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OCSManager Installation Guide¶

Requirements¶

curl¶

sudo apt-get install curl

python-lxml¶

This package is used for processing XML payload on the server and clients

sudo apt-get install python-lxml

python-pycurl¶

This package is exclusively used on clients to connect to the ocsmanager service

sudo apt-get install python-pycurl

python-setuptools¶

This is required to use easy_install:

sudo apt-get install python-setuptools

virtualenv¶

Ubuntu Natty comes with python-virtualenv package, but on September 29th generating a virtualenv with go-pylons results in having an ImportError:

ImportError: No module named _weakrefset

We will instead install latest virtualenv package using easy_install:

sudo easy_install virtualenv

Installation¶

In this guide, we will install pylons 1.0 in an isolated python environment:

$ cd mapiproxy/services/
$ virtualenv mydevenv
$ curl http://pylonshq.com/download/1.0/go-pylons.py | python - mydevenv

Then run the following command to activate the isolated python environment and reconfigure the service:

$ source mydevenv/bin/activate
$ cd ocsmanager
$ python setup.py develop

The next step is to modify your configuration file.

Then the service can be run using:

$ paster serve --reload development.ini

Patchs¶

Signals, select and asynchronous notifications¶

In the paste module installed along pylons, the event loop in serve_forever is calling handle_request from python2.7/SocketServer.py which calls select.select() function.
However when a new notification is received, a signal is emitted and is also catched by select.select() causing it to raise a "Interrupted System Call" error. The following patch add an exception in paste serve_forever loop to avoid raising the exception when the system call is set to EINTR.

Edit mydevenv/local/lib/python2.7/site-packages/Paste-1.7.5.1-py2.7.egg/paste/httpserver.py file (assuming mydevenv is your virtualenv base dir)

At the top of the file, add the following import:
```
import errno
import select
```

Change the serve_forever function with the following code:

    def serve_forever(self):
        """ 
        Overrides `serve_forever` to shut the threadpool down cleanly.
        """ 
        try:
            while self.running:
                try:
                    self.handle_request()
                except socket.timeout:
                    # Timeout is expected, gives interrupts a chance to
                    # propogate, just keep handling
                    pass
                except select.error, v:
                    if v[0] != errno.EINTR: raise
        finally:
            self.thread_pool.shutdown()

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