How the Connection Broker Works

I never really gave much thought to how the Connection Broker (or Docbroker) worked until I stumbled upon an explanation in the EMC Documentum Content Server Administration Guide (chapter 6). I thought it was interesting and worth summarizing for you. Who knows, one day maybe this information will be important to someone?

The Connection Broker is a process that listens (on port 1489, by default) for client session requests and provides connection information in response to these requests. The Connection Broker responds to a connection request for a particular repository with the repository server’s IP address and port number. In addition, the Connection Broker keeps track of the status of each repository reporting to it (possible status values are:  starting, open, stopped, presumed down).

Connection Brokers do not poll for repository statuses. As each repository comes online, it broadcasts its connection information and status to the Connection Brokers configured in its server.ini file. These Connection Brokers then register the repository as “starting”. Once the repository is fully online, it broadcasts a checkpoint message to the Connection Brokers which then changes its status to “open”. The Connection Broker is now ready to service connection requests for this repository.

The repository will continue to send checkpoint messages to the Connection Broker every five minutes (dm_server_config.checkpoint_interval = 300) to let the Connection Broker know it is still “open”. The Connection Broker registers the receipt of the checkpoint message and updates the time at which it expects to hear from the repository next. If the Connection Broker does not hear from the repository at its expected time, its status is changed to “presumed down”. This status is maintained for 24 hours (dm_server_config.keep_entry_interval) or until the Connection Broker receives a checkpoint message from the repository. If the Connection Broker does not receive a checkpoint message from a repository that is “presumed down” within the allotted time, the connection information for that repository is flushed from the Connection Broker.

If a repository is shut down by an administrator, it broadcasts a shutting down message to the Connection Broker which sets the repository’s status to “stopped” and removes the repository from its registry of known repositories after the dm_server_config.keep_entry_interval expires.

Several aspects of the Connection Broker’s operation can be changed and/or configured. See the EMC Documentum Content Server Administration Guide (chapter 6) for more information on overriding defaults, load balancing, and Connection Broker fail-over. You can also programmatically access Connection Broker information via the IDfDocbrokerClient DFC class.

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About Scott
I have been implementing Documentum solutions since 1997. In 2005, I published a book about developing Documentum solutions for the Documentum Desktop Client (ISBN 0595339689). In 2010, I began this blog as a record of interesting and (hopefully) helpful bits of information related to Documentum, and as a creative outlet.

2 Responses to How the Connection Broker Works

  1. prabhu says:

    Your blog is too good and very helpful… thank you so much

    Like

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