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Michigan iSeries Technical Education Conference MQ Series IBM’s Middleware Solution Presented by

Michigan iSeries Technical Education Conference MQ Series IBM’s Middleware Solution Presented by Ryan Technology Resources Michael Ryan michael@ryantechnology.com. (C)opyright 2006 Michael Ryan. What is Middleware?.

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Michigan iSeries Technical Education Conference MQ Series IBM’s Middleware Solution Presented by

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  1. Michigan iSeries Technical Education Conference MQ Series IBM’s Middleware Solution Presented by Ryan Technology Resources Michael Ryan michael@ryantechnology.com (C)opyright 2006 Michael Ryan

  2. What is Middleware? • Middleware is software that manages several parts of a connection between systems • Physical and logical communications • Data translation • Error recovery • Message sequencing

  3. MQ Series • ‘Proper name’ is Websphere MQ • Framework for communications • Multiple levels • Different operating systems • Different hardware platforms • Different communication protocols • Ubiquitous connectivity

  4. AIX Compaq NSK DOS DYNIX/ptx HP-UX Linux MacOS MVS/ESA NUMA-Q OpenVMS Alpha OpenVMS VAX OS/2 OS/390 OS/400 Sun Solaris UNIX Unisys 2200 Series Unisys A Series VM/ESA VSE/ESA Windows Java Multiple Platforms

  5. Access • Programmatically accessed through Application Programming Interfaces (API) • Same concept for each system • ‘Store and Forward’ • Not unlike SNADS • Guaranteed delivery • Asynchronous communication

  6. Components • Four main components of MQ Series • Queue manager • Queues • Channels • Messages

  7. Messages • The data being sent between applications • Has meaning to the application – no particular meaning to MQ Series • Two parts – the application data and a message descriptor • Application data is what the applications are sending and receiving with each other • Message descriptor is something that is not seen by the application programmer. It contains information such as the from and to queue names, the priority, levels of MQ Series, security information and so on

  8. Queues • Message repository - sent to or received from • Not unlike data queues (*DTAQ) • Use APIs to access MQ Series data queues • Independent of the application • Characteristics • Put-enabled (messages can be placed on the queue) • Get enabled (messages may be retrieved from the queue) • Queue depth • Queue size

  9. Queue Manager • Responsible for queues • Every queue belongs to a queue manager, whether the queue is local or remote • A local queue managed by a local queue manager – a queue manager on the same system as a queue • A remote queue is manager by a remote queue manager – a queue manager on a different system • A local application puts messages on a remote queue (which is a local queue to the remote system) and the remote application puts messages on a local queue (which is remote to the local application)

  10. Queue Manager Local System Remote System Managed by remote system queue manager Managed by local system queue manager Remote Queue Local Queue Local Queue Remote Queue

  11. Channels • Link between the actual communications and the MQ Series queue managers • Type of communications (TCP/IP or SNA) • Two types – message channels and client channels • A message channel is used for server-to-server communication • Unidirectional • Two channels - a sending channel and a receiving channel • A client channel connects a client to a server • Bi-directional • Queues exist on the server – there are no client queues

  12. MQ Configuration • Use RSTLICPGM • 5733-A38 • Developed in Hurlsley, supported from Raleigh (Software Group) • Loads • QMQM library • Objects in the IFS • User profiles QMQM and QMQMADM • Read the instructions…

  13. MQ Configuration - WRKMQM

  14. MQ Configuration - CRTMQM

  15. MQ Configuration -CRTMQMCHL

  16. MQ Configuration -CRTMQMQ

  17. MQ Programming • The programming model for MQ Series applications is similar to any communications program • One system (usually the client) sends a message (a request for services) to the other system (usually the server) • The server then replies with the information desired by the client. This process continues until the client or the server desire to end the communication.

  18. MQ Programming • Contrast MQ Series with sockets programming • Amount of code needed for an MQ Series program is much less than a socket program • Don’t need to code for ‘low-level’ handshaking • Low-level error recovery is performed by MQ • Don’t need to ‘connect’ or ‘accept’ • Just read and write to queues

  19. MQ Programming - APIs • Application Programming Interface • Relatively few APIs • Most commonly used • MQCONN – Connect to a Queue Manager • MQDISC – Disconnect from a Queue Manager • MQOPEN – Open an MQ object (Queue) • MQCLOSE – Close an MQ object (Queue) • MQPUT – Put a message to an MQ Queue • MQGET – Get a message from an MQ Queue

  20. MQ Programming - APIs • Other APIs are available but usually not needed • MQINQ – Inquire about an MQ object (Queue, Queue Manager, Channel…) • MQSET – Set some of the attributes of a Queue • MQBEGIN – Begin a Unit of Work in a Commitment Control environment • MQCMIT – Commit a Unit of Work in a Commitment Control environment • MQBACK - Rollback a Unit of Work in a Commitment Control environment

  21. MQ Programming - Model • The general flow of events in an MQ Series application program is: 1. Connect to a queue manager with MQCONN 2. Open the queues needed for communication with MQOPEN 3. Use MQPUT and MQGET to send and receive messages 4. Close the opened queues with MQCLOSE 5. Disconnect from the queue manager with MQDISC

  22. MQ Programming - RPG • MQ Series applications usually follow the model • Using MQ Series in an RPG application is simple • Procedures called by the APIs are in service program QMQM/LIBMQM • Ensure this service program is bound by reference with your RPG program • The data structures and prototype definitions can be found in library QMQM

