Sunday Dec 18, 2011

Creating a Web Service Proxy in ADF to Consume a Web Service

Abstract

There is more than one way to design your ADF application to consume web services.  One example is to use the ADF wizards to create data controls to access the web service. Another example is to use the ADF wizards to create a proxy to the web service you want to consume. This article is an example of the proxy development process.

Introduction

Oracle has made it extremely easy to quickly develop a body of customizable code that can consume a web service. If there are complexities, they will be involved in the creation of the object that is transported as a SOAP message in the web service transmissions. Otherwise, the wizard gets you to a place very quickly where you can utilize the targeted web service.

There are a large number of public web services you can use to practice creating ADF code to consume the web service.  Just query on the Internet for "public web services".  One site is www.service-repository.com. The web service I have selected for this example is Top Movies.

This development example is completed using JDeveloper 11g Release 1 (11.1.1.4.0).

Overview

The following summarizes what is accomplished in this article.

Create the Application

  • Start the Create Application Wizard
  • Name your application
  • Name your project
  • Configure Java settings

Create the Web Service Proxy

  • Select the Create Web Service Proxy wizard
  • Select the Client Style Select the WSDL
  • Select the WSDL to Java packages mappings
  • Define Port Endpoints
  • Define the Asynchronous Methods
  • Define Oracle Web Service Message Policies
  • Define Message Handlers

Review and Understand the Generated Code

  • Review the Project Structure
  • Review the Generated Code and Cross-References to the WSDL
  • Understanding the binding Element

Consuming the Web Service

  • Create the driver class
  • Review and understand the code 

Using Environments and Migrations

  • Identifying Four methods of migrating between environments
  • Using generated class constructors for migrations

Construction

Create the Application

Start the Create Application Wizard

  • Open up JDeveloper. Click on the Application Menu > New. 

Define the Application Dialog

  • Select Generic Application from the Application Template list.
  • Application Name:  TopMovie
  • Directory: D:\JDev\jdev11114\TopMovie
  • Click Next

Define the Project Dialog

  • Select Web Services from the Project Technologies list.
  • Click on the move button to shuttle the service to the selected side.

The wizard will add an additional step > Project Java Settings.

You will see that 2 technologies were added to the selected window: Java and Web Services.

  • Click Next

Configure Java Settings Dialog

  • Assign a Default Package:  webservices
  • Click Finish

Create the Web Service Proxy

Start the ADF Wizard

  • Right mouse click the Project > WebServices
  • Click New

New Gallery Dialog Box

  • When the New Gallery dialog box appears perform the following steps.
  • Select Current Project Technologies tab
  • Select Business Tier > Web Services in the categories list
  • Select Web Service Proxy in the items list
  • Click OK

Create Web Service Proxy Welcome Dialog Box

  • Click Next 

Select Client Style Dialog Box

  • Select JAX-WS Style (this should be the default)
  • Click Next

Select Web Service Description Dialog Box

  • Enter the location of the WSDL file.
    • This can be a local copy or you may have a URL address to enter which is also acceptable.
  • By default, "Copy WSDL Into Project" is selected. Keep the default setting.
  • Click Next

Specify Default Mapping Options Dialog Box

  • Enter a Package Name:  com.topmovie
  • Enter a Root Package for Generated Types:  com.topmovie.types
  • By default, "Unwrap Wrapped Parameters" is selected.  Keep the default.
  • Click Next

Port Endpoints Dialog Box

  • This is an optional task.  Keep the defaults.
  • Click Next

Asynchronous Methods Dialog Box

  • Accept the default selection "Generate asynchronous methods where specified by the JAX-WS binding"
  • Click Next

Policy Dialog Box

  • Accept all the defaults in this dialog box
  • Click Next

Defined Handlers Dialog Box

  • Accept all the defaults in this dialog box
  • Click Next

Finish Dialog Box

  • Review and Click Finish
  • Save your changes (Control-S)

Review Application Structure

Project View

Numerous class files and supporting files such as the WSDL file are generated. Below is a screenshot of the WebServices Project structure that is generated with the proxy web service wizard.

