Understanding MS enterprise integration technologies

ESB, or Enterprise Service Bus, is a concept that's been around for a while. Borrowed from the concept of a computer hardware I/O bus, the purpose of ESB is to facilitate communication between the various software applications -- internal and external -- that comprise an enterprise system.

ESB was traditionally designed as MOM, or Message Oriented Middleware, and implemented with message queuing technologies. This is giving way, however, to a service-based design.

Over the years MS has provided a variety of technologies for moving data around the enterprise, with BizTalk most closely resembling an ESB. Other complementary and overlapping technologies have emerged from MS, however, indicating they are not taking a 'one size fits all' approach to ESB:

• WCF: At the core of these technologies is WCF, or Windows Communication Foundation. WCF supports the development of communication-unaware interfaces and business-logic implementation classes which can then be 'placed' into a WCF host and accessed across networks mostly as if they were local objects.
• BizTalk: BizTalk is the MS technology that most resembles a traditional ESB. One of the features that made BizTalk somewhat unique is its ability to design and 'run' orchestrations, or flow charts of processing and communication steps. With its use of WCF and resemblance to WF Services, it's less clear than in years past what unique value it has to offer.
• WF Services: WF, or Windows Workflow, supports both graphical design of program logic and an engine to run the logic. With the addition of two particular, built-in Workflow Activities, Receive and Send, WF can now graphically create and run WCF services and control the flow of their operations, known as WF Services.
• AppFabric: Used to provide caching, monitoring, and control of WCF Services, including WF Services.
• Azure Service Bus: Used to provide cloud-based WCF Service communication routing between organizations behind network firewalls.
• LOB Adapters: MS also provides pre-built LOB, or Line of Business, Adapters to a variety of third party applications as well as an SDK, or Software Development Kit, for creating them. LOB Adapters expose line of business application capabilities as WCF Services so they can integrate with other applications across enterprise networks using MS technologies.

Instead of writing complex communication protocol code, with WCF it is possible to focus almost exclusively on developing business logic, thereby minimizing the need for a specialized ESB solution.That may be the strategy: make the communication technology full-featured then provide technologies to extend it when necessary instead of confining organizations to a single bus and its way of doing things.