D-Net

h1. Developers' Best Practices

It is time for D-Net development teams to find a strategy to improve our developement work!

The introduction of Jenkins and Nexus helped a lot in terms of code management, but now it is time to establish a set of guidelines to better co-ordinate our teams.

The following best practices are inspired by CNR developers' common sense, so we do not assume they are written in stones and applies as they are also in your cases.

So, you are strongly invited to comment/update this wiki page, so that we can reach a consensus. 

h2. Coding

Most of the D-Net modules have been migrated to from the old build system ant to maven. This implies some changes to the module directories and files, here's the migration guide: 

http://ci.research-infrastructures.eu/public/docbook/MavenMigration.html

Maven compliant D-Net module structure:

<pre>

.

├── pom.xml

├── src

│   ├── main

│   │   ├── java

│   │   │   └── eu

│   │   │       └── dnetlib

│   │   └── resources

│   │       └── eu

│   │           └── dnetlib

│   └── test

│       ├── java

│       │   └── eu

│       │       └── dnetlib

│       └── resources

│           └── eu

│               └── dnetlib

└── target

    └── classes

</pre>

Hint: consider to define the svn:ignore property, set on the module root

<pre>

cd <MODULE_NAME>

svn pe svn:ignore .

.classpath

.project

.settings

target 

</pre>

h2. Branching

It is always recommended to create a new branch when performing heavy changes to a module, rather than directly into trunk.

h2. Use CI: trust Jenkins!

The developer should clean the @.m2/repository/eu@ local repository from time to time to be sure that there are no modules installed locally. 

Modules should be downloaded from Nexus in order to properly resolve dependencies.

h2. Maven dependencies

For information about version conflict resolution with Maven3:

* http://docs.codehaus.org/display/MAVEN/Versioning

* https://cwiki.apache.org/confluence/display/MAVEN/Maven+3.x+Compatibility+Notes

Generally speaking, we suggest to use the keyword @LATEST@ to refer to the last available artifact (snapshot or release) for a module.

Keep in mind that Maven3 considers:

@1.0-alpha-1 < 1.0-beta-1 < 1.0-SNAPSHOT < 1.0 < 1.1-SNAPSHOT@

h2. Release Best Practices

h3. When/Why releasing a module?

* Generally speaking a developer should release a module when the code is mature enough to be used by others. 

* An early release should be available in case others are relying on a module that is currently under heavy development (i.e., frequent commits that imply frequent snapshot updates), in order to avoid blocking other development activities.

* Before updating an interface (e.g., service interfaces) or library (e.g., common and utilities modules) a developer MUST ENSURE there is a release of the current version. 

h3. How to assign a release version number?

Before releasing a module, you must check which kinds of changes have been performed since the last release.

@svn log@ is your friend here :) .

Depending on the kind of changes you can decide to increase the artifact version according to the following guidelines:

* BIG CHANGES impact the MAJOR version number. Ex. @0.0.1 --> 1.0.0@

** Examples of big changes are: updates to service interfaces, shared libraries, new functionalities.

* MINOR CHANGES impact the MINOR version number. Ex. @1.2.5 --> 1.3.0@

** Examples of minor changes are: service internals, non-shared code and libraries, important bug fixes.

* BUG FIXES impact the BUILD version number. Ex. @1.4.2 --> 1.4.3@

** Examples are small bug fixes that do not affect other components 

h3. How to release?

These are the steps for the release of a module, given that developer has a fresh checkout of the module to be released.

# Ensure that the module to be released and the modules depending on it compile fine on Jenkins (http://ci.research-infrastructures.eu/).

# Update and commit the version of the module (trunk) to be released according to the guidelines above. 

This maven command can be helpful:

 @mvn versions:set -DnewVersion={release_version}-SNAPSHOT@

# Copy the trunk source code to a release branch:

@svn cp https://svn.driver.../modules/{MODULE_NAME}/trunk https://svn.driver.../modules/{MODULE_NAME}/releases/{release_version}@

# Switch to the release branch:

@svn switch https://svn.driver.../modules/{MODULE_NAME}/releases/{release_version}@

# A released module MUST depend and inherit ONLY from released modules. Therefore the pom.xml file MUST be updated as follows:

## change the parent version to a released version. Current is 0.0.1-alpha.

## change all snapshot dependencies to a released version. Ex. @0.2.3-SNAPSHOT --> 0.2.3@

## change the artifact version by removing the @-SNAPSHOT@ suffix.

# Commit the updated pom.xml.

# Ensure the module compiles: @mvn clean compile package -U@

# Create the release build job on Jenkins (http://ci.research-infrastructures.eu/):

## Select "New job"

## Type in the name of the job as 

@[module name]-release-[version]@. Ex. @dnet-runtime-release-0.0.9@

## Select "Create from existing job" and type in @dnet-svn-template-release@, then press OK

## Modify the repository URL so that it matches the svn public folder of the release branch: 

http://svn-public.driver.../modules/{MODULE_NAME}/releases/{release_version}  

## Save, enable the job, start the job, watch it compile, ensure it is deployed on nexus, disable the job again (an artifact on the dnet-release repository cannot be overwritten, hence we disable the job just to be sure they are not fired again by mistake).

# Switch back to trunk:

@svn switch https://svn.driver.../modules/{MODULE_NAME}/trunk@

# Increase the build version number and commit the pom.xml. Example: if the version is @1.2.3-SNAPSHOT@ (it means that you've just released version @1.2.3@), increase the number to @1.2.4-SNAPSHOT@.

Possibly a script will be made available to cover the points from 2 to 7, 9, and 10.