Code and WSDL Cross-References

An examination of the WSDL file will help understanding the resulting code generation via the wizard. Every time you use this wizard the code generation will be very similar to the structure reviewed below. By studying this structure you can very quickly know where to go to create code anytime you use this wizard. Below is a table of the structure elements cross-referenced to the WSDL location.

Structure Name

WSDL Location

TopMovies.java

wsdl:service name="TopMovies"

You will always have one class file generated for your service with the name "serviceName.java"

TopMoviesSoap.java

wsdl: portType name="TopMoviesSoap"

Also contains the methods used to invoke the web service

TopMoviesSoap12Client.java

wsdl: binding name="TopMoviesSoap12Client"

A template that provides the beginning code to invoke the web service using SOAP 1.2 bindings

TopMoviesSoapClient.java

wsdl:binding name="TopMoviesSoapClient"

A template that provides the beginning code to invoke the web service using SOAP 1.1 bindings (for backward compatibility)

TopMoviesProxy

a container that encapsulates all the class files and supporting files (such as the wsdl) in the defined structure

Types Section

WSDL Location

ArrayOfString.java

s:complexType name="ArrayOfString"

GetMovieAtNumber.java

s:complexType name="GetMovieAtNumber"

GetMovieAtNumberResponse.java

s:complexType name="GetMovieAtNumberResponse "

GetTop10.java

s:element name="GetTop10"

GetTop10Response.java

s:element name="GetTop10Response"

ObjectFactory.java

provides methods to create object instances of the above types

package-info.java

references the package of class files for the types (com.topmovie.types)

Notes about the binding Element in the WSDL structure

The binding element serves two purposes.

1.   It is a link between the abstract elements (<wsdl:types>, <wsdl:message>, <wsdl:operation>, <wsdl:portType>) and the concrete elements (<wsdl:service>, <wsdl:port>, <wsdl:binding>) in the WSDL.

 The attribute "type" is the name of the portType:

<wsdl:binding name="TopMoviesSoap12" type="tns:TopMoviesSoap">

<wsdl:binding name="TopMoviesSoap" type="tns:TopMoviesSoap">

"tns:TopMoviesSoap" is the portType

Notice that there are two bindings.  The binding with name "TopMoviesSoap12" is a SOAP 1.2 binding element. The binding with name "TopMoviesSoap" is a SOAP 1.1 binding. You can find additional information about the two supported formats with a search on the Internet. Many WSDL files provide both bindings for backward compatibility. There are three key differences of SOAP 1.2 over SOAP 1.1:

1) A new namespace: http://schemas.xmlsoap.org/wsdl/soap12/

2) The encodingStyle attribute is now a single URI, instead of a list of URIs

3) There is a new attribute: soapActionRequired, which is used to indicated that the server needs the SOAPAction value.

2.    The binding element provides a container for information such as the protocol and the operation of the Web service. The transport attribute is the protocol.

In the binding element you can identify the operations that can be executed when consuming the web service and these become the methods used within the Java template code with "Client" in the class name (e.g. TopMoviesSoapClient.java).

Consuming the Web Service

Create a Driver

The next step is to create our code that will execute the newly created methods and consume the Top Movies web service.

The job of accomplishing this is made easier by reviewing either the TopMoviesSoapClient.java or TopMoviesSoap12Client.java class files. Each of these serve as a starting point to writing your own code to execute the operations you want to target.

Below is a segment of the TopMoviesSoapClient.java:


public static void main(String [] args)
{
  topMovies = new TopMovies();
  TopMoviesSoap topMoviesSoap = topMovies.getTopMoviesSoap();
  // Add your code to call the desired methods.
}

This can be used to begin our own coding efforts.

