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--- diana:batch_diana_on_headless_systems [2014-03-11 15:12:08]
davidb created
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-====== Batch Diana on Headless Systems ======
-Normally, Diana is configured to run on systems with an X server, using OpenGL for accelerated rendering of maps and data. When running Diana in batch mode with the ''bdiana'' tool, nothing is displayed on the screen via the X server, but the user is often running ''bdiana'' on a system with an X server present. When building Diana normally, the ''bdiana'' tool that is produced is linked to the X libraries on the system and can be run by users on workstations without problems.
-On servers, where it is not desirable to run an X server, we cannot use the ''bdiana'' tool produced by the normal Diana build without some kind of X server. Traditionally, Xvfb has been used to provide the support that this version of ''bdiana'' needs to run. However, this was not always a reliable solution, so we have used an alternative configuration of Diana to produce a version of ''bdiana'' that runs without an X server. This does two things to avoid dependencies on X:
-  - It uses a custom build of the Qt libraries that do not depend on X libraries.
-  - It provides a wrapper that redirects OpenGL calls to Qt, rendering products entirely in software. Only the subset of OpenGL functions that Diana uses are wrapped.
-===== Building Qt =====
-We build an alternative set of Qt libraries using the standard Qt 4.8.1 sources, applying some patches and using an "embedded" configuration to remove the dependency on X.
-The patches we use are part of the Debian packaging we use to build packages for Ubuntu 12.04. These can be obtained from a git repository:
-<code>
-git clone https://projects.met.no/~davidb/projects/qt4-headless/git qt4-headless
-</code>
-The standard Debian package building process involves applying the patches found in the ''debian/patches'' directory to the Qt 4.8.1 sources then running the ''configure'' script in the way described in the ''debian/rules'' file.
-===== Configuring Diana =====
-**//Note: This is a work in progress. More details to be added.//**