Administering the RPC server for IMS

The EntireX RPC Server for IMS 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.

Customizing the RPC server

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

Configuration file
IBM LE runtime options
Started task JCL

Configuration file

The name of the delivered example configuration file is CONFIGI (see source library EXP110.SRCE). The configuration file is specified as a DD definition with a user-defined DD name in the Started task JCL. The configuration file contains the configuration for the RPC Server for IMS.

The following settings are important:

connection information such as broker ID, server address (class, name, service)
scalability parameters
trace settings

For more information see Configuring the RPC server.

IBM LE runtime options

Depending on the feature the RPC Server for IMS needs to support (see the following table) additional runtime options for IBM's Language Environment need to be set. For a full description of LE runtime options, see IBM Resource Link.

Table 1. Features for IBM LE runtime options
Feature	LE Runtime Options	Description
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 RPC server for IMS 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 previous example 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 EXX110.JOBS).

The started task contains the following:

the target server libraries of the called COBOL or PL/I server
for PL/I, if IMS-specific PCB pointers are used, the stub library; see stublib
the configuration file used; see Configuration file; specified as a DD definition with a user-defined DD name as RPC server startup argument CFG:
```
CFG=DD:ddname
```
Under IMS, server startup arguments are passed with the DD name ERXPARMS. So to pass the argument for the previous example, you need to specify a data set in the DD definition for ERXPARMS. This data set needs a line containing the CFG argument, for example CFG=DD:CONFIGI.
```
//*
//G.ERXPARMS DD *   ERXPARMS - DEFINE ONLY THE CONFIG DD NAME HERE
CFG=DD:CONFIGI
```
LE runtime options used; see IBM LE runtime options

Configuring the RPC server

The following rules apply:

In the configuration file:
- Comments must be on a separate line.
- Comment lines can begin with *, / and ;.
- Empty lines are ignored.
- Headings in square brackets [<topic>] are ignored.
- Keywords are case-insensitive.
Underscored letters in a parameter indicate the minimum number of letters that can be used for an abbreviated command.
For example, in brokerid=localhost, brok is the minimum number of letters that can be used as an abbreviation, that is, the commands/parameters broker=localhost and brok=localhost are equivalents.

