Adapters -- who needs them? Who wants them? The goal of SOA is to simplify, simplify, simplify. However, SOA can also work the other way, and actually introduce a new layer of complexity to systems already choking on complexity. How can you ensure that your service-oriented architecture makes things simpler, and not evolve into a spaghetti-oriented architecture?
George Scott, CTO of Cast Iron Systems, proposes one approach -- integration appliances. In a new post at ebizQ, Scott explains how appliances can force complexity out of the service layer, "integration appliances allow more resource to be applied at the business layer where the ultimate payback for the company lives."
What does Scott mean by "appliances"? Typically, these are preformatted bundles of hardware and firmware that reside on networks, and can be placed wherever they are needed and easily managed and upgraded.
By its very nature, SOA is all about transparency and opposed to the deployment of "black box" solutions within the infrastructure. However, the new generation of integration appliances have their own transparency, are built entirely on standards, and may alleviate much of the performance strain services will put on servers and storage systems.
Integration appliances are the most logical solution for data integration, Scott said, as "they are often the best way to integrate various directory services and can be used to construct the services exposed to the workflow/BPM layer." The three best places to introduce appliances into SOA include the following:
As an alternative to adapters in data integration projects. "By avoiding the complexity of manual process integration, appliances can also avoid the bane of every integration project: Adapters. Adapters are hard to maintain, hard to upgrade, expensive and, by definition, every type of adapter is a thing unto itself. With recent improvements in standards, they are usually unnecessary. In simple cases, direct data integration suffices. In more complex cases, the service can often be built directly on the target applications. Solutions that use adapters don’t scale."
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Directory services. "Directories for entitlements, service discovery, etc., need to present their information in a single format through a unified interface. Though simple in theory, this is almost never the way real corporate directories look and act. This is really a data integration problem in disguise. As such, an appliance can be a very good solution for normalizing directory access."
Service presentation. "A properly designed data integration appliance is not suitable for manual workflow, but is capable of holding and representing enough state (via BPEL, for instance) to serve as an intermediary between applications and the workflow/BPM layer. Since the most common place from which to access a directory is the service layer, it is possible to build a uniform and easily managed infrastructure that abstracts all but the services themselves away from the developer of business process."
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