github.com/annwntech/go-micro/v2@v2.9.5/codec/codec.go (about)

     1  // Package codec is an interface for encoding messages
     2  package codec
     3  
     4  import (
     5  	"errors"
     6  	"io"
     7  )
     8  
     9  const (
    10  	Error MessageType = iota
    11  	Request
    12  	Response
    13  	Event
    14  )
    15  
    16  var (
    17  	ErrInvalidMessage = errors.New("invalid message")
    18  )
    19  
    20  type MessageType int
    21  
    22  // Takes in a connection/buffer and returns a new Codec
    23  type NewCodec func(io.ReadWriteCloser) Codec
    24  
    25  // Codec encodes/decodes various types of messages used within go-micro.
    26  // ReadHeader and ReadBody are called in pairs to read requests/responses
    27  // from the connection. Close is called when finished with the
    28  // connection. ReadBody may be called with a nil argument to force the
    29  // body to be read and discarded.
    30  type Codec interface {
    31  	Reader
    32  	Writer
    33  	Close() error
    34  	String() string
    35  }
    36  
    37  type Reader interface {
    38  	ReadHeader(*Message, MessageType) error
    39  	ReadBody(interface{}) error
    40  }
    41  
    42  type Writer interface {
    43  	Write(*Message, interface{}) error
    44  }
    45  
    46  // Marshaler is a simple encoding interface used for the broker/transport
    47  // where headers are not supported by the underlying implementation.
    48  type Marshaler interface {
    49  	Marshal(interface{}) ([]byte, error)
    50  	Unmarshal([]byte, interface{}) error
    51  	String() string
    52  }
    53  
    54  // Message represents detailed information about
    55  // the communication, likely followed by the body.
    56  // In the case of an error, body may be nil.
    57  type Message struct {
    58  	Id       string
    59  	Type     MessageType
    60  	Target   string
    61  	Method   string
    62  	Endpoint string
    63  	Error    string
    64  
    65  	// The values read from the socket
    66  	Header map[string]string
    67  	Body   []byte
    68  }