demo/ggsn/model/GGSN.java

/**
 * GGSN.java
 * 
 * Core logic of GGSN
 **/

class PDPcontext {
	public int nsapi;
	public String imsi;
	//public int uplinkDataTeid;
	//public int downlinkDataTeid;
}

class GGSN extends StateMachine
{
	private Charging charging;
	private CLI cli;
	private NodeConfiguration nodeConfiguration;
	private int uplinkData;
	private int downlinkData;
	private PDPcontext pdpContext;
	
	public GGSN(Charging charging, CLI cli, NodeConfiguration nodeConfiguration)
	{
		this.charging = charging;
		this.cli = cli;
		this.nodeConfiguration = nodeConfiguration;
		uplinkData = 0;
		downlinkData = 0;
		
		// NB: In our simplified view (for now) we only handle a single context,
		// but the model can be easily enhanced to handle multiple contexts.
		pdpContext = new PDPcontext();
	}

	private void createPDPcontext(CreatePDPcontext request)
	{
		// Control incoming data values - Qtronic specific to
		// control test data generated for test suite.
		
		/**
		 * Snippet of how it may look with a more or less
		 * one-to-one mapping between model and GTPC data:
		require request.imsi_digits != null;
		require request.imsi_digits.length == IMSI_OCTETS;
		for (int i = 0; i < request.imsi_digits.length; i++)
			require request.imsi_digits[i] == imsi1[i];
		
		require request.teidDataI != null;
		require request.teidDataI.length == TEID_OCTETS;
		for (int i = 0; i < request.teidDataI.length; i++)
			require request.teidDataI[i] == teid1[i];
		**/
		
		// Our simplified view on data
		require request.imsi == "240001111231411";
		//require request.downlinkDataTeid == 1;
		require request.nsapi == 5;
		require	request.apn == "apn1.com";
		
		// Handle request - in our simplified view we handle
		// only one single PDP context. The state machine is
		// laid out so that a createPDPcontext will always be
		// done before any update, delete, or sending of payload.
		pdpContext.imsi = request.imsi;
		pdpContext.nsapi = request.nsapi;
		//pdpContext.downlinkDataTeid = request.downlinkDataTeid;

		//pdpContext.uplinkDataTeid = 3;
	}
	
	private void sendRadiusAuthRequest()
	{
		RadiusAccessRequest request;
		GiRadiusOut.send(request);
		requirement "Radius/Authentication/Send Access Request";
	}

	private void confirmCreatePDPcontext()
	{
		// Send response back
		CreatePDPresponse  response;
		response.causevalue = REQUEST_ACCEPTED;
		//response.uplinkDataTeid = pdpContext.uplinkDataTeid;
		GnOut.send(response);
		requirement "PDP context/Confirm successful creation";
	}
	
	private void updatePDPcontext(UpdatePDPcontext request)
	{
		// TODO: what to do with update??
		// Currently it seems TTCN libraries take care of both update
		// details and receiving the correct response, as well as doing
		// the pass/fail verdict.
		// We can have an "empty" update request in the model to just
		// trigger a call to the existing library update function, or
		// we can add more detail to the model and NOT use the existing
		// library update function.
		
		// 100114: we can handle the response to the update on the
		// model level for understanding, but regard it as a NOP on
		// the QtronicHarness level.
		
		
		require request.nsapi == pdpContext.nsapi;
		//require request.downlinkDataTeid == pdpContext.downlinkDataTeid;
		
		// Send response
		UpdatePDPresponse response;
		
		response.causevalue = REQUEST_ACCEPTED;
		GnOut.send(response);
		requirement "PDP context/Confirm successful update";
	}

	private void deletePDPcontext(DeletePDPcontext request)
	{
		// Take care of request parameters
		require request.nsapi == pdpContext.nsapi;
		
		// Send response back
		DeletePDPresponse  response;
		response.causevalue = REQUEST_ACCEPTED;
		GnOut.send(response);
		requirement "PDP context/Confirm successful deletion";
	}

	// forwardGPDUtoGi() - when a GPDU is recieved on the Gn interface
	// the payload should be forwarded to the Gi interface
	private void forwardGPDUtoGi(GPDU pdu)
	{
		//require pdu.header.teid == pdpContext.uplinkDataTeid;
		
		// TODO: how much detail on model level?
		uplinkData++;
		charging.payload(pdu);
		
		// Forward payload
		UDPpdu udpPdu;
		udpPdu.data = pdu.data;
		GiOut.send(udpPdu);
	}

	// forwardUdpPduToGn() - when a UDP pdu is recieved on the Gi interface
	// it should be forwarded/tunneled to the Gn interface
	private void forwardUdpPduToGn(UDPpdu udpPdu)
	{
		// Forward/tunnel payload
		GPDU pdu;
		
		//pdu.header.teid = pdpContext.downlinkDataTeid;
		pdu.data = udpPdu.data;
		GnOut.send(pdu);
		
		// TODO: how much detail on model level?
		downlinkData++;
		charging.payload(pdu);
	}
}

void main()
{
	NodeConfiguration nodeConfiguration = new NodeConfiguration();	
	Charging charging = new Charging();
	CLI cli = new CLI(nodeConfiguration);
	
	GGSN ggsn = new GGSN(charging, cli, nodeConfiguration);
	ggsn.start("GGSN");
}