Exchange 12 APIs Hold Promise and Pain

At the recent Professional Developer’s Conference in Los Angeles, Microsoft detailed its API (Application Programming Interface) strategy for the upcoming Exchange 12. While Microsoft announced many of the features that Exchange 12 would bring, this was the first information to appear about how developers will build applications against the new version. This is critical, because there are many Exchange applications on the market, from system management tools to end user productivity applications. In addition, organizations have written their own in-house, custom solutions. Developers need time to change existing applications, or build new ones that target Exchange 12.

For most developers, the message was good. Most of the existing commonly-used Exchange interfaces, such as Collaboration Data Objects (CDO) or WebDAV, will still be supported, even though they are being de-emphasized. This provides developers time to plan their API migration strategy. There are some interfaces, such as Exchange’s WMI classes or and CDO for Exchange Management, that are being cut altogether, but few applications were written to these interfaces. Any application that was written using these interfaces will have to be revised, since it will not function against Exchange 12.

Microsoft is replacing the de-emphasized and obsolete programming interfaces with a new set based primarily on Web Services, scriptable interfaces called Cmdlets, and the Windows Workflow Foundation. The developers  we interviewed at the PDC are excited about the new interfaces. They open up a larger part of Exchange’s services to developers, making it easier to build more powerful applications. They also are designed to solve many of the problems faced by developers in the past, such as the need to use different programming interfaces to build remote applications vs. intranet applications.

Developers will likely take advantage of the new interfaces quickly because they need to support versions of Exchange as they become available. But they’ll be faced with maintaining two code bases for some time, since existing versions of Exchange will be around for many years, just as we’ve seen with Exchange 5.5. Microsoft hasn’t yet made available beta versions of Exchange to a broad developer community, but no time is too soon, since the development environment will be changing so remarkably.

... Chris Williams

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