Database Integration (Using External Connection)

Difingo operates based on external connection information, such as databases, entered in mashup.msh. However, depending on the nature of the project, there may be cases where a connection created by the WAS or web application must be used. This chapter describes how to apply such a method in those cases.

Structure

To use an external database connection in Difingo, you need to implement the "ExternalDataSourceProvider" interface and pass it as an argument to XIServiceController.

Internally, Difingo calls the "ExternalDataSourceProvider.getDataSource" method with the name defined in mashup.msh as an argument. If the result of this call is an instance of "javax.sql.DataSource", Difingo will invoke its "getConnection" method and use the returned "java.sql.Connection".

DB Connection Usage Priority

The priority for using a DB Connection is as follows:


+ 
# ExternalDataSourceProvider
+ 
# mashup.msh
+ 


In general, if ExternalDataSourceProvider is not defined, the connection information specified in mashup.msh is used.

The transaction policy remains the same regardless of whether the connection is defined via ExternalDataSourceProvider or mashup.msh.

source code

The code for setting ExternalDataSource in XIServiceController is as follows.

XIServiceController x = new XIServiceController();
		
MyExternalDataSourceProvider exp = new MyExternalDataSourceProvider();

DataSource ds1;
DataSource ds2;
try
{	
	InitialContext initialContext = new InitialContext();
	ds1 = (DataSource) initialContext.lookup("java:comp/env/DS_DEVPACK");
    ds2 = (DataSource) initialContext.lookup("java:comp/env/DS_DEVPACK_MARIA");			
	exp.setDS_DEVPACK(ds1);
	exp.setDS_DEVPACK_MARIA(ds2);
	x.setExternalDataSourceProvider(exp);
} catch (NamingException e) {
			
}

The above code should be declared in an initialization method for a Servlet, such as the init method, or in the case of Spring, within an area that executes once at startup, such as ApplicationContextAware.

The following code is an implementation example of ExternalDataSourceProvider.

If the data source names defined in mashup.msh are "DS_DEVPACK" and "DS_DEVPACK_MARIA", the getDataSource() method in ExternalDataSourceProvider is implemented to return the corresponding javax.sql.DataSource based on the defined names.

class MyExternalDataSourceProvider implements ExternalDataSourceProvider
{

	
		DataSource DS_DEVPACK;
		
		DataSource DS_DEVPACK_MARIA;
		
		public DataSource getDS_DEVPACK() {
			return DS_DEVPACK;
		}
		
		public void setDS_DEVPACK(DataSource dS_DEVPACK) {
			DS_DEVPACK = dS_DEVPACK;
		}
		
		public void setDS_DEVPACK_MARIA(DataSource DS_DEVPACK_MARIA) {
			DS_DEVPACK_MARIA = DS_DEVPACK_MARIA;
		}
		
		@Override
		public Object getDataSource(String arg0) {
			
			
			if(arg0.equals("DS_DEVPACK")) {
				return DS_DEVPACK;
			} 
			else if(arg0.equals("DS_DEVPACK_MARIA")) {
				return DS_DEVPACK_MARIA;
			}
			else
			{
				return null;
			}
			
			
		}
		
}