Addressing OLTP Solutions with CICS: The Transaction Server ... - Ibm

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96 CICS for AIX as the Transaction Server files. In reality the data is stored in the underlying DB2 tables that belong to the default XA-enabled DB2 for AIX database for the CICS region. CICS for AIX provides a complete set of administrative utilities to: • Migrate an existing CICS region to use DB2 as a file manager • Configure a new CICS region to use DB2 as a file manager • Create CICS tables on DB2 from SFS schema files containing a description of the CICS file characteristics • Create and populate CICS tables on DB2 from a flat file format • Provide access to these mapped files from COBOL batch programs In a CICS for AIX configuration where DB2 for AIX is used as a resource manager and relational databases are accessed only through the XA interface, administrative costs can be reduced because you no longer have to manage the Encina-SFS-related items. If the following conditions are true: • The application program does not make updates through the Encina PPC Gateway • DB2 for AIX is the only database resource manager • All of your application data and CICS data are on the same database syncpoint processing performance can be improved through the use of the XA single-phase commit optimization or non-XA native SQL commit processing. Results from performance measurements for CICS for AIX indicate that CICS mapped files on DB2 using the single-phase commit optimization perform better than the best case of CICS files on SFS. Be aware of the following limitations and restrictions when you use a DB2 database server as the CICS file manager rather than SFS: • The CICS region uses a single database for all user files and CICS queues. This is the database specified in the RD DefaultFileServer attribute. • Because of the limitation imposed by holding files in a relational database, some facilities of the COBOL external file handler are not supported. These include: − Mixing transactional access and nontransactional access to files in a single application is not permitted. − When there is nontransactional access to a file, only single record locking is enabled. − The facility to dynamically add indexes to a file at run time is not supported. • Nonrecoverable CICS queues are supported as recoverable facilities on DB2. This affects the record locking characteristics of these facilities. The change in semantics means that data is not written to a file until a syncpoint is taken. If your CICS applications are dependent on nonrecoverable file semantics, we recommend that you use an Encina SFS for CICS queue and file management. The following CICS resources are maintained as DB2 recoverable resources: − Nonrecoverable user files − Nonrecoverable auxiliary temporary storage queues − Locally queued unprotected START requests − Physically recoverable transient data queues − Nonrecoverable transient data queues
• SFS fields migrated to DB2 for AIX are not mapped in the DB2 schema definitions. SQL online query tools only show raw data and cannot map the fields. • There is no access control to the mapped files similar to RPC authentication and DCE access control lists (ACLs). The granularity of access to RDBMS from CICS is at the region level, with all online applications running in CICS application server (cicsas) processes accessing a DB2 for AIX database with the same database userid that is authenticated at cicsas (xa_open) initialization time. You can control access to these mapped files by implementing CICS transaction security and CICS resource security in the CICS for AIX region. Where DB2 for AIX Version 2 is integrated with a CICS for AIX region, CICS applications can use the SQL CONNECT command to connect to multiple DB2 databases within the same unit of work. The DB2 database to which CICS files are mapped as the default database requires an SQL CONNECT RESET command to reset the connection to this default database before any dynamic SQL calls can be issued to serve a CICS file control, temporary storage, or transient data request. Figure 28 on page 98 shows how user CICS applications should be coded to switch the access from one DB2 database to another one and reconnect back to the default database before a CICS syncpoint is taken to commit all database changes. Chapter 7. Interactions with the DB2 Family of Products 97
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Addressing OLTP Solutions with CICS
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Take Note! Before using this inform
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iv CICS for AIX as the Transaction
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9.4 Security Issues on the Internet
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viii CICS for AIX as the Transactio
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x CICS for AIX as the Transaction S
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xii CICS for AIX as the Transaction
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The Team That Wrote This Redbook xi
