EGL provides a library and Record definitions to communicate
with data queues and data areas on the iSeries®.
The iSeries operating
system has its own API to handle program-to-program communication.
The communication can take place through one of two objects:
- A data area is a fixed-size object that any job running
on the system can read from or write to. Think of it as a virtual
whiteboard. You can set it up to contain one of the following kinds
of data:
- A character string of up to 2000 bytes
- A decimal number
- A Boolean value (TRUE or FALSE)
- A data queue is a variable-length object that can
hold any number of messages from any number of jobs. Data queues are
similar to WebSphere® MQ
message queues.
A data area has lower overhead than a data queue, so your choice
of which object to use generally depends on the complexity of your
task. You might use a data area, for example, to hold a flag that
lets one program tell another to perform garbage collection. A data
queue scenario is typically more complex, as in the following example:
- One application listens for a specific type of request. For each
request, it creates a record and adds that new record to the queue.
- Other applications listen for new records created by the first
application. One uses the record to update a database. Another uses
the same record to generate an invoice.
EGL supports these iSeries objects
in two ways:
- EGL Record parts that correspond to various iSeries objects, including data areas and
data queues, among others. The Record parts are located in the CommonDataParts.egl file.
- A library of EGL functions that wrap iSeries API calls. The specific library you
use depends on the language you generate:
- iCobolLib.egl is for COBOL generation.
- iJavaLib.egl for Java™ generation.
This library uses ExternalType parts that are implemented by classes
from the IBM® Java Toolbox. See "Required IBM Toolbox for Java"
in this topic.
The simplest way to add these files to your workspace is to add
the EGL with IBM i objects support feature
to your project. For more information, see Features and facets of EGL projects.
For details of these Record parts and function calls, see the "Related
reference" section at the end of this topic.
Required IBM Toolbox
for Java
Remote calls that have
remoteComType =
Java400 in the call linkage originate from Java or Debug and call a program on a System i® machine. EGL uses
classes from the IBM Toolbox
for Java to enable these calls.
Users making Java400 calls must download the
jt400.jar library
from the web and add it to the project classpath:
- Browse to the following location and follow the instructions for
downloading the Toolbox for Java:
http://www.ibm.com/systems/i/software/toolbox/index.html
- Extract the jt400.jar file to a directory
on your system.
- Right-click the project name and click .
- Click Add External JARS.
- Browse to the jt400.jar archive and click Open.
Click OK to close the Properties window.