Scopes

A scope is one client request and everything that follows from it, numbered by the client and ended only by the server.

A scope is one client request and everything that follows from it.

• Opening. A client opens a scope by sending a request (type 1). The client chooses the scope number, and every subsequent frame belonging to the scope — in both directions — carries that number in its scope field.
• Answering. The server answers with zero or more responses (type 2) and ends the scope with exactly one response finish (type 3). The responses to a scope’s request form one stream: their order is significant, and the finish is its end.
• Only the server ends a scope. The client has no frame that closes, cancels, or abandons one. A scope is open from its request until its finish.
• A finish with no response before it is meaningful. It states that the request was received and could not be served. It is not an error frame, and no reason accompanies it at this layer.
• Numbering. The scope number is the client’s to choose. A scope number names one scope from that scope’s request until that scope’s response finish; after the finish the number is free to bear a new scope.
• A request naming an open scope is disregarded. The server disregards a request whose scope field names a scope that is open on the connection. The disregarded request is never answered, and the scope it named continues, unaffected.
• The scope’s exchange is not a channel. The frames that carry it — types 1, 2, and 3 — involve no channel, and their channel fields are ignored. Every other exchange within the scope is a channel.