Comms Suite 5 MEM - It's a Front End...No, It's a Back End...No, It's Gone Completely...No, It's Still There
By joesciallo on Apr 18, 2007
Sometimes we're are own worst enemy, creating confusion rather than developing understanding that makes deploying Communications Suite easier. Case in point: In the Messaging Server 6.3 docs, we've communicated that the Messaging Express Multiplexor (MEM) is "no longer used." We could have done a better job describing what this means. For example, in the Release Notes we wrote:
The webmail server, also known as mshttpd (Messaging Server HTTP Daemon), provides email services to the Messenger Express and Communications Express clients. Now, the webmail server accesses the message store through the IMAP server. This provides several advantages:
- Messenger Express and Communications Express clients are now able to access shared folders that are located on different back-end message stores.
- The webmail server no longer must be installed on each back-end server.
- The webmail server can serve as a front-end server performing the multiplexing capabilities previously performed by Messenger Express Multiplexor (MEM).
- MEM is no longer used. See Deprecated and Removed Features for Messaging Server.
Also, in the Communications Suite 5 Deployment Planning Guide:
Webmail Server or mshttpd daemon. Provides email services to the Messenger Express and Communications Express clients by using HTTP. In previous versions of Messaging Server, the Webmail Server accessed the Message Store directly. Now, the Webmail Server accesses the Message Store through the IMAP server. Such an architecture enables Messenger Express and Communications Express clients to access shared folders that are located in different back-end Message Stores. Additionally, there is no longer a requirement to install the Webmail Server on each back-end server. The Webmail Server can act as a front-end server performing the multiplexing capabilities previously performed by Messenger Express Multiplexor (MEM).
So, what's really going on?
Let's see if we can put this together more clearly. Prior to the Messaging Server 6.3 release, the MEM served as the HTTP proxy for Communications Express and Messenger Express. That HTTP proxy is the part that has been removed in Messaging Server 6.3. As a result of reengineering mshttpd as an IMAP client (instead of accessing the store locally), you no longer need to install mshttpd on the back end. Thus, you don't need need MEM. However, other than that, the Webmail Server is still the same. One could then say that the MEM functionality is now part of the main server. But it's really the MEM that's gone.
In retrospect, then, if MEM had been separate from the mshttpd daemon, like the mmp and httpd daemons are, this would have all been clearer that it's the proxy function that has been removed.
- You run Webmail Server on your front-end machines (rather than back end).
- Communications Express can now communicate to mshttpd on other systems.
- You should typically (recommended from an operational deployment standpoint, rather a functional standpoint) combine Webmail Server with Comms Express on the same machine on the access layer.