Parlez-vous Internet?

Posted on 2 Jul 2002 at 17:35

If you can't speak the Net lingo, don't worry, as Davey Winder has all the answers - in good old plain English.

Link validation software is nothing new, and at the most basic level there are numerous free utilities floating around the Web. However, serious link validators that not only work, but work efficiently across multiple sites, are an altogether rarer breed. The promise of link mapping is usually met by some unnecessarily complex graphical representation of the Web site structure, but LinkScan manages to produce very straightforward hierarchical outlines using a well-understood systematic tree structure. It's also pretty damn fast in operation - its claim to test and validate 40,000 links per hour would seem to be corroborated by my usage. Its speed comes largely from its implementation of multithreaded simultaneous processing.

LinkScan has other advantages apart from speed, such as the ease of installation - it will set up all directories and permissions, as well as build your configuration file automatically. It's easy to split large sites into smaller sub-sites for faster testing and more manageable reporting, and LinkScan will happily handle multiple domains on a single-server host.

LinkScan also comes with two utilities: SiteMap and TapMap. SiteMap produces a hierarchical map showing every link on a Web site, in a straightforward and obvious manner. If you can use the content pages of a large book, you can use the SiteMap index as well, but by the very nature of such displays it's only really workable for smaller sites with a maximum of about 400 pages. TapMap, on the other hand, produces a fully expandable and collapsible site map, enabling you to tap down through the levels using a control panel of icons - as a result, it can cope with as many thousands of pages as your Web site can throw at it. Both utilities are totally irreplaceable for anyone who is serious about their site, especially if their business depends upon it. LinkScan (www.elsop.com/linkscan/) isn't cheap at $495 (£300), but a fully-functional 15-day evaluation version can be found at the Web site, as can interactive examples of the program in action.

Tech talk - know your URs

I guess you all know what a URL is - it's the address of a Web page, right? Er, well it's not quite that simple, as you should have come to expect with anything Internet-related by now. A Uniform Resource Locator is, to be precise, one part of a much bigger notion - that of the Uniform Resource Identifier or URI. Currently URLs are the only instances of the URI in common use, so the terms are pretty much interchangeable. But this state of affairs can be expected to change in the not-too-distant future, so now is a good time to get your URI facts straight.

The official Internet Engineering Task Force (IETF) definition of a URI is 'a compact string representation of a location (URL) or name (URN) for use in identifying an abstract or physical resource', which is fairly self-explanatory, but let's break it down a little further anyway, just for clarification. A uniform syntax enables the actual mechanism for referencing resources to be kept separate from the mechanism used to locate them. A resource is anything that has an identity (collections of files, documents, images, services) and an identifier is an object that acts as a reference to that resource.

The basic syntax for a Web site URL is something like http://host/path, where 'host' is the server to connect to and 'path' is the requested page that is held on that server. Moving on a step, a more universal syntax for URIs in general is scheme://host/path/extra-path-info, where the 'scheme' refers to the protocol used to connect to the site concerned, and 'extra-path-info' is additional information used to identify the precise resource required. URI schemes in use today include 'http' (the Web-based hypertext transfer protocol), 'ftp' (the file-based file transfer protocol), 'mailto' (for email services), 'news' (for Usenet news services), 'telnet' (the telnet protocol), and the now much less common scheme 'gopher' (for gopher protocol services, largely rendered extinct by http developments). There are also a couple of schemes which have as yet no application, but are likely to figure in future URIs. For example, 'tv' is for the reception of television programmes across the Net and 'callto' for telephone services such as voice and fax calls.

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