zope.paste 1.0.0a1

Configuring the application

zope.paste provides a PasteDeploy-compatible factory for Zope 3’s WSGI publisher application and registers it in an entry point. We can therefore create a very simple Zope 3 application in a PasteDeploy configuration file (e.g. paste.ini):

[app:main]
use = egg:zope.paste
site_definition = /path/to/site.zcml
file_storage = /path/to/Data.fs
devmode = on

In this case, /path/to/site.zcml refers to a site.zcml as known from a Zope 3 instance. You can, for example, put paste.ini into an existing Zope 3 instance, next to site.zcml.

Configuring the ZODB database

Instead of referring to a ZODB FileStorage using the file_storage setting, you can also configure multiple or other ZODB database backends in a ZConfig-style configuration file (much like zope.conf), e.g. the following configures a ZEO client:

<zodb>
  <zeoclient>
    server localhost:8100
    storage 1
    cache-size 20MB
  </zeoclient>
</zodb>

Refer to this file from paste.ini this way (and delete the file_storage setting):

db_definition = db.conf

Configuring the server

In order to be able to use our Zope application, we only need to add a server definition. We can use the one that comes with Paste or PasteScript, rather:

[server:main]
use = egg:PasteScript#wsgiutils
host = 127.0.0.1
port = 8080

Now we can start the application using the paster command that comes with PasteScript:

$ paster serve paste.ini

WSGI middlewares can be configured like described above or on the PasteDeploy website.

Multiple WSGI applications within Zope 3

If you wanted to host more than one WSGI application there are a couple ways of doing it:

1. Using a composite application as described in PasteDeploy.

2. Setting up extra IServerType utilities.

I’m going to show you how to do the latter now.

The trick here is that you have the option to use both the zserver and the twisted WSGI servers. zope.paste is just glue code, so we defined a IServerType utility for each, and the only thing special is that the utility name is passed on to the WSGI application factory.

Here’s an excerpt from the configure.zcml as found on this package:

<configure zcml:condition="have zserver">
  <utility
      name="Paste.Main"
      component="._server.http"
      provides="zope.app.server.servertype.IServerType"
      />
</configure>

<configure zcml:condition="have twisted">
  <utility
      name="Paste.Main"
      component="._twisted.http"
      provides="zope.app.twisted.interfaces.IServerType"
      />
</configure>

Depending on which server is available, the right IServerType utility is registered. You are encouraged to use the same pattern when defining yours.

So suppose you want to have a second WSGI application. Here’s how you could do it.

1. Create a new IServerType utility. This excerpt could be added to a configure.zcml in your own package, or to a standalone file in etc/package_includes:

   <configure zcml:condition="have zserver">
     <utility
         name="Paste.Another"
         component="zope.paste._server.http"
         provides="zope.app.server.servertype.IServerType"
         />
   </configure>
   
   <configure zcml:condition="have twisted">
     <utility
         name="Paste.Another"
         component="zope.paste._twisted.http"
         provides="zope.app.twisted.interfaces.IServerType"
         />
   </configure>

2. Change your zope.conf file to define a new server, using the newly-created Paste.Another utility:

   <server>
     type Paste.Main
     address 8080
   </server>
   
   <server>
     type Paste.Another
     address 8180
   </server>

3. Define a WSGI application Paste.Another in paste.ini:

   [pipeline:Paste.Main]
   pipeline = xslt main
   
   [app:main]
   paste.app_factory = zope.paste.application:zope_publisher_app_factory
   
   [filter:xslt]
   paste.filter_factory = xslfilter:filter_factory
   
   [app:Paste.Another]
   paste.app_factory = zope.paste.application:zope_publisher_app_factory

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