Table 2. Parameters to configure the RPC server
Parameter	Default	Values	Req/Opt
brokerid	localhost	Broker ID used by the server. See Using the Broker ID in applications in the RPC Programming documentation. 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). Case-sensitive, up to 32 characters. Corresponds to CLASS attribute of the broker attribute file. Example: `class=MyRPC`	R
codepage	no codepage transferred	The codepage tells the broker the encoding of the data. The application must ensure the encoding of the data matches the codepage. The RPC server itself does not convert your application data. The application's data is shipped and received as given. Often, the codepage must also match the encoding used in the RPC server environment for file and terminal IO, otherwise unpredictable results may occur. By default, no codepage is transferred to the broker. It is assumed the broker's locale string defaults match. See Locale string mapping. If they do not match, provide the codepage here. Example: `codepage=ibm-273` Enable character conversion in the broker by setting the service-specific attribute CONVERSION to `SAGTRPC`. See also Configuring ICU Conversion z/OS \| Linux \| Windows. More information can be found under Internationalization.
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 Server Mapping Deployment Wizard. See Server Mapping Deployment wizard in the Designer 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
etblnk	BROKER	Define the broker stub to be used. See Administering Broker Stubs 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 RPC user ID of the calling RPC client. For how to send the RPC user ID/password pair from an RPC client, see Using the Broker and RPC User ID/Password (.NET Wrapper \| Java Wrapper \| C Wrapper \| PL/I Wrapper \|Web Services Wrapper \| IDL Tester \| Listener for XML/SOAP \| Listener for IBM MQ). For the COBOL Wrapper, refer to Using Broker logon and logoff and Using RPC Authentication (Natural Security, Impersonation, Integration Server). For non-RPC clients, see Using the Broker and RPC user ID/password under EntireX XML Tester in the XML/SOAP Wrapper documentation. Depending on settings, different levels of checks are done prior to RPC server execution. See also Impersonation under Introduction to the RPC Server for IMS. `impersonation=NO\|YES\|AUTO[,sameuser\|,anyuser]` NO The RPC request is executed anonymously, which means the user ID of the calling RPC client is not used. RPC requests are executed under the user ID of the RPC server. YES None. AUTO Same as option `YES`, except that no password validation is performed, that is, the calling RPC client is treated as already authenticated. For this setting, make sure the RPC client is correctly authenticated; use either a secure broker (validation must be against the correct mainframe security repository where the user IDs are defined) and option `sameuser` or 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 calling RPC client using the RPC client user ID). The following options are available for `AUTO`: sameuser The RPC Server for IMS 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 impersonation. The broker client user ID is ignored. Example: `impersonation=auto,anyuser` Using impersonation requires additional installation steps. See Using z/OS privileged services in the z/OS installation documentation.	O
library	no default	`library = search_logic [- library]` Where, `search_logic` is one of FIX(`dllname`) \| PREFIX(`prefix`) \| PREFIX() `library` can be repeated up to four times, that is, five entries are possible 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 RPC Server for IMS can be configured to support either COBOL, PL/I, or C. See also Locating and calling the target server . `marshalling=(LANGUAGE=COBOL \| PLI \|C)` COBOL Server supports COBOL. The COBOL servers are called directly without a server interface object. So-called server mapping files are used to call the COBOL server correctly if one is available. See Usage of server mapping files. PLI Server supports PL/I. 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	The password for secured access to the broker. If possible (write access) the password is encrypted and written to parameter `password.e`. The parameter `password` is removed. To change the password, add the parameter `password` with the new password as value. If the Configuration file is an inline data set in the Started task JCL, password encryption does not take place. Example: `password=MyPwd`	O
restartcycles	15	Number of restart attempts if the broker is not available. This can be used to keep the RPC Server for IMS running while the broker is down for a short time. A restart cycle will be repeated every 60 seconds. Note: Internally, the server waits in periods of 10 seconds (performing six times more cycles), which you can see in the server output. When the number of specified cycles is reached and a connection to the broker is not possible, the RPC Server for IMS stops. Example: `restartcycles=30` The server waits up to 30 minutes (30610 seconds) before it terminates due to a missing broker connection.	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. Example: `return_code=yes`	O
runoption	no default	This parameter is for special purposes. It provides the RPC Server for IMS 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. Example: `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. 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. Case-sensitive, up to 32 characters. Corresponds to SERVICE attribute of the broker attribute file. Example: `service=MYSERVICE`	R
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, define the DD name `PLISTUBS` in the started task JCL of the RPC Server for IMS (see Started task JCL) as `//PLISTUBS DD DISP=SHR,DSN=<plistubs>`	O
svm	ERXSVM	Usage and location of server-side mapping files (Designer files with extension .svm) at runtime, see Server-side mapping files in the RPC server. If the `svm` parameter is omitted, the RPC server tries to open the server-side mapping container using DD name `ERXSVM`. If this DD name is not available, no server-side mapping files are used. If you use server-side mapping files at runtime, the server-side mapping container must be installed and configured; see Installing the server-side mapping container for an RPC server for IMS (optional) in the z/OS Installation documentation. Server mapping files with extension .svm are no longer supported at design time by the Designer. You can still use them at runtime in a server-side mapping container. All special COBOL syntax and features supported by server mapping files with extension .svm are also covered by server mapping files with extension .cvm. See When is a server mapping file required? We recommend migrating .svm files to .cvm files. See Migrating server mapping files under Server Mapping Files for COBOL in the Designer documentation. `svm = no\|ddname` no No server-side mapping files are used. `ddname` DD name of the server-side mapping container in the started task JCL of the RPC Server for IMS. Example: `svm=MYSVM` For the example, define the DD name `MYSVM` in the JCL of the RPC Server for IMS (see Started task JCL) as: `//MYSVM DD DISP=SHR,DSN=<svm.cluster>` See also Usage of server mapping files .	O
timeout	60	Timeout in seconds, used by the server to wait for broker requests. See WAIT under Broker ACI Fields for more information. Also influences restartcycles. Example: `timeout=300`	O
tracedestination	DD:ERXTRACE	The name of the destination file for trace output. See also Activating tracing for the RPC server. `tracedestination=DD:ddname`, where `ddname` is the name of the trace file. Example: `tracedestination=DD:MYTRACE` The DD name `MYTRACE` must be defined in the started task of the RPC Server for IMS (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. Use only when requested by IBM Support. Example:tracelevel=standard	O
traceoption	None	Additional trace option if trace is active. See also Activating tracing for the RPC server. None No additional trace options. STUBLOG If tracelevel is Advanced or Support, the trace additionally activates the broker stublog. NOTRUNC Normally if a data buffer larger than 8 KB is traced, the buffer trace is truncated. Set this option to write the full amount of data without truncation. Note: This can increase the amount of trace output data dramatically if you transfer large data buffers. Example: `traceoption=(STUBLOG,NOTRUNC)`	O
userid	ERX-SRV	The user ID for access to the broker. The default `ERX-SRV` will be used if this parameter is omitted or specified without a value: `userid=`. Example: `userid=MyUid`	O

