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pbf

pbf

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A low-level, fast, ultra-lightweight (3KB gzipped) JavaScript library for decoding and encoding protocol buffers, a compact binary format for structured data serialization. Works both in Node and the browser. Supports lazy decoding and detailed customization of the reading/writing code.

Performance

This library is extremely fast — much faster than native JSON.parse/JSON.stringify and the protocol-buffers module. Here's a result from running a real-world benchmark on Node v6.5 (decoding and encoding a sample of 439 vector tiles, 22.6 MB total):

  • pbf decode: 387ms, or 57 MB/s
  • pbf encode: 396ms, or 56 MB/s
  • protocol-buffers decode: 837ms, or 26 MB/s
  • protocol-buffers encode: 4197ms, or 5 MB/s
  • JSON.parse: 1540ms, or 125 MB/s (parsing an equivalent 77.5 MB JSON file)
  • JSON.stringify: 607ms, or 49 MB/s

Examples

Using Compiled Code

Install pbf and compile a JavaScript module from a .proto file:

$ npm install -g pbf
$ pbf example.proto > example.js

Then read and write objects using the module like this:

var Pbf = require('pbf');
var Example = require('./example.js').Example;
 
// read 
var pbf = new Pbf(buffer);
var obj = Example.read(pbf);
 
// write 
var pbf = new Pbf();
Example.write(obj, pbf);
var buffer = pbf.finish();

Alternatively, you can compile a module directly in the code:

var compile = require('pbf/compile');
var schema = require('protocol-buffers-schema');
 
var proto = schema.parse(fs.readFileSync('example.proto'));
var Test = compile(proto).Test;

Custom Reading

var data = new Pbf(buffer).readFields(readData, {});
 
function readData(tag, data, pbf) {
    if (tag === 1) data.name = pbf.readString();
    else if (tag === 2) data.version = pbf.readVarint();
    else if (tag === 3) data.layer = pbf.readMessage(readLayer, {});
}
function readLayer(tag, layer, pbf) {
    if (tag === 1) layer.name = pbf.readString();
    else if (tag === 3) layer.size = pbf.readVarint();
}

Custom Writing

var pbf = new Pbf();
writeData(data, pbf);
var buffer = pbf.finish();
 
function writeData(data, pbf) {
    pbf.writeStringField(1, data.name);
    pbf.writeVarintField(2, data.version);
    pbf.writeMessage(3, writeLayer, data.layer);
}
function writeLayer(layer, pbf) {
    pbf.writeStringField(1, layer.name);
    pbf.writeVarintField(2, layer.size);
}

Install

Node and Browserify:

npm install pbf

Making a browser build:

npm install
npm run build-dev # dist/pbf-dev.js (development build)
npm run build-min # dist/pbf.js (minified production build)

CDN link: https://unpkg.com/pbf@3.0.4/dist/pbf.js

API

Create a Pbf object, optionally given a Buffer or Uint8Array as input data:

// parse a pbf file from disk in Node 
var pbf = new Pbf(fs.readFileSync('data.pbf'));
 
// parse a pbf file in a browser after an ajax request with responseType="arraybuffer" 
var pbf = new Pbf(new Uint8Array(xhr.response));

Pbf object properties:

pbf.length; // length of the underlying buffer 
pbf.pos; // current offset for reading or writing 

Reading

Read a sequence of fields:

pbf.readFields(function (tag) {
    if (tag === 1) pbf.readVarint();
    else if (tag === 2) pbf.readString();
    else ...
});

It optionally accepts an object that will be passed to the reading function for easier construction of decoded data, and also passes the Pbf object as a third argument:

var result = pbf.readFields(callback, {})
 
function callback(tag, result, pbf) {
    if (tag === 1) result.id = pbf.readVarint();
}

To read an embedded message, use pbf.readMessage(fn[, obj]) (in the same way as read).

