Version 9.5 SP1
 —  EntireX z/OS IMS RPC Server  —

Administering the EntireX RPC Server under z/OS IMS

The EntireX z/OS IMS RPC Server allows standard RPC clients to communicate with RPC servers on the operating system z/OS running with IMS in BMP mode. It supports the programming languages COBOL, PL/I and C and can provide IMS-specific PCB pointers for access to IMS databases if needed.

This document covers the following topics:


Customizing the RPC Server

The following elements are used for setting up the IMS RPC Server:

Configuration File

The name of the delivered example configuration file is CONFIGI (see source library EXP951.SRCE). The configuration file contains the configuration for the IMS RPC Server. The following settings are important:

The configuration file is specified as a DD definition with a user-defined DD name in the started task JCL. The DD name is passed to the RPC server with the following server startup argument:

CFG=DD:ddname

Example using the DD name CONFIGI:

CFG=DD:CONFIGI

Under IMS the server startup arguments are passed with the DD name ERXPARMS. So to pass the argument for the example above, you need to specify a data set in the DD definition for ERXPARMS. This data set needs to have one line containing CFG=DD:CONFIGI.

For more information see Configuring the RPC Server.

IBM LE Runtime Options

Depending on the feature the IMS RPC Server needs to support (see table below) additional runtime options for IBM's Language Environment need to be set. For a full description of LE runtime options, see z/OS V1R4.0 Lang Env Prog Guide.

Feature LE Runtime Options Description
SSL/TLS connections POSIX(ON) If not specified, TCP or NET connections are supported.
Call RPC server programs with AMODE 24 as well ALL31(OFF),STACK(,,BELOW) If not specified, AMODE 31 is supported.

Note:
(1) Set internally by the IMS RPC Server and cannot be changed.

There are various ways to specify LE runtime options, for example during installation; using JCL; using CSECT CEEUOPT (for application-specific LE runtime options) linked to the RPC Server; etc. We recommend you use the IBM standard approach with CEEOPTS DD statement in the started task JCL. See Started Task JCL for this purpose. Add the following lines to your started task JCL:

//...
//CEEOPTS  DD *
ALL31(OFF),STACK(,,BELOW)
/*
//..

The example above uses an in-stream data set to configure ALL31(OFF),STACK(,,BELOW) to allow calling of 24-bit and 31-bit programs and configure RPTOPTS(ON) to list all used LE runtime options to SYSOUT.

Started Task JCL

The name of the started task is EXPSRVI (see EntireX job library EXX951.JOBS). The started task contains the following:

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Configuring the RPC Server

The followings rules apply:

Parameter Default Values Req/
Opt
brokerid localhost Broker ID used by the server. See Using the Broker ID in Applications.

Example:
brokerid=myhost.com:1971

R
ceeoptions   Allows you to change IBM's LE runtime options. This parameter is deprecated. See IBM LE Runtime Options for how to set the LE runtime options. O
class RPC Server class part of the server address used by the server. The server address must be defined as a service in the broker attribute file (see Service-specific Attributes under Broker Attributes). Case-sensitive, up to 32 characters. Corresponds to CLASS.

Example:
class=MyRPC

R
codepage no codepage transferred Depending on the internationalization approach, the codepage (locale string) where incoming data is provided to the COBOL server. Conversely, the COBOL server must provide outgoing data in the given codepage, otherwise unpredictable results occur. See What is the Best Internationalization Approach to use? under Internationalization with EntireX for information on which internationalization approach requires a codepage (locale string).

By default, no codepage is transferred to the broker. For the most popular internationalization approach, ICU Conversion, the correct codepage (locale string) must be provided. This means it must:

  • follow the rules described under Locale String Mapping

  • be a codepage supported by the broker

  • be the codepage used in your environment for file and terminal IO, otherwise unpredictable results may occur.

Example:
codepage=ibm-273

 
compresslevel N Enforce compression when data is transferred between broker and server. See Data Compression in EntireX Broker.

compresslevel= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8| 9 | Y | N

0-9 0=no compression
9=max. compression
N No compression.
Y Compression level 6.

