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Steve Jones is the editor of SQLServerCentral.com and visits a wide variety of data related topics in his daily editorial. Steve has spent years working as a DBA and general purpose Windows administrator, primarily working with SQL Server since it was ported from Sybase in 1990. You can follow Steve on Twitter at twitter.com/way0utwest

TechED - Building an SOA Data Center

Talking about heterogenous systems, usually legacy systems. How do you move to a new architecture?

You must start with the old systems, often you cannot throw it away and need to mitigate the risks of migration to newer systems. One way of doing this is to rip out the presentation layer/logic and move that out as a web service. Now you can modernize the top layer. The underlying layers are still legacy. In this example, an X-Windows on Solaris system, moving to a Microsoft platform. However with webservices, modern types of applications can be built on top of the legacy systems.

There is a perception that the overhead of web services, SSL, etc., will cause problems. This shouldn't be the case

Digging into more systems, often securiy becomes an issue. Certificates can work, but many companies already have a security infrastructure in place with desktops and Kerberos you don't want to duplicate. A header was added to the web service communication to contain a Kerberos token.

The evolution in moving a legacy system, one approach is to slowly rip out some logic and replace with an SOA piece of logic. So the legacy system was a consumer of a web service not a provider. This allows piecemeal for replacement of the application. Eventually most of the application is replaced and you are in an SOA architecture.

It appears that they've found ways to build quick systems, despite the overhead of XML on your data, even with mainframe and other legacy systems. Original and many early web services are poorly implemented and insecure. More modern WS are better written. No real details here, but it's an architecture talk. It does give some hope that SOA and web services make sense and they're can perform well and be secure. I'd like to see good examples of this. Probably need to look out on MSDN for stuff.

One security concern with insecure web services. In an example they used the KErberos token in the header to go out to AD and authenticate the user. The tokens only live for a short time (30s or less) so this worked.

Lots of WSxx acronyms, new standards and performance guarentees for metrics thrown out. So there is some maturity taking place here with web services.

One issue that occurs with legacy systems is often the newer developres don't necessarily know the older technologies and interfaces (CORBA, J2EE, etc). Two skill sets are needed, so be sure that you have development resources in all areas, even if it's double staff. 

OK, it's getting lss interesting. Moving on. 

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