hessian.js

Hessian Serialization 1.0 and 2.0 (base on version 4.0.7) written by pure JavaScript. Support all kind of types in Java, with high performance.

Install

$ npm install hessian.js

Support Types

8 primitive types:

raw binary data
boolean
64-bit millisecond date
64-bit double
32-bit int
64-bit long
null
UTF8-encoded string

3 recursive types:

list for lists and arrays
map for maps and dictionaries
object for objects

one special contruct:

ref for shared and circular object references

Hessian 2.0 has 3 internal reference maps:

An object/list reference map.
An class definition reference map.
A type (class name) reference map.

Encoder

Tips: you can use with js-to-java to help you write java class in js.

Simple javascript type

var hessian = require('hessian.js');
var java = require('js-to-java');
var encoder = new hessian.Encoder();

encoder.write(1); // int
encoder.write(1.1); // double
encoder.write(1e100); // double
encoder.write(Math.pow(2, 18)); // long
encoder.write(true); // boolean
encoder.write(null); // null
encoder.write('test'); // string

// java base types
encoder.write(java.long(3001010320)); // 3001010320L
encoder.write(java.double(100)); // double
encoder.write(java.array.int([0, 1, 2])); // int[] = {0, 1, 2}

var object = {};
object.prop1 = [1, 2, 3];
object.prop2 = 'string';
object.prop3 = {key: 'value'};
object.prop4 = object;  // circular
encoder.write(object); // object

Complex java type

var hessian = require('hessian.js');
var encoder = new hessian.Encoder();

var long = {
  $class: 'java.lang.Long',
  $: 1
}
encoder.write(long); // long type

var testObject = {
  $class: 'com.hessian.TestObject',
  $: {
    a: 1,
    b: 'test',
    c: {$class: 'java.lang.Long', $: 123}
  }
};
encoder.write(testObject);

Java Generic Map

// java code:
// Map<Long, Integer> map = new HashMap<Long, Integer>();
// map.put(123L, 123456);
// map.put(123456L, 123);

var hessian = require('hessian.js');
var encoder = new hessian.Encoder();

// using es6 Map
var map = new Map();
map.set({ '$class': 'java.lang.Long', '$': 123 }, 123456);
map.set({ '$class': 'java.lang.Long', '$': 123456 }, 123);

encoder.write(map); // or encoder.write({ '$class': 'java.util.HashMap', '$': map })

Consistent Java type

If a type of Class contains a plurality of data, you must ensure that the number of attributes, and each instance of the order is the same!

// Wrong

[
  {$class: 'com.X', $: {a: 1, b: 2}},
  {$class: 'com.X', $: {b: 22, a: 11}},
  {$class: 'com.X', $: {a: 1, b: 2, c: 3}}]

// Right

[
  {$class: 'com.X', $: {a: 1, b: 2, c: 0}},
  {$class: 'com.X', $: {a: 11, b: 22, c: 0}},
  {$class: 'com.X', $: {a: 1, b: 2, c: 3}},
]

Decoder

var hessian = require('hessian.js');
var decoder = new hessian.Decoder(buf);

decoder.read(); //return what it is
decoder.readNull();
decoder.readBool();
decoder.readInt();
decoder.readLong();
decoder.readDouble();
decoder.readDate();
decoder.readObect();
decoder.readMap();
decoder.readArray();
decoder.readList();
decoder.readRef();

Simple Usage

hessian 1.0:

var hessian = require('hessian.js');

var testObject = {
  a: 1,
  b: 'string',
  c: true,
  d: 1.1,
  e: Math.pow(2, 40),
  f: [1, 2, 3, '4', true, 5],
  g: {a: 1, b: true, c: 'string'}
};

var buf;
try {
  buf = hessian.encode(testObject);
} catch (err) {
  console.log('encode error: ', err.message);
  process.exit(1);
}

try {
  var res = hessian.decode(buf);
  // res.should.eql(testObject);
} catch (err) {
  console.log('decode error: ', err.message);
}

hessian 2.0:

var hessian = require('hessian.js');

var testObject = {
  a: 1,
  b: 'string',
  c: true,
  d: 1.1,
  e: Math.pow(2, 40),
  f: [1, 2, 3, '4', true, 5],
  g: {a: 1, b: true, c: 'string'}
};

var buf;
try {
  buf = hessian.encode(testObject, '2.0');
} catch (err) {
  console.log('encode error: ', err.message);
  process.exit(1);
}

try {
  var res = hessian.decode(buf, '2.0');
  // res.should.eql(testObject);
} catch (err) {
  console.log('decode error: ', err.message);
}

TODO

more unit test, include test with other language.
benchmark test.
~~hessian 2.0 decode~~
~~hessian 2.0 encode~~

What's different between hassian 1.0 and 2.0?

