AMQP Messages

Universal Messaging 10.15 | Concepts | AMQP | AMQP Guide | AMQP Messages

AMQP Messages

AMQP Types

AMQP defines a set of commonly used primitive types aimed towards a cross-platform interoperable data representation

These primitive types are divided into the following categories:

Primitive

Described

Composite

Restricted

NOTE: In Universal Messaging, an embedded Apache Qpid Proton-J protocol engine is used for type marshalling so all type mappings occur as defined by the Proton-J API. See the Qpid Proton page at https://qpid.apache.org/proton/index.html for details.

AMQP Message Format

AMQP offers a standard message format (default) which can be overridden by an AMQP node. It consists of a bare message (immutable end-end) and an annotated message which may be altered by peer / intermediate nodes.

The following figure illustrates the default AMQP message format:

NOTE: Universal Messaging supports the default message format and provides a transformation layer based on it. Currently no tests have been performed with a custom AMQP message format, at the very least transformers would fail.

Transfer Headers

AMQP header	UM Header	AMQP Type	Java Type	UM 10.15
durable	nPublished.isPersistent	boolean	boolean
priority	nHeader.Priority	ubyte (Default: 4)	byte
ttl	nHeader.TTL	milliseconds (uint)	long
first-acquirer	nEventProperties.JMS_AMQP_FirstAcquirer	boolean	boolean
delivery-count	nHeader.RedeliveredCount	uint (Default: 0)	long

Note:
Transfer headers are always mapped irrespective of whether an AMQP transformer is used or not.

Delivery Annotations

AMQP Delivery annotations offer an optional non-normative section for AMQP vendor defined recipients by typically providing delivery related information from the sending node to the receiving node.

AMQP Delivery Annotation	UM Header Key	AMQP Key/Value Type	Java Key/Value Type	UM 10.15
SomeDeliveryAnnotation	JMS_AMQP_DA_<AMQP_SYMBOL_NAME(SomeDeliveryAnnotation)>	AMQP Symbol / AMQP Value	String / nEventProperties Value

Universal Messaging currently does not make use of any delivery annotations but will preserve any received. The naming convention used is <JMS_AMQP_DA_><delivery annotation symbol>

Message Annotations

AMQP Message annotations offer an optional section for AMQP properties aimed at AMQP infrastructure nodes. The following table illustrates the mappings to Universal Messaging:

AMQP Message Annotation	UM Header Key	AMQP Key/Value Type	Java Key/Value Type	UM 10.15
SomeMessageAnnotation	JMS_AMQP_MA_<AMQP SYMBOL_NAME(SomeMessageAnnotation)>	AMQP Symbol / AMQP Value	String / nEventProperties Value
x-opt-jms-msg-type	JMS_AMQP_MA_x-opt-jms-msg-type	x-opt-jms-msg-type / AMQP byte	String / byte (nHeader.MessageType)
x-opt-jms-dest	JMS_AMQP_MA_x-opt-jms-dest	x-opt-jms-dest / AMQP String	String / byte[] (nHeader.Type)
x-opt-reply-type	JMS_AMQP_MA_x-opt-reply-type	x-opt-reply-type / AMQP byte	String / byte (nHeader.ReplyType)

Note:
Only applies when using the Complete AMQP Transformer.

Standard Message Properties

AMQP standard message properties is a section used for a defined set of immutable standard properties of the message. The section is part of the bare message; therefore, if retransmitted by an intermediary, it must remain unaltered.

The following table illustrates how these standard message properties are mapped to Universal Messaging:

AMQP Standard Property	UM Header Mapping	AMQP Type	Java Value Type	UM 10.15
message-id	nHeader.MessageId	AMQP String	byte[]
user-id	nHeader.UserId	AMQP Binary	byte[]
to	nHeader.Destination	AMQP String	byte[]
subject	nEventProperties.JMS_AMQP_SUBJECT	AMQP String	String
reply-to	nHeader.ReplyToName	AMQP String	byte[]
correlation-id	nHeader.CorrelationId	AMQP Value	byte[]
content-type	nEventProperties.JMS_AMQP_CONTENT_TYPE	AMQP Symbol	String
content-encoding	nEventProperties.JMS_AMQP_CONTENT_ENCODING	AMQP Symbol	String
absolute-expiry-time	N/A (Currently unsupported)	AMQP Date	long
creation-time	nHeader.Timestamp	AMQP Date	long
group-id	nEventProperties.JMSXGroupID	AMQP String	String
group-sequence	nEventProperties.JMS_AMQP_GROUP_SEQUENCE	AMQP uint	int
reply-to-group-id	nEventPropties.JMS_AMQP_ReplyToGroupID	AMQP String	String

Note:
Only applies when using the Complete AMQP Transformer.

Application Message Properties

AMQP offers an optional application-properties section, part of the bare message used for structured application data. Intermediaries can use the data within this structure for the purposes of filtering or routing.

