Description

The MessageEnvelope class allows you to add additional information to messages.

Important points

• A correlation id, message id, and a message type are added to the data being sent/received. Additionally, a MessageEnvelope can reference a lock token.
• A MessageEnvelope’s message is stored as a buffer, so strings are converted using utf8 conversions.

Constructors

Creates a new MessageEnvelope, which adds a correlation id, message id, and a type to the data being sent/received.

MessageEnvelope(String? correlationId, String? messageType, message)

• correlationId: String? - (optional) transaction id used to trace execution through the call chain.
• messageType: String? - string value that defines the message’s type.
• message: dynamic - data being sent/received.

Fields

correlationId

Unique business transaction id that is used to trace calls across components.

correlationId: String?

message

Stored message.

message: String?

message_id

Message’s auto-generated ID.

message_id: String

message_type

String value that defines the stored message’s type.

message_type: String?

sent_time

The time at which the message was sent.

sent_time: DateTime?

Instance methods

getMessageAsString

Returns the information stored in this message as a UTF-8 encoded string.

String getMessageAsString()

• returns: String - information stored in this message as a UTF-8 encoded string.

getReference

Returns the lock token that this MessageEnvelope references.

dynamic getReference()

• returns: dynamic - lock token that this MessageEnvelope references.

setMessageAsString

Stores the given string.

void setMessageAsString(String value)

• value: String - string to set. It will be converted to a buffer using UTF-8 encoding.

setMessageAsJson

Stores the given value as a JSON string.

void setMessageAsJson(dynamic value)

• value: dynamic - the value to convert to JSON and store in this message.

setReference

Sets a lock token reference for this MessageEnvelope.

void setReference(value)

• value: dynamic - lock token to reference the message envelope.

toString

Converts this MessageEnvelope to a string, using the following format:
"[,<message_type>,<message.toString>]".

If any of the values are null, they will be replaced with ---.

@override

String toString()

• returns: String - generated string.

toJSON

Converts this MessageEnvelop to a JSON string. The message payload is passed as string

Map<String, dynamic> toJSON()

• returns: Map<String, dynamic> - A JSON encoded representation is this object.

Static methods

fromJSON

Converts a JSON string into a MessageEnvelop The message payload is passed as string

static MessageEnvelope? fromJSON(String? value)

• value: String? - a JSON encoded string
• returns: MessageEnvelope? - a decoded Message Envelop.