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CICS Runtime Servers

 


The CICS Runtime Servers

This section describes the different servers and the role they play in the overall handling of transactions. The configuration of the servers is described in Server Configuration.

3270 Terminals and User Session Management (ARTTCPL/ARTTCPH)

Description

The role of these servers is to accept and manage user connections made thru a 3270 terminal emulator and manage the resulting user session and related 3270 inputs and outputs until the end of the user session.

Functionally, this role resembles the one played by the Terminal Owning Region in a CICS MRO configuration.

These 3270 user session management tasks are managed by a couple of server types: ARTTCPL and ARTTCPH, where the final ‘L’ stands for listener and the final ‘H’ stands for handler.

It is the role of the ARTTCPL to launch and manage the requested number of handler processes (ARTTCPH).

Each time a user requests a transaction, ARTTCPH transmits (via tpconnect) this transaction request to the transaction server.

This functionality resembles that provided by T.O.R. in a CICS MRO configuration when it routes a transaction to an A.O.R (Application owning Region).

Connection Server (ARTCNX)

This server offers technical services needed by terminal handlers during user connection and disconnection phases.

The technical services are offered using internal message oriented services like connect and disconnect:

The connection server also provides a few classical CICS transactions:

See “Authentication Transactions” in Other Configurations for more information.

Synchronous Transactions and Program Management

Description

The task of these servers (ARTSTRN and ARTSTR1) is to offer application transactions and process the corresponding programs.

This server provides a similar functionality to that provided by an Application Owning Region in a CICS MRO configuration. ARTSTRN/ARTSTR1 servers present application transactions as Tuxedo services and when receiving a transaction request execute the corresponding programs. Theses servers are conversational in order to be able to manage true conversational CICS transactions.

Processing

  1. When starting, a ARTSTRN/ARTSTR1 server publishes one service per transaction it offers.
  2. When a user transmits a transaction request, the ARTTCPH performs a tpconnect to the corresponding transaction (service).
  3. One ARTSTRN/ARTSTR1 server offering this service receives the request with the associated commarea and screen, then processes the transaction.
  4. Then:
    • In the case of a normal pseudo-conversational CICS transaction; on the RETURN {TRANSID} the server replies to the client, finishing the conversation by a tpreturn() returning the new 3270 screen, and the commarea.

Non Concurrent Synchronous Transaction Servers (MAXACTIVE = 1 (ARTSTR1))

The transactions belonging to a tranclass with a maxactive =1, will not be offered by ARTSTRN servers, because several such servers can automatically be started to manage parallel processing.

Instead, a dedicated type of server—ARTSTR1—is allocated to this role. An ARTSTR1 server publishes the transactions belonging to one TRANCLASS with MAXACTIVE = 1, guaranteeing that two transactions of the same tranclass with maxactive =1, will not execute concurrently. In Tuxedo terms, guaranteeing than two such transactions are not published by two different servers.

To summarize the differences:

Temporary Storage Queue Management (ARTTSQ)

Description

The role of the ARTTSQ servers is to centralise the management the TS Queue operations which are requested by applications. These tasks are managed by ARTTSQ servers.

Depending on the workload expected on the TS queue, a single server or many ARTTSQ servers are configured.

ARTTSQ servers publish technical services:

In a simple configuration, a single ARTTSQ server will treat all the TS operations, offering the TSQUEUE service, and all {MODEL}_TSQUEUE services.

In a more complex configuration, one ARTTSQ server may offer the TSQUEUE and some {MODEL}_TSQUEUE services, while other ARTTSQ servers will each offer different {MODEL}_TSQUEUE services.

Transient Data Queue Management (ARTTDQ)

Description

The role of the ARTTDQ servers is to centralise the management the TD Queue operations which are requested by applications. These tasks are managed by one ARTTDQ server.

A single ARTTDQ server publishes one service per declared queue in the configuration file.and will treat all the CICS TD operations, offering the TD QUEUE service for each queue.

DPL Servers (ARTDPL)

In complex configurations an application may need to make distributed program calls. In this case another kind of server is needed to manage DPL. These tasks are managed by ARTDPL servers.

ARTDPL servers publish programs that are callable by EXEC CICS LINK as services, and manage the execution of these services.

Asynchronous Transaction Servers (ARTATRN/ARTATR1)

An application may request an asynchronous transaction launch using 'EXEC CICS START TRANSID' requests. In this case the request needs to be treated asynchronously by another server. These tasks are managed by ARTATRN/ARTATR1 servers.

These servers publish transactions callable by EXEC CICS START TRANSID as services named ASYNC_{Transaction_Name}, and manage execution of these services.

Conversation Server (ARTCTRN/ARTCTR1)

An application may request an a conversation launch using 'EXEC CICS CONVERSE' requests. In this case the request needs to be treated by another server. These tasks are managed by ARTCTRN/ARTCTR1 servers.

These servers publish transactions callable by EXEC CICS CONVERSE as services named {SysId}_{Transaction_Name}, and manage execution of these services.

Delayed Asynchronous Transaction (/Q Part)

Asynchronous transactions are launched using 'EXEC CICS START TRANSID' requests that may also by launched with a delay set to an interval or to a fixed time.

In this case the transaction request is deposited into a Tuxedo /Q Queue, and when the time is ready, the transaction will be automatically invoked.

For this feature to be available, a few extra components must be activated:

Tip: TMQFORWARD will always call the same technical transaction called ASYNC_QUEUE (the name of the queue). This transaction will extract the field CX_TRANSID, which will contain the name of the real application transaction to call and will perform a TPACALL(NOREPLY) of this transaction and tpreturn immediately.

Administration Server (ARTADM)

The administration server is responsible for the administration of CICS resources. It provides the following functionalities:


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