Paths to SOA
Earlier this month, analysts and speakers at Forrester's GigaWorld conference offered some leading thinking on opportunities ahead in the world of SOA. Forrester analyst Randy Heffner made the case that "business drives architecture" in this new era and "you need vision to guide the evolution of SOA." He also argued that SOA creates opportunities for "pluggable business," pointing to Starbucks' use of the Microsoft MapPoint Web service as a store locator.
However, Heffner's most significant recent contribution to SOA thinking lies in his paper, "Your Paths to Service-Oriented Architecture." In the report, he states, "There are multiple paths to SOA, each with its own characteristics and architectural priorities."
He cites six major paths to SOA:
Simple Internal Integration. The goal here is to achieve "greater efficiency and effectiveness by tying together internal applications, including custom and packaged applications...Most of the simple integration SOA platform is provided by your existing platform vendor [BEA, IBM, Microsoft, Oracle, SAP and Sun Microsystems], making Web services cheap and relatively easy to justify."
Infrastructure Services. This is an "IT-centric" way of reducing application delivery costs by "consolidating technical and utility functions behind service interfaces...IT can gain notable benefit from technical services like authentication, authorization, and data access...The business justification is built around cost savings via infrastructure unification, such as reusing a single user directory across multiple applications or cost savings via faster application delivery...But, because the business sees no direct benefit, IT will likely have to fund infrastructure services internally."
Rich Internal Integration. Similar to simple integration in objectives and business justification, the key difference here is a matter of additional complexity and and additional capabilties (such as rich messaging infrastructure and service repositories). The core idea: "What a mess of tangled applications...Service interfaces will help us interconnect them, but there are too many different types of interdependencies and too much overlapping and disconnected functionality for us to just throw a SOAP stack at the problem." Real benefits of this approach include reduced error rates and improved management control (based on a unified view of business operations).
Multi-Channel Applications. Recognizing that the underlying application capabilities for multi-channel applications (covering Web, phone, branch, call center, kiosk) must allow reuse or the result will be massive duplication and expense, this is a no-brainer for some companies. "In many ways, the multi-channel application path is the easiest to justify, since the scenarios for reuse are built in: If thet same services need to be accessible through multiple channels, you will either have to build them once or build them once for each channel." Standard Life and Allstate are two companies that embraced SOA for this reason.
External Partner Integration. FOrrester contends that security is a key driver on this path as well as protocol translation and semantic adaptation. Most companies base justification for external integration "on the value of the business partner relationships it enables...In other words, it is simply the basic cost of doing business electronically."
Core Business Flexibility. This is a path that revolves around long term benefits (see next post) and focuses on leveraging SOA in the transformation of the business overall. It also requires the "deepest transformation of application architecture and design."
As Forrester sees it, "The big strategic impact of of service orientation will come in a long series of smaller increments...[E]valuate your near-term SOA platform investments in terms of their ability to fit into a future SOA platform that supports multiple SOA patterns."