It would be great if the sysl endpoint definition could include constant values

[ghost]

DCX has a few downstream endpoints which has URL vars and headers which are constant for the entire application. We would love to be able to mark up the sysl in some way to have the generated code use the constants instead of the service code having to manually populate those values.

example:

Downstream:
     /foo/{someid<:string}/xxx/{uuid<:string}/accounts/:
        GET (login_flag <: string [~header, ~required, name="LOGIN_FLAG"], channel_id <: string [~header, ~required, name="CHANNEL_ID"]:
            return ok <: FooDetails

I would like to tell sysl that the someid url var and the channel_id header are going to be constant values so they should not end up in the request struct and they should be hardcoded in the generated request.

[anzdaddy]

Supporting this should be fairly straightforward. We could allow calls of the form:

Downstream <- /foo/123/xxx/{uuid}/accounts/ (channel_id=456)