PyLinda 0.6 Readme

By Andrew Wilkinson <[email protected]>

Contents
--------

1. Introduction
2. Installation
3. Using Linda
4. Known Problems
5. Contact
6. License

1. Introduction
---------------

Linda is an widely studied distributed computing environment, centred around
the notion of a tuple space. A tuple space is a bag (also called a multi-set) of
tuples. A tuple is an ordered, typed chunk of data. Tuple spaces exist
independently of processes in the system, and the data placed into a tuple space
also exist independently. See "Generative communication in Linda" (1985) and
"Multiple tuple spaces in Linda" both by David Gelernter for more information on
Linda.

PyLinda is a simple implementation of a linda system, however it also includes
several of the more recently proposed extensions to Linda in the form of
multiple tuple spaces, garbage collection, sane non-blocking primitives and bulk
tuple operations.

2. Installation
---------------

To see the changes in this version read the file ChangeLog

To install simply unpack the tarball, and execute 'python setup.py install'.

tar -xfz linda-0.6.tar.gz
cd linda-0.6
python setup.py install

This will install the server program under /usr/bin. This can be run as
'linda_server.py'
Example files and documentation will be install under /usr/share/pylinda.

PyLinda requires a Python 2.3+ and has only been tested on Windows 2000, Linux
and Solaris, however it should be possible for it to run on other operating systems.

The Windows version is largly untested, so please report any success/failure you
have with it! Under Windows the linda_server.py file is installed in <python
install>\Lib\site-packages\pylinda. The documentation and examples are installed
under <python install>\pylinda. Several examples will not run under Windows as
they require the fork syscall, which is not supported by Windows.

3. Using Linda
--------------

First a server must be started - 'linda_server.py'.

Then a client program must be started, the simplest is just the python
interactive interpreter.

bash$ python
>>> import linda
>>> linda.connect()
>>> linda.uts._out((1,2,3))

Now quit that interpreter, and start a new one...

bash$ python
>>> import linda
>>> linda.connect()
>>> linda.uts._in((int, int, int))
(1, 2, 3)

If you want to add a new computer to the linda network simply run
'linda_server.py -c<ip address or dns name>' where the computer you supply is
already running a linda server.

4. Known Problems
-----------------

Serious Issues:
 * Solaris appears in my brief testing not to support domain sockets, or maybe I
don't have the rights on my server... further investigation is required.

Other Issues:
 * The actual implementation is quite slow. The process of storing tuples is
slow and uses a large amount of memory, this could probably be fixed by
rewriting that bit in C.
 * No support for the eval primitive.
 * Only built-in atomic types, tuples and tuplespace references can be included
in tuples. This will change in the future, and is partly the subject of my PhD.

Windows Issues:
 * The Windows version of Python does not come with a readline module, this
restricts the text interface to the server. A version of this module that works
with Windows can be downloaded from
http://newcenturycomputers.net/projects/readline.html. (Thanks to Pablo
Grigoletti for pointing this out.)

5. Contact
----------

All the latest news and information about PyLinda can be found at
http://www-users.cs.york.ac.uk/~aw/pylinda.
Comments, suggestions and bug reports are all welcome at [email protected]

6. License
----------
For full details of the license see the file LICENSE.

Copyright 2004-2006 Andrew Wilkinson <[email protected]>.

This file is part of PyLinda (http://www-users.cs.york.ac.uk/~aw/pylinda)

PyLinda is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.

PyLinda is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License
along with PyLinda; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA