Apache Solr Extension
The module changes the behavior of apachesolr and allows for extending / overriding the SolrPHPClient behavior.
As of now, it writes the index to a directory rather than posting it to the Solr server.
The module came up due to a security requirement at one of my clients where Applications were not allowed to write to the solr server. Now, there will be a process by which, Drupal application will generate the xml and write it to a file. A cron running on the UNIX server can post the xml in the file to the solr server (using solr's java utility).
The module extends Drupal_Apache_Solr_Service class and overrides the _sendRawPost() method to write the xml to a file instead of posting to the server.
This same class can be extended to override other behavior of the original client.