IBM MQ - Comparing Distributed and z/OS platforms

IBM MQ - Comparing Distributed and z/OS platforms

• 1.
  HHM-2835: IBM MQon z/OS & distributed – are they like oil and water? Mark Taylor [email protected] IBM Hursley Lyn Elkins [email protected] IBM zGrowth (WSC)
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  Introduction • One objectiveof MQ is isolating apps from needing to understand platforms ‒ There is a common API that can be expressed in many languages • Another objective is to have (reasonably) common operational model ‒ Much of admin is the same on all platforms • But it’s not all the same ‒ One dichotomy has always been whether to be natural to MQ-ness or behave like other things on the platform ‒ Some features don’t make sense on some platforms  For example, .Net interface is only on Windows ‒ Some features have not been implemented everywhere for other reasons • So there are differences, and that is what this presentation will cover • This is based on V8
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  Code Streams • Thereare essentially two implementations of MQ from Hursley lab ‒ z/OS ‒ Distributed (Windows, Unix, Linux, i) ‒ There are some further subspecies variants like VSE or NSS • Within Distributed implementation, there are some platform unique features ‒ But we won’t discuss those here ‒ Most platform-unique code abstracts OS facilities like locking or NLS or threads • In the early days, some code was written for one and then “ported” ‒ In particular, the channel code ‒ Meant double-fixing, and re-porting for each release • Internal architecture (eg tasks, threads) very different ‒ But we won't discuss much of that. Understanding externals is more important • Since V7.0, some code is truly common ‒ Just one copy of the source part shared between both ‒ New features generally use common code where feasible
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  Sections • Setting up •Application Programming • Administration
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  How this presentationworks • Lyn will talk about z/OS in this color • Mark will talk about Distributed in this colour
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  Setting Up
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  Getting started • Lotsof differences in initial installation and setup • Getting the code on the box is part of the job ‒ MQ uses native installation techniques for all platforms ‒ Needs a suitably-authorised person to do that installation  SMPE for z/OS, installp for AIX, rpm for Linux etc • But other differences primarily due to ‒ Security ‒ Storage • Share philosophy of needing no more features than is found on the system ‒ So no prereq software for core capabilities of MQ ‒ Product ships components that are needed such as gskit ‒ But can exploit things that we know are there  For example, on z/OS we use the system-provided SSL ‒ Some extended capabilities may have additional prereqs  Shared Queues need DB2
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  Security • On Distributed,MQ implements its own authorisation mechanism ‒ There is no generally-accepted standard interface on these systems • And relies on the existence of certain userids ‒ There are differences even between individual platforms • On z/OS, MQ exploits the common authorization interface, SAF ‒ And so the z/OS security administrator has to be involved ‒ Define the profiles etc. • Will look more at security later on
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  Storage (Distributed) • OnDistributed, MQ uses directories such as /var/mqm/qmgrs and /var/mqm/logs ‒ The system administrator will probably allocate filesystems and mount them ‒ These days, may have separate SAN administrator • Each queue has its own file within the filesystem ‒ To store the message data ‒ Each queue could hold 1TB • Queues do not interfere with each other's storage requirements ‒ Subject to max size of filesystem • Logs can be LINEAR or CIRCULAR ‒ Choice made when qmgr is created ‒ With linear logging, you then need a job to remove old log files ‒ MQ does not directly implement dual-logging; relies on RAID filesystems
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  Storage (z/OS) • Queuesare handled via pagesets and bufferpools • Multiple queues may use the same pageset and bufferpool ‒ Can lead to storage contention ‒ V8 increases number of bufferpools to match number of pagesets • No direct equivalent of circular logging but constraints can be applied to achieve a similar effect ‒ Semi-circular? ‒ Active logs are ‘almost like circular’, with offloading to archive logs • Logs are managed via the BSDS • MQ understands and implements Dual Logging • Tool provided to format and extract messages from log
