Define constants for Channel IDs

[carlosscastro]

In dotnet we have centralized constants for channel ids here. However, in Javascript there are channel id constants defined within the choice prompt classes, but they are used in nearby classes and I found occurrences of the string literals for channel ids.

We have new adapters for new channels coming and each one has a const for the channelId, it may be better to have this in BotBuilder.Connector to avoid future collisions but I'm not 100% sure.

The alternative would be to have each new channel adapter expose a const with the channelId they handle so we don't have to modify the product when we add new channels, but we probably need to agree on where a dev would expect to find this definition so we are consistent across the board.

If we go with the alternative, devs would have two places for ChannelId (Connector and the adapter), which may be confusing I am more inclined to have it in a single place for consistency.

[stevengum]

As I mentioned internally, we should duplicate the constants in the connector and keep the current location in botbuilder-dialogs. We can't add a botframework-connector dependency in botbuilder-dialogs because that would introduce Node.js dependencies in a browser-compatible library.

To maintain consistency between the two, we can add Azure DevOps Pipeline Task to verify that the channelIds are the same in the two files.

P.S. I'm all for a single source of truth, but I don't think we can have a single source in this scenario.

[v-kydela]

The C# channel constants used to be in a nested class called Channel.Channels but then they were moved to just Channels (still in the same package). Perhaps it would be best to move them again to a more centralized shared location like the Bot Framework Schema package.

[stevengum]

If we move it to the schema package, it's accessible by all packages, even though the libraries used in the context of the browser should theoretically not need the channelIds. This works for me 👍

[stevengum]

New issue filed for this: #1354

We could add the constants to botbuilder-core....

[v-kydela]

@carlosscastro
@stevengum

Are there any plans to fix this?

[stevengum]

This is not tied to any milestone currently so it hasn't been up for discussion. I'm going to assign it to R8 for now to get it into triaging discussion.