Calling a Web service from Oracle9i
Forms.
Oracle9iAS Forms Services
provides a comprehensive application framework to deploy enterprise-class applications
to the Internet with a rich Java interface. A key feature of Oracle Forms is
that it provides a number of integration points to allow Forms to communicate
with other technologies.
One of the most popular technologies now emerging is Web Services. A Web Service
can be used to encapsulate any kind of business information from a whole application
to providing a simple service. Oracle Forms allows you to easily integrate Web
services with an existing Forms application through the use of the Java Importer.
Calling a Web Service from Forms
In order to call a Web Service from a Forms application, you must complete
two main steps. The first is the creation of the Web Service stub, which will
be performed through Oracle9i JDeveloper, and the second is to call the
stub from the Forms application.
Create a Web Service Stub
The first step will be to create the Web Service stub. In this example, we
are going to use a simple Web Service available on the Internet which provide
currency conversion. The Web Service is defined by its WSDL.
We will use Oracle9i JDeveloper to create the Web Service stub. This
stub is a Java class which provides the interface to the Web Service and this
is the interface that will be called by Forms
| 1. |
From within a new project in Oracle9i JDeveloper select File>
New> General> Web Services>Web Service Stub/Skeleton and
then press OK
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| 2. |
If the Welcome screen appears press Next> to go to screen 1
of 2. On this screen, in the WSDL Document URL enter the name of
the URL which points to the WSDL of the Web Service. In this example we
will use:
http://www.xmethods.net/sd/2001/CurrencyExchangeService.wsdl
.
Press Next>
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| 3. |
Screen 2 of 2 shows the facilities available to be called on this Web
Service. These should be selected by default, press Finish
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| 4. |
JDeveloper automatically creates the code required to call the Web Service.
Save and Rebuild the project.
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| 5. |
(Optional Step).When you run a Web Service stub from within JDeveloper,
the proxy settings are read from the IDE (Tools > Preferences >
Web Browser/Proxy). Since you will be calling the Web Service stub
from Forms, you may have to define the proxy settings in the code. If
you are using a proxy then you have to replace the following line the
in CurrencyExchangeServiceStub constructor.
Replace
m_httpConnection = new OracleSOAPHTTPConnection();
with
Properties prop = new Properties();
prop.setProperty(OracleSOAPHTTPConnection.PROXY_HOST, "myproxy"); prop.setProperty(OracleSOAPHTTPConnection.PROXY_PORT,"80");
m_httpConnection = new OracleSOAPHTTPConnection(prop);
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| 6. |
While you have only created one class, that class relies on a number
of other Java classes. The next step will be to "package" all
the relevant files into a single Jar file.
Select File > New > General > Deployment
Profiles > JAR File - Simple Archive and press OK.
A dialog will appear showing the name and location of the deployment
descriptor. Accept the defaults and press Save.
|
| 7. |
The JAR Deployment Profile Settings Dialog will now appear. Select Dependency
Analyzer and check the check box for Oracle SOAP. Press OK.
|
| 8. |
This will create a deployment node on in the system navigator. Select
the node, right mouse click and select Deploy to JAR File. This
will save the JAR file out to disk. Note the full directory path and name
of this JAR file.
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| |
|
Create a Form
It is assumed that for this part of the exercise, you have a working installation
of Oracle9i Forms.
Once you have created the Web Service stub the next step is to create a simple
form to call the Web Service. For the sake of making this test case as simple
as possible, we will simply add a button which will call the Web Service and
return (and message out) the rate of exchange. This can of course be elaborated
to fit the needs of your application.
| 1. |
Select Start > Settings > Control Panel. Double-click on
System, then click the Advanced tab then click the Environment
Variables button. From the System Variables, select CLASSPATH
and then press Edit. Add the full directory name to the JAR file
created in step 7 above. Press the OK buttons to dismiss the dialog.
|
| 2. |
The next step is to update the Forms environment file to indicate the
location of the Jar file (this file is called default.env in a default
installation.)
Prepend the full directory path and Jar filename to the CLASSPATH entry.
E.g.
CLASSPATH=
D:\9.0.4.11.71\jdev\mywork\Webservice\Project1\deploy\archive1.jar;D:\...
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| 3. |
Start up Oracle9i Forms and create a new Form. Create a block
and canvas.
|
| 4. |
Select Program > Import Java Classes and select the
Java class created in JDeveloper. Press Import. This will create
a PL/SQL package for the CurrencyExchangeServiceStub Java
class.
|
| 5. |
Change the Import Classes field to java.lang.Float and press Import.
This will create a PL/SQL package for the Float Java class. This is required
because the CurrencyExchangeServiceStub returns an object
of type Float. This is not native to Forms and so we also need to import
the Float object.
|
| 6. |
Change the Import Classes field to java.lang.Exception and press
Import. This will create a PL/SQL package for the Exception Java
class. While this is not essential, it does make error reporting easier.
Now press Close to dismiss the dialog.
|
| 7. |
Add a button to the canvas and add a When-Button-Pressed trigged and
add the following code
DECLARE
jo ora_java.jobject;
rv ora_java.jobject;
ex ora_java.jobject;
BEGIN
jo :=
CurrencyExchangeServiceStub.new;
--
--This will get the exchange rate from US Dollars to UK Sterling.
--
rv :=
CurrencyExchangeServiceStub.getRate(jo,'USA','UK');
message (float_.floatValue(rv));
EXCEPTION
WHEN ORA_JAVA.JAVA_ERROR then
message('Unable
to call out to Java, ' ||ORA_JAVA.LAST_ERROR);
WHEN ORA_JAVA.EXCEPTION_THROWN then
ex := ORA_JAVA.LAST_EXCEPTION;
message(Exception_.toString(ex));
END;
This will call out to the Java class with two parameters and will return
the exchange rate to be displayed as a message.
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| 8. |
Run the form and press the button. This will now display the exchange
rate from US to UK currency.
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Sample code and more information
The following links point to more sources of information related to this topic.
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