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  Shared Queues • Az/OS-unique feature ‒ Multiple queue managers can see the same queue ‒ Continuous processing of messages from a queue even when one LPAR fails • Relies on the Coupling Facility hardware ‒ And relies on DB2 Data Sharing • Results in several unique possibilities ‒ Inter-qmgr communication without standard channels ‒ Dynamic selection of which qmgr to connect to • Effects appear in many places ‒ For example, single MQSC command can be issued to multiple queue managers giving multiple responses
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  Extra Features • MQV7.5 on Distributed incorporated MFT (nee FTE) and AMS ‒ "MQ Advanced" license covers all features • On z/OS, these are available as separate products ‒ V8 improved technical integration but still separate licenses • On z/OS, use of inbound client connections was restricted ‒ Restriction removed in V8 (no longer a CAF) • Distributed MQ has the MQXR service for mobile (MQTT) clients ‒ Not available on z/OS ‒ Expected that mobile clients connect via front-end qmgr before hitting z/OS apps
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  Application Programming
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  General • Default codepagesand encoding differ by platform • Always use the header files for your platform ‒ Don't be tempted to cross-compile • Maximum lengths of fields may vary • Language support may vary ‒ Assembler only on z/OS ‒ And some APIs: MQAI only on Distributed • MQI return codes may be different ‒ Often because underlying storage mechanisms have different error conditions ‒ For example, Coupling Facility errors on shared queues • z/OS does not have MQ clients ‒ Some parameters to some verbs only apply in client environments ‒ For example, the MQCD passed during MQCONNX
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  API - Connections •MQCONN/MQCONNX ‒ Verbs not required for CICS transactions  MQHC_DEF_HCONN can be used for subsequent verbs in applications ‒ ConnTag is available to control serialization  An application (especially an MCA) can tell if another instance of itself is already running  On either the same local qmgr or any other in the QSG ‒ Group connection to QSG ‒ Lots of client-only options for connection  MQCD can be specified  Reconnect options ‒ MQCNO_SHARED options for multi-threaded applications  Controls whether an hConn can be (serially) used by other threads in the same process ‒ Fastpath binding ‒ Control of accounting  When accounting information is being collected, some apps may request exclusion
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  API - Disconnections •MQDISC ‒ Always recommended ‒ Rollback when application abends  Although definition of "abend" is not clear in every case  CICS and IMS do make it clear!  A JVM has been known to return OK to the operating system even when the user's code has caused a fatal exception ‒ Rollback when not used and application ends
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  API - Objects •MQOPEN ‒ Default dynamic queue names begin with CSQ.* or AMQ.* ‒ Distributed can open multiple queues simultaneously via Distribution List  Publish/Subscribe preferred cross-platform model • MQCLOSE ‒ No platform differerences in practice • MQSET ‒ Follows the same rules as MQSC attributes for platforms • MQINQ ‒ Follows the same rules as MQSC attributes for platforms
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  API - Messages •MQPUT/MQPUT1 ‒ Messages can be automatically segmented  But Message groups are cross-platform ‒ Distributed supports "Reference messages" which can avoid putting large amounts of data on a queue • MQGET ‒ z/OS has "get with signal" to asyncronously notify app when messages appear  MQCB is now preferred cross-platform model ‒ z/OS has MARK_SKIP_BACKOUT for simpler processing of poison messages  Bad messages can be moved to an application-specific DLQ while backing out other resource changes ‒ Distributed can get portions of messages via segmentation • MQSUB ‒ No platform differences • MQSUBRQ ‒ No platform differences
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  API – Flowcontrol • MQCB ‒ Definition of the callback function in MQCBD varies by environment ‒ eg C function pointer, CICS program name • MQCTL ‒ Not in IMS adapter ‒ In CICS, cannot use MQOP_START – use MQOP_START_WAIT ‒ On z/OS, apps must be authorized to use USS to use MQOP_START • MQSTAT ‒ Client applications only ‒ But usable regardless of server platform
