Program call: a practical example

In this post, I will show a practical example of using the jtopen plugin to call a program on the AS/400.

We will create a grails service to execute commands on the AS/400.

We assume we have a grails application with the jtopen plugin installed.

We first have to set the AS/400 host, user and password. We will edit the grails-app/conf/Config.groovy file and add the three following lines:

jtopen.as400 = 'as400'

jtopen.user = 'user'

jtopen.password = 'password'

Of course, you should customize the values to your environment. As they are typically per-environement values, we will set them with the grails.serverURL variable.

We then create a new service:

grails create-service Command

This will create the file grails-app/services/CommandService.groovy, we will change it to:

import org.codehaus.groovy.grails.plugins.jtopen.types.*

class CommandService {

boolean transactional = false

def ibmI

def executeCommand(String command) {

def cr = ibmI.call('QCMDEXC',[

new IChar(command),

new IPacked(command.length(),15,5)] as Type[])

cr.success?:cr.messageList

}

}

And that's it!

Let's have a closer look.

import org.codehaus.groovy.grails.plugins.jtopen.types.*

We import the parameter types used to call the program.

def ibmI

This line creates a property named ibmI. It will automatically be injected with an IbmI object.

def cr = ibmI.call('QCMDEXC',[

new IChar(command),

new IPacked(command.length(),15,5)] as Type[])

Here is the heart of the service. This will call the QCMDEXC API with the two parameters it expects:

• The command to execute as a CHAR variable
• The command length as a (15,5) packed decimal

You can see that the QCMDEXC parameters are surrounded by [ and ] as Type[]. This is necessary because of a bug in groovy. This bug has been fixed in the groovy trunk and this circumvention shouldn't be necessary in future grails releases.

cr.success?:cr.messageList

This line makes the service return true if the command execution is successful or the array of messages returned by the command will be returned.

Now let's create a controller using this service:

grails create-controller DataArea

This will create the file grails-app/controllers/DataAreaController.groovy, change it to:

class DataAreaController {

def commandService

def create = {

def result = commandService.executeCommand("CRTDTAARA ${params.name} TYPE(*CHAR) LEN(10)")

render result==true?"Data area ${params.name} created":result.inspect()

}

}

We now start the application:

grails run-app

Now point your browser to:

http://localhost:8080/yourAppName/dataArea/create?name=grails

You should see the message "Data area grails created". On your AS/400, you should have a data area named grails in the jtopen.user user current library (or QGPL).

That's all for this example.