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+.. -*- coding: utf-8 -*-
+
+.. _cubes:
+
+Cubes
+-----
+
+Standard library
+~~~~~~~~~~~~~~~~
+
+A library of standard cubes are available from `CubicWeb Forge`_
+Cubes provide entities and views.
+
+The available application entities are:
+
+* addressbook: PhoneNumber and PostalAddress
+
+* basket: Basket (like a shopping cart)
+
+* blog: Blog (a *very* basic blog)
+
+* classfolder: Folder (to organize things but grouping them in folders)
+
+* classtags: Tag (to tag anything)
+
+* file: File (to allow users to upload and store binary or text files)
+
+* link: Link (to collect links to web resources)
+
+* mailinglist: MailingList (to reference a mailing-list and the URLs
+  for its archives and its admin interface)
+
+* person: Person (easily mixed with addressbook)
+
+* task: Task (something to be done between start and stop date)
+
+* zone: Zone (to define places within larger places, for example a
+  city in a state in a country)
+
+The available system entities are:
+
+* comment: Comment (to attach comment threads to entities)
+
+
+Adding comments to BlogDemo
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To import a cube in your application just change the line in the
+``__pkginfo__.py`` file and verify that the cube you are planning
+to use is listed by the command ``cubicweb-ctl list``.
+For example::
+
+    __use__ = ('comment',)
+
+will make the ``Comment`` entity available in your ``BlogDemo``
+application.
+
+Change the schema to add a relationship between ``BlogEntry`` and
+``Comment`` and you are done. Since the comment cube defines the
+``comments`` relationship, adding the line::
+
+    comments = ObjectRelation('Comment', cardinality='1*', composite='object')
+
+to the definition of a ``BlogEntry`` will be enough.
+
+Synchronize the data model
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Once you modified your data model, you need to synchronize the
+database with your model. For this purpose, `CubicWeb` provides
+a very useful command ``cubicweb-ctl shell blogdemo`` which
+launches an interactive migration Python shell. (see 
+:ref:`cubicweb-ctl-shell` for more details))
+As you modified a relation from the `BlogEntry` schema,
+run the following command:
+::
+
+  synchronize_rschema('BlogEntry')
+  
+You can now start your application and add comments to each 
+`BlogEntry`.