WebSphere MQ
functions not available
There are various functions available
in a WebSphere MQ network
that are not available on a service integration bus that has a WebSphere MQ link or a WebSphere MQ client link.
The following list helps you identify those functions but it is given
as guidance rather than a complete definition. Functions not supported
include:
- Native MQ client (this includes client applications that make
use of the base MQ classes for Java™)
attach.
- Message segmentation.
- Message grouping.
- The MQMD Offset. Original length, MsgFlags, MsgSeqNumber, and
GroupId fields are not supported because Message grouping and message
segmentation are not supported.
- Distribution lists.
- Reference messages.
- Triggering.
- Alternate user authority.
- Pass/set identity context.
- In a program, setting the attributes of a queue (that is, the
equivalent function of MQSET).
- Confirmation of arrival/delivery.
- Cluster sender/receiver channels (and cluster workload exits),
because a messaging engine cannot participate in a WebSphere MQ cluster.
- Server and requestor channels.
- API crossing exits.
- Data conversion exits.
- Channel exits.
- The equivalent to the MCAUSER and PUTAUTH fields of a channel.
- Networks based on NetBIOS, SPX or SNA.
- Message based command server.
- PCF (Programmable Canonical Form messages).
- Model queues. Service integration does not allow you to define
model queues of a given name. Service integration technology supports
only one model queue called the SYSTEM.DEFAULT.MODEL.QUEUE.
- Dynamic queue name prefix length. Service integration all dynamic
queue names with '_Q' and suffixes them with a unique id. This restricts
the name specified in the dynamic queue name field of the Object Descriptor
to up to 12 chars. If this name is greater than 12 characters, then
it is truncated to 12 characters. In service integration, it is not
possible to create a dynamic queue with the full name specified in
the dynamic queue name field of the Object Descriptor.
- Mark skip backout option.
- Signal option on a get request.
- Version 3 get message options structures.
- All queue properties (the properties of a service integration
destination do not map, one for one, to the properties of a WebSphere MQ local queue,
for example).
- Poisoned messages. Service integration bus local destination definitions
have a maximum failed deliveries count (that is, the equivalent to
the WebSphere MQ BackoutThreshold
value) but there is no equivalent of the WebSphere MQ backout requeue queue name.
In service integration technology, poisoned messages are instead backed
out to an exception destination. Additionally, in service integration
technology, when the number of times an application backs out a poisoned
message is equal to the maximum failed deliveries count, the message
is automatically backed out to an ExceptionDestination. If there
is more than one message in the current unit of recovery, only the
poisoned message is backed out to the ExceptionDestination. The remainder
of the messages in the unit of recovery are backed out to the destination
from which they were read.
- A strict limitation of 48 bytes on the name of a queue. Service
integration bus destination names can be greater than 48 bytes in
length. If a destination name is to be returned to a WebSphere MQ JMS application, then it is
important to use 48 byte destination lengths. Though, in some cases,
it may be feasible to define an alias destination with a name length
of up to 48 bytes) to map to a local destination with a name of length
greater than 48 bytes.
Differences from WebSphere MQ delivery options
While WebSphere MQ supports persistent
and nonpersistent messages, service integration supports five delivery
options (also known as qualities of service (QoS).
- BEST_EFFORT_NONPERSISTENT
- RELIABLE_NONPERSISTENT
- EXPRESS_NONPERSISTENT
- RELIABLE_PERSISTENT
- ASSURED_PERSISTENT
Outbound BEST_EFFORT_NONPERSISTENT, RELIABLE_NONPERSISTENT,
and EXPRESS_NONPERSISTENT messages sent to a WebSphere MQ network, are sent as nonpersistent
messages in the WebSphere MQ
network. Outbound RELIABLE_PERSISTENT and ASSURED_PERSISTENT messages,
when sent to a WebSphere MQ
network, are sent as persistent messages.
For inbound messages
from a WebSphere MQ network,
the inbound nonpersistent reliability (with possible values
of BEST_EFFORT_NONPERSISTENT, RELIABLE_NONPERSISTENT, and EXPRESS_NONPERSISTENT)
and the inbound persistent reliability (with possible values
of RELIABLE_PERSISTENT and ASSURED_PERSISTENT), fields of the MQLinkReceiver
channel can be set to specify the service integration delivery options
to be used for nonpersistent and persistent messages.
Similarly,
for inbound messages from WebSphere MQ
JMS clients, the inbound nonpersistent reliability and the inbound
persistent reliability fields of the MQ client link can be set to
control the message persistence.