micro/codec/codec.go

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// Package codec is an interface for encoding messages
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package codec
import (
"errors"
"io"
"github.com/unistack-org/micro/v3/metadata"
)
// Message types
const (
Error MessageType = iota
Request
Response
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Event
)
var (
// ErrInvalidMessage returned when invalid messge passed to codec
ErrInvalidMessage = errors.New("invalid message")
// ErrUnknownContentType returned when content-type is unknown
ErrUnknownContentType = errors.New("unknown content-type")
)
var (
// DefaultMaxMsgSize specifies how much data codec can handle
DefaultMaxMsgSize = 1024 * 1024 * 4 // 4Mb
// DefaultCodec is the global default codec
DefaultCodec Codec = NewCodec()
// DefaultTagName specifies struct tag name to control codec Marshal/Unmarshal
DefaultTagName = "codec"
)
// MessageType specifies message type for codec
type MessageType int
// Codec encodes/decodes various types of messages used within micro.
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// ReadHeader and ReadBody are called in pairs to read requests/responses
// from the connection. Close is called when finished with the
// connection. ReadBody may be called with a nil argument to force the
// body to be read and discarded.
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type Codec interface {
ReadHeader(r io.Reader, m *Message, mt MessageType) error
ReadBody(r io.Reader, v interface{}) error
Write(w io.Writer, m *Message, v interface{}) error
Marshal(v interface{}, opts ...Option) ([]byte, error)
Unmarshal(b []byte, v interface{}, opts ...Option) error
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String() string
}
// Message represents detailed information about
// the communication, likely followed by the body.
// In the case of an error, body may be nil.
type Message struct {
Header metadata.Metadata
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Target string
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Method string
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Endpoint string
Error string
ID string
Body []byte
Type MessageType
}
// NewMessage creates new codec message
func NewMessage(t MessageType) *Message {
return &Message{Type: t, Header: metadata.New(0)}
}