Create a New Class File

  • Right mouse click the project and click New on the menu

New Gallery Dialog Box

  • Select Current Project Technologies tab
  • Select General > Java from the Categories list
  • Select Java Class from the Items list
  • Click OK

Create Java Class Dialog Box

Complete the form as follows:

  • Name:  TopMovieWS
  • Package:  webservices
  • Extends:  java.lang.Object
  • Select Main Method check box
  • Click OK

The defaults that should already be selected are: Access Modifiers > public, Other Modifiers > None, Constructors from Superclass and Implement Abstract Methods.

Complete the new Class file to look like the following:



package webservices;

import com.topmovie.TopMovies;
import com.topmovie.TopMoviesSoap;
import com.topmovie.types.ArrayOfString;

import java.io.UnsupportedEncodingException;

import java.net.MalformedURLException;
import java.net.URL;

import java.net.URLDecoder;

import java.util.Iterator;
import java.util.List;

import javax.xml.namespace.QName;

import oracle.xquery.parser.Qname;

public class TopMovieWS {

    private static TopMovies topMovies;

    public TopMovieWS() {
        super();
    }

    public static void main(String[] args) {
        int movieRank = 1;

        // sample from TopMoviesSoapClient.java
        topMovies = new TopMovies();
        QName serviceName = topMovies.getServiceName();
        System.out.println("Service Name: " + serviceName + "\n");
        URL wsdlDocumentLocation = topMovies.getWSDLDocumentLocation();
        System.out.println("WSDL Location: " + wsdlDocumentLocation);
        URLDecoder decoder = new URLDecoder();
        String decodedURL = null;
        try {
            decodedURL = decoder.decode(wsdlDocumentLocation.toString(), "UTF-8");
        } catch (UnsupportedEncodingException e) {
            System.out.println("Error");
        }
        System.out.println("WSDL Location without URL Escape codes: " + decodedURL);

        // consume the web service with SOAP 1.1 binding
        TopMoviesSoap topMoviesSoap = topMovies.getTopMoviesSoap();
        movieRank = 2;
        String movieAtNumber = topMoviesSoap.getMovieAtNumber(movieRank);
        System.out.println("SOAP 1.1 binding - Movie at number " + movieRank + " is " +
                           movieAtNumber + "\n");

        // consume the web service with SOAP 1.2 binding
        TopMoviesSoap topMoviesSoap12Client = topMovies.getTopMoviesSoap12();
        movieAtNumber = topMoviesSoap12Client.getMovieAtNumber(movieRank);
        System.out.println("SOAP 1.2 binding - Movie at number " + movieRank + " is " +
                           movieAtNumber + "\n");

        // also execute the Top 10 Movie operation
        TopMoviesSoap top10MoviesSoap = topMovies.getTopMoviesSoap();
        ArrayOfString top10MoviesArrayOfString = top10MoviesSoap.getTop10();
        List listOfTop10Movies = top10MoviesArrayOfString.getString();
        Iterator iterator = listOfTop10Movies.iterator();
        int iMovieCount = 0;
        while (iterator.hasNext()) {
            String movieDesc = (String)iterator.next();
            iMovieCount++;
            System.out.println(iMovieCount + ". Top 10 Movie: " + movieDesc);
        }
    }
}


Notes About the Code

The auto-complete feature in JDeveloper makes it very easy to inspect your possibilities as you begin typing your code. One of the very nice features is to use the control-space key stroke to use the Declaration Insert operation on your code. They will do the necessary casting and shortcuts your work considerably. All you need to do is modify the variable names to your own coding standards.

A provided enough code to explore the two operations made available and some of the other more interesting methods (e.g. getServiceName(), getWSDLDocumentLocation()).

Sample of Output

Below is a sample of the output produced by the code.