  23. MQ Programming - RPG • Here’s an example of /INCLUDEs I use in my MQ Series programs: * MQI Named Constants /COPY QMQM/QRPGLESRC,CMQG * Object Descriptor D MQOD DS /COPY QMQM/QRPGLESRC,CMQODG * Message Descriptor D MQMD DS /COPY QMQM/QRPGLESRC,CMQMDG * Get Message Options D MQGMODS /COPY QMQM/QRPGLESRC,CMQGMOG * Put message options D MQPMO DS /COPY QMQM/QRPGLESRC,CMQPMOG

  24. MQ Programming - RPG • These includes will copy in • Named constants • Object descriptor information • Message descriptor information • Put and get option information • Review these include files to identify the field names and prototyped names you will use in your program

  25. MQ Programming - RPG • Example of connecting to a queue manager: * Connect to MQ Series queue manager. C CallP MQConn(QMName : C HConn : C OCode : C Reason) C If OCode = CCFail * Error occurred... C EndIf

  26. MQ Programming - RPG • QMName contains the name of the queue manager • HConn is returned from the API call • Contains the ‘handle’ that will be used in later calls • The handle identifies the specific queue manager and is used internally by MQ Series • OCode and Reason are returned by the API call and identify if an error occurred • Note: I check OCode to see if it is equal to the named constant CCFail – if so, an error occurred • Appropriate error recovery code goes here • This call completes the first step in the MQ Series application flow – connecting to the queue manager

  27. MQ Programming - RPG • Example of opening a queue: * Options are input-as-queue-def and fail-if-quiescing C Eval Opts = OOInpq + OOFIQ C Eval ODon = ReplyQue C CallP MQOpen(HConn : C MQOD : C Opts : C HInObj : C OCode : C Reason) C If Reason <> RCNone * Error occurred... C EndIf

  28. MQ Programming - RPG • Variable Opts is set to special named constant values OOInpq and OOFIQ • Open the queue as input • Fail if quiescing • Variable ODon has the value of ReplyQue • Contains the name of a queue • Association already established between the queue manager and the queue during creation • HConn is the queue manager handle • Obtained from the MQConn call

  29. MQ Programming - RPG • MQOD variable specified in the MQOpen call is a data structure. • ODon is one of the many subfields in the data structure • HinObj is returned from the API call and contains the handle for the opened queue • Used for puts and gets • OCode and Reason are returned from the API call and indicate an error • If Reason does not contain the value in named constant RCNone, an error has occurred

  30. MQ Programming - RPG • An example of MQPut: • MQGet follows the same pattern C Eval MdFmt = FmStr C Eval MDRQ = ReplyQue C Eval MDRM = QMName C CallP MQPut(HConn : C HOutObj : C MQMd : C MQPmo : C BufLen : C BufPtr : C CCode : C Reason) C If Reason <> RCNone * Error occurred... C EndIf

  31. MQ Programming - RPG • Note the MQ* variables • These are subfields in data structure MQMD and MQPMO • Set these variables to specific values that are determined by the needs of the application • BufLen contains the length of the buffer of information that we are sending • BufPtr is a variable of type pointer that contains the address of the buffer of information • As before, we interrogate the Reason to determine if an error has occurred

  32. MQ Programming - RPG • An example of MQGet: C CallP MQGet(HConn : C HInObj : C MQMd : C MQGmo : C BufLen : C BufPtr : C MsgLen : C CCode : C Reason) * Note: Reason should be 0 (RCNone). If return code = 2033 (RC2033), * no messages are available. C If Reason <> RCNone C If Reason <> RC2033 * Error occurred... C EndIf C Else * process the data… C EndIf

  33. MQ Programming - RPG • Note the MQ* variables • Contain the specific values that are used by the MQGet call to control its operation and are subfields in the MQMD and MQGMO data structures • BufLen is the length of the receive buffer • BufPtr is a pointer to the buffer • MsgLen is the number of bytes returned from the MQGet call • Lookingfor a specific Reason code and not signaling an error if it’s encountered • A 2033 Reason code (in named constant RC2033) indicates that an MQGet was performed and no data was available to be read • This is certainly possible – the other system may have no data to send at that time.

  34. MQ Programming - RPG • An example of MQClose: * Close input MQ Series connection. C Eval Opts = CONone C CallP MQClose(HConn : C HInObj : C Opts : C CCode : C Reason) C If Reason <> RCNone * Error occurred... C EndIf

  35. MQ Programming - RPG • Queue manager handle • HConn – specified in the MQConn call • Queue handle • HinObj – specified in the MQOpen call • An options field • Check the returned Reason to see if an error occurred

  36. MQ Programming - RPG • An example of MQDisc: * Disconnect from MQ Series Queue Manager. C CallP MQDisc(HConn : C OCode : C Reason) * Report reason and stop if failed. C If OCode = CCFail * Error occurred... C EndIf

  37. MQ Programming - RPG • Specify the handle from the MQConn call • Check for an error

  38. MQ Programming - C An MQOpen Example in C: O_options = MQOO_INPUT_AS_Q_DEF /* open queue for input */ + MQOO_FAIL_IF_QUIESCING; /* but not if stopping */ MQOPEN(Hcon, /* connection handle */ od, /* object descriptor for queue */ O_options, /* open options */ &HInobj, /* object handle */ &InOpenCode, /* completion code */ &Reason); /* reason code */

  39. MQ Series • MQ Series (or the WebSphere MQ Family) • Very strong and robust solution to middleware problems • Reliable • Flexible • Easy to configure • Easy to program • Excellent choice for connectivity and system integration issues

  40. Getting More Information • IBM Websphere MQ Site • http://www-306.ibm.com/software/integration/wmq/ • AS/400 Red Books • MQSeries Version 5.1 Administration and Programming Examples • http://www.redbooks.ibm.com/redbooks/SG245849.html • Great forum for MQ stuff • http://www.mqseries.net/

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