MessagePack for Java

MessagePack is a binary serialization format. If you need a fast and compact alternative of JSON, MessagePack is your friend. For example, a small integer can be encoded in a single byte, and short strings only need a single byte prefix + the original byte array. MessagePack implementation is already available in various languages (See also the list in http://msgpack.org) and works as a universal data format.

• Message Pack specification: https://github.com/msgpack/msgpack/blob/master/spec.md

MessagePack v7 (or later) is a faster implementation of the previous version v06, and supports all of the message pack types, including extension format.

JavaDoc is available at javadoc.io.

Quick Start

For Maven users:

<dependency>
   <groupId>org.msgpack</groupId>
   <artifactId>msgpack-core</artifactId>
   <version>(version)</version>
</dependency>

For sbt users:

libraryDependencies += "org.msgpack" % "msgpack-core" % "(version)"

For gradle users:

repositories {
    mavenCentral()
}

dependencies {
    compile 'org.msgpack:msgpack-core:(version)'
}

• Usage examples

Java 17 Support

For using DirectByteBuffer (off-heap memory access methods) in JDK17, you need to specify two JVM options:

--add-opens=java.base/java.nio=ALL-UNNAMED
--add-opens=java.base/sun.nio.ch=ALL-UNNAMED

Integration with Jackson ObjectMapper (jackson-databind)

msgpack-java supports serialization and deserialization of Java objects through jackson-databind. For details, see msgpack-jackson/README.md. The template-based serialization mechanism used in v06 is deprecated.

• Release Notes

For MessagePack Developers

msgpack-java uses sbt for building the projects. For the basic usage of sbt, see:

• Building Java projects with sbt

Coding style

• msgpack-java uses the same coding style with Facebook Presto
• IntelliJ setting file

Basic sbt commands

Enter the sbt console:

$ ./sbt

Here is a list of sbt commands for daily development:

> ~compile                                 # Compile source codes
> ~test:compile                            # Compile both source and test codes
> ~test                                    # Run tests upon source code change
> ~testOnly *MessagePackTest               # Run tests in the specified class
> ~testOnly *MessagePackTest -- (pattern)  # Run tests matching the pattern 
> project msgpack-core                     # Focus on a specific project
> package                                  # Create a jar file in the target folder of each project
> jcheckStyle                              # Run check style
> scalafmtAll                              # Reformat code

Publishing

> publishLocal            # Install to local .ivy2 repository
> publishM2               # Install to local .m2 Maven repository
> publish                 # Publishing a snapshot version to the Sonatype repository

Publish to Sonatype (Maven Central)

To publish a new version, add a new git tag and push it to GitHub. GitHub Action will deploy a new release version to Maven Central (Sonatype).

$ git tag v0.x.y
$ git push origin v0.x.y

A new release note will be generated automatically at the GitHub Releases page.

Publishing to Sonatype from Local Machine

If you need to publish to Maven central using a local machine, you need to configure sbt-sonatype plugin. First set Sonatype account information (user name and password) in the global sbt settings. To protect your password, never include this file in your project.

$HOME/.sbt/(sbt-version)/sonatype.sbt

credentials += Credentials("Sonatype Nexus Repository Manager",
        "oss.sonatype.org",
        "(Sonatype user name)",
        "(Sonatype password)")

You may also need to configure GPG. See the instruction in sbt-pgp.

Then, run publishedSigned followed by sonatypeBundleRelease:

# [optional] When you need to perform the individual release steps manually, use the following commands:
> publishSigned           # Publish GPG signed artifacts to the Sonatype repository
> sonatypeBundleRelease   # Publish to the Maven Central (It will be synched within less than 4 hours)

If some sporadic error happens (e.g., Sonatype timeout), rerun sonatypeBundleRelease again.

Project Structure

msgpack-core                 # Contains packer/unpacker implementation that never uses third-party libraries
msgpack-jackson              # Contains jackson-dataformat-java implementation