Service Name: {http://www.kirupafx.com}TopMovies
WSDL Location: http://www.kirupafx.com/WebService/TopMovies.asmx/#%7Bhttp%3A%2F%2Fwww.kirupafx.com%7DTopMovies?wsdl
WSDL Location without URL Escape codes: http://www.kirupafx.com/WebService/TopMovies.asmx/#{http://www.kirupafx.com}TopMovies?wsdl
Note that the WSDL location is a combination of the WSDL URL plus the Service Name.
SOAP 1.1 binding - Movie at number 2 is The Godfather: Part II (1974)
SOAP 1.2 binding - Movie at number 2 is The Godfather: Part II (1974)
1. Top 10 Movie: The Godfather (1972)
2. Top 10 Movie: The Shawshank Redemption (1994)
3. Top 10 Movie: The Godfather: Part II (1974)
4. Top 10 Movie: The Lord of the Rings: The Return of the King (2003)
5. Top 10 Movie: Casablanca
6. Top 10 Movie: Schindler's List
7. Top 10 Movie: Shichinin no samurai (1954)
8. Top 10 Movie: Buono, il brutto, il cattivo, Il (1966)
9. Top 10 Movie: Pulp Fiction (1994)
10. Top 10 Movie: Star Wars: Episode V - The Empire Strikes Back (1980)

Environments and Migrations

As developers we will most likely be working in a setting that has the traditional division of environments (e.g. Development, Testing, QA, PreProduction, Production). When this is your setting you will most likely have a separate WSDL file for the web service(s) to be consumed. If this is your case, then you must also prepare your code to make migrations easier.

The code generated by the wizard is very specifically tied to the addresses provided in your WSDL file. Consequently, if you migrate your code from a development environment to a test environment, your code will be calling the development web service by default. This needs to be corrected for the migration process.

There are at least four ways that I know about to accomplish this:

  1. Hard code your changes for each migration
  2. Make references to each environment's WSDL in the connections.xml file
  3. Use the BindingProvider Interface
  4. Use one of the additional constructors provided in the generated Java code where the class file name is the ServiceName.java (our example is TopMovies.java)

For this discussion I will illustrate using one of the additional constructors for the TopMovies.java class file.

TopMovies Class Constructors and Migrations

TopMovies()

This constructor has no parameters. Below is the constructor generated from the wizard. With no parameters, the constructor will use the hard-coded URL that was generated by the wizard from your WSDL file and assign it to "wsdlLocationURL".

  public TopMovies()
  {
    super(wsdlLocationURL,
          new QName("http://www.kirupafx.com", "TopMovies"));
  }

TopMovies(URL wsdlLocation, QName serviceName)

This constructor is expecting two parameters.  Below is the constructor generated from the wizard.

  public TopMovies(URL wsdlLocation, QName serviceName)
  {
    super(wsdlLocation, serviceName);
  }

You must supply the wsdlLocation and the serviceName.  One way you can use this in multiple environments is to store your WSDL location for that corresponding environment in a file (topMovies.properties for example). You write your code to read the targeted properties file and retrieve the designated WSDL location.

Below is my sample code with the new code (in yellow) needed to call the constructor with two parameters. I have hard coded the wsdlLocation but in a multi-environment setting you will use another means to supply the wsdlLocation based upon the current environment.


package webservices;

import com.topmovie.TopMovies;
import com.topmovie.TopMoviesSoap;
import com.topmovie.types.ArrayOfString;

import java.io.UnsupportedEncodingException;

import java.net.MalformedURLException;
import java.net.URL;

import java.net.URLDecoder;

import java.util.Iterator;
import java.util.List;

import javax.xml.namespace.QName;

import oracle.xquery.parser.Qname;

public class TopMovieWS {

    private static TopMovies topMovies;

    public TopMovieWS() {
        super();
    }

    public static void main(String[] args) {
        int movieRank = 1;

        URL topMoviesURL = null;
        try {
            topMoviesURL = new URL("http://www.kirupafx.com/WebService/TopMovies.asmx?wsdl");
        } catch (MalformedURLException e) {
            System.out.println("An error occurred creating the URL: " + e.toString());
        }
        QName qualifiedName = new QName("http://www.kirupafx.com", "TopMovies");
        topMovies = new TopMovies(topMoviesURL, qualifiedName);

