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EDT:Accessing a service
This page contains code snippets for service access.
You can access a service from a Rich UI application or (in the future) from code generated to Java.
Contents
EDT version .8
In EDT version .8, your task is to code a call statement such as this one:
myBindingVar IHTTP? = SysLib.getResource("binding:myResource"); call MyInterface.myOperation() using myBindingVar returning to myCallBackFunction onException myExceptionHandler;
Your call statement typically has the following aspects:
- Invokes a specific operation by referring either to a function in a Service type or to a function prototype in an Interface type.
- Identifies service-access details by referring to a binding variable, which is specific to a kind of service binding. That variable includes service-access details. You might have retrieved the details from the EGL deployment descriptor and then customized them; or you might have created the details from scratch, in your code.
Otherwise, the call statement operates as follows:
- In a Rich UI application, the statement causes an asynchronous invocation and identifies a callback function and an exception handler.
- Outside of Rich UI (in the future), the statement causes a synchronous invocation and does not identify a callback function or exception handler. If a returned value is expected, the statement identifies a variable to receive the returned value.
The synchronous call statement is now supported for accessing an IBM i called or service program, as described here:
Support for IBM i.
Accessing a dedicated service (version .8)
You can reference a Service type...myBindingVar HttpProxy; call MyService.functionName(InField.text) using myBindingVar returning to handleResponse onException serviceExceptionHandler;
call MyService.functionName(InField.text) using new HttpProxy returning to handleResponse onException serviceExceptionHandler;
myBindingVar HttpProxy = new HttpProxy("server.MyService"); call IMyService.functionName(InField.text) using myBindingVar returning to handleResponse onException serviceExceptionHandler;
call IMyService.functionName(InField.text) using new HttpProxy("server.MyService") returning to handleResponse onException serviceExceptionHandler;
Accessing an EGL REST-RPC service (version .8)
myBindingVar httpRest{@Resource {uri="binding:myEntry"}}; call IMyServiceType.calculate(myList) using myBindingVar returning to theCallBack onException theExceptionHandler;
Accessing a third-party REST service (version .8)
Accessing a called or service program on IBM i (version .8 only)
See Support for IBM i.
EDT version .7
In EDT version .7, your task follows this pattern: declare a service-access variable and use it in a call statement.
Accessing a dedicated service (version .7)
// 1. declare the service-access variable myService MyServiceType?{@dedicatedService} // 2. call the service call myService.theFunction() returning to theCallBack onException theExceptionHandler; /* * Example: create a new EGL project for * "Web 2.0 application with services". Add the * the Service type shown next to the server package, * and add the Handler type to the client package. * * Test the example in the Rich UI Preview tab * by typing valid input into the first text box; for example: * 5, 12, 4 */ // the file with a Service type package server; Service MyServiceType // variables and constants can be here function calculate(myScores Int[] in) returns (Decimal(4,2)) numberOfScores, i, mySum Int; numberOfScores = myScores.getSize(); for (i from 1 to numberOfScores by 1) mySum = myScores[i] + mySum; end return(mySum/numberOfScores); end end // the file with a Handler type package client; import server.MyServiceType; import org.eclipse.edt.rui.widgets.GridLayout; import org.eclipse.edt.rui.widgets.TextField; import org.eclipse.edt.rui.widgets.GridLayoutData; import dojo.widgets.DojoButton; import dojo.widgets.DojoTextField; handler MyHandler type RUIhandler{initialUI =[ui], onConstructionFunction = start, cssFile = "css/ProjectInEDT.7.css", title = "MyHandler"} ui GridLayout{columns = 3, rows = 4, cellPadding = 4, children =[myResult, myButton, scores]}; scores TextField{layoutData = new GridLayoutData{row = 2, column = 2}}; myButton DojoButton{layoutData = new GridLayoutData{row = 4, column = 2}, text = "Calculate", onClick ::= ui_onClick}; myResult DojoTextField{layoutData = new GridLayoutData{row = 4, column = 3}}; function start() end function theExceptionHandler(exp AnyException in) SysLib.writeStdOut(exp.messageID + " " + exp.message); if (exp isa ServiceInvocationException) SysLib.writeStdOut((exp as ServiceInvocationException).detail1); SysLib.writeStdOut((exp as ServiceInvocationException).detail2); SysLib.writeStdOut((exp as ServiceInvocationException).detail3); end end function theCallBack(retResult decimal(4, 2) in) myResult.text = retResult; end function ui_onClick(event Event in) inputLength int = scores.text.length(); myDelimiters string = ", "; myPosition int = 1; myToken string; myList int[]; while(myPosition < inputLength) myToken = StringLib.getNextToken(scores.text, myPosition, myDelimiters); if(myToken != null) myList.appendElement(myToken as int); end end /************ Service access statements ***************************/ myService MyServiceType?{@DedicatedService}; call myService.calculate(myList) returning to theCallBack onException theExceptionHandler; /*******************************************************************/ end end
Accessing an EGL REST-RPC service (version .7)
Access of an EGL REST-RPC function is similar to accessing a dedicated service, but typically involves coding the variable declaration to reference an entry in the EGL deployment descriptor.
For example, you might change the previous handler to reference a deployment descriptor entry named myService
. You can change the related variable declaration in one of two ways:
myService MyServiceType?{@Resource}; // or myService MyServiceType?{@Resource{bindingKey="myService"}};
You can demonstrate the access of a Service type under development only after you update two aspects of your deployment descriptor: Service Deployment and Resource Bindings. For details and a look at the version .8 code syntax, see Service bindings.
To retrieve the details from the HTTP response, add a parameter of type IHTTP to the callback function:function theCallBack(retResult decimal(4, 2) in, myHttp IHTTP in) myResult.text = retResult; // display the response in JSON format SysLib.writeStdOut(myHttp.getResponse().body); end