Example:
compresslevel=6

O
deployment NO Activates the deployment service, see Deployment Service. Required to use the deployment wizard. See Server Mapping Deployment Wizard in the COBOL Wrapper documentation.
YES Activates the deployment service. The RPC server registers the deployment service in the broker.
NO The deployment service is deactivated. The RPC server does not register the deployment service in the broker.

Example:
deployment=yes

O
encryptionlevel 0 Enforce encryption when data is transferred between client and server. Requires EntireX Security. See ENCRYPTION-LEVEL under Broker ACI Fields.
0 Encryption is enforced.
1 Encryption is enforced between server and broker kernel.
2 Encryption is enforced between server and broker kernel, and also between client and broker.

Example:
encryptionlevel=2

O
etblnk BROKER Define the broker stub to be used. See Administration of Broker Stubs under z/OS for available stubs.

Example:
etblnk=broker

O
extractor NO The extractor service is a prerequisite for remote extractions. See Extractor Service.

extractor=YES|NO

Example:
extractor=yes

O
impersonation NO
Defines if RPC requests are executed under the user ID of the RPC client. Depending on settings, different levels of checks are done prior to RPC server execution. See also Impersonation.

impersonation= NO | YES | AUTO [, sameuser | , anyuser ]
 

NO The RPC request is executed anonymously, which means the user ID of the RPC client is not used. The user ID used to execute RPC requests is defined by the Started Task JCL.
YES The RPC request runs impersonated under the supplied RPC client user ID. Prior to RPC execution, the IMS RPC Server uses the RPC client user ID/password pair and calls the SAF interface (RACROUTE VERIFY) to verify with a mainframe security repository (RACF, CA Top Secret or CA ACF2) and set the ACEE block to the RPC client user ID.
AUTO The RPC request runs impersonated under the supplied RPC client user ID. Prior to RPC execution, the IMS RPC Server uses the RPC client user ID and calls the SAF interface (RACROUTE VERIFY PASSCHK=NO) and sets the ACEE block to the RPC client user ID. No password validation is performed.

For this setting you have to take care the RPC client is correctly authenticated: use either a secure EntireX Broker (validation must be against the correct mainframe security repository where the user IDs are defined) and option sameuser, or use your own security implementation (option anyuser is supported for compatibility reasons if you need different broker and server user IDs - the customer-written security implementation must validate the RPC client using the RPC client user ID).

sameuser The IMS RPC Server checks whether the broker client user ID matches the RPC client user ID. This is the default if AUTO is used.
anyuser The RPC client user ID is used for authentication. The broker client user ID is ignored.

Notes:

  1. EntireX supports two user ID/password pairs: a broker client user ID/password pair and an (optional) RPC user ID/password pair sent from RPC clients to the RPC server.
  2. With EntireX Security, the broker client user ID/password pair is checked. The RPC user ID/password pair is designed to be checked by the target RPC server. Thus it is possible to use different user IDs in the broker and target RPC server.
  3. RPC clients send the (optional) RPC user ID/password pair in the same way as specifying the Natural user ID/password pair for a Natural RPC Server. See for example Using Natural Security for applications in C | COBOL | PL/I | Web Services | SOAP/XML | Java.
  4. If the RPC client does not specify the optional RPC user ID/password pair, the broker client user ID/password pair is inherited to the RPC user ID/password pair and thus used for impersonation by the IMS RPC Server.

Example:
impersonation=auto,anyuser

Using impersonation requires additional installation steps. See Using z/OS Privileged Services.

O
library no default library = search-logic [- library] where search-logic is one of FIX(dllname) | PREFIX(prefix) | PREFIX()

This parameter applies to programming language C only. Do not set if other programming languages for RPC server are used.

FIX(dllname)
              
The IDL library name coming from the RPC client is ignored, thus long IDL library names can be used. You have to define the DLL names for all client interface objects and RPC servers.
PREFIX(prefix) The IDL library name coming from the RPC client is used to form the DLL name. As prefix you can define any character. If an RPC client sends, for example, "SYSTEM" as the IDL library name and "D" is defined as prefix, the DLL name derived is "DSYSTEM". This configuration restricts the IDL library names to max. 7 characters.
PREFIX() The IDL library name coming from the RPC client is used as DLL name. This configuration restricts the IDL library names to max. 8 characters.

