[seek-dev] get operation in ecogrid query

Jing Tao tao at nceas.ucsb.edu
Tue Dec 2 16:47:10 PST 2003

Hi, Bing:

On Tue, 2 Dec 2003, Bing Zhu wrote:

> Jing,
> I have some comments here.
> 1. In SRB, the identifier will be the SRB ID.
>     In the get operation for SRB, this SRB ID is translated into following:
>             host name  (e.g. multivac.sdsc.edu)
>             Physical file name with path in that machine.
>     In this case, the source will be either NULL or a port number in getting
> a SRB file.

The source URI is for gsiftp server. So you may just put 
"gsiftp://multivac.adsc.edu:5678" as the source URI.

For example, here is you get method:

get("gsiftp://multivac.adsc.edu:5678", "file:///tmp/hello.jpg", 

In your implemenation, you can tolken the identifier and get the file path 
-"data/image/hello" and combine it with the uri of ftp server 

The combination - "gsiftp://multivac.adsx.edu:5678/data/image/hello.jpg" 
will be passed to another class EcoGridFTPTransfer as source uri and 
"file:///tmp/hello.jpg" will be passed to EcoGridFTPTransfer as 
destination uri. Then you call transfer() method, the file transfer will be finished 
by ftp server. (The detail is in EcoGridFTPTransfer.java)

> 2. It is better for the return value from 'get' operation to:
>         0 --> succeeded.
>         a negative number -> failed. The number is the error code
> corresponding to an error.
>                                        In SRB, failure to retrieve a file
> has many causes. 0 and 1 is not
>                                        not sufficient to handle error code
> information.
  That is good suggestion, we may do that.

> 3.  We need to have a way to let system admin to turn on or off the Debug
>      by modifying some configuration file(s) such as server-config.wsdd
> before starting SEEK Ecogrid
>      factory services. I wonder how Tomcat is handling this. If they already
> have a build-in function to
>      check if Debug is on or off, we need to put such function call for each
> System.out.println statement.

Yes, we need a way to turn on or off the debug. This is the reseaon I want 
create a debugger class. According the configuration, this debugger will 
be turned on or off. Metacat already have this mechanism. You can turn on 
or off in build.xml when you install it.



> Bing
> -----Original Message-----
> From: seek-dev-admin at ecoinformatics.org
> [mailto:seek-dev-admin at ecoinformatics.org]On Behalf Of Jing Tao
> Sent: Tuesday, December 02, 2003 2:59 PM
> To: seek-dev at ecoinformatics.org
> Subject: [seek-dev] get operation in ecogrid query
> Hi, everyone:
> After struggling with some issues, the framework of get operation in
> ecogrid query interface is almost done(I have not implmented read document
> from metacat part, but that is not hard). Before I do that, I would
> like to get some response.
> The get method looks like:
> int get(URI source, URI destination, String identifier).
> This method is base on gsiftp and will return 1 if transfer successfully,
> otherwise return 0. Besides server to client transfer, this method also
> support third party transfer (ftp sever to another ftp server) too.
> Now the query porttype is secured because running gsiftp need the user's
> credential. So user should have a certification if he need to run the
> client.
> Some issues:
> 1.
> The tansfer is base on file system. For example, you call the method like
> this way:
> URI source = new URI("gsiftp://pine.nceas.ucsb.edu:5678");
> URI dest   = new URI("file:///tmp/file1");
> get(source, dest, "tao.11.1");
> Metacat would like read tao.11.1 from database and write it to a file.
> Then gsiftp server will transfer this file  to local file /tmp/file1. It has
> lot of I/Os. Maybe this way is good for srb (they store data as file).
> 2.
> In the code, System.out.println is used for debug info. I am think if we
> need a debug class for whole seek java code or for ecogrid java code?
> Any comments and suggestion are appreciated!
> Jing
> --
> Jing Tao
> National Center for Ecological
> Analysis and Synthesis (NCEAS)
> 735 State St. Suite 204
> Santa Barbara, CA 93101
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Jing Tao
National Center for Ecological
Analysis and Synthesis (NCEAS)
735 State St. Suite 204
Santa Barbara, CA 93101

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