MongoDB Wire ProtocolMongoDB有线协议

Port端口

The default port number for mongod and mongos instances is 27017. mongod和mongos实例的默认端口号是27017。The port number for mongod and mongos is configurable and may vary.mongod和mongos的端口号是可配置的，可能会有所不同。

Byte Ordering字节排序

All integers in the MongoDB wire protocol use little-endian byte order: that is, least-significant byte first.MongoDB wire协议中的所有整数都使用小端字节顺序：也就是说，最低有效字节优先。

OP_COMPRESSED

Any opcode can be compressed and wrapped in an OP_COMPRESSED header. 任何操作码都可以压缩并封装在OP_compressed头中。The OP_COMPRESSED message contains the original compressed opcode message alongside the metadata necessary to process and decompress it.OP_COMPRESSED消息包含原始压缩操作码消息以及处理和解压缩它所需的元数据。

The format of the OP_COMPRESSED message is:OP_COMPRESSED消息的格式为：

struct {
    MsgHeader header;            // standard message header
    int32  originalOpcode;       // value of wrapped opcode
    int32  uncompressedSize;     // size of deflated compressedMessage, excluding MsgHeader
    uint8  compressorId;         // ID of compressor that compressed message
    char    *compressedMessage;  // opcode itself, excluding MsgHeader
}

Each compressor is assigned a predefined compressor ID as follows:每个压缩程序都分配了一个预定义的压缩程序ID，如下所示：

OP_MSG

OP_MSG is an extensible message format used to encode both client requests and server replies on the wire.是一种可扩展的消息格式，用于对网络上的客户端请求和服务器回复进行编码。

OP_MSG has the following format:具有以下格式：

OP_MSG {
    MsgHeader header;           // standard message header
    uint32 flagBits;            // message flags
    Sections[] sections;        // data sections
    optional<uint32> checksum;  // optional CRC-32C checksum
}

Legacy Opcodes遗留操作码

Starting in MongoDB 5.1, these opcodes are removed in favor of OP_MSG:从MongoDB 5.1开始，为了支持OP_MSG，删除了这些操作码：

• OP_DELETE
• OP_GET_MORE
• OP_INSERT
• OP_KILL_CURSORS
• OP_QUERY [1]
• OP_REPLY
• OP_UPDATE

If you are running an older version of MongoDB and need detailed information on the previous opcodes, see Legacy Opcodes.如果您运行的是旧版本的MongoDB，并且需要有关以前操作码的详细信息，请参阅遗留操作码。