At first view, Custom Web Publishing might sound a lot like the XML Export capability we discussed in Chapter 20, “Getting Data Out of FileMaker.” There are some similarities, but there are also many significant differences. The main ones are these:
XML export is a “push” technology rather than a “pull” technology. New data becomes available to potential clients only when you decide to “publish” the data by performing a new export, possibly manually, possibly via an automated script. CWP is a server-side technology that can be made available on demand, enabling clients to “pull” new data at any time by accessing a specific URL that you provide.
Using CWP, you can publish your FileMaker data in a new XML grammar, called fmresultset. This new grammar has the richness of the FMPXMLRESULT grammar, while being easier to work with for stylesheet writers. The grammar is available only through CWP.
CWP is a server-side technology, which means you don't need a copy of the FileMaker client to take advantage of CWP. All necessary programming occurs on the server side. On the other hand, exporting XML can take place only from a client application.