Blog entries

  • CubicWeb 3.7 released


    Hi there !

    I'm pleased to announce the 3.7 release of CubicWeb, after a much shorter development cycle than for the 3.6...

    But it still have some interesting changes:

    • use the newly created logilab.database package (you'll have to install it as well as upgrade logilab.common and rql)
    • proper behaviour on the repository side of cubiweb:
      • dropped unsafe_execute, execute is now unsafe by default in hooks and operations. You can still explicitly control security using the enabled_secury context manager
      • proper transaction hooks control using the hooks_control context manager
    • started some transaction undo support (only undo of deletion supported right now)
    • various other bug fixes and improvments

    Notice the 3.6 branch will still be maintained for some time.


  • Undoing changes in CubicWeb

    2012/02/29 by Anthony Truchet

    Many desktop applications offer the possibility for the user to undo the recent changes : a similar undo feature has now been integrated into the CubicWeb framework.

    Because a semantic web application and a common desktop application are not the same thing at all, especially as far as undoing is concerned, we will first introduce what is the undo feature for now.

    What's undoing in a CubicWeb application

    A CubicWeb application acts upon an Entity-Relationship model, described by a schema. This ensures some data integrity properties. It also implies that changes are made by group called transaction : so as to insure the data integrity the transaction is completely applied or none of it is applied. What may appear as a simple atomic action to a user can actually consist in several actions for the framework. The end-user has no need to know the details of all actions in those transactions. Only the so-called public actions will appear in the description of the an undoable transaction.

    Lets take a simple example: posting a "comment" for a blog entry will create the entity itself and the link to the blog entry.

    The undo feature for CubicWeb end-users

    For now there are two ways to access the undo feature when it has been activated in the instance configuration file with the option undo-support=yes. Immediately after having done something the undo** link appears in the "creation" message.

    Screenshot of the undo link in the message

    Otherwise, one can access at any time the undo-history view accessible from the start-up page.

    Screenshot of the undo link in the message

    This view shows the transactions, and each provides its own undo link. Only the transactions the user has permissions to see and undo will be shown.

    Screenshot of the **undo** link in the message

    If the user attempts to undo a transaction which can't be undone or whose undoing fails, then a message will explain the situation and no partial undoing will be left behind.

    What's next

    The undo feature is functional but the interface and configuration options are quite limited. One major, planned, improvement would be enable the user to filter which transactions or actions he sees in the undo-history view. Another critical improvement would be to selectively enable the undo feature on part of the entity-relationship schema to avoid storing too much data and reduce the underlying overhead.

    Feedback on this undo feature for specific CubicWeb applications is welcome. More detailed information regarding the undo feature will be published in the CubicWeb book when the patches make it through the review process.

  • What's new in CubicWeb 3.15

    2012/05/14 by Sylvain Thenault

    CubicWeb 3.15 introduces a bunch of new functionalities. In short (more details below):

    • ability to use ZMQ instead of Pyro to connect to repositories
    • ZMQ inter-instances messages bus
    • new LDAP source using the datafeed approach, much more flexible than the legacy 'ldapuser' source
    • full undo support

    Plus some refactorings regarding Ajax function calls, WSGI, the registry, etc. Read more for the detail.

    New functionalities

    • Add ZMQ server, based on the cutting edge ZMQ socket library. This allows to access distant instances, in a similar way as Pyro.
    • Publish/subscribe mechanism using ZMQ for communication among cubicweb instances. The new zmq-address-sub and zmq-address-pub configuration variables define where this communication occurs. As of this release this mechanism is used for entity cache invalidation.
    • Improved WSGI support. While there are still some caveats, most of the code which was twisted only is now generic and allows related functionalities to work with a WSGI front-end.
    • Full undo/transaction support: undo of modifications has finally been implemented, and the configuration simplified (basically you activate it or not on an instance basis).
    • Controlling HTTP status code returns is now much easier:
      • WebRequest now has a status_out attribute to control the response status ;
      • most web-side exceptions take an optional status argument.

    API changes

    • The base registry implementation has been moved to a new logilab.common.registry module (see #1916014). This includes code from :

      • cubicweb.vreg (everything that was in there)
      • cw.appobject (base selectors and all).

      In the process, some renaming was done:

      • the top level registry is now RegistryStore (was VRegistry), but that should not impact CubicWeb client code;
      • former selectors functions are now known as "predicate", though you still use predicates to build an object'selector;
      • for consistency, the objectify_selector decorator has hence been renamed to objectify_predicate;
      • on the CubicWeb side, the selectors module has been renamed to predicates.

      Debugging refactoring dropped the need for the lltrace decorator. There should be full backward compat with proper deprecation warnings. Notice the yes predicate and objectify_predicate decorator, as well as the traced_selection function should now be imported from the logilab.common.registry module.

    • All login forms are now submitted to <app_root>/login. Redirection to requested page is now handled by the login controller (it was previously handled by the session manager).

    • Publisher.publish has been renamed to Publisher.handle_request. This method now contains a generic version of the logic previously handled by Twisted. Controller.publish is not affected.

    Unintrusive API changes

    • New 'ldapfeed' source type, designed to replace 'ldapuser' source with data-feed (i.e. copy based) source ideas.
    • New 'zmqrql' source type, similar to 'pyrorql' but using ømq instead of Pyro.
    • A new registry called 'services' has appeared, where you can register server-side cubicweb.server.Service child classes. Their call method can be invoked from a web-side AppObject instance using the new self._cw.call_service method or a server-side one using self.session.call_service. This is a new way to call server-side methods, much cleaner than monkey patching the Repository class, which becomes a deprecated way to perform similar tasks.
    • a new ajaxfunction registry now hosts all remote functions (i.e. functions callable through the asyncRemoteExec JS api). A convenience ajaxfunc decorator will let you expose your python functions easily without all the appobject standard boilerplate. Backwards compatibility is preserved.
    • the 'json' controller is now deprecated in favor of the 'ajax' one.
    • WebRequest.build_url can now take a __secure__ argument. When True, cubicweb tries to generate an https url.

    User interface changes

    A new 'undohistory' view exposes the undoable transactions and gives access to undo some of them.