The keys of this map are restricted to be of type string (which excludes the possibility of a null key) and the values are restricted to be of simple types only, that is, excluding map, list, and array types. The following table illustrates how these are mapped to Universal Messaging:

AMQP Application Message Properties	UM Dictionary Key	AMQP Key/Value Type	Java Key/Value Type	UM 10.15
MAP < STRING, SIMPLE VALUE >		AMQP String / AMQP Value	String / nEventProperties Value
example_application_key1	example_application_key1	AMQP String / AMQP Value	String / nEventProperties Value

Note:
In Universal Messaging the nEventProperties and nHeader objects are mapped to a few AMQP message format sections. Therefore there will be property keys mappable to different sections stored in the same structure, implying that this section refers to all keys that do not fall in the other sections.

Message Body

AMQP message body is defined in 3 possible ways:

One or more AMQP Data sections

One or more AMQP Sequence sections

A single AMQP Value section

Universal Messaging currently aims to offer support for JMS 1.1 use cases via AMQP and therefore has implemented some mappings via the Complete AMQP transformer.

The mappings are based on the following UM constants:

UM nHeader.MessageType	UM Dictionary Key (transformed)	Value (byte)	UM 10.15
JMS_BASE_MESSAGE_TYPE	AMQP_Type	0
JMS_MAP_MESSAGE_TYPE	AMQP_Type	1
JMS_BYTES_MESSAGE_TYPE	AMQP_Type	2
JMS_OBJECT_MESSAGE_TYPE	AMQP_Type	3
JMS_STREAM_MESSAGE_TYPE	AMQP_Type	4
JMS_TEXT_MESSAGE_TYPE	AMQP_Type	5

Universal Messaging extended message types, such as protobuf, are not supported by the transformation framework.

Additionally, mappings (depending on the direction) are based on the following UM AMQP Transformation constants:

UM AMQP transformation Constant	UM Dictionary Key (transformed)	Value (int)	UM 10.15
sAMQPData	AMQP_Type	0
sAMQPValue	AMQP_Type	1
sAMQPList	AMQP_Type	2
sAMQPEmpty	AMQP_Type	3
sAMQPUnknown	AMQP_Type	-1

Message Body: AMQP payloads to UM Native payloads

Initially, the Universal Messaging realm will check for an AMQP message annotation x-opt-jms-msg-type on the AMQP message. If detected and within the range of the above mentioned table, then the following conversions are performed:

x-opt-jms-msg-type Message Annotation	AMQP Body	UM Stamping	UM payload	UM 10.15
JMS_BASE_MESSAGE_TYPE	Any	AMQP_Type=sAMQPEmpty	byte[0]
JMS_BYTES_MESSAGE_TYPE	null		byte[0]
JMS_BYTES_MESSAGE_TYPE	Data	AMQP_Type=sAMQPData	Binary.Array
JMS_BYTES_MESSAGE_TYPE	AMQP Value <Binary>	AMQP_Type=sAMQPValue	Binary.Array
JMS_TEXT_MESSAGE_TYPE	null		byte[0]
JMS_TEXT_MESSAGE_TYPE	Data	AMQP_Type=sAMQPData	Binary.Array (UTF-8)
JMS_TEXT_MESSAGE_TYPE	AMQP Value <Binary>	AMQP_Type=sAMQPValue	Binary.Array (UTF-8)
JMS_OBJECT_MESSAGE_TYPE	null	AMQP_Type=sAMQPData	byte[0]
JMS_OBJECT_MESSAGE_TYPE	Data	AMQP_Type=sAMQPData	Binary.Array
JMS_STREAM_MESSAGE_TYPE	null		byte[0]
JMS_STREAM_MESSAGE_TYPE	AMQP Value <List>	AMQP_Type=sAMQPValue	byte[](Serialized Vector<Binary>)
JMS_STREAM_MESSAGE_TYPE	AMQP Sequence	AMQP_Type=sAMQPList	byte[](Serialized Vector<Binary>)
JMS_MAP_MESSAGE_TYPE	null		byte[0]
JMS_MAP_MESSAGE_TYPE	AMQP Value <Map>	AMQP_Type=sAMQPValue	byte[](Externalized fEventDictionary)

Note:
Only applies when using the Complete AMQP Transformer

If the message annotation is not present, then the mapping starts looking for payload hints in message properties as follows:

