of what REST has to offer in future IT management protocols. Just so you can plan ahead, in part 4 I will reform the US health care system and in part 5 I will provide a practical roadmap for global nuclear disarmament. Suggestions for part 6 are accepted.

11 Comments

Filed under API, Application Mgmt, Automation, Cloud Computing, CMDB, CMDB Federation, CMDBf, DMTF, Everything, IT Systems Mgmt, Mashup, Mgmt integration, Modeling, REST, SOAP, SOAP header, Specs, Standards, Utility computing

July 27, 2009

Cloud catalog catalyst or cloud catalog cataclysm?

Like librarians, we IT wonks tend to like things cataloged. To date, the last instance of this has been SOA governance and its various registries and repositories. With UDDI limping along as some kind of organizing standard for the effort. One issue I have with UDDI  is that its technical awkwardness is preventing us from learning from its failure to realize its ambitious goals (“e-business heaven”). It would be too easy to attribute the UDDI disappointment to UDDI. Rather, it should be laid at the feet of unreasonable initial expectations.

The SOA governance saga is still ongoing, now away from the spotlight and mostly from an implementation perspective rather than a standard perspective (by the way, what’s up with GIF?). Instead, the spotlight has turned to Cloud computing and that’s what we are supposedly going to control through cataloging next.

Earlier this year, I commented on the release of an ITSM catalog product for Cloud computing (though I was addressing the convergence of ITSM and Cloud computing more than catalogs per se).

More recently, Lori MacVittie related SOA governance to the need for Cloud catalogs. She makes some good points, but I also see some familiar-looking “irrational exuberance”. The idea of dynamically discovering and invoking a Cloud service reminds me too much of the initial “yellow pages” scenarios for UDDI (which quickly got dropped in favor of a more modest internal governance focus).

I am not convinced by the reason Lori gives for why things are different this time around (“one of the interesting things virtualization brings to the table that SOA did not is the ability to abstract management of services”). She argues that SOA governance only gave you access to the operational WSDL of a Web service, while Cloud catalogs will give you access to their management API. But if your service is an IT service, then your so-called management API (launch/configure/control VMs) is really its operational interface. The real management interface is the one Amazon uses under the cover and they are not going to expose it to you anymore than your bank is going to expose its application server administration console to you (if they do, move your money somewhere else before someone does it for you).

After all, isn’t SOA governance pretty close to a SaaS catalog which is itself a small part of the overall Cloud (IaaS+PaaS+SaaS) catalog question? If we still haven’t succeeded in the smaller scope, what are the odds of striking gold quickly in the larger effort?

Some analysts take a more pragmatic view, involving active brokers rather than simply a new DNS record type. I am doubtful about these brokers (0.2 probability, as Gartner would put it) but at least this moves the question onto business terms (leverage, control) rather than technical terms. Which is where the battle will be fought.

When it comes to Cloud catalogs, I think they are needed (if only for the categorization of Cloud services that they require) but will only play a supporting role, if any, in any move towards dynamic Cloud provisioning. As with SOA governance it’s as an internal tool, supported by strong processes, that they will be most useful.

Throughout human history, catalogs have been substitutes for control more often than instruments of control. Think of astronomy, zoology and… nephology for example. What kind will IT Cloud catalogs be?

2 Comments

Filed under Application Mgmt, Automation, Business, Cloud Computing, Everything, Governance, Manageability, Mgmt integration, Portability, Specs, Utility computing

July 24, 2009

A small step for SCA, a giant leap for BSM

In a very short post, Khanderao Kand describes how configuration properties for BPEL processes in Oracle SOA Suite 11G are attached to SCA components. Here is the example he provides:

<component name="myBPELServiecComponent">
  ...
  <property name="bpel.config.inMemoryOptimization">true</property>
</component>

It doesn’t look like much. But it’s an major step for application-driven IT management (and eventually BSM).

Take a SCA component. Follow the SCA-defined component-to-composite and service-to-reference relationships upwards and eventually you’ll get to top level application services that have a decent chance of mapping well to business-relevant activities (e.g. order processing). Which means that the metrics of these services (e.g. availability, response time) are likely to be meaningful and important to the line of business. Follow the same SCA relationships downward and you’ll end up (in a SCA-based infrastructure like Oracle SOA Suite 11G), with target components that are meaningful to the IT administrator. Which means that their metrics and configuration settings (like “inMemoryOptimization”) are tracked and controlled by IT. You now have a direct string of connections between this configuration setting and a business relevant metric. You can navigate the connection in both directions: downward/reactive (“my service just went down, what changed in the infrastructure”) versus upward/proactive (“my service is always slow, what can I do to optimize the execution”).

