From the pattern: "solves the problem of getting, processing and
showing data. In this pattern, XML holds the place of the in and out trays that a worker uses
to receive petitions. This pattern solves the problem of getting and giving data from and to
applications where the internal processes are hidden."
This pattern is described in an article XML Patterns by Maria Laura Ponisio and Gustavo Rossi
This is a one of a group of the four related patterns described in the article about processing XML on a Web server.