Linking Pipes and Filters

While we're still going to use pipes and filters for the general architectural style, we have at least two different choices for the types of pipe we use. The current utilities use the file system as a pipe. For simplicity, version 1.0 could continue to use the file system and simply fork child processes to execute stand-alone filters as necessary. However, all our conversion utilities are coded to deal with DOM documents. If we're passing them off to something else that can use a DOM document as input, there's no reason to write it out to the disk and read it back in again. This is no problem for the converters and presents only a minor problem for XSLT transformations. It is likely we'll want to set up direct calls to Xalan (Java or C++) from the main program rather than fork a child process.