Of course these examples are over-simplistic (and the title of this post is a bit too lyrical, on account of this). Following these SCA relationships in brute-force fashion will yield tens of thousands of low-level configuration settings for any top-level service, with widely differing importance and impact (not to mention that they interact). You need rules to make sense of this. Plus, configuration-based models are a complement to runtime transaction discovery, not a replacement (unless your model of the application includes every single line of code). But it’s not that often that you can see a missing link snap into place that clearly.

What this shows is the emergence of a common set of entities between the developer’s model and the IT admin model. And if the application was developed correctly, some of the entities in the developer’s model correspond to entities in the mental model of the application user and the line of business manager. SCA is the skeleton for this. Attaching configuration to SCA components puts muscle on the bone.

The road to BSM is paved with small improvements in the semantic alignment between IT infrastructure and application services. A couple of years ago, I tried to explain why SCA is very relevant for IT management. Now we can see it.

4 Comments

Filed under Application Mgmt, BPEL, BSM, Business, Business Process, Everything, IT Systems Mgmt, Mgmt integration, Middleware, Modeling, Oracle, SCA, Standards

June 12, 2009

With M (Oslo), is Microsoft on the path to reinventing RDF?

I have given up, at least for now, on understanding what Microsoft wants Oslo (and more specifically the “M” part) to be. I used to pull my hair reading inconsistent articles and interviews about what M tries to be (graphical programming! DSL! IT models! generic parser! application components! workflow! SOA framework! generic data layer! SQL/T-SQL for dummies! JSON replacement! all of the above!). Douglas Purdy makes a valiant 4-part effort (1, 2, 3, 4) but it’s still not crisp enough for my small brain. Even David Chapell, explainer extraordinaire, seems to throw up his hands (“a modeling platform that can be applied in lots of different ways”, which BTW is the most exact, if vague, description I’ve heard). Rather than articles, I now mainly look at the base specifications and technical documents that show what it actually is. That’s what I did  when the Oslo SDK first came out last year. A new technical document came out recently, an update to the MGraph Object Model so I took another a look.

And it turns out that MGraph is… RDF. Or rather, “RDF minus entailment”. And with turtle as the base representation rather than an add-on.

Look at section 3 (“RDF concepts”) in this table of content from W3C. It describes the core RDF concepts. Keep the first five concepts (sections 3.1 to 3.5) and drop the last one (“3.6: Entailment”). You have MGraph, a graph-oriented object model.

On top of this, the RDF community adds reasoning capabilities with RDF entailment, RDFS, OWL, SWRL, SPIN, etc and a variety of engines that implement these different levels of reasoning.

Microsoft, on the other hand, seems to ignore that direction. Instead, it focuses on creating a good mapping from this graph object model to programming languages. In two directions:

  • from programming languages to the graph model: they make it easy for you to create a domain-specific language (DSL) that can easily be turned into M instances.
  • from the graph model to programming languages: they make it easy for you to work on these M instances (including storing them) using the .NET technology stack.

So, if Microsoft is indeed reinventing RDF as the title of this entry provocatively suggests, then they are taking an interesting detour on the way. Rather than going straight to “model-based inferencing”, they are first focusing on mapping the core MGraph concepts to programming (by regular developers) and user interactions (with regular users). Something that for a long time had not gotten much attention in the RDF world beyond pointing developers to Jena (though it seemed to have improved over the last few years with companies like TopQuadrant; ironically, the Oslo model browser/editor is code-named “Quadrant”).

Whether the Oslo team sees the inferencing fun as a later addition or something that’s not needed is another question, on which I don’t see any hint at this point.

I hope they eventually get to it. But I like the fact that they cleanly separate the ability to represent and manipulate the graph model from the question of whether instances can be inferred. We could use such a reusable graph representation mechanism. Did CMDBf, for example, really have to create a new graph-oriented metamodel and query language? I failed to convince the group to adopt RDF/SPARQL, but I may have been more successful if there had been a cleanly-separated “static” version of RDF/SPARQL, a way to represent and query a graph independently of whether the edges and nodes in the graph (and their types) are declared or inferred. Instead, the RDF stack has entailment deeply embedded and that’s very scary to many.

