XmlBlaster is XML based MOM (Message oriented Middleware) with a lot of features. It is a publish/subscribe and point-to-point MOM server which exchanges XML-encoded messages. Communication with the server is based on CORBA (using JacORB), RMI, XML-RPC, native socket, or a persistent HTTP plugin. Subscribers can use XPath expressions to filter the messages they wish to receive and add their own MIME-based filter plugins. C/C++, Java, Perl, Python, VisualBasic.net, C#, and PHP client demos are included in the xmlBlaster test suite, and Tcl and Python demo clients are scheduled. XmlBlaster also provides a browser callback framework, allowing browsers (Netscape, Mozilla, MSIE) to receive instant callbacks over a persistent http connection. A security plugin framework allows authentication/authorization in many ways. Currently there are LDAP- and passwd-based plugins available.