TelnetTransportFactory.java

package org.opennaas.extensions.transports.telnet;

import org.opennaas.core.resources.protocol.ProtocolSessionContext;
import org.opennaas.core.resources.transport.ITransport;
import org.opennaas.core.resources.transport.ITransportConstants;
import org.opennaas.core.resources.transport.ITransportFactory;
import org.opennaas.core.resources.transport.TransportException;

/**
 * Provides a factory method to create TCP transport instances. The following properties need to be present in the capability descriptor: transport =
 * TCP transport.host = <ip_address or hostname> transport.port = <port number>
 */
public class TelnetTransportFactory implements ITransportFactory {

	public ITransport createTransportInstance(ProtocolSessionContext protocolSessionContext) throws TransportException {
		String transportId = null;
		try {
			transportId = (String) protocolSessionContext.getSessionParameters().get(ITransportConstants.TRANSPORT);
		} catch (ClassCastException ex) {
			throw new TransportException(ex.getMessage());
		}

		if (transportId == null) {
			throw new TransportException("No transport id has been specified at the resource configuration");
		} else if (transportId.equals(TelnetTransport.TELNET)) {
			return createTelnetTransport(protocolSessionContext);
		} else {
			throw new TransportException("Transport " + transportId + " cannot be created by this factory");
		}
	}

	private ITransport createTelnetTransport(ProtocolSessionContext protocolSessionContext) throws TransportException {
		String host = getAndValidateProperty(protocolSessionContext, ITransportConstants.TRANSPORT_HOST);
		String port = null;
		try {
			port = getAndValidateProperty(protocolSessionContext, ITransportConstants.TRANSPORT_PORT);
		} catch (TransportException ex) {
			port = "23";
		}

		return new TelnetTransport(host, port);
	}

	private String getAndValidateProperty(ProtocolSessionContext protocolSessionContext, String propertyName) throws TransportException {
		String property = null;
		try {
			property = (String) protocolSessionContext.getSessionParameters().get(propertyName);
		} catch (ClassCastException ex) {
			throw new TransportException(ex.getMessage());
		}

		if (property == null) {
			throw new TransportException("Could not create an instance of transport. Property " + propertyName + " has not been specified");
		}

		return property;
	}
}