From the pattern: "a pattern that solves the problem of transferring
data between foreign applications by automatically collecting data from those applications
on behalf of a working client collector. It uses a process that collects XML data from data
providers. This process takes the different feeds and builds a compilation of the data in an
XML document, even when foreign applications run on different platforms. Through this
pattern, a thin client receives distributed information that it requires. Furthermore, the
process of collecting information is transparent to the user (usually a person at a browser,
but potentially an automated process) except when he declares what data he requires."
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.