One of the most commonly touted features of commercial Enterprise Service Bus products (ESB’s) is the out-of-box adapters for other COTS products (eg. SAP, PeopleSoft, Siebel). But organizations who become dependent on these adapters and take a “use ‘em if you’ve got ‘em” approach inevitably find that the implementations are a lot more complex than advertised. This is because the decision on whether or not to use adapters should be driven by the alignment of the organization’s skillsets and support structure, not the perceived simplicity in using out-of-box components.
I’ve created a simple decision tree to help clients determine whether they’re better off using the adapters provided by their ESB vendor or whether they should consider some alternative method of integrating with the ESB:
- Is the integrating system a data component with no business logic layer and with no built-in ability to be exposed as a web service (eg. Database, LDAP, MQueue)?
Yes – Use the provided adapters. There’s no point adding an additional layer of complexity when simple data integration is very mature among all the leading ESB products. Also ask yourself if you’re doing data mappings and translations within the adapters? Whether there will be a DBA on the ESB support team or not. ESB’s are excellent at handling simple data translations (ie. Field-to-field). Any complex data translations such as multi-table selects and data merges should be handled in the data tier where you have DBA teams who are equipped to manage them.
No – Go to question 2.
- Does the integrating system have the built-in ability to generate a web service or ESB-compatible API?
Yes – Go to question 3.
No – Use the provided adapters. The whole point of SOA is to leverage existing assets as much as possible and to avoid building new custom code for integration. Putting in a custom coded service layer between the ESB and the target defeats the objective.
- Will the support team for the integrating system be cross-trained on configuring the ESB adapters?
Yes – Use the provided adapters. The support team of the integrating system will ensure that the adapters and reconfigured as necessary based on any changes in the application in question.
No – Expose web services and/or API’s on the integrating system. The support team for that system are the experts on that application. They know the data model and the implications of seemingly inconsequential details on the business logic in the backend. I’ve seen many an adapter implementation go off the rails because the team implementing the ESB simply are not experts on every system they’re connecting to. Let the team with the expertise manage the abstraction and register their endpoint on the ESB so you can still take advantage of features like version management and BAM.
Next time you’re opening the box to your shiny new ESB, resist the urge to take all the adapters out and deploy them everywhere possible. Ask yourself in the long run, who’s going to own the integration point? And whether their lives will be made easier with the adapter or without? An IT landscape that is well supported is much more important than an IT landscape that matches exactly to the vendor’s product sheet.