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xvi CICS for AIX as the Transaction
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2 CICS for AIX as the Transaction S
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1.2 Complex OLTP Business Environme
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Figure 2. OLTP Complex for XYZ Insu
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By using common application program
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1.5 OLTP Market 10 CICS for AIX as
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Figure 5. OLTP Market Segmentation
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14 CICS for AIX as the Transaction
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2.1 IBM Software Servers 2.1.1 Lotu
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2.2.1 CICS Clients V1.1.0 A Transac
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2.2.4 CICS Internet Gateway for AIX
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3.1 Services CICS for AIX is a very
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3.1.2 CICS API 24 CICS for AIX as t
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3.1.3.1 Terminal Users and CICS Reg
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3.2 Implementation 3.2.1 Components
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3.2.2 Processes 3.2.1.3 Application
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3.3.1 DCE RPC 3.3.2 TCP/IP 32 CICS
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Figure 9. Interconnection Using Enc
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connect to a PPC Gateway server mac
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Figure 12. Interconnection Using TC
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3.4.3 Configuration 3.4.4 Managing
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3.4.6 Intersystem Communication CIC
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3.4.8 Data Location 44 CICS for AIX
Page 64 and 65: 3.4.11 Operations plan to cope with
Page 66 and 67: 3.5 Summary 48 CICS for AIX as the
Page 68 and 69: Figure 13. Application Server Model
Page 70 and 71: 4.2.1 CICS External Call Interface
Page 72 and 73: By means of mapping files, you can
Page 74 and 75: 4.3 Versions 56 CICS for AIX as the
Page 76 and 77: 4.4 Sample Network Configurations 4
Page 78 and 79: 4.5.1 CICS Client for OS/2 60 CICS
Page 80 and 81: 4.5.2 CICS Client for DOS 62 CICS f
Page 82 and 83: 4.5.5 CICS Client for AIX CICS Clie
Page 84 and 85: 66 CICS for AIX as the Transaction
Page 88 and 89: 5.1.1 DCE Threads 5.1.2 Remote Proc
Page 90 and 91: The GDS is based on the CCITT X.500
Page 92 and 93: egion or server it is looking for.
Page 96 and 97: 6.1.2 Encina Toolkit Server Core 6.
Page 100 and 101: is also necessary to use native AIX
Page 104 and 105: 7.1 X/Open XA Interface 7.1.1 X/Ope
Page 108 and 109: Communication between the transacti
Page 112 and 113: 7.2.2 Single-Phase and Two-Phase co
Page 116 and 117: Figure 28. Switching Access among D
Page 120 and 121: Figure 30. CICS Access to Remote DB
Page 122 and 123: emote DRDA database. Information ab
Page 124 and 125: As the COMMAREA has an allowable ma
Page 130 and 131: 8.2 Workload Management 112 CICS fo
Page 134 and 135: 8.4.2 System Management Application
Page 136 and 137: Figure 36. The CICS SM GUI 8.4.6 Di
Page 138 and 139: Figure 37. CICS SM Component Distri
Page 140 and 141: Figure 38. Combining Resources 122
Page 142 and 143: 8.5.2 The Reference System 124 CICS
Page 146 and 147: 8.6 Planning Considerations for CIC
Page 152 and 153: 9.1 Some Terminology 9.2 Services 1
Page 154 and 155: Figure 41. CICS Internet Gateway fo
Page 156 and 157: 9.3.3 Data Integrity The Web was or
Page 158 and 159: 9.3.5 High Availability The drawbac
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• Type, size, and quantity of rec
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10.3.3 Writing ECI and EPI Applicat
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The ANIMATOR debugging tool enables
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10.8 Summary 154 CICS for AIX as th
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11.1 The Big Picture 158 CICS for A
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11.2 User Access 160 CICS for AIX a
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Figure 44. Access to Various DB2 Da
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takes place over TCP/IP or SNA comm
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provide greater protection in the u
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How Customers Can Get ITSO Redbooks
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design. The process of composing a
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A year later ISC gave SQL formal in
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designing efficient applications 15
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IBML ® Printed in U.S.A. SG24-4752
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