#18 Support Last-Modified date in HTTP GET

[Peter Darton]

Nearly all web-browsers and web-caches use the "Last-Modified" HTTP header field to determine whether or not a URL that was previously cached needs to be downloaded again.
What happens is the web-client says "please give me the file if the server copy was modified more recently than XXX" where XXX is the Last-Modified date the client was given when it previously downloaded the file. The server can then compare the client's file date with its own file date and decide whether to tell the client that it already has the latest (a short response), or to upload the entire file content again.

At present, it is not possible for gSOAP custom HTTP-Get handling code to return a "Last-Modified" date, or any other "validity lifetime" fields.
Equally, such code cannot see the request header information from the browser that would indicate whether or not it is necessary for the webserver to upload the entire file again or if it can just tell the web-client that the client already has the most recent version in the cache.

This means that it's not really feasible to use gSOAP's HTTP GET handling facility for anything other than 100% dynamic content, which means one cannot have, for example, a gSOAP server and a Java SOAP client applet on the same service, otherwise the client browsers will download the applet code every single time they visit the site, as they can't tell if they've got the latest version or not.
This puts a much larger load on the server than is really necessary.