R meaning ref on 1.0, but x52 ('R') represents any non-final string chunk on 2.0

Hessian 2.0 Serialization Grammar

           # starting production
top        ::= value

           # 8-bit binary data split into 64k chunks
binary     ::= x41 b1 b0 <binary-data> binary # non-final chunk
           ::= 'B' b1 b0 <binary-data>        # final chunk
           ::= [x20-x2f] <binary-data>        # binary data of
                                                 #  length 0-15
           ::= [x34-x37] <binary-data>        # binary data of
                                                 #  length 0-1023

           # boolean true/false
boolean    ::= 'T'
           ::= 'F'

           # definition for an object (compact map)
class-def  ::= 'C' string int string*

           # time in UTC encoded as 64-bit long milliseconds since
           #  epoch
date       ::= x4a b7 b6 b5 b4 b3 b2 b1 b0
           ::= x4b b3 b2 b1 b0       # minutes since epoch

           # 64-bit IEEE double
double     ::= 'D' b7 b6 b5 b4 b3 b2 b1 b0
           ::= x5b                   # 0.0
           ::= x5c                   # 1.0
           ::= x5d b0                # byte cast to double
                                     #  (-128.0 to 127.0)
           ::= x5e b1 b0             # short cast to double
           ::= x5f b3 b2 b1 b0       # 32-bit float cast to double

           # 32-bit signed integer
int        ::= 'I' b3 b2 b1 b0
           ::= [x80-xbf]             # -x10 to x3f
           ::= [xc0-xcf] b0          # -x800 to x7ff
           ::= [xd0-xd7] b1 b0       # -x40000 to x3ffff

           # list/vector
list       ::= x55 type value* 'Z'   # variable-length list
           ::= 'V' type int value*   # fixed-length list
           ::= x57 value* 'Z'        # variable-length untyped list
           ::= x58 int value*        # fixed-length untyped list
           ::= [x70-77] type value*  # fixed-length typed list
           ::= [x78-7f] value*       # fixed-length untyped list

           # 64-bit signed long integer
long       ::= 'L' b7 b6 b5 b4 b3 b2 b1 b0
           ::= [xd8-xef]             # -x08 to x0f
           ::= [xf0-xff] b0          # -x800 to x7ff
           ::= [x38-x3f] b1 b0       # -x40000 to x3ffff
           ::= x59 b3 b2 b1 b0       # 32-bit integer cast to long

           # map/object
map        ::= 'M' type (value value)* 'Z'  # key, value map pairs
           ::= 'H' (value value)* 'Z'       # untyped key, value

           # null value
null       ::= 'N'

           # Object instance
object     ::= 'O' int value*
           ::= [x60-x6f] value*

           # value reference (e.g. circular trees and graphs)
ref        ::= x51 int            # reference to nth map/list/object

           # UTF-8 encoded character string split into 64k chunks
string     ::= x52 b1 b0 <utf8-data> string  # non-final chunk
           ::= 'S' b1 b0 <utf8-data>         # string of length
                                             #  0-65535
           ::= [x00-x1f] <utf8-data>         # string of length
                                             #  0-31
           ::= [x30-x34] <utf8-data>         # string of length
                                             #  0-1023

           # map/list types for OO languages
type       ::= string                        # type name
           ::= int                           # type reference

           # main production
value      ::= null
           ::= binary
           ::= boolean
           ::= class-def value
           ::= date
           ::= double
           ::= int
           ::= list
           ::= long
           ::= map
           ::= object
           ::= ref
           ::= string

Hessian 2.0 Bytecode map

Hessian 2.0 is organized as a bytecode protocol. A Hessian reader is essentially a switch statement on the initial octet.

x00 - x1f    # utf-8 string length 0-32
x20 - x2f    # binary data length 0-16
x30 - x33    # utf-8 string length 0-1023
x34 - x37    # binary data length 0-1023
x38 - x3f    # three-octet compact long (-x40000 to x3ffff)
x40          # reserved (expansion/escape)
x41          # 8-bit binary data non-final chunk ('A')
x42          # 8-bit binary data final chunk ('B')
x43          # object type definition ('C')
x44          # 64-bit IEEE encoded double ('D')
x45          # reserved
x46          # boolean false ('F')
x47          # reserved
x48          # untyped map ('H')
x49          # 32-bit signed integer ('I')
x4a          # 64-bit UTC millisecond date
x4b          # 32-bit UTC minute date
x4c          # 64-bit signed long integer ('L')
x4d          # map with type ('M')
x4e          # null ('N')
x4f          # object instance ('O')
x50          # reserved
x51          # reference to map/list/object - integer ('Q')
x52          # utf-8 string non-final chunk ('R')
x53          # utf-8 string final chunk ('S')
x54          # boolean true ('T')
x55          # variable-length list/vector ('U')
x56          # fixed-length list/vector ('V')
x57          # variable-length untyped list/vector ('W')
x58          # fixed-length untyped list/vector ('X')
x59          # long encoded as 32-bit int ('Y')
x5a          # list/map terminator ('Z')
x5b          # double 0.0
x5c          # double 1.0
x5d          # double represented as byte (-128.0 to 127.0)
x5e          # double represented as short (-32768.0 to 327676.0)
x5f          # double represented as float
x60 - x6f    # object with direct type (` ... n, o)
x70 - x77    # fixed list with direct length (p, q, r, s, t, u, v, w)
x78 - x7f    # fixed untyped list with direct length (x, y, z, {, |, }, ~, .....)
x80 - xbf    # one-octet compact int (-x10 to x3f, x90 is 0)
xc0 - xcf    # two-octet compact int (-x800 to x7ff)
xd0 - xd7    # three-octet compact int (-x40000 to x3ffff)
xd8 - xef    # one-octet compact long (-x8 to xf, xe0 is 0)
xf0 - xff    # two-octet compact long (-x800 to x7ff, xf8 is 0)

About Hessian 2.0 Optimized Decoder

Hessian 2.0 introduced ref to avoid sending duplicated class definition in the same context. Actully, the context can promote to connection level in some RPC framework. For example, EADS, Requests using the same connection will not change their class definition.