Example PREFIX configuration (this configuration matches the standard names produced by the C Wrapper):
library=PREFIX(D)-PREFIX()

Example FIX configuration:
library=FIX(MYSTUBS)-FIX(MYRPCS)

O
logon YES Execute broker functions LOGON/LOGOFF in worker threads. Must match the setting of the broker attribute AUTOLOGON. Reliable RPC requires logon set to YES. See Reliable RPC.
NO No logon/logoff functions are executed.
YES Logon/logoff functions are executed.

Example:
logon=no

O
marshalling COBOL
The IMS RPC Server can be configured to support either COBOL, PL/I or C. See also Locating and Calling the Target Server.

marshalling=(LANGUAGE=COBOL|PLI [flavor=ENTERPRISE | MVS] | C)

COBOL Server supports COBOL. The COBOL servers are called directly without a server interface object. So-called server mapping (SVM) files are used to call the COBOL server correctly if one is available. See Server Mapping Deployment.
PLI Server supports PL/I Server compiled with IBM's PL/I. In z/OS load modules produced by newer IBM PL/I compilers and linkers, the flavor can be detected automatically, thus flavor can be omitted.
ENTERPRISE Enterprise compiler z/OS. This is the default if PL/I is used. See prerequisites for PL/I Wrapper.
MVS Server supports PL/I Server compiled with older IBM compiler PL/I MVS & VM V1R1 and above. See prerequisites for PL/I Wrapper.
C Server supports C. The modules are called using a server interface object built with the C Wrapper.
O
password no default Password for broker logon. Case-sensitive, up to 32 characters. For more information see broker ACI control block field PASSWORD.

Example:
password=MyPwd

O
restartcycles 15 Number of restart attempts if the broker is not available. This can be used to keep the IMS RPC Server running while the broker is down for a short time. A restart cycle will be repeated at an interval which is calculated as follows:

timeout + ETB_TIMEOUT + 60 seconds

where timeout is the RPC server parameter (see this table), and
  ETB_TIMEOUT is the environment variable (see Environment Variables in EntireX)

When the number of cycles is reached and a connection to the broker is not possible, the RPC server stops.

Example:
restartcycles=30

O
return_code NO Enable application-specific errors.
return_code=(NO|YES)
NO No tests of COBOL special register RETURN-CODE for application-provided error.
YES After execution of the RPC server, tests COBOL special register RETURN_CODE for application provided error. See Returning Application Errors from a Server under z/OS IMS to a Client in the COBOL Wrapper documentation.

Example:
return_code=yes

O
runoption no default This parameter is for special purposes. It provides the IMS RPC Server with additional information. The runoptions are normally set to meet the platform's requirements. Set this parameter only if a support representive provides you with an option and asks you to do so. The parameter can be defined multiple times.

Example:
runoption=<option>
runoption=<option>

O
servername SRV1 Server name part of the server address used by the server. The server address must be defined as a service in the broker attribute file. See Service-specific Attributes under Broker Attributes. Case-sensitive, up to 32 characters. Corresponds to SERVER of the broker attribute file.

Example:
servername=mySrv

R
service CALLNAT Service part of the server address used by the server. The server address must be defined as a service in the broker attribute file. See Service-specific Attributes under Broker Attributes. Case-sensitive, up to 32 characters. Corresponds to SERVICE attribute of the broker attribute file.

Example:
service=MYSERVICE

R
smhport 0 The port where the server listens for commands from the System Management Hub (SMH). If this port is 0 (default), no port is used and management by the SMH is disabled.

Example:
smhport=3001

O
ssl_file no default Set the SSL parameters. See Using SSL or TLS with the RPC Server for examples and more information. O
stublib no default For PL/I server if its interface has IMS-specific PCB Pointers to access IMS databases. Provide the DD name of the library where the PL/I server interface object(s) are located. Not required for COBOL or if the interface of your PL/I server does not have IMS-specific PCB pointers.

stublib=ddname

Example:
stublib=PLISTUBS

For the example above, define the DD name PLISTUBS in the started task JCL of the IMS RPC Server (see Started Task JCL) as

//PLISTUBS  DD DISP=SHR,DSN=<plistubs>
O
svm ERXSVM Usage and location of SVM files. If no svm parameter is given, the RPC server tries to open the SVM container using ddname ERXSVM. If this ddname is not available, no server mappings are used. For more information see Handling SVM Files.

svm = no| ddname

no No SVM files are used.
ddname DD name of the SVM file container in the started task JCL of the IMS RPC Server. See Started Task JCL.

