Invocation Flow Lines: Patterns of Invocation and Message Processing in Object Remoting Middleware

Object remoting middleware greatly facilitates creating distributed, object-oriented systems. However, developers face many situations in which a middleware’s invocation and message processing architecture fails to fully support all their requirements. This problem is caused, for instance, by limitations in realising certain invocation styles (e.g., one-way and two-way conversations) on top of a shared processing infrastructure, in adding extensions to invocation handling (i.e., add-on services such as security and inspection), and in bypassing selected steps in the invocation handling to balance resource consumption and invocation performance. Often, these limitations are caused by design and implementation decisions taken early when crafting the middleware framework. To better explain the needed decision making, and help developers to apply adaptations or guide the selection of alternatives, we present a pattern language that captures the essentials of invocation and message processing in object remoting middleware. We also outline instantiations of the patterns and their relationships in existing middleware frameworks.