Net/Z3950/AsyncZ version 0.04
=======================

Net::Z3950::AsyncZ adds a layer of asynchronous support for the Z3950
module through the use of multiple forked processes. This approach
enables it to handle queries to a large numbers of servers in a
single session. The speed of Net::Z3950::AsyncZ depends on the
responsiveness of the servers; if the servers are responsive,
Net::Z3950::AsyncZ can be very fast. 

Users should also find that it provides a useful front end to
Net::Z3950, by providing convenient facilities to process and format
Z39.50 records. 

See the DESCRIPTION section of AsyncZ.html/AsyncZ.pod.


DEPENDENCIES

This module requires these other modules and libraries:

      MARC::Record =>1.15,
      MARC::Base => 0.0, 	******* INCLUDED WITH THIS DISTRIBUTION********
      Net::Z3950 => 0.31,	
      Event => 0.86,
      IPC::ShareLite => 0.09	      

     MARC::Charset   **** not required but needed if you want unicode support****     

MARC::BASE is from MARC,a small package which I include with this distribution,
because (as far as I can tell) it is not a CPAN module: see  MARC/MARC.tar.  

ISSUES

Net::Z3950::AsyncZ uses shared memory and so there is always a chance that
some shared memory and semaphores will not be freed.  This is rare
with AsyncZ. I have found IPC::ShareLite extremely reliable, and
AsyncZ has features built into it which work to prevent unfreed
memory problems. Nevertheless, I've provided ipc.pl 
to free unfreed memory and semaphores, should they occur.
You run it as:

	perl ipc.pl <userid>

where userid is the userid of the user who created the shared
memory.  Where this is not yourself you'll have to su to root
in order to free the resources of a user other than yourself.
If you don't have admnistrative privileges, you'll most likely
have to go to your server administrator.



INSTALLATION

To install this module type the following:

   perl Makefile.PL
   make
   make test
   make install


One of the test suite scripts requires an open Internet connection.

You can also run the demo scripts in the script directory using:

		perl <script.pl>

There have been some problems installing Net::Z3950 on Redhat 8. Users
on the Z3950 mailing list have provided the following fixes:

 [1] In Makefile.PL and yazwrap/Makefile.PL  set
  
   	    'DEFINE'    => '-D_GNU_SOURCE',

 [2] I found that this was all I needed.  But it has been suggested
that the following change also be made in yazwrap/Makefile.PL:    

 	  'CCFLAGS'   => $defaultCCFLAGS . ' -Wall',
   to

	 'CCFLAGS'   => $defaultCCFLAGS . ' -Wall -D_GNU_SOURCE',



COPYRIGHT AND LICENCE

Copyright (C) 2003 Myron Turner

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.