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.
This document covers the following topics:
The following elements are used for setting up the RPC Server for IMS:
The name of the delivered example configuration file is
CONFIGI (see source library EXP109.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
etc.
For more information see Configuring the RPC Server.
Depending on the feature the RPC Server for IMS 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 IBM Z Publications Library Archive.
| 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 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.
The name of the started task is EXPSRVI
(see EntireX job library EXX109.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 example above, 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
etc.
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.
| 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: |
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: |
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: Enable character conversion in the broker by setting the service-specific attribute |
|||||||||||||
compresslevel |
N |
Enforce compression when data is transferred between
broker and server. See Data Compression in EntireX Broker.
Example: |
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.
Example: |
O | ||||||||||||
etblnk |
BROKER |
Define the broker stub to be used. See Administering Broker Stubs for available stubs.
Example: |
O | ||||||||||||
extractor |
NO |
The extractor service is a prerequisite
for remote extractions. See Extractor Service.
Example: |
O | ||||||||||||
impersonation |
NO |
Defines if RPC requests are executed under the RPC user ID of the calling RPC client.
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.
|
O | ||||||||||||
library |
no default | library = search_logic [-
This parameter applies to programming language C only. Do not set if other programming languages for RPC server are used.
Example Example |
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.
Example: |
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)
|
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: |
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: When the number of specified cycles is reached and a connection to the broker is not possible, the RPC Server for IMS stops. Example: The server waits up to 30 minutes (30*6*10 seconds) before it terminates due to a missing broker connection. |
O | ||||||||||||
return_code |
NO |
Enable application-specific errors.return_code=(NO|YES)
Example: |
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: |
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: |
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: |
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.
Example: For the example above, define the DD name //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?
Example: For the example above, define the DD name 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: |
O | ||||||||||||
tracedestination |
DD:ERXTRACE |
The name of the destination file for trace output. See also Activating Tracing for the RPC Server.
Example: The DD name //MYTRACE DD DISP=SHR,DSN=<rpctrace-file> |
O | ||||||||||||
tracelevel |
None |
Trace level for the server. See also Activating Tracing for the RPC Server.
Example: |
O | ||||||||||||
traceoption |
None |
Additional trace option if trace is active. See also Activating Tracing for the RPC Server.
Example: |
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: |
O |
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:
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 Z Publications Library Archive for more information)
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
See also Scenario I: Calling an Existing COBOL Server or Scenario II: Writing a New COBOL Server.
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, BS2000).
See also Scenario V: Writing a New C Server.
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.
See also Scenario VI: Writing a New Assembler Server.
RPC servers can use Secure Sockets Layer/Transport Layer Security (SSL/TLS) as the transport medium. The term "SSL" in this section 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.
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.
|
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:
may vary per operating system, for example a Web browser for z/OS 2.1.
includes other administration and management tasks in addition to 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, Software AG provides sample certificates, but we strongly recommend that you create your own. See SSL/TLS Sample Certificates Delivered 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:
To start the RPC Server for IMS
Modify the member EXPSRVI
(see EntireX job library EXX109.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)
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).
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.