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  API - Properties •MQDLTMP • MQBUFMH • MQCRTMH • MQDLTMH • MQMHBUF • MQSETMP • MQINQMP • No platform differences
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  API - Transactions •MQBEGIN ‒ Only available on Distributed ‒ z/OS always has a transaction manager available • MQCMIT ‒ On all platforms when not running under external TM • MQBACK ‒ On all platforms when not running under external TM • Default for MQ transactional behaviour is different ‒ MQI on Distributed assumes NO_SYNCPOINT ‒ MQI on z/OS assumes SYNCPOINT ‒ Always specify syncpoint options on MQI calls • Environments for two-phase transactions differ ‒ On z/OS, RRS CICS and IMS are all available for transaction management ‒ On Distributed, XA is available as the standard interface  And MQ can act as a transaction manager
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  Exits • z/OS hasAPI-Crossing exit for CICS ‒ But no other environments • Distributed has API exit for all environments ‒ With a very different interface • Installable Services on Distributed ‒ But very few people write these so not too interesting ‒ Primarily used for the OAM security module • Channel send exit – ExitSpace field ‒ Used to reserve space in network transmission buffers for send exits ‒ Always zero on z/OS • No publish exit on z/OS • z/OS exits have MQXWAIT ‒ Necessary because process/thread model for channels is different
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  Administration
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  Object Definitions • Attributesand ini files ‒ Some items are queue manager attributes on one platform but not other ‒ z/OS has lots related to its storage • Some unique object types ‒ z/OS has STGCLASS and CFSTRUCT ‒ Distributed has SERVICES and COMMINFO • Startup ‒ CSQZPARM is assembled/linked and other inputs run during startup  Reset configuration, define default objects etc ‒ On Distributed, standard objects are created by qmgr creation and updated during migration
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  Object Attributes –Queue Manager • Apart from shared queue and storage-related attributes … ‒ Various events differ as shown in other charts ‒ Some z/OS attributes are in qm.ini for Distributed • z/OS only ‒ ACTCHL, MAXCHL ‒ ADOPTCHK/ADOPTMCA ‒ CHIDISPS, CHIADAPS ‒ DNSGROUP, DNSWLM ‒ EXPIRYINT ‒ GROUPUR ‒ IGQ, IGQAUT, IGQUSER ‒ LSTRTMR,LU62ARM, LU62CHL, OPORTMIN, OPORTMAX, RCVTMIN, RCVTTYPE, TCPNAME, TCPKEEP, TCPSTACK ‒ SCYCASE ‒ SSLTASKS ‒ TRAXSTR, TRAXTBL • Distributed only ‒ ACCTCONO, ACCTINT, ACCTMQI, ACCTQ ‒ ACTIVREC ‒ CCSID ‒ CERTVPOL ‒ CHAD ‒ SCHINIT, SCMDSERV
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  Object Attributes –Queues and Channels • Apart from shared queue and storage-related attributes … • Queue ‒ DEFTYPE(SHAREDYN) z/OS ‒ HARDENBO only effective on z/OS ‒ INDXTYPE z/OS ‒ DISTL Distributed ‒ NPMCLASS Distributed ‒ SCOPE Distributed only, but obsolete ‒ STATQ Distributed ‒ TriggerData for transmission queues can be blank on Distributed, names channel on z/OS • Channel ‒ CONNAME 48 characters on z/OS, 264 elsewhere ‒ Format of exit names and exit data is platform-specific ‒ STATCHL Distributed only before V8 ‒ PUTAUT ONLYMCA/ALTMCA ‒ KAINT only effective on z/OS
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  Queue Manager operations •Message Expiry ‒ z/OS has explicit config for timing of task to remove expired messages ‒ Distributed has a similar task but no documented configuration • Security Cache Scavenger ‒ z/OS has parameters to control authority cache lifetime ‒ No equivalent on Distributed; use REFRESH SECURITY explicit command • Storage Scavengers ‒ z/OS has tasks to release bufferpool and pageset storage ‒ Distributed will release queue file storage at intervals • Queue Indexing ‒ z/OS has explicit indexes on queues to assist with retrieval patterns ‒ Distributed has hashing to perform similar role but no documented configuration
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  Intercommunication and Clusters •Channels are the same • Clustering is essentially the same across all platforms • MQ 7.5 introduced concept of multiple cluster transmission queues ‒ Made common in V8
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  Security (1) • Authenticationfeature added in V8 ‒ Distributed supports userid validation in operating system and explicit LDAP ‒ z/OS supports userid validation in operating system ‒ Both support LDAP when transparently used by OS • SSL/TLS configuration ‒ Distributed (mostly) qmgr uses gskit toolkit ‒ z/OS qmgr uses System SSL ‒ Can lead to discrepancies in crypto algorithms supported ‒ Different versions support different algorithms ‒ And there may also be client-related discrepancies  Java programs rely on JSSE implementations  .Net programs (from V8) can use Microsoft inbuilt implementations  NSS client uses OpenSSL ‒ There is a good common overlap between all of these, but not identical sets ‒ Current versions have significantly reduced the sets supported on all platforms
