June 2009 - saga-rg - lists.ogf.org

missing(?) method reporting last modification time
by Thilo Kielmann 29 Sep '09

29 Sep '09

Folks, within our group we are currently delving into issues with accessing remote file systems. What strikes us is that such access is SLOW. As such, it would be very beneficial if one could find out when (and thus whether) a remote file or directory has been modified. While returning this piece of information sounds to be "trivial", it strikes us that the SAGA spec has no such call in the name space package (where files reside). In POSIX terms, this is the info returned by the stat system call (see: man 2 stat), with the st_mtime parameter. In Java, files have a method lastmodified(). Both POSIX and Java report the time in milliseconds since 01/01/1970 (epoch). Of course, it looks like nobody has ever been thinking about such a use case, but here we are! Our feeling is that the last modification time is very essential meta data about files, so such a call should certainly be there. With our current problem certainly not being the only use case for finding out how old/new a given file or directory is... Our favourite proposal is to add a method that returns the last modification time to both ns_entry and ns_directory as this makes sense with physical as well as with logical (replicated) files. Any reactions/objections ??? Thilo Kielmann -- Thilo Kielmann http://www.cs.vu.nl/~kielmann/

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SD Spec Proposed Errata
by Steve Fisher 09 Jul '09

09 Jul '09

We propose to make the following changes to the SD spec - attribute names to start with a capital letter This has already been discussed and agreed - add attribute "InformationServiceUrl" containing a ref to the source of the information We want this so that it is possible to determine where the information has come from. It will not be possible to use this attribute for selection - use the URL in the discoverer constructor instead. Note that it is "InformationServiceUrl" rather than "InformationServiceURL" - add attribute "ImplementationVersion" - taken from the corresponding GLUE field - add attribute "InterfaceVersion" - taken from the corresponding GLUE field - add multi-valued attribute "Capability" to match the GLUE-2 capability which in turn uses the OGSA defined set of values This was discussed within a small group at LSU F2F This will be more useful than the current "Type" as service types tend to be peculiar to one grid. The description of type will simply say: "type of service. This API does not restrict values of the service type - it might be a DNS name, a URN or any other string." and table 1 will be deleted. Comments please

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Re: [SAGA-RG] missing(?) method reporting last modification time
by Andre Merzky 04 Jun '09

04 Jun '09

Dear Sylvain, two small of comments to points not covered in your second mail. Quoting [Sylvain Reynaud] (Jun 04 2009): > > > NSEntry.remove() allows !Recursive flag: > > > > The is actually in the spec, as > > > > saga::directory d (url); > > d.remove (0); // 0: empty flag set, i.e. Recursive is not set > > > > I think what you want is to change the semantics, from > > > > - a â??BadParameterâ?? exception is thrown if the > > entry is a directory and the â??Recursiveâ?? flag > > is not set. > > > > - a â??BadParameterâ?? exception is thrown if the > > entry is a *nonempty* directory and the > > â??Recursiveâ?? flag is not set. > > > > Would that solve your use case? > > > Yes (my use-case is: "how to implement rmdir"). I'll fix that in the spec, if nobody objects. > > job attribute 'NativeJobDescription' added > > > > I assume that is a read-only attribute? > > Yes. > > >What is the use > > case for this one? Debugging? > > > Yes. I don't expect it to be included in the specification. Understand. For what its worth: this feature has been discussed multiple times, but mostly in the other direction: people wanted to be able to submit natve job submission via SAGA. That might (or might not) make it into the spec in the next version. Best, Andre. -- Nothing is ever easy.

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