
Chirp in Condor

Chirp is used by Condor (http://www.cs.wisc.edu/condor/) as an I/O proxy
protocol.  Proxy support is requested by adding the following line to
the submit file:

want_io_proxy = true


The job starter will then create a file called ".chirp.config" in the
execution directory.  When the program calls chirp_client_connect_default()
or chirp_client_connect_url("chirp:path"), it will connect and authenticate
itself with the starter, using the connection information in chirp.config.

Chirp is similar but not the same as the remote system call functionality
used by programs linked with Condor's Standard Universe libraries
(see condor_compile).  Chirp is intended for Vanilla and Java Universe
programs that wish to do explicit remote I/O.  The advantage in the Vanilla
Universe is that you are not restricted by the limitations of the
system calls supported in the Standard Universe.  The dissadvantage is
that you have to explicitly call chirp client functions in place of
the normal system file operations.

Note that the Condor starter uses a completely different protocol internally
when it forwards the Chirp I/O requests to the shadow process on the submit
machine.  The Chirp protocol itself is merely used in communication between
the job and the Condor starter, which both reside on the execute machine.

