spring-cloud-stream/README.adoc

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

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:github-code: https://github.com/{github-repo}/tree/{github-tag}

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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.
--

== 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]
----
<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-stream-binder-kafka</artifactId>
</dependency>
----

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

[source,xml]
----
<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-stream-kafka</artifactId>
</dependency>
----

== 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]
----
<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-stream-binder-kafka-streams</artifactId>
</dependency>
----

= 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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