Apache Incubator Samza is a distributed stream processing framework. It uses Apache Kafka for messaging, and Apache Hadoop YARN to provide fault tolerance, processor isolation, security, and resource management.
- Simpe API: Unlike most low-level messaging system APIs, Samza provides a very simple call-back based "process message" API that should be familiar to anyone that's used Map/Reduce.
- Managed state: Samza manages snapshotting and restoration of a stream processor's state. Samza will restore a stream processor's state to a snapshot consistent with the processor's last read messages when the processor is restarted.
- Fault tolerance: Samza will work with YARN to restart your stream processor if there is a machine or processor failure.
- Durability: Samza uses Kafka to guarantee that messages will be processed in the order they were written to a partition, and that no messages will ever be lost.
- Scalability: Samza is partitioned and distributed at every level. Kafka provides ordered, partitioned, re-playable, fault-tolerant streams. YARN provides a distributed environment for Samza containers to run in.
- Pluggable: Though Samza works out of the box with Kafka and YARN, Samza provides a pluggable API that lets you run Samza with other messaging systems and execution environments.
- Processor isolation: Samza works with Apache YARN, which supports processor security through Hadoop's security model, and resource isolation through Linux CGroups.
Check out Hello Samza to try Samza. Read the Background page to learn more about Samza.
To build Samza, run:
./gradlew clean build
Samza builds with Scala 2.10 and YARN 2.2.0, by default. Use the -PscalaVersion switches to change Scala versions. Samza supports building Scala with 2.9.2, or 2.10.
./gradlew -PscalaVersion=2.9.2 clean build
To run all tests:
./gradlew clean test
To run a single test:
./gradlew clean :samza-test:test -Dtest.single=TestStatefulTask
To run a job (defined in a properties file):
./gradlew samza-shell:runJob -PconfigPath=file:///path/to/job/config.properties
To inspect a job's latest checkpoint:
./gradlew samza-shell:checkpointTool -PconfigPath=file:///path/to/job/config.properties
To modify a job's checkpoint (assumes that the job is not currently running), give it a file with the new offset for each partition, in the format systems.<system>.streams.<topic>.partitions.<partition>=<offset>:
./gradlew samza-shell:checkpointTool -PconfigPath=file:///path/to/job/config.properties \
-PnewOffsets=file:///path/to/new/offsets.properties
Samza uses Kafka, which is not managed by Maven. To use Kafka as though it were a Maven artifact, Samza installs Kafka into a local repository using the mvn install command. You must have Maven installed to build Samza.
To get eclipse projects, run:
./gradlew eclipse
For IntelliJ, run:
./gradlew idea
Apache Samza is currently undergoing incubation at the Apache Software Foundation.