Programming Jabber

Custom Configuration

The custom configuration section in our xdb component instance definition is specific to the data storage mechanism that we’re going to be using. In this case, it’s the xdb_file mechanism, and so we have the custom configuration wrapped by a tag qualified with a namespace to match:

<xdb_file xmlns="jabber:config:xdb_file">
  <spool><jabberd:cmdline flag="s">./spool</jabberd:cmdline></spool>
</xdb_file>

Again, the tag name xdb_file is unimportant; the part that must be correct is the namespace jabber:config:xdb_file.

The configuration describes a single setting: where the spool area is. This, in the context of our xdb_file mechanism, is the root directory within which hostname-specific directories are created and used to store JID-specific and global XML datafiles. As the configuration stands here, the value (./spool) can be overridden at server startup time with the -s switch.

There is another configuration tag available for use here too. Using the configuration as it stands here, the xdb_file component would cache data indefinitely; if you were to modify data directly in the files in the spool area, the modifications wouldn’t have any effect for data that had already been retrieved for a JID in the course of a server’s uptime.^[6] In other words, once data has been read from the file, it is cached until the server is stopped.

The <timeout/> configuration tag can be employed to control this caching. Used with a value that represents a number of seconds, ...