avsc
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5.7.7 • Public • Published

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Pure JavaScript implementation of the Avro specification.

Features

Installation

$ npm install avsc

avsc is compatible with all versions of node.js since 0.11.

Documentation

Examples

Inside a node.js module, or using browserify:

const avro = require('avsc');
  • Encode and decode values from a known schema:

    const type = avro.Type.forSchema({
      type: 'record',
      name: 'Pet',
      fields: [
        {
          name: 'kind',
          type: {type: 'enum', name: 'PetKind', symbols: ['CAT', 'DOG']}
        },
        {name: 'name', type: 'string'}
      ]
    });
    
    const buf = type.toBuffer({kind: 'CAT', name: 'Albert'}); // Encoded buffer.
    const val = type.fromBuffer(buf); // = {kind: 'CAT', name: 'Albert'}
  • Infer a value's schema and encode similar values:

    const type = avro.Type.forValue({
      city: 'Cambridge',
      zipCodes: ['02138', '02139'],
      visits: 2
    });
    
    // We can use `type` to encode any values with the same structure:
    const bufs = [
      type.toBuffer({city: 'Seattle', zipCodes: ['98101'], visits: 3}),
      type.toBuffer({city: 'NYC', zipCodes: [], visits: 0})
    ];
  • Get a readable stream of decoded values from an Avro container file compressed using Snappy (see the BlockDecoder API for an example including checksum validation):

    const snappy = require('snappy'); // Or your favorite Snappy library.
    const codecs = {
      snappy: function (buf, cb) {
        // Avro appends checksums to compressed blocks, which we skip here.
        return snappy.uncompress(buf.slice(0, buf.length - 4), cb);
      }
    };
    
    avro.createFileDecoder('./values.avro', {codecs})
      .on('metadata', function (type) { /* `type` is the writer's type. */ })
      .on('data', function (val) { /* Do something with the decoded value. */ });
  • Implement a TCP server for an IDL-defined protocol:

    // We first generate a protocol from its IDL specification.
    const protocol = avro.readProtocol(`
      protocol LengthService {
        /** Endpoint which returns the length of the input string. */
        int stringLength(string str);
      }
    `);
    
    // We then create a corresponding server, implementing our endpoint.
    const server = avro.Service.forProtocol(protocol)
      .createServer()
      .onStringLength(function (str, cb) { cb(null, str.length); });
    
    // Finally, we use our server to respond to incoming TCP connections!
    require('net').createServer()
      .on('connection', (con) => { server.createChannel(con); })
      .listen(24950);

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Install

npm i avsc

Weekly Downloads

402,698

Version

5.7.7

License

MIT

Unpacked Size

264 kB

Total Files

17

Last publish

Collaborators

  • mtth