        QName serviceName = topMovies.getServiceName();
        System.out.println("Service Name: " + serviceName + "\n");
        URL wsdlDocumentLocation = topMovies.getWSDLDocumentLocation();
        System.out.println("WSDL Location: " + wsdlDocumentLocation);
        URLDecoder decoder = new URLDecoder();
        String decodedURL = null;
        try {
            decodedURL = decoder.decode(wsdlDocumentLocation.toString(), "UTF-8");
        } catch (UnsupportedEncodingException e) {
            System.out.println("Error");
        }
        System.out.println("WSDL Location without URL Escape codes: " + decodedURL);

        // consume the web service with SOAP 1.1 binding
        TopMoviesSoap topMoviesSoap = topMovies.getTopMoviesSoap();
        movieRank = 2;
        String movieAtNumber = topMoviesSoap.getMovieAtNumber(movieRank);
        System.out.println("SOAP 1.1 binding - Movie at number " + movieRank + " is " +
                           movieAtNumber + "\n");

        // consume the web service with SOAP 1.2 binding
        TopMoviesSoap topMoviesSoap12Client = topMovies.getTopMoviesSoap12();
        movieAtNumber = topMoviesSoap12Client.getMovieAtNumber(movieRank);
        System.out.println("SOAP 1.2 binding - Movie at number " + movieRank + " is " +
                           movieAtNumber + "\n");

        // also execute the Top 10 Movie operation
        TopMoviesSoap top10MoviesSoap = topMovies.getTopMoviesSoap();
        ArrayOfString top10MoviesArrayOfString = top10MoviesSoap.getTop10();
        List listOfTop10Movies = top10MoviesArrayOfString.getString();
        Iterator iterator = listOfTop10Movies.iterator();
        int iMovieCount = 0;
        while (iterator.hasNext()) {
            String movieDesc = (String)iterator.next();
            iMovieCount++;
            System.out.println(iMovieCount + ". Top 10 Movie: " + movieDesc);
        }
    }
}

The qualified name logic used in the code above was found by referring to line 67 in TopMovies.java (shown in yellow below).

  public TopMovies()
  {
    super(wsdlLocationURL,
          new QName("http://www.kirupafx.com", "TopMovies"));
  }

The URL is simply the place where the WSDL file is located. If you add this code to your previous TopMovieWS.java you and run it you will notice a slight difference in the display of the wsdlDocumentLocation:

  WSDL Location: http://www.kirupafx.com/WebService/TopMovies.asmx?wsdl
  WSDL Location without URL Escape codes: http://www.kirupafx.com/WebService/TopMovies.asmx?wsdl

The display now reflects the URL assignment you made in your code.

Summary

Once you know how, ADF development to support consuming web services becomes a very simple and straight forward task. The heavy lifting has already been done for you. You only need to provide the parameter values needed to execute your targeted operations and when necessary, make adjustments to allow for code migration from one environment to another.

Additional Resources

Harvard Lecture by Prof. David J. Malan about Web Services, SOAP 1.2, and WSDL 1.1

W3C: From SOAP/1.1 to SOAP Version 1.2 in 9 points

Oracle: Integrating Web Services Into a Fusion Web Application

JDeveloper Tutorial - Developing an ADF Client Using a Web Service Data Control

Oracle: Calling a Web Service from an Application Module

I

Thursday Dec 01, 2011

Welcome to the BPM in practice blog!

Hello and welcome to this space on Oracle blogs dedicated to practical implementation of Oracle's BPM Suite and surrounding technologies.  This space is designed to host dozens of guest bloggers from the ranks of Oracle engineers, field solutions consultants, architects and general developers.  The goal is to disseminate practical guidelines and examples from actual implementations or proof of concept exercises.  Our hope is that it not only promotes greater use but better and more defined use of Oracle's BPM Suite by those who have engaged it's powerful capabilities.

As best practices, design patterns and common use cases emerge or are refined they will be discussed in detail here for the good of the BPM community.  Technical deep dives and short hands-on lab-like posts will also be a regular part of the menu so stay tuned and enjoy.

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