SOA, ESBs, and Legacy Integration
“Get on the bus!”
I wanted to follow-up on my post about legacy migration from Nov. 30th to comment on some blog posts about ESBs (Enterprise Service Bus) and SOA (Service Oriented Architecture).
For a definition of SOA, I saw a great one on a recent post “SOA Essentials, Part 1,” by Jeff Davis,
“A Service Oriented Architecture, or SOA, represents an approach towards software development that emphasizes the creation of reusable software services that are based upon discrete units of business functionality.”
In other words, certain functions from applications like a CRM or ERP application are “componentized,” and can be put together to make distinct services that serve a particular function such as “create account,” and these services can then be put together to form an “orchestrated business process.” These new business processes are essentially composite applications that can be created on-the-fly with the new web services technology available today.
An ESB is supposed to the be messaging layer in a SOA environment. Messages from different applications are communicated, using WSDL and SOAP protocols, and transported in the ESB, or service bus. However, Blogger Loraine Lawson from IT Business Edge, today references an article by fellow blogger Robin Bloor which essentially expands the mission of an ESB from that of being a SOA-enabler to being an “integration-on-demand” enabler.
ESBs, according to Bloor, after interviewing executives at ESB provider CapeClear Software, “…actually herald from the Enterprise Application Integration days. So, he contends, it’s really more than “just” a messaging software for SOA – it’s an integration engine or mediation engine…”
That still does not address the issue of making the functionality from legacy applications available as a service in a SOA environment. ESB vendors essentially need other integration software, such as Pervasive’s Data Integrator, to provide the “on-ramp to the bus,” or “last-mile connectivity,” on to the ESB. Our experience at Pervasive, with ESB provider Sonic Software, has been that older versions of ERP, accounting or CRM packages, or home-grown applications, don’t have web services APIs. They need a tool that can connect natively to these applications or to the underlying databases and expose their data or functionality as a service first, before they can actually connect to the ESB.
So in the beautiful brave new world of web services and SOA, where every application uses XML and can communicate with every other application out there, legacy applications do not fit into this perfect picture. However, it will rear it’s ugly head again and again, and as in my previous post, the majority of data in companies out there is still locked away in legacy applications.
Add New Comment
Viewing 3 Comments
Thanks. Your comment is awaiting approval by a moderator.
Do you already have an account? Log in and claim this comment.
Do you already have an account? Log in and claim this comment.
Do you already have an account? Log in and claim this comment.
Do you already have an account? Log in and claim this comment.
Add New Comment
Trackbacks
(Trackback URL)