Read values:

var value = pbf.readVarint();
var str = pbf.readString();
var numbers = pbf.readPackedVarint();

For lazy or partial decoding, simply save the position instead of reading a value, then later set it back to the saved value and read:

var fooPos = -1;
pbf.readFields(function (tag) {
    if (tag === 1) fooPos = pbf.pos;
});
...
pbf.pos = fooPos;
pbf.readMessage(readFoo);

Scalar reading methods:

  • readVarint(isSigned) (pass true if you expect negative varints)
  • readSVarint()
  • readFixed32()
  • readFixed64()
  • readSFixed32()
  • readSFixed64()
  • readBoolean()
  • readFloat()
  • readDouble()
  • readString()
  • readBytes()
  • skip(value)

Packed reading methods:

  • readPackedVarint(arr, isSigned) (appends read items to arr)
  • readPackedSVarint(arr)
  • readPackedFixed32(arr)
  • readPackedFixed64(arr)
  • readPackedSFixed32(arr)
  • readPackedSFixed64(arr)
  • readPackedBoolean(arr)
  • readPackedFloat(arr)
  • readPackedDouble(arr)

Writing

Write values:

pbf.writeVarint(123);
pbf.writeString("Hello world");

Write an embedded message:

pbf.writeMessage(1, writeObj, obj);
 
function writeObj(obj, pbf) {
    pbf.writeStringField(obj.name);
    pbf.writeVarintField(obj.version);
}

Field writing methods:

  • writeVarintField(tag, val)
  • writeSVarintField(tag, val)
  • writeFixed32Field(tag, val)
  • writeFixed64Field(tag, val)
  • writeSFixed32Field(tag, val)
  • writeSFixed64Field(tag, val)
  • writeBooleanField(tag, val)
  • writeFloatField(tag, val)
  • writeDoubleField(tag, val)
  • writeStringField(tag, val)
  • writeBytesField(tag, buffer)

Packed field writing methods:

  • writePackedVarint(tag, val)
  • writePackedSVarint(tag, val)
  • writePackedSFixed32(tag, val)
  • writePackedSFixed64(tag, val)
  • writePackedBoolean(tag, val)
  • writePackedFloat(tag, val)
  • writePackedDouble(tag, val)

Scalar writing methods:

  • writeVarint(val)
  • writeSVarint(val)
  • writeSFixed32(val)
  • writeSFixed64(val)
  • writeBoolean(val)
  • writeFloat(val)
  • writeDouble(val)
  • writeString(val)
  • writeBytes(buffer)

Message writing methods:

  • writeMessage(tag, fn[, obj])
  • writeRawMessage(fn[, obj])

Misc methods:

  • realloc(minBytes) - pad the underlying buffer size to accommodate the given number of bytes; note that the size increases exponentially, so it won't necessarily equal the size of data written
  • finish() - make the current buffer ready for reading and return the data as a buffer slice
  • destroy() - dispose the buffer

For an example of a real-world usage of the library, see vector-tile-js.

Proto Schema to JavaScript

If installed globally, pbf provides a binary that compiles proto files into JavaScript modules. Usage:

$ pbf <proto_path> [--no-write] [--no-read] [--browser]

The --no-write and --no-read switches remove corresponding code in the output. The --browser switch makes the module work in browsers instead of Node.

The resulting module exports each message by name with the following methods:

  • read(pbf) - decodes an object from the given Pbf instance
  • write(obj, pbf) - encodes an object into the given Pbf instance (usually empty)

The resulting code is clean and simple, so feel free to customize it.

Changelog

3.0.4 (Nov 14, 2016)

  • Fixed compiling repeated packed enum fields.

3.0.3 (Nov 14, 2016)

  • Fixed a regression that broke compiling repeated enum fields with defaults.

3.0.2 (Sep 30, 2016)

  • Fixed a regression that broke decoding of packed fields with a tag that didn't fit into one byte.

3.0.1 (Sep 20, 2016)

  • Fixed a regression that broke encoding of long strings.

3.0.0 (Aug 30, 2016)

This release include tons of compatibility/robustness fixes, and a more reliable Node implementation. Decoding performance is expected to get up to ~15% slower than v2.0 in Node (browsers are unaffected), but encoding got faster by ~15% in return.

