The WebSpeed Messenger listens for WebSpeed requests coming in to the Web server. The Messenger asks the NameServer where to send each request. Alternately, the Messenger can bypass the NameServer as described in the NameServer. The Messenger then handles the transfer of data between the Web server and the WebSpeed Agent. There are Messengers for use on different Web servers: a CGI Messenger, an ISAPI Messenger, and an NSAPI Messenger.

There is also a Messenger that works with Microsoft's Active Server Pages, the WSASP Messenger. Using the WSASP Messenger, you can call out of an Active Server Page to a WebSpeed application.

The WebSpeed Messenger always resides on the same machine with your Web server. Because the Messenger is not itself an OpenEdge application, it is sometimes the only part of the WebSpeed environment installed on a Web server machine. This is sometimes incorrectly described as a "Messenger-only deployment." Your WebSpeed applications cannot run without a WebSpeed Transaction Server. "Messenger-only installation" is a more appropriate term for this setup.