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RPC Progressive Results
WAMP 1.0 is an open WebSocket subprotocol that provides two asynchronous messaging patterns: RPC and PubSub.
From sgcWebSockets 4.3.8, a new method is supported, not included in WAMP 1.0 specification, but it can be very useful for our users. WAMP allows RPC calls, but server response can only be successful or not. Sometimes, an RPC requires more than one result (streaming news, quotes, show progress...) and here specification doesn't allow to do it (WAMP 2.0 it allows but is much more complex).
So, from sgcWebSockets 4.3.8, RPC with multiple results is available.
Basically it works equal than previous RPC, but there is a new Event in client side called OnCallProgressResult which is raised if server sends a partial result and there are still more results to be received. At the same time, server has a new method called CallProgressResult, which is called to send a partial result to client.
Client can cancel an active RPC call, using the new method CancelCall and passing CallId as parameter.
Server Example
procedure OnServerCall(Connection: TsgcWSConnection; const CallId, ProcUri, Arguments: string);
var
vNum: Integer;
begin
if ProcUri = 'GetProgressiveTime' then
begin
vNum := StrToInt(Arguments);
for i := 1 to vNum do
begin
if i = 20 then
oServerWAMP.CallResult(CallId, FormatDateTime('yyyymmdd hh:nn:ss', Now))
else
oServerWAMP.CallProgressiveResult(CallId, FormatDateTime('yyyymmdd hh:nn:ss', Now));
end
end
else
oServer.WAMP.CallError(CallId, 'Unknown method');
end;
oServer := TsgcWebSocketServer.Create(nil);
oServer.Port := 80;
oServerWAMP := TsgcWSPServer_WAMP.Create(nil);
oServerWAMP.OnCall := OnServerCallEvent;
oServerWAMP.Server := oServer;
oServer.Active := True;
Client Example
procedure OnCallResultClient(Connection: TsgcWSConnection; CallId, Result: string);
begin
// This is the last result
ShowMessage(Result);
end;
procedure OnCallProgressResultClient(Connection: TsgcWSConnection; CallId, Result: string);
begin
// Partial result, there are still more results to receive
ShowMessage(Result);
end;
procedure OnCallErrorClient(Connection: TsgcWSConnection; const Error: string);
begin
ShowMessage(Error);
end;
oClient := TsgcWebSocketClient.Create(nil);
oClient.Host := '127.0.0.1';
oClient.Port := 80;
oClientWAMP := TsgcWSPClient_WAMP.Create(nil);
oClientWAMP.OnCallResult := OnCallResultClient;
oClientWAMP.OnCallProgressResult := OnCallProgressResultClient;
oClientWAMP.OnCallError := OnCallErrorClient;
oClientWAMP.Client := oClient;
oClient.Active := True;
// After client has connected, request GetTime from server
oClientWAMP.Call('GetProgressiveTime');
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