Encoder/decoder
  • Breaking: changed Node implementation to use Uint8Array instead of Buffer internally (and produce corresponding result on finish()), making it fully match the browser implementation for consistency and simplicity.
  • Fixed writeVarint to write 0 when given NaN or other non-number to avoid producing a broken Protobuf message.
  • Changed readPacked* methods signature to accept an optional arr argument to append the results to (to support messages with repeated fields that mix packed/non-packed encoding).
  • Added an optional isSigned argument to readVarint that enables proper reading of negative varints.
  • Deprecated readVarint64() (it still works, but it's recommended to be changed to readVarint(true)).
  • Faster string encoding.
Proto compiler
  • Breaking: Full support for defaults field values (both implicit and explicit); they're now included in the decoded JSON objects.
  • Fixed reading of repeated fields with mixed packed/non-packed encoding for compatibility.
  • Fixed proto3 compiler to use packed by default for repeated scalar fields.
  • Fixed reading of negative varint types.
  • Fixed packed fields to decode into [] if they're not present.
  • Fixed nested message references handling.
  • Fixed packed=false being interpreted as packed.
  • Added a comment to generated code with pbf version number.

2.0.1 (May 28, 2016)

  • Fixed a regression with writeVarint that affected certain numbers.

2.0.0 (May 28, 2016)

  • Significantly improved the proto compiler, which now produces a much safer reading/writing code.
  • Added the ability to compile a read/write module from a protobuf schema directly in the code.
  • Proto compiler: fixed name resolutions and collisions in schemas with nested messages.
  • Proto compiler: fixed broken top-level enums.

1.3.7 (May 28, 2016)

  • Fixed a regression with writeVarint that affected certain numbers.

1.3.6 (May 27, 2016)

  • Improved read and write performance (both ~15% faster).
  • Improved generated code for default values.

1.3.5 (Oct 5, 2015)

  • Added support for syntax keyword proto files (by updating resolve-protobuf-schema dependency).

1.3.4 (Jul 31, 2015)

  • Added writeRawMessage method for writing a message without a tag, useful for creating pbfs with multiple top-level messages.

1.3.2 (Mar 5, 2015)

  • Added readVarint64 method for proper decoding of negative int64-encoded values.

1.3.1 (Feb 20, 2015)

  • Fixed pbf proto compile tool generating broken writing code.

1.3.0 (Feb 5, 2015)

  • Added pbf binary that compiles .proto files into Pbf-based JavaScript modules.

1.2.0 (Jan 5, 2015)

Breaking API changes
  • Changed writeMessage signature to (tag, fn, obj) (see example in the docs) for a huge encoding performance improvement.
  • Replaced readPacked and writePacked methods that accept type as a string with readPackedVarint, etc. for each type (better performance and simpler API).
Improvements
  • 5x faster encoding in Node (vector tile benchmark).
  • 40x faster encoding and 3x faster decoding in the browser (vector tile benchmark).

1.1.4 (Jan 2, 2015)

  • Significantly improved readPacked and writePacked performance (the tile reading benchmark is now 70% faster).

1.1.3 (Dec 26, 2014)

Brings tons of improvements and fixes over the previous version (0.0.2). Basically makes the library complete.

Improvements
  • Improved performance of both reading and writing.
  • Made the browser build 3 times smaller.
  • Added convenience readFields and readMessage methods for a much easier reading API.
  • Added reading methods: readFloat, readBoolean, readSFixed32, readSFixed64.
  • Added writing methods: writeUInt64, writeSFixed32, writeSFixed64.
  • Improved readDouble and readString to use native Buffer methods under Node.
  • Improved readString and writeString to use HTML5 TextEncoder and TextDecoder where available.
  • Made Pbf buffer argument optional.
  • Added extensive docs and examples in the readme.
  • Added an extensive test suite that brings test coverage up to 100%.
Breaking API changes
  • Renamed readBuffer/writeBuffer to readBytes/writeBytes.
  • Renamed readUInt32/writeUInt32 to readFixed32/writeFixed32, etc.
  • Renamed writeTaggedVarint to writeVarintField, etc.
  • Changed writePacked signature from (type, tag, items) to (tag, type, items).
Bugfixes
  • Fixed readVarint to handle varints bigger than 6 bytes.
  • Fixed readSVarint to handle number bigger than 2^30.
  • Fixed writeVarint failing on some integers.
  • Fixed writeVarint not throwing an error on numbers that are too big.
  • Fixed readUInt64 always failing.
  • Fixed writing to an empty buffer always failing.