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A.2.1 Request types

A DODS server is equipped to respond to several different request types. Each request type is signified by a different URL suffix. The server itself is just a dispatch script, that determines the type of a request, and dispatches the request to the appropriate service program, and relays its result back to the client.

In figure A.2.1, a DODS client makes a GET request to a DODS server (which is just an httpd daemon equipped with a bunch of CGI programs). The daemon invokes the DODS Server, which is a simple-minded dispatch script which in turn invokes the DAS, DDS, Data, or other service program.

 

The Architecture of a DODS Data Server.

The request types, their suffixes, and the service programs are listed in table A.2.1.

Table of URL suffixes.
 

Suffix Service Program Description
.dds *_dds Returns the Data Descriptor Structure for the specified dataset.
.das *_das Returns the Data Attribute Structure for the specified dataset.
.dods *_dods Returns binary data in the form of a DODS data document. See Section A.1.3.
.asc asciival Converts data requests to ASCII values before sending them back to the client. This service is useful for invoking from simple web browsers.
.info usage Returns an HTML formatted version of the dataset DDS and DAS, and any other server and dataset information provided in *.ovr files.
.html none Returns a URL constraint expression builder form, based on the dataset DDS and DAS. This is the DODS WWW interface.
.ver none Returns the server version information.


Tom Sgouros, July 2, 2004

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