Add descriptions to MessageProperties

types.go

@@ -2010,21 +2010,84 @@ func (h *MessageHeader) unmarshal(r *buffer) error {
 
 // MessageProperties is the defined set of properties for AMQP messages.
 type MessageProperties struct {
-	// TODO: add useful descriptions from spec
-
-	MessageID          interface{} // uint64, UUID, []byte, or string
-	UserID             []byte
-	To                 string
-	Subject            string
-	ReplyTo            string
-	CorrelationID      interface{} // uint64, UUID, []byte, or string
-	ContentType        string
-	ContentEncoding    string
+	// Message-id, if set, uniquely identifies a message within the message system.
+	// The message producer is usually responsible for setting the message-id in
+	// such a way that it is assured to be globally unique. A broker MAY discard a
+	// message as a duplicate if the value of the message-id matches that of a
+	// previously received message sent to the same node.
+	MessageID interface{} // uint64, UUID, []byte, or string
+
+	// The identity of the user responsible for producing the message.
+	// The client sets this value, and it MAY be authenticated by intermediaries.
+	UserID []byte
+
+	// The to field identifies the node that is the intended destination of the message.
+	// On any given transfer this might not be the node at the receiving end of the link.
+	To string
+
+	// A common field for summary information about the message content and purpose.
+	Subject string
+
+	// The address of the node to send replies to.
+	ReplyTo string
+
+	// This is a client-specific id that can be used to mark or identify messages
+	// between clients.
+	CorrelationID interface{} // uint64, UUID, []byte, or string
+
+	// The RFC-2046 [RFC2046] MIME type for the message's application-data section
+	// (body). As per RFC-2046 [RFC2046] this can contain a charset parameter defining
+	// the character encoding used: e.g., 'text/plain; charset="utf-8"'.
+	//
+	// For clarity, as per section 7.2.1 of RFC-2616 [RFC2616], where the content type
+	// is unknown the content-type SHOULD NOT be set. This allows the recipient the
+	// opportunity to determine the actual type. Where the section is known to be truly
+	// opaque binary data, the content-type SHOULD be set to application/octet-stream.
+	//
+	// When using an application-data section with a section code other than data,
+	// content-type SHOULD NOT be set.
+	ContentType string
+
+	// The content-encoding property is used as a modifier to the content-type.
+	// When present, its value indicates what additional content encodings have been
+	// applied to the application-data, and thus what decoding mechanisms need to be
+	// applied in order to obtain the media-type referenced by the content-type header
+	// field.
+	//
+	// Content-encoding is primarily used to allow a document to be compressed without
+	// losing the identity of its underlying content type.
+	//
+	// Content-encodings are to be interpreted as per section 3.5 of RFC 2616 [RFC2616].
+	// Valid content-encodings are registered at IANA [IANAHTTPPARAMS].
+	//
+	// The content-encoding MUST NOT be set when the application-data section is other
+	// than data. The binary representation of all other application-data section types
+	// is defined completely in terms of the AMQP type system.
+	//
+	// Implementations MUST NOT use the identity encoding. Instead, implementations
+	// SHOULD NOT set this property. Implementations SHOULD NOT use the compress encoding,
+	// except as to remain compatible with messages originally sent with other protocols,
+	// e.g. HTTP or SMTP.
+	//
+	// Implementations SHOULD NOT specify multiple content-encoding values except as to
+	// be compatible with messages originally sent with other protocols, e.g. HTTP or SMTP.
+	ContentEncoding string
+
+	// An absolute time when this message is considered to be expired.
 	AbsoluteExpiryTime time.Time
-	CreationTime       time.Time
-	GroupID            string
-	GroupSequence      uint32 // RFC-1982 sequence number
-	ReplyToGroupID     string
+
+	// An absolute time when this message was created.
+	CreationTime time.Time
+
+	// Identifies the group the message belongs to.
+	GroupID string
+
+	// The relative position of this message within its group.
+	GroupSequence uint32 // RFC-1982 sequence number
+
+	// This is a client-specific id that is used so that client can send replies to this
+	// message to a specific group.
+	ReplyToGroupID string
 }
 
 func (p *MessageProperties) marshal(wr *buffer) error {