Further refine entity samples, add .http files and launch task

[jviau]

1. Addresses feedback from previous samples PR
2. Adds more HTTP endpoints for counter and lifetime examples
3. Adds .http files to show quick ways to call these examples.
4. Adds launch.json and tasks.json for running this sample in vscode

[cgillum]

I'm surprised to see this as a feature since I don't recall it ever being discussed. What are the use-cases? I'm also interested to understand the lifetime implications, etc.

[jviau]

This was to help migration so customers don't have to derive from ITaskEntity if they do not want to.

What lifetime implications are you concerned about?

[cgillum]

I'm wondering what happens if the state object is null, etc. I don't recall any such feature existing for the in-proc model. But maybe I'm misunderstanding what is being referred to by TState? Is that not the entity state?

[jviau]

In proc model does not have a concept of ITaskEntity base class. This is here to align closer with how inproc behaves: you can dispatch entity operations to some POCO. We have designed it so that POCO dispatching is done through the TState here.

If state is null we will use Activator.CreateInstance.

[sebastianburckhardt]

Trying to summarize the discussions and design a bit:

For in-proc we had two models:

• class-based. Entity state must be defined by a class, and operations are dispatched to methods.
• function-based. Very low level but totally customizable, with entity state being an arbitrary type.

For isolated we have three (but only the first two are expected to be widely used):

• class-based. Pretty much the same as for in-proc.
• TaskEntity<TState>. Similar to class-based but with one layer of indirection, which allows advanced scenarios (arbitrary TState types, dependency injection, customizable code for constructing the state) without having to give up the convenience of the class-based approach.
• ITaskEntity. Very similar to function-based. Very general but verbose. Not recommended unless you are building some kind of framework on top of entities.