BibDesk EZProxy Support

Adding EZProxy support to BibDesk looks pretty straightforward.

Currently it looks like bibdesk/BDSKWebParser.m has a method called “itemsFromDocument” which is responsible for extracting certain data from a document. This includes webType, which is an enum identifying which repository the data came from (ACM, WoS, etc). This is then used to choose an appropriate parser for the document.

(Note: I’ve added /* Some code skipped */ comments where I’ve cut out some code)

+ (NSArray *)itemsFromDocument:(DOMDocument *)domDocument fromURL:(NSURL *)url error:(NSError **)outError{
    BDSKASSERT(self == [BDSKWebParser class]);

/* ... some code skipped ... */

    int webType = [self webTypeOfDocument:domDocument xmlDocument:xmlDoc fromURL:url];

    Class parserClass = webParserClassForType(webType);

    BDSKASSERT(parserClass != [BDSKWebParser class]);

    // don't return nil here; this may be the Google Scholar homepage or something, and we don't want to display an error message for it
    // this may lead to some false negatives if the heuristics for canParseDocument::: change.
    if (Nil == parserClass)
        return [NSArray array];

    return [parserClass itemsFromDocument:domDocument xmlDocument:xmlDoc fromURL:url error:outError];

This in turn calls “webTypeOfDocument” which iterates through all the parsers and returns the first successful one,

+ (int)webTypeOfDocument:(DOMDocument *)domDocument xmlDocument:(NSXMLDocument *)xmlDocument fromURL:(NSURL *)url{
/* Some code skipped */
    if([BDSKACMDLParser canParseDocument:domDocument xmlDocument:xmlDocument fromURL:url])
        return BDSKACMDLWebType;
/* Some code skipped */
    return BDSKUnknownWebType;
}

For the ACM example, this is in bibdesk/BDSKACMDLParser.m
I tried a simple test which appears to work. I’m no Objective C coder but I imagine it would be straightforward to write this well (e.g., make it data-driven so users can define their own sets of domains to append to repository domains; replace the hardcoded strings with const’s; probably refactor the whole URL-repository testing and parsing code as it looks like there’s a lot of tight coupling all over the place)

+ (BOOL)canParseDocument:(DOMDocument *)domDocument xmlDocument:(NSXMLDocument *)xmlDocument fromURL:(NSURL *)url{

    if ([[url host] caseInsensitiveCompare:@"portal.acm.org"] != NSOrderedSame){
		/* [GARETH] Test support for ezproxy */
		    if ([[url host] caseInsensitiveCompare:@"portal.acm.org.ezproxy.sussex.ac.uk"] != NSOrderedSame){
				return NO;
			}
    }
/* Some code skipped */

—
Some useful links:

• Download EZproxy
• EZproxy Wikipedia
• EZProxy Technical Details
• The Unofficial EZproxy Self-Support Wiki
• BibDesk Subversion Repository
• Building BibDesk from SVN
• Foundation Data Types Reference (for info on NSRange)
• NSURL Class Reference
• Searching, Comparing, and Sorting Strings