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173 lines
4.4 KiB
Markdown
173 lines
4.4 KiB
Markdown
---
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category: tool
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tool: messagepack
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filename: learnmessagepack.mpac
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contributors:
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- ["Gabriel Chuan", "https://github.com/gczh"]
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---
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MessagePack is an efficient binary serialization format. It lets you exchange data among multiple languages like JSON. The benefits over other formats is that it's faster and smaller.
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In MessagePack, small integers are encoded into a single byte, and typical short strings require only one extra byte in addition to the strings themselves. This makes MessagePack useful for efficient transmission over wire.
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```
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# 0. Understanding The Structure ====
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JSON, 40 Bytes UTF-8
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----------------------------------------------
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| {"name":"John Doe","age":12} |
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----------------------------------------------
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| {" | 7B 22 |
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| name | 6E 61 6D 65 |
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| ":" | 22 3A 22 |
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| John Doe | 4A 6F 68 6E 20 44 6F 65 |
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| "," | 22 2C 22 |
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| age | 61 67 65 |
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| ": | 22 3A 20 |
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| 12 | 31 32 |
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| } | 7D |
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----------------------------------------------
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MessagePack, 27 Bytes UTF-8
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----------------------------------------------
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| ‚¤name¨John Doe£age.12 |
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----------------------------------------------
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| ‚¤ | 82 84 |
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| name | 6E 61 6D 65 |
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| ¨ | A8 |
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| John Doe | 4A 6F 68 6E 20 44 6F 65 |
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| £ | A3 |
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| age | 61 67 65 |
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| . | 0C |
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| 12 | 31 32 |
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----------------------------------------------
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# 1. JAVA ====
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""" Installing with Maven
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"""
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<dependencies>
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...
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<dependency>
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<groupId>org.msgpack</groupId>
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<artifactId>msgpack</artifactId>
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<version>${msgpack.version}</version>
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</dependency>
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...
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</dependencies>
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""" Simple Serialization/Deserialization
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"""
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// Create serialize objects.
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List<String> src = new ArrayList<String>();
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src.add("msgpack");
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src.add("kumofs");
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MessagePack msgpack = new MessagePack();
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// Serialize
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byte[] raw = msgpack.write(src);
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// Deserialize directly using a template
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List<String> dst1 = msgpack.read(raw, Templates.tList(Templates.TString));
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System.out.println(dst1.get(0));
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System.out.println(dst1.get(1));
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// Or, Deserialze to Value then convert type.
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Value dynamic = msgpack.read(raw);
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List<String> dst2 = new Converter(dynamic)
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.read(Templates.tList(Templates.TString));
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System.out.println(dst2.get(0));
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System.out.println(dst2.get(1));
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# 2. RUBY ====
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""" Installing the Gem
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"""
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gem install msgpack
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""" Streaming API
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"""
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# serialize a 2-element array [e1, e2]
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pk = MessagePack::Packer.new(io)
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pk.write_array_header(2).write(e1).write(e2).flush
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# deserialize objects from an IO
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u = MessagePack::Unpacker.new(io)
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u.each { |obj| ... }
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# event-driven deserialization
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def on_read(data)
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@u ||= MessagePack::Unpacker.new
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@u.feed_each(data) { |obj| ... }
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end
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# 3. NODE.JS ====
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""" Installing with NPM
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"""
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npm install msgpack5 --save
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""" Using in Node
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"""
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var msgpack = require('msgpack5')() // namespace our extensions
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, a = new MyType(2, 'a')
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, encode = msgpack.encode
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, decode = msgpack.decode
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msgpack.register(0x42, MyType, mytipeEncode, mytipeDecode)
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console.log(encode({ 'hello': 'world' }).toString('hex'))
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// 81a568656c6c6fa5776f726c64
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console.log(decode(encode({ 'hello': 'world' })))
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// { hello: 'world' }
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console.log(encode(a).toString('hex'))
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// d5426161
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console.log(decode(encode(a)) instanceof MyType)
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// true
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console.log(decode(encode(a)))
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// { value: 'a', size: 2 }
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function MyType(size, value) {
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this.value = value
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this.size = size
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}
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function mytipeEncode(obj) {
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var buf = new Buffer(obj.size)
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buf.fill(obj.value)
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return buf
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}
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function mytipeDecode(data) {
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var result = new MyType(data.length, data.toString('utf8', 0, 1))
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, i
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for (i = 0; i < data.length; i++) {
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if (data.readUInt8(0) != data.readUInt8(i)) {
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throw new Error('should all be the same')
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}
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}
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return result
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}
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```
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# References
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- [MessagePack](http://msgpack.org/index.html)
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- [MsgPack vs. JSON: Cut your client-server exchange traffic by 50% with one line of code](http://indiegamr.com/cut-your-data-exchange-traffic-by-up-to-50-with-one-line-of-code-msgpack-vs-json/)
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