Direct download to native libraries and explanations

[oliviercailloux]

Please consider providing a direct link to download the native libraries (dll, so) for use with Java for the main platforms supported by Google OR-Tools.

I have provided a Maven library for Google OR-Tools (here, see issue #202). To use it, users have to add the native library for their platform. Currently it is not easy, as they have to download the zipped whole distribution for Google OR-Tools and extract the required files from it. It would be much easier if I could simply provide them with a link.

To make it worse, I ignore to which extent a native library compiled on some linux version is useable on some other linux version. Can I provide a single version of the native libraries (say, the Ubuntu 18.10 one) and suggest to linux users to use this one? Or should I insist that they each go download the one version for their specific variant?

[Mizux]

For python we use the manylinux official docker image which is an "old" Centos:5 IIRC so or-tools python NATIVE package is built against a glibc 2.12 which should provide maximum compatibility for most linux distro (according to Python).
see: https://www.python.org/dev/peps/pep-0513/
I guess for java you should use the same binaries, using an ubuntu 18.10 you are pretty sure it won't for any previous version like the 16.04 LTS or 18.04 LTS...

[oliviercailloux]

Thanks for the help. Let me check if I understood correctly.

I understand that picking a native library built for a recent OS is a bad idea as it generally won’t run on an OS using older system (or shared) native libraries. As I understand it, you suggest to me to rather point, for a general linux audience, to the native library version that is built by Google OR Tools on a platform specifically designed for maximal compatibility, namely, a CentOS 5 based one (as explained in the referenced PEP), labelled as manylinux1.

BUT, downloading and opening the file ortools-7.0.6546-cp37-cp37m-manylinux1_x86_64.whl, I can’t find the libraries I need for Java (understandably, as it is a release file for Python). All files in the release page that are labeled manylinux seem to be Python wheels package; and I see no library in the Java download page built for CentOS 5 or marked as manylinux.

Do I understand correctly that manylinux distribution is provided only for Python packages, and not currently provided for Java consumption? If so, is this expected in the future?

[Mizux]

Yes, you are right.

If you look at tools/docker directory you can see:

1. We provide a "Manylinux" python only package using the container provided by the python community which is call manylinux2010, and it is based on a Centos 7 image -> Yes it is used for python package so there is no the necessary Java tools directly available
2. Several dockers for few majors distro

We drop our Centos5/6 containers since they don't work with a recent Linux distro (TL;DR they use a now forbidden vsyscall that any recent kernel don't have anymore).
ref: https://mail.python.org/pipermail/wheel-builders/2016-December/000239.html

For Java/.Net I would use a Centos 7 based container to have the maximum compatibility out there.

see the glibc currently used by few distros:

[lperron]

I assume we have nothing more to do.
I do not want to add another binary artifact, but with the centos7 linux build, you only need to incorporate 3 native libraries in your build.