AMQP Message Property	AMQP Body	UM nHeader.MessageType	UM payload	UM 10.15
content-type
text/plain	null	JMS_TEXT_MESSAGE_TYPE	byte[0]
application/x-java-serialized-object	null	JMS_OBJECT_MESSAGE_TYPE	byte[0]
application/octet-stream	null	JMS_BYTES_MESSAGE_TYPE	byte[0]
null or other	null	JMS_BASE_MESSAGE_TYPE	byte[0]
text/plain	Data	JMS_TEXT_MESSAGE_TYPE	Binary.Array(UTF-8)
application/x-java-serialized-object	Data	JMS_OBJECT_MESSAGE_TYPE	Binary.Array
application/octet-stream or null	Data	JMS_BYTES_MESSAGE_TYPE	Binary.Array
other	Data	JMS_BYTES_MESSAGE_TYPE	Binary.Array
AMQP Value <Type> body
null	AMQP Value <null>	JMS_BASE_MESSAGE_TYPE	byte[0]
String	AMQP Value <String>	JMS_TEXT_MESSAGE_TYPE	Binary.Array (UTF-8)
Binary	AMQP Value <Binary>	JMS_BYTES_MESSAGE_TYPE	Binary.Array
List	AMQP Value <List>	JMS_STREAM_MESSAGE_TYPE	byte[](Serialized Vector<Binary>)
Map	AMQP Value <Map>	JMS_MAP_MESSAGE_TYPE	byte[](Externalized fEventDictionary)
other	AMQP Value <Object>	JMS_OBJECT_MESSAGE_TYPE	Binary.Array
AMQP Sequence <Object> body
Binary	AMQP Sequence<Binary>	JMS_OBJECT_MESSAGE_TYPE	Binary.Array

Note:
Only applies when using the Complete AMQP Transformer.

Message Body: UM Native Payloads to AMQP payloads

Initially, the Universal Messaging realm will check for an nEventProperties keys called AMQP_Type which is expected to be within the range defined by the AMQP Transformation Constants table. Typically these are AMQP messages previously transformed to native but as there are multiple possibilities with regard to the type of payload this should be transformed to, this value gives us a hint. If not present, it defaults to sAMQPUnknown.

Based on the UM nHeader.MessageType values the following conversions are performed:

UM nHeader.MessageType	UM Dictionary Key AMQP_Type	AMQP Payload	UM 10.15
JMS_BASE_MESSAGE_TYPE	sAMQPEmpty or sAMQPUnknown or sAMQPData	Data(byte[0])
JMS_BASE_MESSAGE_TYPE	sAMQPValue	AMQPValue(null)
JMS_BASE_MESSAGE_TYPE	sAMQPList
JMS_MAP_MESSAGE_TYPE	sAMQPEmpty	Data(byte[0])
JMS_MAP_MESSAGE_TYPE	sAMQPValue or sAMQPUnknown	AMQPValue<Map> (from byte[](Externalized fEventDictionary)
JMS_MAP_MESSAGE_TYPE	sAMQPList or sAMQPData
JMS_BYTES_MESSAGE_TYPE	sAMQPEmpty	Data(byte[0])
JMS_BYTES_MESSAGE_TYPE	sAMQPData orsAMQPUnknown	Data(Binary(byte[])) (from UM native payload)
JMS_BYTES_MESSAGE_TYPE	sAMQPValue	AMQPValue(Binary(byte[])) (from UM native payload)
JMS_BYTES_MESSAGE_TYPE	sAMQPList
JMS_OBJECT_MESSAGE_TYPE	sAMQPEmpty	Data(byte[0])
JMS_OBJECT_MESSAGE_TYPE	sAMQPData orsAMQPUnknown	Data(Binary(byte[])) (from UM native payload)
JMS_OBJECT_MESSAGE_TYPE	sAMQPList or sAMQPValue
JMS_STREAM_MESSAGE_TYPE	sAMQPEmpty	Data(byte[0])
JMS_STREAM_MESSAGE_TYPE	sAMQPList	AMQPSequence<Vector> (byte[](Serialized Vector<Binary>)
JMS_STREAM_MESSAGE_TYPE	sAMQPValue or sAMQPUnknown	AMQPValue<Vector> (byte[](Serialized Vector<Binary>)
JMS_STREAM_MESSAGE_TYPE	sAMQPData
JMS_TEXT_MESSAGE_TYPE	sAMQPEmpty	Data(byte[0])
JMS_TEXT_MESSAGE_TYPE	sAMQPData	Data(Binary(byte[])) (from UM native payload)
JMS_TEXT_MESSAGE_TYPE	sAMQPValue orsAMQPUnknown	AMQPValue<String> (from UM native payload)
JMS_TEXT_MESSAGE_TYPE	sAMQPList

Note:
Only applies when using the Complete AMQP Transformer.

Message Footer

AMQP Message footer offers an optional non-normative section for delivery or message metadata that can be calculated / validated only after the whole message has been processed (e.g digital signature verification, encryption etc).

The following table shows how these are mapped in Universal Messaging:

AMQP Message Footer	UM Sub Dictionary Key	AMQP Key/Value Type	Java Key/Value Type	UM 10.15
MAP < SYMBOL, VALUE >	Footer	AMQP Symbol / AMQP Value	String / nEventProperties Value
example_footer_key1	Footer.example_footer_key1	AMQP Symbol / AMQP Value	String / nEventProperties Value

Note:
Only applies when using the Complete AMQP Transformer.