Example:
svm=MYSVM

For the example above, define the DD name MYSVM in the started task JCL of the IMS RPC Server (see Started Task JCL) as

//MYSVM  DD  DISP=SHR,DSN=<svm.cluster>
O
timeout 60 Timeout in seconds, used by the server to wait for broker requests. See broker ACI control block field WAIT for more information. Also influences restartcycles.

Example:
timeout=300

O
tracedestination DD:ERXTRACE The name of the destination file for trace output.

tracedestination=DD:ddname, where ddname is the name of the trace file.

Example:
tracedestination=DD:MYTRACE

The DD name MYSVM must be defined in the started task of the IMS RPC Server (see Started Task JCL):

//MYTRACE DD  DISP=SHR,DSN=<rpctrace-file>
O
tracelevel None Trace level for the server. See also Activating Tracing for the RPC Server.
tracelevel = None | Standard | Advanced | Support
None No trace output.
Standard For minimal trace output.
Advanced For detailed trace output.
Support This trace level is for support diagnostics and should only be switched on when requested by Software AG support.

Example:
tracelevel=standard

O
userid ERX-SRV Used to identify the server to the broker. See broker ACI control block field USER-ID. Case-sensitive, up to 32 characters.

Example:
userid=MyUid

R

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Locating and Calling the Target Server

The IDL library and IDL program names that come from RPC client are used to locate the RPC server. See library-definition and program-definition. This two-level concept (library and program) has to be mapped to the IMS RPC Server environment. Different mechanisms are used depending on the language:

COBOL

The approach used to derive the z/OS module name for the RPC server depends on whether so-called server mapping files are used or not. See Usage of SVM Files for an introduction.

Start of instruction setTo use the IMS RPC Server with COBOL

  1. Make sure that all z/OS modules called as RPC servers

  2. Configure the parameter marshalling for COBOL, for example:

    mashalling=COBOL
  3. Configure the parameter svm depending on whether SVM files are used or not.

See also Scenario I: Calling an Existing COBOL Server or Scenario II: Writing a New COBOL Server.

PL/I

There is a simple mechanism to derive the RPC server z/OS module name:

Start of instruction setTo use the IMS RPC Server with PL/I

  1. Make sure that all z/OS modules called as RPC servers

  2. Configure the parameter marshalling for PL/I, for example marshalling=PLI.

  3. If one or more server interface objects are used, configure the parameter stublib.

See also Scenario III: Calling an Existing PL/I Server or Scenario IV: Writing a New PL/I Server.

C

The approaches needed to derive the dynamic-link libraries (DLLs) names for the RPC server are more complex for C, for the following reasons:

Either you restrict yourself in short IDL library names (up to 8 characters) and use the flexible PREFIX configuration, or, if you need independence from the IDL library length and names, use the FIX configuration. The parameter library is used for this purpose.

Start of instruction setTo use the IMS RPC Server with C

  1. Make sure all dynamic-link libraries (DLLs) called as RPC servers and client interface objects are accessible through the IMS RPC Server started task JCL STEPLIB concatenation. See Started Task JCL.

  2. Configure the parameter marshalling for C, for example marshalling=C.

  3. Configure the parameter library either with the FIX configuration or PREFIX configuration, depending on how you have built your DLLs. See Using the C Wrapper for the Server Side (z/OS, UNIX, Windows, BS2000/OSD, IBM i).

See also Scenario V: Writing a New C Server.

Assembler (IBM 370)

There is a simple mechanism to derive the RPC server z/OS module name:

Start of instruction setTo use the IMS RPC Server with Assembler

See also Scenario VI: Writing a New Assembler Server.

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Using SSL or TLS with the RPC Server

The IMS RPC Server supports certificates stored in RACF as keyrings. There are two ways of specifying the RACF keyring and other SSL or TLS parameters, depending on the complexity of the parameters:

As an alternative, you can use for this purpose IBM's Application Transparent Transport Layer Security (AT-TLS), where the establishment of the SSL or TLS connection is pushed down the stack into the TCP layer.

