[opam-devel] ANNOUNCE: OWS, the Opam Wheather Service

[Roberto Di Cosmo]

Dear fellow Opam developers, 

     We are proud to announce the first public release of a new and fully
refactored version of OWS, the Opam Weather Service, and we are now reaching out
to everybody on opam-devel for feedback and contribution to its evolution.

If you are in hurry, the short message is: 

  - explore the dashboard available online at http://ows.irill.org/ ! 

    The packages listed there are arranged by package name and sorted according
    to the number of issues found on all available versions, you can click on a
    package to get details of these issues, and zone-in on specific packages
    using the search box. 

    On http://ows.irill.org/latest/today/summary.html you will find the list of
    the causes of package installability problems, sorted by their impact:
    packages causing the largest number of problems come first, to help focus
    developer energy when improving the quality of the Opam repository

  - use this information to look after the packages you are responsible for:
    hints on how to fix dependency issues are displayed for each package

  - if you want new features, make suggestions or report a bug, look at the
    source code, available under AGPL from https://github.com/OCamlPro/ows
    You are very welcome to contribute using github

--
Pietro Abate, Roberto Di Cosmo, Louis Gesbert and Fabrice Le Fessant


Here are more details for who wants to know more.
-------------------------------------------------

OWS and distcheck

Built on top of the distcheck tool from the dose library [1], OWS scans daily
the packages in the Opam repository to spot all packages that cannot be
installed at all because of dependency issues, and presents a dashboard that
provides a bird's eye overview of the state of the repository.

This static check is blazingly fast and does not require any physical
installation: it catches *all* dependency issues, and it catches *only*
dependency issues, so it does not replaces the other testing tools that are
needed to catch compilation, configuration and installation issues encountered
when actually deploying a package.

A dashboard based on distcheck has been used in the Debian distribution for
almost ten years [2], and we know well that it can be extremely beneficial to
improve a package repository if it is properly integrated in a quality assurance
process.

A full paper describing how distcheck has been used is going to be presented at
MSR 2015 in a week [3]; a preprint is already availabe [4].

The new OWS
--------------------

An experimental prototype of OWS has been running for almost a year; the new
version we unveil today is rebuilt from scratch in order to:

 - clearly separate the presentation of the results in a dashboard from the
   distcheck backend from dose: this required changes to opam, dose and
   distcheck

 - provide improved presentation of the results, in order to facilitate
   the identification of the most problematic packages

 - make available all relevant source code, properly released under an
   Open Source licence, written by Pietro Abate (Inria/Irill)

[1] http://dose.gforge.inria.fr/
[2] http://qa.debian.org/dose
[3] http://2015.msrconf.org/program.php 
[4] http://www.dicosmo.org/preprints/msr-2015-distcheck.pdf