First milestone is to have things working over GRPC

Workflow spec services that can be deployed over GRPC, thereby running in separate processes. Manually start the processes and submit a workload on the same machine.

Plugins required:

• Workflow Spec Services Plugin
• Golang Process Plugin
• GRPC Plugin

Detailed task list:

• Golang Process Plugin
  • Tidying
    • Update DICodeBuilder and Impl to add an ImportType method for convenience. Remove the current Import implementation on DICodeBuilder and replace its usage with the gogen.Imports struct. Simplify template generation
    • Update the workflow spec plugin implementation to use the above, simplifying the implementation. Also move codegen parts into a codegen subdir
  • Generated DI code
    • Generated graph() method must declare all string args in di. It should return the container (with Get method), not graph.
  • DI runtime graph/container
    • container Get method should receive a context so that things like server goroutines can shutdown on process exit
    • Container should have a waitgroup so that callers can wait on things like server goroutines
    • Add an Await method on the DI container to wait for the waitgroup
  • Generated main method
    • Main-method generation that takes cmd line args, puts them in a map, and invokes the graph function
    • Process IRNode should keep track of which nodes must be explicitly instantiated. Generated main() should do that instantiation by calling get() after the definitions.
    • Generated main method should create a context for cancellation, pass it to the DI container, and await the waitgroup after getting all definitions
• GRPC Plugin
  • Client and Server Handler
    • Finish implementing generated client methods; see if using copier is sufficient
    • Finish implementing generated server methods
    • Implement instantiation code for client, making use of the ctx above
    • Implement instantiation code for server, making use of the ctx and waitgroup above
  • Configuration
    • Add a general IRNode representing runtime configuration -- ie specifying that this config should come from runtime
    • Add config for timeout, allowing both a runtime configured value, or a directly configured value