Deficiencies of URLs

There are several features which URLs as defined by either DODS or the WWW lack. These include:

1. Poor support for version information

2. No support for location-independent naming

3. No formal support for quality rating of data sets

4. No support for binding extent information within the name-space (e.g., for how long will this data set exist)

5. No support for security information

While these are important issues, many are being investigated by the Internet Engineering Task Force (IETF) and the evolving Uniform Resource Name (URN) standard. By following the de facto URL standard now, DODS is in a good position to benefit from the future standardization of URNs. Further, some of these deficiencies are not as severe as they might seem at first. For example, it is not clear that security information (providing access to a limited-access resource) belongs in a resource name. It might be more secure to design the resource so that it prompts specially for any security information required. Similarly, version and quality information may be incorporated informally to the existing URL syntax. Finally, a crude type of location independence may be achieved using domain name service aliases for important resources. These approaches are already in widespread use with the WWW.

Rather than form our own solutions for the deficiencies of URLs, DODS will wait until either the IETF or WWW community modifies URLs and/or adopts URNs or until continued development of DODS is significantly hampered by the problems.