A covenant is an if-then-else way of versioning approach. This can be done using multiple strategies which we saw earlier. In any strategy, the covenant approach looks for some ifs, and depending upon the outcome of the condition a suitable then clause will be executed. It can also have an else or a default clause. Hence this approach is usually combined with a versioning flag and this flag can be either in the form of a version parameter or in the form of a version sensitive value in the targetNamespace. This is shown in the following figure:

A covenant is usually exposed in a Single Endpoint Address. Hence, all Consumers will send messages to the same address. Depending upon which version of the service contract the Consumer is using a suitable version flag will be passed either as a version parameter or through...