Opening Documents

Besides crawling resources, we should also be able to open them.

At first this may look like a job for the DataAccessor?, which after all has knowledge about the details of the physical source.

On second thought, I believe that for the opening of files you need some other service, parallel to DataAccessor?, that is also scheme-specific and that takes care of opening the files. Reasons:

• DataAccessors? actually retrieve the files, which is not necessary for some file openers. For example, for opening a local file you can instruct Windows to do just that. Similarly, a web page can be retrieved and shown by a webbrowser, there is no need for us to retrieve the contents and feed it to the browser.

• There may be several alternative ways of opening a resource. For example, the java.net JDIC project contains functionality for opening files and webpages, whereas we have our own classes to do that.

This may be a good reason to decouple this functionality from the DataAccessor? and run it in parallel.