pbs

pbs

Streaming protocol buffers encoder/decoder

npm install pbs

Usage

var pbs = require('pbs')

var messages = pbs(`
  message Company {
    required string name = 1;
    repeated Employee employees = 2;
    optional string country = 3;

    message Employee {
      required string name = 1;
      required uint32 age = 2;
    }
  }
`)

// create a streaming encoder
var encoder = message.Company.encode()

// create a streaming decoder
var decoder = message.Company.decode()

Encoding

Use pbs to encode a protocol buffers message (no matter low large!) to a stream

The encoder stream will expose all properties of the protobuf message as methods on the stream that you can pass the value you want to write to.

encoder.someProperty(aValue, [callback])

The callback is called when the stream has been flushed.

Here is an example using the above protobuf schema:

// all the properties of Company are exposed as methods
var encoder = messages.Company.encode()

// encoder is a readable stream containing the protobuf message.
// you can pipe it anywhere!
encoder.pipe(fs.createWriteStream('my-protobuf-message.pb'))

// write a name to the stream
encoder.name('my-company')

// write an employee to the stream
encoder.employees({
  name: 'mathias',
  age: 28
})

// write another one
encoder.employees({
  name: 'jane doe',
  age: 32
})

// no more data -  will end the readable stream
encoder.finalize()

The encoder stream produces a valid protobuf message that can be decoded with any other parser that follows the protobuf spec.

Decoding

Similar to encoding you can use pbs to decode a protobuf message

The decoder stream also exposes the properties as methods but instead of passing a value you pass a function that is called then that property is found in the stream

decoder.someProperty(fn)

Here is an example using the above schema:

// all the properties of Company are exposes as methods
var decoder = messages.Company.decode()

decoder.name(function (name, cb) {
  console.log('message has name:', name)
  cb() // done processing
})

decoder.employees(function (employee, cb) {
  console.log('employee array member:', employee)
  cb() // done processing
})

decoder.country(function (country, cb) {
  console.log('message has country:', country)
  cb()
})

decoder.on('finish', function () {
  console.log('(no more data)')
})

fs.createReadStream('my-protobuf-message.pb').pipe(decoder)

License

MIT