Locating and calling the target server

The IDL library and IDL program names that come from the 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 RPC Server for IMS environment. Different mechanisms are used depending on the language:

COBOL
C
Assembler (IBM 370)

COBOL

The z/OS module name for the RPC server called is taken from the server mapping if one is available. See Usage of server mapping files for an introduction. If no server mapping is used, the IDL program name is used as the z/OS module name of the RPC server and the IDL library name is ignored.

To use the RPC server for IMS with COBOL:

Make sure that all z/OS modules called as RPC servers
- are compiled with IBM's Language Environment (see IBM Resource Link)
- use COBOL calling conventions
- can be called dynamically ("fetched") from any Language Environment program
- are accessible through the RPC Server for IMS started task JCL STEPLIB concatenation. See Started task JCL.
Configure the parameter marshalling for COBOL, for example:
```
marshalling=COBOL
```

C

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

the limitation of 8 characters per (physical) member (DLL name in PDSE)
the maximum length of 128 characters per IDL library name (see Rules for coding library, library alias, program, program alias and structure names).

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.

To use the RPC server for IMS with C:

Make sure all dynamic-link libraries (DLLs) called as RPC servers and client interface objects are accessible through the RPC Server for IMS started task JCL STEPLIB concatenation. See Started task JCL.
Configure the parameter marshalling for C, for example marshalling=C.
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, Linux, Windows).

Assembler (IBM 370)

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

The IDL program name is used as the z/OS module name
The IDL library name is not used.

To use the RPC server for IMS with Assembler:

Make sure all z/OS modules called as RPC servers:
- are accessible through the RPC Server for IMS started task JCL STEPLIB concatenation. See Started task JCL.
- Use PL/I or COBOL calling conventions. Configure the parameter marshalling for PL/I or COBOL.

Using SSL/TLS with the RPC Server

RPC servers can use Secure Sockets Layer/Transport Layer Security (SSL/TLS) as the transport medium. The term SSL here refers to both SSL and TLS. RPC-based servers are always SSL clients. The SSL server can be either the EntireX Broker, Broker SSL Agent, or Direct RPC in webMethods Integration Server (IS inbound). For an introduction see SSL/TLS, HTTP(S), and certificates with EntireX in the platform-independent Administration documentation.

