读DataSnap源代码（四）

继续篇中的

function TCustomWebDispatcher.DispatchAction(Request: TWebRequest;
  Response: TWebResponse): Boolean;
var
  I: Integer;
  Action, Default: TWebActionItem;
  Dispatch: IWebDispatch;
begin
  FRequest := Request;
  FResponse := Response;
  I := 0;
  Default := nil;
  if Response.Sent then
  begin
    Result := True;
    { Note that WebSnapSvr enabled apps have no way to mark response as sent }
    Exit;
  end;
  Result := DoBeforeDispatch(Request, Response) or Response.Sent;
  while not Result and (I < FActions.Count) do
  begin
    Action := FActions[I];
    Result := Action.DispatchAction(Request, Response, False);
    if Action.Default then Default := Action;
    Inc(I);
  end;
  // Dispatch to self registering components
  I := 0;
  while not Result and (I < FDispatchList.Count) do
  begin
    if Supports(IInterface(FDispatchList.Items[I]), IWebDispatch, Dispatch) then
    begin
      Result := DispatchHandler(Self, Dispatch,
        Request, Response, False);
    end;
    Inc(I);
  end;

  if not Result and Assigned(Default) then
    Result := Default.DispatchAction(Request, Response, True);
  if Result and not Response.Sent then
    Result := DoAfterDispatch(Request, Response);

end;

在第26行代码之前，是执行WebModule中的Action, 然后是遍例WebModule上的Component, 只要支持IWebDispatch，都有机会处理WEB请求。

当然就包括了   TDSHTTPWebDispatcher = class(TDSHTTPServerTransport, IWebDispatch)。 继续代码：

function DispatchHandler(Sender: TObject; Dispatch: IWebDispatch; Request: TWebRequest; Response: TWebResponse;
  DoDefault: Boolean): Boolean;
begin
  Result := False;
  if (Dispatch.Enabled and ((Dispatch.MethodType = mtAny) or
    (Request.MethodType = Dispatch.MethodType)) and
    Dispatch.Mask.Matches(string(Request.InternalPathInfo))) then
  begin
    Result := Dispatch.DispatchRequest(Sender, Request, Response);
  end;
end;

function TDSHTTPWebDispatcher.DispatchRequest(Sender: TObject;
  Request: TWebRequest; Response: TWebResponse): Boolean;
begin
  try
    if Owner is TWebModule then
      DataSnapWebModule := TWebModule(Owner);
    try
      try
        RequiresServer;
        TDSHTTPServerWebBroker(Self.FHttpServer).DispatchDataSnap(Request, Response);
        Result := True;
      except
        on E: Exception do
        begin
          { Default to 500, like web services. }
          Response.StatusCode := 500;
          Result := True;
        end;
      end;
    except
      { Swallow any unexpected exception, it will bring down some web servers }
      Result := False;
    end;
  finally
    { Reset current DataSnapWebModule }
    DataSnapWebModule := nil;
  end;
end;

 至此，WEB请求转入到WebModule中的TDSHTTPWebDispatcher来处理了。