pycom 0.6.0
Distributed component model for Python.
License: BSD

Introduction
=============

PyCOM is simple and easy-to-use distributed component model written in Python.
PyCOM makes different parts of your network application isolated and
independent, while allowing easy and straightforward interaction between them.
PyCOM may be seen as an easy and lightweight web services replacement.

Ideology highlights:

- Non-intrusive design without black magic and lots of auto-generated code
- Easily adapts to a rapidly changing environment
- ... and matches pythonic
  `EAFP <http://docs.python.org/glossary.html#term-eafp>`_ approach
- Effective, easy-to-implement and portable protocol
- Support for binary attachments
- Support for stateful services via HTTP-alike sessions
- Low level enough to build your own frameworks
- ... and still simple enough to be used as is
- Free software (new BSD license)

Technical highlights:

- Separate (potentially replaceable) *ZeroJSON* protocol implementation
- Easily extensible core library
- Does not required special "container" software
- Introspection support for services
- Load balancing over several services with the same interface
- Comprehensive test suite and documentation
- Python 2 and Python 3 support out-of-box

There is ongoing effort to create a C++ client library for PyCOM:
https://bitbucket.org/divius/libpycom

Main concepts
--------------

With PyCOM you build your application as a number of *services*,
each running in it's own process (or even on it's own computer).
You maintain a PyCOM *nameserver* for finding services by their names
(by the way, nameserver itself is a service).

Services provide *interfaces*, i.e. a named way of interacting with service.
They are somewhat similar to interfaces in e.g. Java, but note that
PyCOM does not perform any checks on interfaces. Interface usually has
some amount of *methods*.

Services are identified by path with parts separated by slashes,
e.g. ``/com/foo/group/service``.

Interfaces are identified by name with parts separated by dots,
e.g. ``com.foo.my-interface``.

Examples
---------

Service example (module ``package1.module1``)::

    import pycom

    @pycom.interface("com.foo.example")
    class MyService(pycom.Service):

        @pycom.method
        def bar(self, request, name, value=None):
            return {name : value}

Example command line for running this service (provided nameserver is running
on ``192.168.10.1:2012``)::

    python -m pycom -a tcp://192.168.10.2:2013 -n tcp://192.168.10.1:2012 package1.module1

Example client code for this service::

    import pycom

    context = pycom.ProxyContext(nameserver="tcp://192.168.10.1:2012")
    with context.locate("com.foo.example") as component:
        print component.bar(name="field1", value=42)
        # Prints {"field1" : 42}
        print component.bar("field1", value=42)
        # Prints {"field1" : 42}
        print component.bar("field1")
        # Prints {"field1" : None}
        print component.introspect()
        # Prints a lot of introspection information

Quick start
------------

Our requirements are:

- POSIX-compatible OS (other may work)
- `Python <http://www.python.org>`_ 2.6, 2.7 or >= 3.1
- `0MQ Python bindings <http://www.zeromq.org/bindings:python>`_ >= 2.1.11
- `six <http://packages.python.org/six/>`_ for Python 3 compatibility
  (maybe we'll drop it later)

To run test suite you'll also need:

- `coverage.py <http://nedbatchelder.com/code/coverage/>`_
- `unittest2 <http://pypi.python.org/pypi/unittest2>`_ (Python 2.6 only)
- `unittest2py3k <http://pypi.python.org/pypi/unittest2py3k>`_ (Python 3.1 only)

To test (logs will be saved in `test.log`)::

    $ python test.py

To build HTML documentation (requires `Sphinx <http://sphinx.pocoo.org>`_)::

    $ python setup.py build_sphinx
    $ <your-browser> build/sphinx/html/index.html

To install from sources::

    $ python setup.py install

or via `pip`::

    $ pip install pycom

To start nameserver use script::

    $ /usr/local/bin/pycom-nameserver

You may need to adjust nameserver configuration.

Do not forget to read about known issues in the current version:
http://packages.python.org/pycom/status.html#known-issues

Support
--------

PyCOM repository and issue tracker are hosted on BitBucket.

    Download releases: http://pypi.python.org/pypi/pycom#downloads

    Latest source code: https://bitbucket.org/divius/pycom/overview

    Report bugs: https://bitbucket.org/divius/pycom/issues

    Read documentation: http://www.pycom.org

Enjoy =)