amzshar

2007年12月15日 星期六

.
. IBM WebSphere MQ v6.0
. Chapter 5.2 IBM MQ Administration in a Mixed Environment.
.

=== Three fields in the Message Descriptor ===
1. Encoding :
　- Representation of the numeric data in the message.
　- iSeries, Windows, and so forth
　　MQENC_NATIVE
2. CodedCharSetId :
　- Representation of the character data in the message.
　　MQCCSI_Q_MGR
3. Format :
　- Indicates the nature of the data in the message.
　- Values MQ ... are reserved for WebSphereMQ


=== Requesting Application Data conversion ===
1. Request data conversion on the MQGET call :
　- MQGMO_CONVERT
　- Encoding and CodedCharSetId
　　a. On input, requested representation of the message.
　　b. On output, what the application actually receives.
　- Conversion performed, if necessary, on the basis of what is contained in the Format field.
　- A warning, and the message returned in its original form, if the conversion cannot be done.
2. Otherwise, request data conversion at the sending end of a message channel :
　- CONVERT(YES)
　- Unconverted messages are put on the Dead Letter Queue at the sending end.


=== What Application Data Conversion Can Be done ? ===
1. Some formats are built-in, and the data conversion is performed
　　by a built-in conversion routine :
　- A message consisting entirely of characters.
　- A message structure definedd by WebSphereMQ.
2. A user written data conversion exit is required when :
　- The format of a message is defined by the application, not by WebSphereMQ.
　- A message with a built-in format fails to convert.
3. There is a WebSphereMQ utility to help write a data conversion exit.
　# crtmqcvx SourceFile TargetFile

※ Exit 掛勾 : —↓＿↑—↓＿↑—↓＿↑—
　- Security Exit
　- Conversion Exit
　- Compress Exit
　- Message Exit


=== What Applications Should Do ===
1. Put messages with the following values in the Encoding and CodedCharSetId fields :
　- MQENC_NATIVE　(for native encoding)
　- MQCCSI_Q_MGR　(for the same CCSID as the Queue Manager)
2. Put all messages with a format name :
　- MQFMT_STRING　(for a message consisting entirely of characters)
3. Use the MQGMO_CONVERT option on the MQGET call :
　- Check what is delivered by the call.
4. If necessary, use CONVERT(YES) at the sending end of a message channel.


=== Command Server === (MQ V6已經自動與QM啟動)
1. Command Queue :
　- SYSTEM.ADMIN.COMMAND.QUEUE
　- Messages contain Programmable Command Format (PCF) commands.
2. Command server process the messages in the Queue :
　# strmqcsv QMgrName　
　# endmqcsv QMgrName　(Ends the command server)
　# dspmqcsv QMgrName　(Displays the status of the command server)
3. Enables network administration applications :
　- "Single point of control"


=== Support for PCF Commands ===
1. All Queue Managers have a command server which accepts PCF commands,
　except :
　- WebSphereMQ for z/OS Version 5
2. Administration utilities which issue PCF commands :
　- SupportPacs for WebSphereMQ for UNIX, Linux and Windows.
　- Vendor products.
　- # runmqsc -w 　(indirect mode)
3. Application using the WebSphereMQ Administration Interface.


=== Program Example ===
1. Assume a utility to purge any Queues that have existed beyond their retention interval (賞味期...哈).

[ Application ]　　　　　　　　　　　　　　[ Command Server ]
　　MQPUT →→→→→→→→→→→→→→→→ MQGET
　　　　　　　　　　MQCMD_INQUIRE_Q　　　　Inquire attributes
　　　　　　　　　　- generic quene name　　　　 of selected queues
　　MQGET ←←←←←←←←←←←←←←←← MQPUT
Determine which　　 　- Qname　　　　　　　　　Response for each
queues have　　　　　- RetentionInterval　　　　　 matching queue
expired, and for 　　 　- CreationDate
each one ...　　　　　　- CreationTime
　　MQPUT →→→→→→→→→→→→→→→→ MQGET
　　　　　　　　　　MQCMD_DELETE_Q　　　　Delete named queue
　　　　　　　　　　- QueueName


=== Indirect Mode ===
1. Each WebSphereMQ command is sent within an Escape PCF command to the command Queue
　of the named Queue Manager :
　- Connects to the default Queue Manager.
　- Escape PCF command processed at the target Qeueu Manager.
2. Waits for the replies :
　- Time limit for the wait.
　- Writes a report based on the replies received.

