Enterprise SOA

What are ESA's practical implementation issues?

The first step, which Microsoft, IBM, and many others have already taken, is to begin transforming monolithic applications into web services. SAP has gone a step further, seeking instead to create less granular, more sophisticated enterprise services designed to support the business processes and scenarios present in any given company. To that end, SAP has created a preview system with more than 500 defined and published enterprise services. (For a more complete description of SAP's enterprise services, see Chapter 8.)

It then falls to you to think long and hard about the makeup of your current IT landscape. We're back to core/context again. Which scenarios, applications, servers, and so on support core processes, and which ones support context? Which of those supporting services can you buy from vendors? Which are commoditized productivity tools, and which are truly differentiating the company—the processes that can't be bought? All of the services underlying these will be added to the Enterprise Services Repository, a dictionary of services created in the context of business maps, scenarios, processes, and process steps and illustrated in Figure 2-6. Only after you've begun abstracting the functionality from the hard-wired applications are you able to see how a once-ingenious integration solution could just as easily be replaced with an out-of-the-box scenario from SAP or one of a hundred Independent Software Vendors (ISVs). The following ...