Oracle Tips

Integrating Web Services With Oracle BI Beans

If you've read any of my previous articles on Qubeview, our new Oracle 9i OLAP analysis and reporting suite, you'll know that it was developed using Oracle JDeveloper 9i, Oracle Business Intelligence Beans and Java J2SE 1.4. Because of the technology we used, it's been relatively easy to extend Qubeview's functionality and an interesting new area we've been developing is integration with web services.

The term 'web services' describes a standardized way of integrating Web-based applications using the XML, SOAP, WSDL and UDDI open standards over an Internet protocol. XML is used to tag the data, SOAP is used to transfer the data, WSDL is used for describing the services available and UDDI is used for listing what services are available. Used primarily as a means for businesses to communicate with each other and with clients, Web services allow organizations to communicate data without intimate knowledge of each other's IT systems behind the firewall. Web services allow different applications from different sources to communicate with each other without time-consuming custom coding, and because all communication is in XML, Web services are not tied to any one operating system or programming language. For example, Java can talk with Perl, Windows applications can talk with UNIX applications.

This exercise used JDeveloper 9i to access a freely available Currency Conversion web service from www.xmethods.net. The generated stub is then deployed in a Qubeview Plug-In that provides a data table with the currently selected dataview translated into the corresponding currency.

Building the Currency Conversion Stub

Oracle9i JDeveloper makes creating and consuming Web services a point-and-click exercise. First find the Currency Exchange Service located under the UDDI Registry node.

Next, establish the relevant Service Name (in this case getRate).

The wizard then generates the appropriate XmethodsCurrencyExchangeStub class. You can test the generated class by adding a line to the class's Main method

//main class
  public static void main(String[] args)
  {
    try
    {
      XMethodsCurrencyExchangeStub stub = new       
                                  XMethodsCurrencyExchangeStub();
      // Returns the current conversion rate between the US & UK
      System.out.println( stub.getRate("usa", "united kingdom") );
    }
    catch(Exception ex)
    {
      ex.printStackTrace();
    }

  }

The getRate method takes two string arguments and returns a number of type float. The two arguments represent the to and from countries ( a complete list of countries is available from www.xmethods.com. The returned value represents the current exchange rate.

Using the new Conversion class In Qubeview

Oracle's BI Bean technology provides a set of Java Beans that allow you to build reporting and analysis tools on Oracle's OLAP technology. The Qubeview suits of products is available in beta forma at www.qubeview.com and provides an implementation of the technology.

One facet of Qubeview is the ability to build customized plug-ins for Qubeview Desktop that allow the analysis layer to be augmented and moulded to the user. By following the framework of the Qubeview SDK, a plug-in can be developed that will show the user's presentation alongside the corresponding converted values.

The following code shows how to loop over and return the data values from a BI Beans crosstab. The values are then converted and added to a vector which can be used to display the new values in a JTable.

//create exchange class
XMethodsCurrencyExchangeStub xmCurrency = new XMethodsCurrencyExchangeStub();

//get selected currency
String s2 = xmCurrency.getRate("UK", currency).toString();
double d2 = Double.parseDouble(s2);;

//get row & data info
for(int row=0;row < da.getEdgeExtent(DataDirector.ROW_EDGE);row++)
{

//use a temporary vector
Vector tmp = new Vector();

//retrieve header values from the dataview
for(int layer=0;layer<layerCount;layer++)
tmp.add( getHeaderMembers(da,DataDirector.ROW_EDGE, row, layer ) );

//data
for(int col=0;col<da.getEdgeExtent(DataDirector.COLUMN_EDGE);col++)
{
//get data value
String s1 = da.getValue(row,col,DataMap.DATA_UNFORMATTED).toString();

//convert string to double
double d1 = Double.parseDouble(s1);

//get converted value
double val = d1 * d2;
 

//add value to vector
tmp.add(Double.toString(val) ) ;

}

data.add(tmp);

}

When deployed, the end-user can bring up the Currency Conversion table by clicking the corresponding icon on the Qubeview toolbar and selecting the desired currency option from the menu system.

For many businesses and developers, the power of web services will be the ability to hurdle cross-platform barriers and to integrate the inherent, data related power of individual business applications. In this particular example, the gain is simply one of productivity afforded by JDeveloper. Embedding currency conversion abilities into systems is not new- being able to do this in a few lines of code is.

Publicly available web services include currency conversions such as this, SMS, messaging and fax modules that allow developers to aggregate services to provide highly available and feature rich applications. The next generation of web services will see modules of business logic made available for the exchange of information, workflow and decision making. For Business and Data Warehousing this means making all your reports available as published Web services. This not only allows the business to view and interrogate reports on any device from laptop to PDA to mobile phone - it also provides the ability for you to