This section convers the following topics:

For more information, see SSL or TLS and Certificates with EntireX.

Specifying the SSL or TLS Parameters as Part of the Broker ID

Start of instruction setTo specify the SSL or TLS parameters as part of the Broker ID

  1. In the Started Task JCL set the LE runtime option POSIX(ON), see IBM LE Runtime Options.

  2. Add the RACF keyring <user-id>/<ring-name> and other SSL or TLS parameters to the server parameter brokerid in the Configuration File. SSL or TLS parameters are separated by ampersand (&).

    Example with Transport-method-style Broker ID:

    ETB024:1609:SSL?TRUST_STORE=<user-id>/<ring-name>&VERIFY_SERVER=N

    Example with URL-style Broker ID:

    ssl://localhost:2010?TRUST_STORE=<user-id>/<ring-name>&VERIFY_SERVER=N
  3. Make sure the target the IMS RPC Server connects to is prepared for SSL/TLS connections as well. See the following sections:

Specifying the SSL or TLS Parameters in a Separate File

Start of instruction setTo specify the SSL or TLS parameters in the SSL file

  1. In the Started Task JCL set the LE runtime option POSIX(ON), see IBM LE Runtime Options.

  2. Define a so-called SSL file in text format (for example as a PDS member) with the RACF keyring <user-id>/<ring-name> and other SSL or TLS parameters.

    Example:

    TRUST_STORE=<user-id>/<ring-name>
    VERIFY_SERVER=N
    

    Note:
    Each line in the SSL file must be terminated with hexadecimal zero.

  3. In the Configuration File, define a DDNAME to be used in the Started Task JCL to enable the IMS RPC Server to access the SSL file defined in Step 2 above.

    Example:

    ... 
    SS_FILE=DD:MYSSL
    ... 
    
  4. Add a DD statement to the Started Task JCL using the DDNAME defined in Step 3 above to point to the SSL file defined in Step 2 above.

    Example:

    //...
    //MYSSL    DD DISP=SHR,DSN=<high-level-qualifier>.MYPDS(SSLFILE)
    //...
    
  5. In the Configuration File define the server parameter brokerid for SSL or TLS connections.

    Example with Transport-method-style Broker ID:

    ETB024:1609:SSL

    Example with URL-style Broker ID:

    ssl://localhost:2010
  6. Make sure the target the IMS RPC Server connects to is prepared for SSL/TLS connections as well. See the following sections:

Using IBM's Application Transparent Transport Layer Security (AT-TLS)

Start of instruction setTo set up SSL or TLS with AT-TLS

  1. Set up the IMS RPC Server for a TCP/IP connection.

  2. Configure the rules for the AT-TLS policy agent the IMS RPC Server matches, for example by using the job name and remote port number the IMS RPC Server connects to. Used certificates are also defined with those rules. Refer to your IBM documentation for further information.

  3. Make sure the target the IMS RPC Server connects to is prepared for SSL/TLS connections as well. See the following sections:

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Starting the RPC Server

Start of instruction setTo start the IMS RPC Server

  1. Modify the member EXPSRVI (see EntireX job library EXX951.JOBS) according to your system requirements and copy the started task JCL to your system PROCLIB concatenation. See Started Task JCL.

  2. Modify the server parameters Configuration File according to your system requirement. For details, see Configuring the RPC Server.

  3. Start the task manually with

    /s EXPSRVI

    Or:
    Add the task to your system automation tool(s)

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Stopping the RPC Server

Start of instruction setTo stop the IMS RPC Server

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Activating Tracing for the RPC Server

Start of instruction setTo switch on tracing for IMS RPC Server

  1. Set the parameters tracelevel and tracedestination.

  2. Dynamically change the trace level with the operator command

    F EXPSRVI,TRACELEVEL=<tracelevel>,

    for valid tracelevel values, see tracelevel.

    The TRACELEVEL command without any value will report the currently active trace options, for example:

    F EXPSRVI,TRACELEVEL

    might reply with the operator message

    Tracelevel=0 TraceFile=DD:ERXTRACE

    To evaluate the return codes, see Component Return Codes in EntireX.

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