Creating data provider extensions

The following Java code shows a data provider extension. The java.naming and java.sql must be added to the extension project bundle manifest. The example uses the customer ID from the request to query an SQL database. It assumes that the server configuration includes a data source for the database that is bound to the JNDI name "jdbc/CustomerProviderDB".

package com.example.extensions.provider;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;

import com.ibm.ia.common.ComponentException;
import com.ibm.ia.extension.DataProvider;
import com.ibm.ia.extension.annotations.DataProviderDescriptor;

import com.example.providers.CustomerProvider;
import com.example.providers.CustomerProviderRequest;
import com.example.providers.CustomerProviderResponse;
import com.example.providers.ConceptFactory;

@DataProviderDescriptor(dataProvider = CustomerProvider.class,
                        responseCacheTimeout = 300)
public class CustomerDataProvider
        extends DataProvider<CustomerProviderRequest, CustomerProviderResponse>
        implements CustomerProvider {
    
    // Data source JNDI name
    private static final String DATA_SOURCE_JNDI = "jdbc/CustomerProviderDB";

    // Select SQL from DB
    private final static String SELECT_CUSTOMER =
            "SELECT FIRST_NAME, LAST_NAME FROM CUSTOMER WHERE CUSTOMER_ID = ?";
    
    // Cached reference to the DataSource
    private ThreadLocal<DataSource> dataSource = new 
				ThreadLocal<DataSource>();

    @Override
    public CustomerProviderResponse processRequest(CustomerProviderRequest request)
            throws ComponentException {
        
        Connection conn = null;
        try {
            // Lookup the DataSource for the database if not already cached
            if (dataSource.get() == null) {
                Context initialContext = new InitialContext();
                dataSource.set(
                        (javax.sql.DataSource) initialContext
                            .lookup(DATA_SOURCE_JNDI));
            }

            // Make a connection to the database
            conn = dataSource.get().getConnection();

            // Prepare the statement to retrieve the data from the database
            PreparedStatement prepSt = conn.prepareStatement(SELECT_CUSTOMER);

            // Get customer ID from the request
            String customerId = request.getCustomerId();
            prepSt.setString(1, customerId);

            // Execute the query
            ResultSet resultSet = prepSt.executeQuery();

            // Read the first row from the result set
            if (resultSet.next()) {
                
                // Create a response object
                ConceptFactory factory = getConceptFactory(ConceptFactory.class);
                CustomerProviderResponse response =
                        factory.createCustomerProviderResponse();
                
                // Set the response fields
                response.setFirstName(resultSet.getString(1));
                response.setLastName(resultSet.getString(2));
                
                // Return the response
                return response;
                
            } else {
                throw new ComponentException(
                        "CustomerDataProvider: No result for " + customerId);
            }

        } catch (NamingException | SQLException e) {    
            throw new ComponentException(
                    "CustomerDataProvider: " + e.getLocalizedMessage(), e);
        } finally {
            // Always try close the connection
            if (conn != null) {
                try {
                    conn.close();
                } catch (SQLException e2) {
                    // Assume it's closed
                }
            }
        }
    }
}

The previous example also assumes that the following data is defined in the BMD and has the package name com.example.providers.

The names that you use to reference request and response data in the Java implementation are mapped directly to the definitions in the BMD. For example, the following definition returns a given name ("first name") and a surname ("last name"):

a CustomerProvider is a data provider ,
        accepts a customer id,
        returns a first name, a last name.

The implementation uses these names in the response fields:

response.setFirstName(resultSet.getString(1));
response.setLastName(resultSet.getString(2));

Input values can be derived from values in the entity, and output values can be derived from both the entity and the results of the data provider execution.