But as much as I like this separation, I can’t help squirming when I see the first example in the MGraph document:

// Populate a small village with some people
Villagers => {
  Jenn => Person { Name => 'Jennifer', Age => 28, Spouse => Rich },
  Rich => Person { Name => 'Richard', Age => 26, Spouse => Jenn },
  Charly => Person { Name => 'Charlotte', Age => 12 }
},
HaveSpouses => { Villagers.Rich, Villagers.Jenn }

That last line is an eyesore to anyone who has been anywhere near RDF. I have just declared that Rich and Jenn are one another’s spouse, why do I have to add a line that says that they have spouses? What I want is to say that participation in a “Spouse” relationship entails membership in the “hasSpouse” class. And BTW, I also want to mark the “Spouse” relationship as symmetric so I only have to declare it one way and the inverse can be inferred.

So maybe I don’t really know what I want on this. I want the graph model to be separated from the inference logic and yet I want the syntactic simplicity that derives from base entailments like the example above. Is June too early to start a Christmas wish list?

While I am at it, can we please stop putting people’s ages in the model rather than their dates of birth? I know it’s just an example, but I see it over and over in so many modeling examples. And it’s so wrong in 99% of cases. It just hurts.

There are other things about MGraph edges that look strange if you are used to RDF. For example, edges can be labeled or not, as illustrated on this first example of the graph model:

In this example, “Age” is a labeled edge that points to the atomic node “42”, while the credit score is modeled as a non-atomic node linked from the person via an unlabeled edge. Presumably the “credit score” node is also linked to an atomic node (not shown) that contains the actual score value (e.g. “800”). I can see why one would want to call out the credit score as a node rather than having an edge (labeled “credit score”) that goes to an atomic node containing the actual credit score value (similar to how “age” is handled). For one thing, you may want to attach additional data to that “credit score” node (when was it calculated, which reporting agency provided it, etc) so it helps to have it be a node. But making this edge unlabeled worries me. Originally you may only think of one possible relationship type between a person and a credit score (the person has a credit score). But other may pop up further down the road, e.g. the person could be a loan agent who orders the credit score but the score is about a customer. So now you create a new edge label (“orders”) to link the loan agent person to the credit score. But what happens to all the code that was written previously and navigates the relationship from the person to the score with the expectation that the score is about the person. Do you think that code was careful to only navigate “unlabeled” edges? Unlikely. Most likely it just grabbed whatever credit score was linked to the person. If that code is applied to a person who happens to also be a loan agent, it might well grab a credit score about other people which happened to be ordered by the loan agent. These unlabeled edges remind me of the practice of not bothering with a “version” field in the first version of your work because, hey, there is only one version so far.

The restriction that a node can have at most one edge with a given label coming out of it is another one that puzzles me. Though it may explain why an unlabeled edge is used for the credit score (since you can get several credit scores for the same person, if you ask different rating agencies). But if unlabeled edges are just a way to free yourself from this restriction then it would be better to remove the restriction rather than work around it. Let’s take the “Spouse” label as an example. For one thing in some countries/cultures having more than one such edge might be possible. And having several ex-spouses is possible in many places. Why would the “ex-spouse” relationship have to be defined differently from “spouse”? What about children? How is this modeled? Would we be forced to have a chain of edges from parent to 1st child to next sibling to next sibling, etc? Good luck dealing with half-siblings. And my model may not care so much about capturing the order (especially if the date of birth is already captured anyway). This reminds me of how most XML document formats force element order in places where it is not semantically meaningful, just because of XSD’s bias towards “sequence”.

Having started this entry by declaring that I don’t understand what M tries to be, I really shouldn’t be criticizing its design choices. The “weird” aspects I point out are only weird in the context of a certain usage but they may make perfect sense in the usage that the Oslo team has in mind. So I’ll stop here. The bottom line is that there are traces, in M, of a nice, reusable, graph-oriented data model with strong bridges (in both directions) to programming languages and user interfaces. That is appealing to me. There are also some strange restrictions that puzzle me. We’ll see where this goes (hopefully this article, “Designing Domains and Models Using M” will soon contain more than “to be submitted” and I can better understand the M approach). In any case, kuddos to the team for being so open about their work and the evolution of their design.

8 Comments

Filed under Application Mgmt, Articles, Everything, Graph query, Mgmt integration, Microsoft, Modeling, RDF, Semantic tech