About a year ago I was asked by a client to update their existing web service because of some changes in the way they wanted to process their sales data. Luckily this client has always understood the importance of a Service-Oriented Architecture ( SOA ) since they deal with large amounts of resellers who need to access, edit and create data. All I had to do was apply the changes to their web service.

He lists the steps he followed when making the update - thinking about backwards compatibility, evaluating current functionality for use and possibly decommissioning older pieces.

One of these situations occurs when you suddenly that find you don't have access to data you want, or you can't pass back (or forward) data as part of the common flow of your application. [...] The solution was to create a singleton class which uses references to bind a name to a already defined variable.

In his example, he illustrates (and explains) how to use a class he developed (varmap) to handle the assignment/removal/etc of the data to the common Singleton object.