blog entries created by Julien Cristau
  • Status of the CubicWeb python3 porting effort, February 2016

    2016/02/05 by Julien Cristau

    An effort to port CubicWeb to a dual python 2.6/2.7 and 3.3+ code base was started by Rémi Cardona in summer of 2014. The first task was to port all of CubicWeb's dependencies:

    • logilab-common 0.63
    • logilab-database 1.14
    • logilab-mtconverter 0.9
    • logilab-constraint 0.6
    • yams 0.40
    • rql 0.34

    Once that was out of the way, we could start looking at CubicWeb itself. We first set out to make sure we used python3-compatible syntax in all source files, then started to go and make as much of the test suite as possible pass under both python2.7 and python3.4. As of the 3.22 release, we are almost there. The remaining pain points are:

    • cubicweb's hadn't been converted. This is fixed in the 3.23 branch as of (don't follow that link, the commit is huge)
    • the CubicWebServerTC test class uses twisted to start an http server thread, and twisted itself is not available for python3
    • the current method to serialize schema constraints into CWConstraint objects gives different results on python2 and python3, so it needs to be fixed (
    • various questions around packaging and deployment: what happens to e.g. the cubicweb-common package installing into python2's site-packages directory? What does the ${prefix}/share/cubicweb directory become? How do cubes express their dependencies? Do we need a flag day? What does that mean for applications?

  • CubicWeb Sprint report for the "ZMQ" team

    2012/02/27 by Julien Cristau

    There has been a growing interest in ZMQ in the past months, due to its ability to efficiently deal with message passing, while being light and robust. We have worked on introducing ZMQ in the CubicWeb framework for various uses :

    • As a replacement/alternative to the Pyro source, that is used to connect to distant instances. ZMQ may be used as a lighter and more efficient alternative to Pyro. The main idea here is to use the send_pyobj/recv_pyobj API of PyZMQ (python wrapper of ZMQ) to execute methods on the distant Repository in a totally transparent way for CubicWeb.
    • As a JSONServer. Indeed, ZMQ could be used to share data between a server and any requests done through ZMQ. The request is just a string of RQL, and the response is the result set formatted in Json.
    • As the building block for a simple notification (publish/subscribe) system between CubicWeb instances. A component can register its interest in a particular topic, and receive a callback whenever a corresponding message is received. At this point, this mechanism is used in CubicWeb to notify other instances that they should invalidate their caches when an entity is deleted.