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  Security (2) –Access Control • z/OS ‒ Uses system-provided interface for authorization  SAF is common API to RACF, Top Secret, ACF2 ‒ Has to work with the 4 permissions available in SAF ‒ No distinction between PUT and GET  Often alias queues are used to isolate permissions ‒ Granular control of "impersonation" (setting context, alt-user) ‒ One operation may result in several authorization queries • Distributed ‒ MQ-provided authorisation interface  Implemented in the OAM – OS or LDAP-based ‒ Many permissions on objects ‒ Global controls on impersonation  If you have authority to use alt-user, there are no constraints on which user ‒ Well-known "mqm" id for full authority
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  Commands • Basic OS-levelcommands are different ‒ Create, start, stop, delete queue manager procedures ‒ Distributed has command-line interface ‒ z/OS has JCL • Issuing configuration commands like ALTER QLOCAL ‒ Distributed has runmqsc shell ‒ z/OS has ISPF panels for most commands ‒ And the +cpf commands for runmqsc equivalence ‒ MQ Explorer is product-provided common GUI • Common programming interface (PCF) for configuration commands ‒ z/OS requires an "extended" format which may have multiple sets of responses  Supporting a Queue Sharing Group environment ‒ Distributed supports the same format but not the default ‒ Differences are hidden in the Java PCF classes
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  MQSC Commands • Somecommands not available in all platforms • RESET QSTATS is only on z/OS ‒ PCF available on all platforms • ARCHIVE LOG is only on z/OS even though Distributed also have logs • DISPLAY SYSTEM • MOVE QLOCAL ‒ V8 has dmpmqmsg • DISPLAY QMSTATUS only on Distributed ‒ Some items have z/OS specific commands like DISPLAY CMDSERV • STOP CONN only on Distributed ‒ All platforms have STOP CHL to kill client connections • Client application name shows differently in DISPLAY CONN/QSTATUS ‒ Program name shown on Distributed, "CHIN" on z/OS • Some z/OS MQSC have command-line equivalents on Distributed ‒ STOP QMGR == endmqm
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  Monitoring • Many queuemanager event messages are common ‒ For example, queue full • But not every event is on every platform ‒ Authorisation, Logging, and Channel auto-definition events are Distributed only ‒ IMS Bridge events are only on z/OS • Recording queue manager and application activity is very different ‒ z/OS has SMF 115 and 116 records ‒ Distributed has accounting, statistics and application activity events • Distributed accounting and stats events are analogous to SMF 116 ‒ No equivalent to 115 records
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  Events Images
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  Problem Determination • OnDistributed, there are several places to look for PD information ‒ Error logs written to /var/mqm/errors and /var/mqm/qmgrs/<qmgr>/errors ‒ FFST written to /var/mqm/errors for serious errors ‒ Trace provided by MQ commands and written to /var/mqm/trace • On z/OS, also numerous places to follow the clues: ‒ The MSTR and CHIN JES log  Should always be the first place to look ‒ MQ API trace (aka user parameter trace) – a GTF trace ‒ SMF 115 statistical information ‒ SMF 116 class(3) accounting (task related) data ‒ A dump for serious problems
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  Backup • MAKEDEF anddmpmqcfg are tools to backup configuration ‒ With V8, have dmpmqmsg to backup messages • On Distributed, backup of log files is done by stopping qmgr and copying /var/mqm/log directory ‒ rcdmqing takes images of queues into logs • On z/OS, full and fuzzy backups of pagesets are supported • CFSTRUCT backup required for QSG ‒ takes image of shared queue into logs
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  High Availability andDisaster Recovery • Shared queues on z/OS for continuous processing • On Distributed, MQ provides multi-instance ‒ Not on z/OS because ARM is provided • Cross-site DR will usually use disk replication for any platform
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  Summary • Title asksabout oil and water • Perhaps (olive) oil and (balsamic) vinegar is better description ‒ Blending together
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