[seek-dev] get data from a remote place to Ecogrid client

[Bing Zhu]

Jing,

I didn't realize that currently we depend on 'url_copy' in the server side
only. In this case, we have to install grid-ftp server in client
side.

But there is a quick solution for this problem in current 'get'
in which we allow client to call 'url_copy' too. So there are two scenarios
in our 'get'.

1. dest_url=ecogrid://..., src_url=ecogrid://
   This is a 3rd-party file transfer request from a client. The server
   calls 'url_copy' to do the 3rd-party file transfer for client.

2. dest_url=file://...,src_url=ecogrid://...
   The 'get' proxy (in server side) will talk to underneath system to
translate 'src_url'
   to actual hostname and physical file path along with filename and send
them back to 'get'
   client. Then the 'get' client calls 'url_copy' to get the file. In this
   approach, there is no need to require grid-ftp server running in client
   machine. But we have to ship the 'url_copy' in our client package.

Bing