Wire Protocol

MongoDB wire protocol is socket based, request-response style protocol. Clients communicate with the database serve through a regular TCP/IP socket, without connection handshake.

Standard Message Header

struct MsgHeader {
    int32   messageLength; // total message size, including this
    int32   requestID;     // identifier for this message
    int32   responseTo;    // requestID from the original request
                           //   (used in responses from db)
    int32   opCode;        // request type - see table below
}