SSL delivered on a z/OS mainframe will typically use the Resource Access Control Facility (RACF) as the certificate authority (CA). Certificates managed by RACF can only be accessed through the RACF keyring container. A keyring is a collection of certificates that identify a networking trust relationship (also called a trust policy). In an SSL client/server network environment, entities identify themselves using digital certificates called through a keyring. Server applications on z/OS that wish to establish network connections to other entities can use keyrings and their certificate contents to determine the trustworthiness of the client or peer entity. Note that certificates can belong to more than one keyring, and you can assign different users to the same keyring. Because of the way RACF internally references certificates, they must be uniquely identifiable by owner and label, and also unique by serial number plus data set name (DSN).

For establishing an SSL connection on z/OS, IBM's Application Transparent Transport Layer Security (AT-TLS) can be used, where the establishment of the SSL connection is pushed down the stack into the TCP layer.

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

Configure the AT-TLS rules for the policy agent (PAGENT) using an appropriate client and the z/OS Management Facility (z/OSMF) . Together with SSL parameters (to provide certificates stored in z/OS as RACF keyrings) define AT-TLS rules, for example by using the application job name and remote TCP port number. If the rules match, the TCP connection is turned into an SSL connection . Refer to your IBM documentation for more information, for example the IBM Redbook Communications Server for z/OS VxRy TCP/IP Implementation Volume 4: Security and Policy-Based Networking.

Table 3. Legend information
Legend	Description
	Client to interact with z/OS Management Facility (z/OSMF).
	AT-TLS rules are defined with z/OSMF policy management.
	Policy Repository with AT-TLS rules stored as z/OS files.
	Policy Agent, MVS task PAGENT, provides AT-TLS rules through a policy enforcement point (PEP) to TCP/IP stack.
	Application using TCP connection.
	If AT-TLS rules match, the TCP connection is turned into an SSL connection.

Notes:

The client may vary per operating system, for example a web browser for z/OS 2.1.
z/OSMF includes other administration and management tasks in addition to policy management.
Policy Management includes other rules, such as IP filtering, network address translation etc.

To set up SSL with AT-TLS:

To operate with SSL, certificates need to be provided and maintained. Depending on the platform, IBM EntireX provides sample certificates, but we strongly recommend that you create your own. See SSL/TLS, HTTP(S), and certificates with EntireX in the EntireX Security documentation.
Set up the RPC Server for IMS for a TCP/IP connection. On mainframe platforms, use Transport-method-style Broker ID. Example:
```
ETB024:1699:TCP
```
Configure AT-TLS to turn the TCP/IP connection to an SSL connection, using a client to interact with the z/OS Management Facility (z/OSMF) See z/OSMF considerations in the z/OS Administration documentation. The outcome of this configuration is a Policy Repository with AT-TLS rules stored as z/OS files. This file is the configuration file for the Policy Agent, MVS task PAGENT.
Make sure the SSL server to which the RPC Server for IMS connects is prepared for SSL connections as well. The SSL server can be EntireX Broker, Broker SSL Agent, or Direct RPC in webMethods Integration Server (IS inbound). See:
- Running Broker with SSL/TLS Transport under z/OS | Linux | Windows
- Broker SSL Agent (Linux | Windows)
- Support for SSL/TLS in the EntireX Adapter documentation (for Direct RPC)

Starting the RPC server

To start the RPC server for IMS:

Modify the member EXPSRVI (see EntireX job library EXX110.JOBS) according to your system requirements and copy the started task JCL to your system PROCLIB concatenation. See Started task JCL.
Modify the server parameters Configuration file according to your system requirement. For details, see Configuring the RPC server.
Start the task manually with:
```
/s EXPSRVI
```
Or:

Add the task to your system automation tool(s)

Stopping the RPC server

To stop the RPC server for IMS:

Use the operator command STOP. Examples:
```
/p EXPSRVI
/f EXPSRVI,STOP
```
Or:

Add the STOP command to your system automation tool(s).

Activating tracing for the RPC server

To switch on tracing for the RPC server for IMS:

Set the parameters tracelevel, traceoption and tracedestination. See Configuring the RPC server.
Start the RPC Server for IMS. See Starting the RPC server.
Temporarily 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 switch off tracing, set the tracelevel parameter to None.