infrae.wsgi 2.0

WSGI support for Zope 2

infrae.wsgi provides a support to run Zope 2 as a WSGI application.

Contents

• Introduction

  • Errors

• Installation

  • Paste Deploy

  • Virtual Hosting

• Testing

• Changes

  • 2.0 (2012-09-04)

  • 1.3 (2011-07-27)

  • 1.2 (2011-02-02)

  • 1.1 (2010-10-07)

  • 1.0 (2010-07-15)

Introduction

It basically does the same work than:

• repoze.zope2,

• Zope 2 new builtin WSGI publisher.

Except than:

• It work with real Zope 2 applications and no monkey-patches,

• It pay specially attention to properly implement streaming. You can use your ZODB connection while streaming, (either with the .write method of request, or returning an IResult or an IStreamIterator iterator). ConflictError generate a final error if they happens during a streaming operation, not re-sending things again on the same HTTP connection,

• All ConflictError are properly managed.

• All those cases are tested.

It does not:

• Provide Zope 2 as a collection of WSGI middlewares, as Zope 2 paradigm / code base is not good for it,

• Do all fancy request body changes that old Zope 2 publisher does, as nobody use it anymore since a very long time.

Errors

Error messages are handled a bit differently than in traditional Zope 2, in order to make things simpler.

They are views on errors (called error.html), and wrapped in acquisition around the context where they happened:

from five import grok

class CorpError(Exception):
    """Custom corporate error.
    """

class CorpErrorMessage(grok.View):
    grok.context(CorpError)
    grok.name('error.html')

    def render(self):
        # aq_parent(self) is where the error happened
        return u'I Failed: %s' % str(self.error.args)

Errors are logged with useful information:

• Which is the URL triggering this error,

• The user-agent,

• The referent,

• The logged in username,

• On which object, its physical path and meta_type if possible.

The error log can be accessible online via /errorlog.html on any Zope 2 content.

Installation

infrae.wsgi has been and deployed with Paste Deploy and mod_wsgi. It correctly respect the WSGI specification and should work with any WSGI server.

Paste Deploy

The application is available with the entry point infrae.wsgi#zope2.

It expect an option variable called zope_conf that point to the Zope 2 configuration file.

The option debug_mode can as well be specified, to run Zope in debug mode. In debug mode, error pages will not be rendered by Zope and the errors will propagate in the wsgi stack. This behavior will let you debug errors with specialized middlewares.

The option zope_workers can be used to specify the maximum of threads Zope should allow to process requests at the same time (default to 4). This can be usefull if you wish to allow more threads in your wsgi environment, in case you have middlewares or other applications that intercept the requests and support more threads than Zope does.

Virtual Hosting

You can add two headers in your proxy in order to control the virtual hosting:

• X-VHM-URL: That would the complete URL of your site, where you want to see your Zope application, like http://www.mysite.com/application.

• X-VHM-Path: That would be an optional path to Zope folder you see instead of the Zope root, lile /my/folder.

Testing

A layer inheriting of infrae.testing Zope2Layer layer called BrowserLayer let you write functional tests.

It provides both an http function and a Browser class (like the one provided by zope.testbrowser) that you can use, and that will connect to the tested application using the WSGI support provided by this package.

This will let you do functional testing, and things will work exactly like in your browser, as the requests will be processed the same way than they are in real life (which is not really the case with the Testing module of Zope 2).

You will be actually able to test applications that do use streaming:

import unittest

from infrae.wsgi.testing import Browser, BrowserLayer
import corp.testpackage


class CorpTestCase(unittest.TestCase):
   layer = BrowserLayer(corp.testpackage)

   def setUp(self):
       self.root = self.layer.get_application()
       # Create some test content

   def test_feature(self):
       browser = Browser()
       browser.open('http://localhost/somepage')
       self.assertEqual(browser.status, 200)
       ...

Changes

2.0 (2012-09-04)

• Refactor the virtual hosting, traversing and authentication code from Zope 2 BaseRequest into three different pieces of code, that can customizable. This makes possible to change how authentication, or virtual hosting is done.

• Add a TestRequest that can be used in tests. This is the same thing than a zope.publisher test request, except it is based on a Zope 2 request, and have all the same behavior than a Zope 2 request.

• A configurable semaphore have been added to limit the number of concurrent threads that can access the Zope 2 application. This is usefull when you have middleware that handles requests on their own, so they are not limited to the restriction imposed by Zope 2 on the number of threads.

1.3 (2011-07-27)

• Improve logging.

• BadRequest and Forbidden exceptions are now ignored by default in the logs.

• Fix a bug the original CONTENT_LENGTH header is empty.

• When an error happens on an IBrowserPage, use the page’s context when handling the error (to prevent falling back to the nearest Site)

1.2 (2011-02-02)

• Add a view debugzope.html that display a dump of the server threads. You need to be manager to access it.

• You can from the errorlog.html configure the error you wish to ignore (not log). This is a non persistent setting.

• Handle buggy PAS unauthorized plugins, by catching any error, and logging them. In case of problem, a basic 401 response is sent back.

• Add the ZPublisher insertBase functionality: if a base is set by the request, and we render HTML, with an HEAD tag and no BASE tag, insert a BASE tag with the value provided by the request. This fix broken ZMI screens.

1.1 (2010-10-07)

• Fix a bug where Content-Length is not set and cannot be set.

• Correctly encode payload when needed before sending it (if it was a unicode string).

• Error codes less when 500 triggers a commit now, this let you support login pages that uses a Zope session ID.

• Add some hooks in the testing code to be more extensible (used for infrae.testbrowser).

1.0 (2010-07-15)

• Initial release.