　# runmqsc -w 5 QMgrName　　(WaitTime in seconds specifies the indirect mode)

3. Can also send a WebSphereMQ command to the system-command input Queue
　of a z/OS Queue Manager.
　-　-x parameter


=== Instrumentation Events === 提供給Monitor程式用
1. Have a Queue Manager report a problem condition immediately :
　- Number of messages on a Queue is increasing.
　- Get requests are inhibited for a Queue.
　- Message channel has stopped.
2. Enabled events are reort as event messages on event Queues :
　- SYSTEM.ADMIN.QMGR.EVENT
　- SYSTEM.ADMIN.PERFM.EVENT
　- SYSTEM.ADMIN.CHANNEL.EVENT
　- SYSTEM.ADMIN.CONFIG.EVENT　　(z/OS only)
　- SYSTEM.ADMIN.COMMAND.EVENT　　(z/OS only)
　- SYSTEM.ADMIN.LOGGER.EVENT　　(not z/OS)


=== Responding to an Instrumentation Event ===
1. Queue Manager events :
　- Enable a Queue for put or get requests if it is not intentionally disabled.
　- Corrent the authorizations for a Queue, or stop unauthorized users
　　trying to put messages on the Queue.
2. Performance events :
　- Start a process to clear the backlog of messages.
　- Syspend a process that is putting too many messages on a Queue.
3. Channel events :
　- Restart a CHANNEL.
　- Process the Dead Letter Queue.
4. Logger events :
　- Archive unneeded log files.


=== Dead Letter Queue ===
1. When a problem relating to a message is detected asynchronously,
　　an exception report is generated if one has been requested
　　and the report is sent to the specified reply-to Queue.
2. The Feedback field in the message descriptor of the report message
　　indecates the reason for the report.
3. The original message is put on the Dead Letter Queue unless
　　MQRO_DISCARD_MSG is requested as a report option.
4. If a message cannot be delivered, it is put on the Dead Letter Queue
　　at the receiving end of a message CHANNEL, if one is defined.
5. Message-retry at the receiving end of a CHANNEL may be useful
　　if the problem is only temporary.
6. If CONVERT(YES) is specified in the CHANNEL definition at the sending end
　　of a message CHANNEL and a message cannot be converted,
　　the message is put on the Dead Letter Queue at the sending end.
7. If a message cannot be put on the Dead Letter Queue,
　　the CHANNEL is stopped and the message remains on the Transission Queue.
　　A fast non-persistent message, however, is just discarded in these circumstances
　　and the CHANNEL ramains open.


=== Dead Letter Queue Handler ===
1. Rules table contains a set of rules.
　- Each rule consists of pattern matching keywords and an action.
　- For each message on the Dead Letter Queue, each rule whose pattern
　　matches the message is attempted in turn.
　- A message can be retried, forwarded, discarded or ingored.
　- A message can be forwarded with, or without the dead letter header.
2. Can have multiple instances, each with a different rules table.
3. Source of a sample Dead Letter Queue handler is supplied as well.

　# runmqdlq < Rules_Table

　DESTQM(QM17) ACTION(FWD) FWDQ(&DESTQ) FWDQM(QM17A)
　MSGTYPE(MQMT_REPORT) FEEDBACK(MQFB_EXPIRATION) ACTION(DISCARD)
　REASON(MQRC_Q_FULL) ACTION(RETRY)
　DESTQ(XYZ*) ACTION(FWD) FWDQ(XYZ_DEADQ) FWDQM(' ')


=== Using Dead Letter Queues ===
1. Create a Dead Letter Queue on all Queue Managers :
　- Use message-retry on message CHANNELs for transient conditions.
　- Consider "return to sender".
2. Use a Dead Letter Queue handler :
　- Trigger when a message arrives on the Dead Letter Queue.
　- Possibly attempt further retries.
　- If unsuccessful, forward to an application Dead Letter Queue associated with :
　　a. The distination Queue.
　　b. The application specified by the PutApplName field in the message descriptor.
3. Don't allow an application Dead Letter Queue to become full.