Features and Configuration

This package was inspired by the PiLLoW project. The XSB Libwww package offers much better performance and a superset of the PiLLoW functionality as related to the HTTP protocol, but this package does not implement the part of PiLLoW that deals with construction of Web pages.

The XSB Libwww is implemented in C and relies on the basic HTTP functions provided by the Libwww library developed by the WWW Consortium (http://www.w3c.org/Library). Therefore, this library must be installed in order for the XSB Libwww package to work. In addition, XSB must be configured to work with the Libwww library as follows:

    configure --with-libwww=directory-where-Libwww-is-installed

If you forgot to configure XSB for use with the Libwww library, you do not need to reconfigure and recompile XSB. Instead, you can cd to packages/libwww and type the above command in that directory. This will enable the previously compiled version of XSB to work with Libwww.

Note that the Libwww library cannot be moved after you configured it. If it is moved, XSB will not be able to find it, because hard path names are built into some parts of this library at configuration time. Use the -prefix argument of configure to specify where you want to install the Libwww library.

One of the most important aspects of the Libwww package is that it allows XSB to dispatch multiple HTTP requests, which interleave their Web access phases. This can be a significant performance boost. Furthermore, the HTML, the XML, and the RDF parsers begin their work as the fragments of pages arrive, so by the time the page is fully accepted, it is also parsed. Here is a list of features provided by the XSB Libwww package:

• HTML-4 parser.
• XML parser (non-validating).
• RDF parser.
• Page fetching (without parsing).
• Form handling.
• HTTP header information.
• Multiple, interleaved HTTP requests.
• Basic and digest authentication.
• Redirection and proxies.