A web service request begins when a web client agent (for example, JavaScript in a browser) sends an HTTP request for a URL designating an SRF file (also known as a BIS stencil file). When the HTTP server receives this request, it determines that the appropriate 'request handler extension' for such a request is the BIS Request Handler.
The BIS request handler interprets the tags in the SRF file in the order in which the tags appear. A tag is composed of text surrounded by {{ and }} sequences, and tags may be interpreted as processing instructions or placeholders that are replaced by plain text, HTML or XML that is generated by the BIS service engine or by the BIS request handler. In the case of SOAP web services the SRF file is very succinct as shown below.
One of the tags, the XMLExchange tag, causes the request handler to format the request information, including the state of the HTTP server variables, cookies, query parameters and the request payload., into a standard BIS request. The BIS request is transmitted to the service program via the 'exchange file'. Then, the request handler suspends its processing of the request until the service program informs it that a response is available.