Hi Terry! Quoting [Terry Sloan] (Aug 26 2005):
Terry Sloan
1. Are both source and target relative to a current working directory ?
Yes. I made that clearer in the spec.
2. Can the absolute path be used in the source and target ?
Yes.
3. Can source be remote (ie. not local) ?
Yes. All file names, dir names etc. are supposed to be URI's, and are allowed to be local or remote, absolute or relative.
4. If the source and target working directories are persistent for a user session where are they to be stored?
That is up to the implementation - the API does not imply any persistency right now, so any implementation not providing persistency between sessions can still be SAGA compliant. I am actually not sure if the API is allowing persistency for many things. PWD should be no problem, the same for the default session and context.
5. If both absolute and relative paths can be used how are these to be distinguished?
Long asnwer: This is a difficult question, as we had many (and I expect we will have many more) discussions about URI's, and how to express absolute and relative paths. For simple file names it is, well, simple: - absolute file names start with '/' - relative file names don't start with '/' For URI's is tricky. Several parties expressed the opinion, that it is impossible to specify relative paths with URI's. Consider http://www.host.net:1234/tmp/data.txt The 3rd '/', which separates host/port from the path element, is often considered part of the path. That would result in '/tmp/data.txt', and is absolute. Other people say, that the 3rd slash is not part of the path, and the above uri points to 'tmp/data.txt', which is relative. In their opinion, an absolute URI would need two slashes, like: http://www.host.net:1234//tmp/data.txt I am personally not sure which way is 'correct'. I think acceptable are both. Now, it is probably not part of the SAGA groups agenda to semantically define URI's. Hence we could just throw up hands and cry "implementation dependend". However, it would be good to include a proposal for URI handling into the spec. Its not in there yet. Short answer: *shrug*
6. In the very first call to a SAGA API, if the source or target is relative to a current working directory then where is the source or target current working directory set ? Particularly if the source is non-local.
Short answer: *shrug* ;-) Long answer: it depends... For example, if you are using http as protocol for the rmote URI, your 'pwd', which would be the default directory on the remote host, would be http-root, e.g. /var/www/htdocs/. For an ftp uri, it might be /usr/ftp/pub/, for ssh it might be your home directory. Or a sandbox. We are not happy about that mess. In particular, it makes it difficult to translate an uri with scheme A into an uri with scheme B - unless you know the local setting for that scheme on that host, for the respective user. Ugh! The same remark as above holds I think: SAGA cannot solve that problem, really, but it would be nice to have a sensible, simple and acceptable description/recommendation for that in the spec - right now we don't. I hope that helps. Thanks for the remarks, Andre. -- +-----------------------------------------------------------------+ | Andre Merzky | phon: +31 - 20 - 598 - 7759 | | Vrije Universiteit Amsterdam (VU) | fax : +31 - 20 - 598 - 7653 | | Dept. of Computer Science | mail: merzky@cs.vu.nl | | De Boelelaan 1083a | www: http://www.merzky.net | | 1081 HV Amsterdam, Netherlands | | +-----------------------------------------------------------------+