Durable Entities: Entity operation dispatching

[jviau]

Part of #19

Overview

This issue is to track adding the ability for entity implementations to dispatch an operation to entity instance level methods or properties.

Requirements

• Entity operations can be implemented as public instance level methods or properties
• All bindings are case-insensitive
• Properties: not dispatched to.
  • We do not want to conflate entity serialized state and operations, so we will not dispatch to properties.
• Methods: will look for a method matching operation name
  • Will examine method parameters and bind appropriately

Non-Requirements

• Support for Task, Task<T>, ValueTask, or ValueTask<T>
  • We need to further examine if it makes sense for entities to have any async support
• Dispatching to non-ITaskEntity types

Design

We will introduce a base class TaskEntity : ITaskEntity which will perform mapping from the operation payload to an appropriate instance-level property or method.

Method Binding

Parameter support

The below table is what parameters we support and what we will bind. We will only bind one of these parameters once. Any unsupported parameter types or already bound parameter types will cause an exception to be thrown.

Param type	Action
Entity context	Bind current entity context
Entity operation	Bind current entity operation
object	Bind from operation input

Return value support

We will return the value of the bound method, if any, to the caller. We will not support async dispatching (so no Task or ValueTask) at this time.

Overload resolution

We will throw on any discovered overloads with an ambiguous operation exception.