title: ServiceProxy for current Service
body: <p>I am trying to figure out how to generate a <code>ServiceProxy</code> that points to the service that I'm currently executing within. I have a need to convey information about it, so that another service can call back into this specific instance: since it's stateful.</p>
  
  <p><code>ServiceProxy</code> seems to do resolution by partition keys. However, I don't see how I can obtain a partition key for the currently executing service. I can obtain the partition Guid. But, ServiceProxy cannot be used with that.</p>
  
  <p>Example use case: I have a <code>StatefulService</code> which invokes an external HTTP API. It posts a message to this API, which results in the API calling back into my infrastructure after some period. The HTTP endpoint that I have built needs to resolve the original <code>StatefulService</code> in order to route the response back to it.</p>