spring-cloud/spring-cloud-stream-binder-kafka

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:jdkversion: 1.8 :github-tag: master :github-repo: spring-cloud/spring-cloud-stream-binder-kafka

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//= Overview [partintro]

This guide describes the Apache Kafka implementation of the Spring Cloud Stream Binder. It contains information about its design, usage, and configuration options, as well as information on how the Stream Cloud Stream concepts map onto Apache Kafka specific constructs. In addition, this guide explains the Kafka Streams binding capabilities of Spring Cloud Stream.

== ANNOUNCEMENT

IMPORTANT: This repository is now migrated as part of core Spring Cloud Stream - https://github.com/spring-cloud/spring-cloud-stream. Please create new issues over at the core repository.

== Apache Kafka Binder

=== Usage

To use Apache Kafka binder, you need to add spring-cloud-stream-binder-kafka as a dependency to your Spring Cloud Stream application, as shown in the following example for Maven:

[source,xml]

org.springframework.cloud spring-cloud-stream-binder-kafka

Alternatively, you can also use the Spring Cloud Stream Kafka Starter, as shown in the following example for Maven:

[source,xml]

org.springframework.cloud spring-cloud-starter-stream-kafka

== Apache Kafka Streams Binder

=== Usage

To use Apache Kafka Streams binder, you need to add spring-cloud-stream-binder-kafka-streams as a dependency to your Spring Cloud Stream application, as shown in the following example for Maven:

[source,xml]

org.springframework.cloud spring-cloud-stream-binder-kafka-streams

= Appendices [appendix] [[building]] == Building

:jdkversion: 1.7

=== Basic Compile and Test

To build the source you will need to install JDK {jdkversion}.

The build uses the Maven wrapper so you don't have to install a specific version of Maven. To enable the tests, you should have Kafka server 0.9 or above running before building. See below for more information on running the servers.

The main build command is

$ ./mvnw clean install

You can also add '-DskipTests' if you like, to avoid running the tests.

NOTE: You can also install Maven (>=3.3.3) yourself and run the mvn command in place of ./mvnw in the examples below. If you do that you also might need to add -P spring if your local Maven settings do not contain repository declarations for spring pre-release artifacts.

NOTE: Be aware that you might need to increase the amount of memory available to Maven by setting a MAVEN_OPTS environment variable with a value like -Xmx512m -XX:MaxPermSize=128m. We try to cover this in the .mvn configuration, so if you find you have to do it to make a build succeed, please raise a ticket to get the settings added to source control.

The projects that require middleware generally include a docker-compose.yml, so consider using https://compose.docker.io/[Docker Compose] to run the middeware servers in Docker containers.

=== Documentation

There is a "full" profile that will generate documentation.

=== Working with the code If you don't have an IDE preference we would recommend that you use https://www.springsource.com/developer/sts[Spring Tools Suite] or https://eclipse.org[Eclipse] when working with the code. We use the https://eclipse.org/m2e/[m2eclipe] eclipse plugin for maven support. Other IDEs and tools should also work without issue.

==== Importing into eclipse with m2eclipse We recommend the https://eclipse.org/m2e/[m2eclipe] eclipse plugin when working with eclipse. If you don't already have m2eclipse installed it is available from the "eclipse marketplace".

Unfortunately m2e does not yet support Maven 3.3, so once the projects are imported into Eclipse you will also need to tell m2eclipse to use the .settings.xml file for the projects. If you do not do this you may see many different errors related to the POMs in the projects. Open your Eclipse preferences, expand the Maven preferences, and select User Settings. In the User Settings field click Browse and navigate to the Spring Cloud project you imported selecting the .settings.xml file in that project. Click Apply and then OK to save the preference changes.

NOTE: Alternatively you can copy the repository settings from https://github.com/spring-cloud/spring-cloud-build/blob/master/.settings.xml[`.settings.xml] into your own~/.m2/settings.xml`.

==== Importing into eclipse without m2eclipse If you prefer not to use m2eclipse you can generate eclipse project metadata using the following command:

[indent=0]

$ ./mvnw eclipse:eclipse

The generated eclipse projects can be imported by selecting import existing projects from the file menu. [[contributing] == Contributing

Spring Cloud is released under the non-restrictive Apache 2.0 license, and follows a very standard Github development process, using Github tracker for issues and merging pull requests into master. If you want to contribute even something trivial please do not hesitate, but follow the guidelines below.

=== Sign the Contributor License Agreement Before we accept a non-trivial patch or pull request we will need you to sign the https://support.springsource.com/spring_committer_signup[contributor's agreement]. Signing the contributor's agreement does not grant anyone commit rights to the main repository, but it does mean that we can accept your contributions, and you will get an author credit if we do. Active contributors might be asked to join the core team, and given the ability to merge pull requests.

=== Code Conventions and Housekeeping None of these is essential for a pull request, but they will all help. They can also be added after the original pull request but before a merge.

Use the Spring Framework code format conventions. If you use Eclipse you can import formatter settings using the eclipse-code-formatter.xml file from the https://github.com/spring-cloud/build/tree/master/eclipse-coding-conventions.xml[Spring Cloud Build] project. If using IntelliJ, you can use the https://plugins.jetbrains.com/plugin/6546[Eclipse Code Formatter Plugin] to import the same file.
Make sure all new .java files to have a simple Javadoc class comment with at least an @author tag identifying you, and preferably at least a paragraph on what the class is for.
Add the ASF license header comment to all new .java files (copy from existing files in the project)
Add yourself as an @author to the .java files that you modify substantially (more than cosmetic changes).
Add some Javadocs and, if you change the namespace, some XSD doc elements.
A few unit tests would help a lot as well -- someone has to do it.
If no-one else is using your branch, please rebase it against the current master (or other target branch in the main project).
When writing a commit message please follow https://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html[these conventions], if you are fixing an existing issue please add Fixes gh-XXXX at the end of the commit message (where XXXX is the issue number).

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