Welcome
Developing
Developing EGL applications
Enterprise Generation Language (EGL) is a programming language that you can use to focus on business problems instead of software technologies. Within the Rational® development environment, you can use EGL wizards and other tools to write complex applications with minimal effort.
EGL Language Reference
The EGL Language Reference covers the fundamental use of the language, including its concepts, syntax, and keywords. This volume is intended for a developer writing EGL applications with some experience in procedural programming.
EGL core system libraries and variables
EGL library lobLib
The lobLib system library provides support functions for large objects (BLOB and CLOB types).
truncateBlob()

Overview
Getting started
Installing
Upgrading and migrating
EGL Code Accelerator for IBD
Developing
- Model driven development of EGL code
- Generating source code from UML models
  You can use transformations to create source code from a UML model. First you must create a transformation parameters file and then apply those parameters to a model.
- Generating the EGL Dependency Graph from EGL projects
- Generating Source Code from OpenAPI Documents
- Developing EGL applications
  Enterprise Generation Language (EGL) is a programming language that you can use to focus on business problems instead of software technologies. Within the Rational® development environment, you can use EGL wizards and other tools to write complex applications with minimal effort.
  - How to use this documentation
  - Additional information about EGL
    The most recent EGL documentation is in the IBM Business Developer documentation.
  - EGL Programmer's Guide
    The EGL Programmer's Guide covers using EGL within the Eclipse Integrated Development Environment (IDE), as well as some of the common programming tasks that EGL developers perform.
  - EGL Generation Guide
    The EGL Generation Guide covers the process of converting EGL code to Java™ or COBOL source code, including the processes and the files involved. This section is intended for a developer who will generate or deploy EGL applications.
  - EGL Language Reference
    The EGL Language Reference covers the fundamental use of the language, including its concepts, syntax, and keywords. This volume is intended for a developer writing EGL applications with some experience in procedural programming.
    - General syntax
    - System data parts
    - User-defined data parts
    - Logic parts
    - Correspondence between a JSON string and an EGL variable
      This topic describes the EGL record that corresponds to a JavaScript™ Object Notation (JSON) string. Other topics describe the functions (serviceLib.convertFromJSON() and serviceLib.convertToJSON()) that are used by a Rich UI developer to convert JSON data to or from a variable, as may be necessary to access a third-party REST service. A failure in either function causes a RuntimeException.
    - Correspondence between a JSON string and an EGL variable for zOS and IBM i
      This topic describes the EGL record that corresponds to a JavaScript Object Notation (JSON) string. This topic describes the functions—serviceLib.convertFromJSON() and serviceLib.convertToJSON()—that are used by an EGL developer to convert JSON data to or from a variable either for zOS or IBM i systems. A failure in either function causes a RuntimeException.
    - Special considerations for JSON support on IBM i:
    - Correspondence between an XML string and an EGL variable
      This topic describes the EGL record that corresponds to an Extensible Markup Language (XML) string. Other topics describe the functions (serviceLib.convertFromXML and serviceLib.convertToXML) that are used by a Rich UI developer to convert XML data to or from a variable, as may be necessary to access a third-party REST service.
    - EGL statements
    - EGL core system libraries and variables
      - EGL library dateTimeLib
        The date and time system functions and variables let you manipulate and retrieve the system date and time in a variety of formats.
      - EGL library JavaLib
        The javaLib library access local Java® objects and classes through your generated Java™ code.
      - EGL library lobLib
        The lobLib system library provides support functions for large objects (BLOB and CLOB types).
        attachBlobToFile()
        The lobLib.attachBlobToFile() system function associates a specified file with a BLOB variable.
        attachBlobToTempFile()
        The lobLib.attachBlobToTempFile() system function creates a unique, temporary system file and associates that file with a BLOB variable. This function minimizes the memory used at run time.
        attachClobToFile()
        The lobLib.attachClobToFile() system function associates a specified file with a CLOB variable.
        attachClobToTempFile()
        The lobLib.attachClobToTempFile() system function creates a unique, temporary system file and associates that file with a CLOB variable. This function minimizes the memory used at run time.
        freeBlob()
        freeClob()
        getBlobLen()
        getClobLen()
        getStrFromClob()
        getSubstrFromClob()
        loadBlobFromFile()
        loadClobFromFile()
        setClobFromString()
        setClobFromStringAtPosition()
        truncateBlob()
        truncateClob()
        updateBlobToFile()
        updateClobToFile()
      - EGL library logLib
        The logLib utility offers a set of logging functions that support multiple log levels DEBUG, ERROR, INFO, TRACE and WARN. These functions are designed to help developers effectively monitor, debug, and trace the behavior of EGL applications during execution.
      - EGL library mathLib
        The EGL mathLib functions perform common mathematical and trigonometric functions.
      - EGL library serviceLib
        The serviceLib functions get and set service variable information.
      - EGL library strLib
        The strLib functions manipulate and convert data to and from STRING variables and format date/time variables.
      - EGL library sysLib
        The sysLib system library contains miscellaneous functions and one variable.
      - sysVar system variable
        The sysVar system variable holds a variety of values.
      - EGL library XMLLib
        This topic describes the XMLLib functions and variable definitions.
    - Accessing data in EGL
      Whenever you access a data store in EGL, the data goes into a record.
    - Applications with user interfaces
    - VisualAge® Generator compatibility
    - Appendices
    - Importing product-supplied projects
      You can click a link to download the current version of Rich UI projects. The capability is useful if you deleted a project or want a clean version.
  - Rational® COBOL Runtime Guide for zSeries®
    This manual provides information about customizing and administering the IBM® Rational® COBOL Runtime.
  - IBM Business Developer EGL Server Guide for IBM® i
    This manual provides information about customizing and administering EGL Server for IBM® i on the host.
  - Generation for VSE Feature Reference
    This reference manual provides z/VSE-specific information about developing and generating EGL programs in the VSE environment.
- Source code analysis with code review
  With code review, you can create configurations of coding rules for EGL source code. You can then run the configurations to check the source code for consistency with the rules.
- Responsive Design Support in IBD
  What is Responsive Design? Responsive design is an approach for creation of web pages that automatically scales its content and elements to match the screen size on which it is viewed. So, instead of designing multiple websites for different devices with variable screen sizes, we can design just one website that scales up or down automatically, to match the device it’s being viewed on.
- Containerizing an EGL RUI Application
Samples
Troubleshooting and support
EGL runtime error messages
Reference
Glossary
Using the help
Notices for IBM Business Developer documentation

truncateBlob()

The lobLib.truncateBlob() system function truncates the value referenced by a BLOB variable.

Syntax

  lobLib.truncateBlob(
    blobVariable BLOB inOut,
    length BIGINT in)

blobVariable: A BLOB variable. If this parameter has a null value, EGL throws a NullValueException.
length: The number of bytes in the output. If length is less than 0 or greater than the length of the CLOB, EGL throws a RuntimeException.