# Build scripts that publish pre-compiled protoc artifacts
``protoc`` is the compiler for ``.proto`` files. It generates language bindings
for the messages and/or RPC services from ``.proto`` files.

Because ``protoc`` is a native executable, the scripts under this directory
build and publish a ``protoc`` executable (a.k.a. artifact) to Maven
repositories. The artifact can be used by build automation tools so that users
would not need to compile and install ``protoc`` for their systems.

## Versioning
The version of the ``protoc`` artifact must be the same as the version of the
Protobuf project.

## Artifact name
The name of a published ``protoc`` artifact is in the following format:
``protoc-<version>-<os>-<arch>.exe``, e.g., ``protoc-3.0.0-alpha-3-windows-x86_64.exe``.

## System requirement
Install [Apache Maven](http://maven.apache.org/) if you don't have it.

The scripts only work under Unix-like environments, e.g., Linux, MacOSX, and
Cygwin or MinGW for Windows. Please see ``README.md`` of the Protobuf project
for how to set up the build environment.

## To install artifacts locally
The following command will install the ``protoc`` artifact to your local Maven repository.
```
$ mvn install
```

## Cross-compilation
The Maven script will try to detect the OS and the architecture from Java
system properties. It's possible to build a protoc binary for an architecture
that is different from what Java has detected, as long as you have the proper
compilers installed.

You can override the Maven properties ``os.detected.name`` and
``os.detected.arch`` to force the script to generate binaries for a specific OS
and/or architecture. Valid values are defined as the return values of
``normalizeOs()`` and ``normalizeArch()`` of ``Detector`` from
[os-maven-plugin](https://github.com/trustin/os-maven-plugin/blob/master/src/main/java/kr/motd/maven/os/Detector.java).
Frequently used values are:
- ``os.detected.name``: ``linux``, ``osx``, ``windows``.
- ``os.detected.arch``: ``x86_32``, ``x86_64``

For example, MingGW32 only ships with 32-bit compilers, but you can still build
32-bit protoc under 64-bit Windows, with the following command:
```
$ mvn install -Dos.detected.arch=x86_32
```

## To push artifacts to Maven Central
Before you can upload artifacts to Maven Central repository, make sure you have
read [this page](http://central.sonatype.org/pages/apache-maven.html) on how to
configure GPG and Sonatype account.

Use the following command to upload artifacts:
```
$ mvn clean deploy -P release
```