Piqi is a multi-format data serialization system for Erlang. It provides a uniform interface for serializing Erlang data structures to JSON, XML and Protocol Buffers formats.

A typical Piqi usage scenario involves the following steps:

1. Include Piqi as a rebar depedency -- add this entry to your rebar.config file:

{deps, [
    ...
    {piqi, "", {git, "git://github.com/alavrik/piqi-erlang.git", {branch, "master"}}},
    ...
]}.

2. Describe data structures using the Piqi data definition language or Protocol Buffers .proto files

The Piqi data definition language can describe many Erlang types, both primitive and user-defined. This includes integers, floats, booleans, strings, binaries, lists, records and variants (i.e. {tag, Value} tuples).

.piqi modules can be converted to and from Protocol Buffers .proto files:

piqi to-proto X.piqi
piqi of-proto X.proto

3. Call the Piqi compiler to generate Erlang type definitions and serialization code

4. Use generated serializes/deserializers in a user's program -- the desired serialization format can be specified at runtime. For examples:

% deserialize a data structure from Protocol Buffers
AddressBook = addressbook_piqi:parse_address_book(Bytes, 'pb'),

% serialize it as JSON
Json = addressbook_piqi:gen_address_book(AddressBook, 'json'),

% serialize it as pretty-printed JSON
JsonPretty = addressbook_piqi:gen_address_book(AddressBook, 'json_pretty'),

% serialize it as XML
Xml = addressbook_piqi:gen_address_book(AddressBook, 'xml').

Examples

See examples/addressbook and other projects in the examples directory.

Documentation

Piqi Erlang documentation is available at http://piqi.org/doc/erlang/

The master copy is located in the repository: doc/piqi-erlang.md

Bugs

Please report found problems using GitHub issues.

Mailing list

http://groups.google.com/group/piqi

Advanced installation

Sometimes, it may be useful or even necessary to use a custom version of the piqi binary executable instead of the pre-built one that comes with piqi-erlang.

For example, there may not be a pre-built piqi for your platform. Or organization policies may prohibit installing third-party binaries.

In this case, you can build the piqi binary from source code, put it somewhere in the local filesystem and point to it using the PIQI environment variable before running any rebar commands and starting the piqi Erlang application. For example:

export PIQI=/usr/local/bin/piqi

Contributing

Your contributions are always welcome. Just open a pull request. Check TODO list for ideas.

Some useful commands:

make deps  # the same as "rebar get-deps"
make       # the same as "rebar compile"

make test
make dialyzer
make -C tests all test
make -C tests clean

License

Apache License Version 2.0