(This document is still under discussion)
The OpenLCB group provides prototype implementations to make it easier for hobbyists to experiment with OpenLCB, to demonstrate the OpenLCB protocols in action, and as concrete documentation. The prototypes are made available in the OpenLCB SVN repository. These prototypes are under continuous development, and the code will change from time-to-time. The group therefore has procedures and conventions for “versioning” the code so that people can use a preferred version for as long as they want, moving forward to a more recent one only when they wish to.
The versioning is done in the standard way using SVN to create copies of specific versions of a prototype.
OpenLCB uses a four-part version number (I.J.K.L) where each part has a conventional meaning:
I: OpenLCB specification version, increments when the specification for OpenLCB itself is updated in an incompatible way. These changes are quite rare. This number is coordinated across the entire project.
J: OpenLCB implementation version, increments when there are changes to the uses of OpenLCB that effect compatibility. A particular prototype can stay at e.g. “1.1.j.k” as long as needed, but once it is updated to use additional OpenLCB protocol features that are incompatible with the existing code, it should be updated to “1.2.j.k”
K: Software structure version, increments when the software structure has changed enough that existing users may have to update. A reorganization of code or class structure would be an example of this. Version 1.1.2.* and 1.1.3.* should operate with other devices in a compatible way, with only internal changes to the software.
L: Internal version, increments on minor implementation changes that don't effect software structure or OpenLCB protocol. This kind of change is quite common.
Version numbers are applied at several levels within OpenLCB and the prototypes. For example, the Java prototype might have version numbers 184.108.40.206, 220.127.116.11, 18.104.22.168, etc, while the C prototype(s) might have numbers 22.214.171.124, 126.96.36.199, 188.8.131.52, 184.108.40.206, 220.127.116.11, etc. There is no connection assumed among K and L version number parts between different prototypes; it is not necessary to increment the K part on one prototype just because another did. More effort is generally put into maintaining consistent I and J numbers across the set of prototypes so that all current development can interoperate.
At each level of the /prototypes file tree in SVN and on the web, there's an index.html file (example). This is where we document the versions that are available for that section of prototypes. A typical entry would be:
Now echoes back the messages received over TCP/IP to allow multiple connections.
svn co http://svn.code.sf.net/p/openlcb/svn/tags/18.104.22.168/prototypes/C/CAN2EtherNetServer
As more versions are defined, their descriptions will accumulate in the file. By including the SVN command or commands necessary to pull that particular version from the repository, there's no ambiguity as to how to get a specific version.
This section discusses how OpenLCB developers (people who can directly commit to OpenLCB SVN) can create tags when needed.
SVN doesn't provide a label or alias facility similar to a CVS tag. Instead, it provides an efficient copy mechanism to make a copy of a specific set of files. The procedure to label a new version (in this case, labeled 22.214.171.124) from your existing code (CAN2EtherNetServer directory, all checked into SVN) is;:
svn mkdir -–parents -m”comment” http://svn.code.sf.net/p/openlcb/svn/tags/126.96.36.199/prototypes/C/ svn copy -m”comment” CAN2EtherNetServer https://openlcb.svn.sourceforge.net/svnroot/openlcb/tags/188.8.131.52/prototypes/C/
The mkdir operation ensures that the directories exist, but may not be necessary depending on what versions have already been created.
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