msgpack/msgpack-java

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
• Scala test code uses Scalafmt with Scala 3 dialect (always use the latest Scala 3 version)

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                              # Format all Scala and sbt 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 credentials for Sonatype Central. 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/1.0/credentials.sbt

credentials += Credentials(Path.userHome / ".sbt" / "sonatype_central_credentials")

Then create a credentials file at ~/.sbt/sonatype_central_credentials:

host=central.sonatype.com
user=<your username>
password=<your password>

Alternatively, you can use environment variables:

export SONATYPE_USERNAME=<your username>
export SONATYPE_PASSWORD=<your password>

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

Then, run publishSigned followed by sonaRelease:

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

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

Project Structure

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