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

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8.4.2 System Management Application 8.4.3 The Agent 8.4.4 Workload Management 116 CICS for AIX as the Transaction Server The SMappl provides the logic that manages part or all of an enterprise. It relates the definitions stored in the EIB to the real images of systems and resources in the real enterprise, that is, the actual definitions in the systems being managed. The SMappl composes the data defined to CICS SM with the data that it can determine from the real world. The composed data is presented to you on the GUI. It is through the GUI that you operate systems and resources on the managed AIX nodes. The CICS SM agent acts as the delegate of the SMappl on a managed node. The agent interacts directly with the managed objects, passing data back to the SMappl and acting on the managed objects when directed by the SMappl. The agent comprises a resource controller and some system-specific code. One resource controller runs on each AIX node that has CICS systems to be managed. It runs independently of those systems. A single resource controller typically can connect to multiple managed systems on the same node. Some operations cannot be directed to a CICS system. Operations such as the install, start, and uninstall of a CICS system are handled by interactions with the operating system. Within each CICS for AIX system to be managed there is a long-running CICS task. This task contains CICS SM code. It enables communication with the systems resource controller. The long-running transaction is started when CICS system initialization is started. It establishes communication with the resource controller to which the managed system is connected. Requests from the resource controller to the managed system along with notifications from the managed system to the resource controller are sent by means of the Internet Protocol transport mechanism. The workload management component consists of the following: • The workload management application • The workload management cache manager • The workload management client 8.4.4.1 Workload Management Application Workload management makes routing decisions on the basis of data that it has available to it about the CICS systems and resources. This data is held in two types of cache: global and local. Both caches are similar in structure and are based on a semantic network. There is one global cache and potentially many local caches. The global cache is used by the workload management application (WLMAppl). A local cache is used by the workload management cache manager and a workload management client (see 8.4.4.2, “Workload Management Cache Manager” on page 117 for more details). The WLMAppl adds information about the currently active systems to a global cache that it has discovered from the SMappl about the currently active systems. This information is obtained at WLMAppl startup. Only sufficient information for WLMAppl to manage the work of each CICS system is passed to it. With this global cache, WLMAppl can resolve workload routing requests faster than if the EIB had to be accessed each time.
8.4.5 Graphical User Interface The WLMAppl subscribes to changes in state of managed objects, that is, a CICS system or resource, so that it can keep the global cache up to date. When the WLMAppl is subsequently informed by the SMappl of changes, it updates the global cache. The WLMAppl is also responsible for informing the workload management cache manager of relevant changes made in the global cache. Thus the workload management component is kept abreast with what is happening in the real world. For example, if a transaction is no longer active in a particular CICS system, the cache must be updated so that routing decisions for new pieces of work can take into account the fact that the transaction is no longer available in that CICS system. 8.4.4.2 Workload Management Cache Manager There is typically one workload management cache manager on each system on which routing decisions are to be made. The workload management cache manager interfaces with the WLMAppl to transfer data from the global cache to the local cache. It also processes requests for data from workload management clients. If the requested data is not available in the local cache, a request is forwarded to the WLMAppl to get the data from the global cache. If the data is not available in the global cache, the WLMAppl requests it from the SMappl. The workload management cache manager also informs clients that their requests have been satisfied or that the requested data could not be found. 8.4.4.3 Workload Management Client There is one workload management client for each CICS component that wants to determine which is the best CICS system to which to route work. CICS SM provides a CICS exit for dynamic transaction routing, DPL, CICS Client for AIX ECI work, CICS Client for AIX EPI work, and data-dependent routing. For session-level load balancing, CICS SM provides versions of cicsterm and cicsteld called bhgwterm and bhgwteld, respectively. The workload management client performs the following functions: • Processes requests from CICS clients that want to determine to which CICS system to route work • Searches the local cache for the data to fulfill the workload management requests from CICS clients • Applies a workload balancing algorithm to determine which of a set of CICS systems is best able to do the work for a CICS client and then updates the cache to reflect the decision that it has made • Requests information from the workload management cache manager when it cannot be found in the local cache The CICS SM GUI is based on a set of windows that have standard elements common to many GUIs, such as a title bar, maximize and minimize buttons, a tool bar, and a status line. The functions of the GUI are based on a menu structure that can be accessed through the menu bar items and their pull-down menus. CICS SM has been designed so that it can be operated from the menu bar only; that is, without the tool or action bars. This is particularly useful for users with limited screen space. Figure 36 on page 118 shows the layout of the CICS SM GUI. Chapter 8. Using CICS System Manager for AIX 117
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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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3.2 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
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3.4.11 Operations plan to cope with
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3.5 Summary 48 CICS for AIX as the
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Figure 13. Application Server Model
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4.2.1 CICS External Call Interface
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By means of mapping files, you can
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design. The process of composing a
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