D10 - Dubbo2 Protocol Specification

  • Authors: Jun Liu

Background

Dubbo2 遗留系统运行的 RPC 协议规范

Related Proposals

D0-triple

Specification

dubbo_protocol_header

  • Magic - Magic High & Magic Low (16 bits)

    Identifies dubbo protocol with value: 0xdabb

  • Req/Res (1 bit)

    Identifies this is a request or response. Request - 1; Response - 0.

  • 2 Way (1 bit)

    Only useful when Req/Res is 1 (Request), expect for a return value from server or not. Set to 1 if need a return value from server.

  • Event (1 bit)

    Identifies an event message or not, for example, heartbeat event. Set to 1 if this is an event.

  • Serialization ID (5 bit)

    Identifies serialization type: the value for fastjson is 6.

  • Status (8 bits)

    Only useful when Req/Res is 0 (Response), identifies the status of response

    • 20 - OK
    • 30 - CLIENT_TIMEOUT
    • 31 - SERVER_TIMEOUT
    • 40 - BAD_REQUEST
    • 50 - BAD_RESPONSE
    • 60 - SERVICE_NOT_FOUND
    • 70 - SERVICE_ERROR
    • 80 - SERVER_ERROR
    • 90 - CLIENT_ERROR
    • 100 - SERVER_THREADPOOL_EXHAUSTED_ERROR

  • Request ID (64 bits)

    Identifies an unique request. Numeric (long).

  • Data Length (32)

    Length of the content (the variable part) after serialization, counted by bytes. Numeric (integer).

  • Variable Part

    Each part is a byte[] after serialization with specific serialization type, identifies by Serialization ID.

Every part is a byte[] after serialization with specific serialization type, identifies by Serialization ID

  1. If the content is a Request (Req/Res = 1), each part consists of the content, in turn is:

    • Dubbo version
    • Service name
    • Service version
    • Method name
    • Method parameter types
    • Method arguments
    • Attachments

  2. If the content is a Response (Req/Res = 0), each part consists of the content, in turn is:

    • Return value type, identifies what kind of value returns from server side: RESPONSE_NULL_VALUE - 2, RESPONSE_VALUE - 1, RESPONSE_WITH_EXCEPTION - 0.
    • Return value, the real value returns from server.

注意： 对于(Variable Part)变长部分，当前版本的dubbo框架使用json序列化时，在每部分内容间额外增加了换行符作为分隔，请选手在Variable Part的每个part后额外增加换行符， 如：

Dubbo version bytes (换行符)
Service name bytes  (换行符)
...