IT Transformation with SOA

A number of new needs have emerged with the advent of SOA. First of all, there was no standard way for an application to construct and deliver a service call.  Secondly, there was no standard way to ensure the service would be delivered.  Thirdly, it was not clear how this SOA environment could be managed and operated effectively. Fourthly . . .  well, you get the idea; the list goes on and on.

SOA demands the existence of an enabling infrastructure layer known as middleware. Middleware provides all necessary services, independent of the underlying technical infrastructure.  To satisfy this need, vendors began to define SOA architectures around a relatively abstract concept: the Enterprise Service Bus, or ESB.   Now, there has never been disagreement about the need to have a foundational layer to support common SOA functions—an enterprise bus of sorts. The problem is that each vendor took it upon himself to define the specific capabilities and mechanisms of their proprietary ESB, oftentimes by repackaging preexisting products and rebranding them to better fit their sales strategies.

As a result, depending on the vendor, the concept of Enterprise Service Bus encompasses an amalgamation of integration and transformation technologies that enable the cooperative work of any number of environments: Service Location, Service Invocation, Service Routing, Security, Mapping, Asynchronous and Event Driven Messaging, Service Orchestration, Testing Tools, Pattern Libraries, Monitoring and Management, etc. Unfortunately, when viewed as an all-or-nothing proposition, ESB’s broad and fuzzy scope tends to make vendor offerings somewhat complex and potentially expensive.

The term ESB is now so generic and undefined that you should be careful not to get entrapped into buying a cornucopia of vendor products that are not going to be needed for your specific SOA environment.  ESBs resemble more a Swiss army knife, with its many accessories, of which only a few will ever be used. Don’t be deceived; vendors will naturally try to sell you the complete superhighway, including rest stops, gas stations and the paint for the road signs, when all you really need is a quaint country road. You can be choosy and build your base SOA foundation gradually.  Because of this, I am willfully avoiding use of the term “Enterprise Service Bus”, preferring instead to use the more neutral term, “SOA Fabric.”

Of all the bells and whistles provided by ESB vendors (data transformation, dynamic service location, etc.), the one key function the SOA Fabric should deliver is ensuring that the services and service delivery mechanisms are abstracted from the SOA clients.

A salient feature that vendors tell us ESBs are good for is their ability to integrate heterogeneous environments. However, if you think about it, since you are going through the process of transforming the technology in your company (the topic of this writings after all!), you should really strive to introduce a standard protocol and eliminate as many of legacy protocols as you can.

Ironically, a holistic transformation program should have the goal of deploying the most homogeneous SOA environment possible; thus obviating the need for most of the much touted ESB’s transformation and mapping functions. In a new system, SOA can be based upon canonical formats and common protocols; thus minimizing the need for data and service format conversion. This goal is most feasible when applied to the message flows occurring in you internal ecosystem.

Now, you may still need some of those conversion functions for several other reasons, migration and integration with external systems being the most obvious cases. If the migration will be gradual, and therefore requires the interplay of new services with legacy services, go ahead and enable some of the protocol conversion features provided by ESBs. The question would then be how important this feature is to you, and whether you wouldn’t be better off following a non-ESB integration mechanism in the interim.  At least, knowing you will be using this particular ESB function only for migration purposes, you can try to negotiate a more generous license with the vendor.

There are cases whereby, while striving for a homogeneous SOA environment, you may well conclude that your end state architecture must integrate a number of systems under a  federated view. Your end state architecture in this case will be a mix of hybrid technologies servicing autonomous problem domains. Under this scenario, it would be best to reframe the definition of the problem at hand from one of creating an SOA environment to one of applying Enterprise Application Integration (EAI) mechanisms. If your end state revolves more around integration EAI, it would be better suited to performing boundary-level mapping and transformation work.  In this case, go and shop for a great EAI solution; not for an ESB.

If the vendor gives you the option of acquiring specific subsets of their ESB offering (at a reduced price) then that’s something worth considering. At the very least, you will need to provide support for service deployment, routing, monitoring, and management, even if you won’t require many of the other functions in the ESB package. Just remember to focus in deploying the fabric that properly matches your SOA objectives and not the one that matches your vendor’s sales quota.

A quick word regarding Open Source ESBs. . . There are many, but the same caveats I’ve used for vendor-based ESB’s apply. Open Source ESBs are not yet as mature, and the quality of functions they provide varies significantly according to the component. Focus on using only those components you can be sure will work in a reliable and stable manner or those which are not critical to the system. Remember you are putting in place components that will become part of the core fabric. Ask yourself, does it make sense in order to save a few dollars to use a relatively unsupported ESB component for a critical role (Service Invocation or Messaging, come to mind), versus using a more stable vendor solution?

In the end, if you are planning to use the protocol conversion features packaged in a vendor-provided or open source ESBs, I suggest you use them in a discrete, case-by-case basis, and not as an inherent component of your SOA fabric. This way, even as you face having to solve integration problems associated with the lack of standards, at least you won’t be forced into drinking the Kool-Aid associated with a particular vendor’s view of ESB!

Early Ford Model Ts were the most successful automobile for a good portion of the twentieth century. Millions of Model Ts roamed the roads of America, and if you had opened the hood of one of them, you would have found a very basic machine design consisting of an engine, a magneto (similar to an alternator) and perhaps a battery.

In contrast, when looking under the hood of a modern car, it’s easy to be bewildered by its complexity.  With their fuel-injection systems, anti-lock brakes, intelligent steering systems, safety mechanism, and many other features, a modern car can better be described as a computerized mobility machine. About the only thing Model Ts have in common with modern cars is the fact that they both move.

Trying to explain the workings of a new a vehicle in terms of 1920’s terminology is almost impossible. Such an explanation requires the use of a new language. The same is true for SOA. The traditional computing paradigm of centralized mainframe-based processing represents the Model T of computing, and designing and explaining SOA, even if only to represent another computer environment, requires a new language.

This new language would have more in common with, say, the language used to describe a Broadway play or the workings of  interacting organisms in biology than with the language used to describe the original computing paradigms (a “computer”, after all, was a term originally used for the female staff in charge of manually performing census calculations). In this new language you have actors playing the roles of specific services, a script to define the storyline and the orchestrators to execute it.  SOA is a play; not a monologue.

Still, regardless of the internal workings, a new car still requires the existence of a command console, an engine, and wheels and chassis.  SOA can be defined by the Presentation, Processing, and Data Layers. The Presentation occurs in the Access space, and the interface could be viewed as a “membrane” enclosing the system. The Processing layer provides the orchestration of services and the Data represents the stuff that makes it all worthwhile.

Remember, the SOA meshed diagram I showed you earlier?

The diagram gives a somewhat chaotic and anarchic representation of the manner in which a truly distributed service oriented environment operates. It behooves us to impose some order and structure so that the actual SOA system is something we can implement and operate appropriately.  I refer to this structure as “The Framework”; the following are its elements:

In the future everything will be virtual, an abstraction. Enabling this capability is the role of the SOA Framework. Next I will describe in detail each of the previous SOA Framework elements.