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Asynchronous Native Java Client for Kudu
- Java 7
- Maven 3
- protobuf 2.5.0
$ mvn package -DskipTests
The client jar will can then be found at kudu-client/target.
By default, the Kudu CSD will be built along with the rest of the client. It requires access to the Kudu binaries which may not be available. For example, when building on OSX.
Here's how to skip building the kudu-csd module:
$ mvn package -DskipTests -DskipCSD
Most of the unit tests will start their own cluster but it is also possible to provide your own.
By default, the unit tests will start a master and a tablet server using the flags file located in the src/test/resources/ directory. The tests will locate the master and tablet server binaries by looking in 'build/latest/' from the root of the git repository. If you have recently built the C++ code for Kudu, those should be present already.
Once everything is setup correctly, run:
$ mvn test
In order to point the unit tests to an existing cluster, you need to use a command line like this one:
$ mvn test -DstartCluster=false
If you choose to not start a cluster, the tests will look for a master running on localhost:7051. If you would like to run against a remote cluster, you can override this using -DmasterAddress:
$ mvn test -DstartCluster=false -DmasterAddress=foo.example.com:7051
If for some reason you would like to start a cluster, but use binaries other than the ones in build/latest/, you can pass -DbinDir=/path/to/directory.
Maven projects can be integrated with Eclipse in one of two ways:
- Import a Maven project using Eclipse's m2e plugin.
- Generate Eclipse project files using maven's maven-eclipse-plugin plugin.
Each approach has its own pros and cons.
The m2e approach is generally recommended as m2e is still under active development, unlike maven-eclipse-plugin. Much of the complexity comes from how m2e maps maven lifecycle phases to Eclipse build actions. The problem is that m2e must be told what to do with each maven plugin, and this information is either conveyed through explicit mapping metadata found in pom.xml, or in an m2e "extension". m2e ships with extensions for some of the common maven plugins, but not for maven-antrun-plugin or maven-protoc-plugin. The explicit metadata mapping found in kudu-client/pom.xml has placated m2e in both cases (in Eclipse see kudu-client->Properties->Maven->Lifecycle Mapping). Nevertheless, maven-protoc-plugin isn't being run correctly.
To work around this, you can download, build, and install a user-made m2e extension for maven-protoc-plugin:
http://www.masterzen.fr/2011/12/25/protobuf-maven-m2e-and-eclipse-are-on-a-boat
See http://wiki.eclipse.org/M2E_plugin_execution_not_covered for far more excruciating detail.
The maven-eclipse-plugin approach, despite being old fashioned and largely unsupported, is easier to use. The very first time you want to use it, run the following:
$ mvn -Declipse.workspace= eclipse:configure-workspace
This will add the M2_REPO classpath variable to Eclipse. You
can verify this in
Preferences->Java->Build Path->Classpath Variables. It
should be set to /home/<user>/.m2/repository.
To generate the Eclipse project files, run:
$ mvn eclipse:eclipse
If you want to look at Javadoc/source in Eclipse for dependent artifacts, run:
$ mvn eclipse:eclipse -DdownloadJavadocs=true -DdownloadSources=true
So what's the problem with maven-eclipse-plugin? The issue lies with maven-protoc-plugin. Because all of our .proto files are in src/kudu, the "resource path" in maven-protoc-plugin must be absolute and prefixed with ${project.baseDir). This absolute path is copied verbatim to an Eclipse .classpath , and Eclipse doesn't know what to do with it, causing it avoid building kudu-client altogether. Other plugins (like maven-avro-plugin) don't seem to have this problem, so it's likely a bug in maven-protoc-plugin.
There's a simple workaround: delete the errant folder within Eclipse and refresh the kudu-client project.