Brian Kelly, UK Web Focus, UKOLN, University of Bath, Bath, UK
This paper describes a technique for providing access to HTML validation services using a URI interface to validation services. Details of the implementation in Apache is given. The author proposes a small set of standard URI interfaces to validation and testing services which would ensure a consistent interface for users as well as authors.
Quality Assurance, Standards, Digital Libraries
The importance of compliance with Web standards is well-understood. However although tools such as W3C's HTML and CSS validation services [W3C] are valuable use of the tools is not integrated with normal Web publishing process: using the interactive mode requires the URI to be copied, going to the validation service and pasting the URI. It is desirable to deploy a simpler interface.
An alternative approach is to provide an interface to the validation tool which can be accessed using a URI. This approach has been deployed on the UKOLN Web server [UKOLN]. Access to the HTML validation service can be obtained by appending ,validate to any URI on the UKOLN Web server. This >has been extended to include additional validation and testing services (e.g. CSS validation and link checking).
The interface is implemented using a simple server-side redirect. On the Apache Web server the ,validate tool is implemented using the following code:
RewriteRule /(.*),validate http://validator.w3.org/check? uri=http:// www.ukoln.ac.uk/$1 [R=301]
This approach has the advantages that it can be used from anywhere: no software needs to be installed. It is easily maintained as a change to the testing service requires a single change to the server configuration file. A disadvantage with this approach is the reliance on a third party service and the associated dangers that the third party may change its conditions of use. However if solutions based on open source software are used it will be possible to migrate the service from the original host to a local service if necessary.
This technique will work on appropriately configured Web servers. Since the approach is easy to implement and has clear benefits it is hoped that the approach will be widely deployed. There will be a temptation to provide one's own naming conventions for the tools. However providing a standard naming convention has a number of advantages: a consistent interface across different domains used within an organisation; support help desk activities by providing consistent approach for collecting data an promotion of use of standards.
The author proposes the following standard set of URI for core validation and testing services: ,validate, ,rvalidate, ,cssvalidate, ,checklink, ,rchecklink and ,http-headers.