hApplication.m

classdef hApplication < handle
%hApplication Implement application layer functionality
%   APP = hApplication creates an object for application layer. It is a
%   container of different application traffic generators and application
%   receiver to terminate the packets. It is responsible for invoking
%   different traffic model objects for generating packets. It also
%   maintains the application level statistics.
%
%   APP = hApplication(Name, Value) creates an object for application layer
%   with the specified property Name set to the specified Value. You can
%   specify additional name-value pair arguments in any order as (Name1,
%   Value1, ..., NameN, ValueN).
%
%   hApplication properties:
%
%   NodeID           - Node identifier
%   MaxApplications  - Maximum number of applications that can be
%                      added
%
%   hApplication methods:
%
%   run            - Run application layer to generate packets
%   addApplication - Add application traffic model to application layer
%   receivePacket  - Receive and terminate packet

%   Copyright 2020-2021 The MathWorks, Inc.

%#codegen

properties
    % NodeID Node identifier
    NodeID {mustBeInteger, mustBeGreaterThanOrEqual(NodeID, 0)}= 0;

    % MaxApplications Maximum number of applications that can be added
    MaxApplications {mustBeInteger, mustBeGreaterThanOrEqual(MaxApplications, 0)} = 16;
end

properties(SetAccess = private, Hidden)
    % Applications Context of the applications added to the application
    % layer. This is a cell array of size N-by-1 where N is the maximum
    % number of applications that can be added to the application layer.
    % Each cell in the cell array is a structure with these fields:
    %   App            - Handle object for application traffic pattern
    %                    such as networkTrafficOnOff, networkTrafficFTP,
    %                    networkTrafficVoIP, networkTrafficVideoConference.
    %   TimeLeft       - Time left for the generation of next packet from 
    %                    the associated traffic pattern object.
    %   DestinationID  - Destination node identifier of the application.
    %   PriorityID     - Traffic priority identifier.
    Applications
    
    % ApplicationsCount Count of applications that has been added
    ApplicationsCount = 0;

    % NextInvokeTime Next invoke time
    %   Next invoke time for application packet generation
    NextInvokeTime = 0;
end

properties(Constant)
    % ApplicationPacket Format of the packet that will be sent to lower
    % layer
    ApplicationPacket = struct('MSDULength', 0, ...
        'PriorityID', 0, ... % Traffic priority
        'DestinationID', 0, ... % Immediate destination node ID
        'Timestamp', 0, ... % Packet generation time stamp at origin
        'PacketID', 0, ... % Packet identifier assigned at origin
        'Data', zeros(2304, 1, 'uint8'));
end

methods
    function obj = hApplication(varargin)
        % Name-value pairs
        for idx = 1:2:nargin
            obj.(varargin{idx}) = varargin{idx+1};
        end
        
        obj.Applications = cell(obj.MaxApplications, 1);
    end
    
    function nextInvokeTime = run(obj, elapsedTime, txPacketFcn)
        %run Run application layer to generate packets
        %
        % NEXTINVOKETIME = run(OBJ, ELAPSEDTIME, TXPACKETFCN) runs the
        % configured traffic models in the application layer to generate
        % packet, if time elapsed since last call is sufficient to generate
        % a packet. Otherwise, returns remaining wait time for generating
        % the packet.
        %
        % NEXTINVOKETIME - Time remaining for the next packet generation
        % (in microseconds).
        %
        % ELAPSEDTIME - Time elapsed since last run (in microseconds).
        %
        % TXPACKETFCN - Function handle for sending data to the lower
        % layer.
        
        minNextInvokeTime = inf;
        if elapsedTime < obj.NextInvokeTime
            % Next packet generatation time has not yet arrived. Reduce the
            % invoke times of traffic generators as per the elapsed time
            % and set the new invoke time to the minimum of the invoke
            % times of the applications
            for idx=1:obj.ApplicationsCount
                obj.Applications{idx}.TimeLeft = obj.Applications{idx}.TimeLeft - elapsedTime;
                if obj.Applications{idx}.TimeLeft < minNextInvokeTime
                    minNextInvokeTime = obj.Applications{idx}.TimeLeft;
                end
            end
            obj.NextInvokeTime = minNextInvokeTime;
        else
            % Time to generate the next packet
            for idx=1:obj.ApplicationsCount
                obj.Applications{idx}.TimeLeft = obj.Applications{idx}.TimeLeft - elapsedTime;
                if obj.Applications{idx}.TimeLeft <= 0
                    % Generate data from the application traffic pattern
                    [packetInterval, packetSize, packetData] = generate(obj.Applications{idx}.App);
                    % Put data and its associated context in the packet
                    % structure
                    packet = obj.ApplicationPacket;
                    packet.Data = packetData;
                    packet.MSDULength = packetSize;
                    packet.PriorityID = obj.Applications{idx}.PriorityID;
                    packet.DestinationID = obj.Applications{idx}.DestinationID;

                    obj.Applications{idx}.TimeLeft = packetInterval * 1000; % In microseconds

                    % Send packet to lower layer
                    txPacketFcn(packet, obj.Applications{idx}.TimeLeft);
                end

                % Find the minimum of next invoke times
                if obj.Applications{idx}.TimeLeft < minNextInvokeTime
                    minNextInvokeTime = obj.Applications{idx}.TimeLeft;
                end
            end
            obj.NextInvokeTime = minNextInvokeTime;
        end
        nextInvokeTime = obj.NextInvokeTime;
    end
    
    function addApplication(obj, app, metaData)
        %addApplication Add application traffic model to application layer
        %
        % addApplication(OBJ, APP, METADATA) adds the application traffic
        % model to application layer.
        %
        % APP is a handle object that generates the application traffic. It
        % should be one of networkTrafficOnOff, networkTrafficVoIP,
        % networkTrafficFTP, or networkTrafficVideoConference.
        %
        % METADATA is a structure and contains following fields.
        %   DestinationNode - Destination node id.
        %   PriorityID      - Traffic priority identifier to differentiate
        %                     priorities of different traffic at lower
        %                     layers.
        
        if obj.ApplicationsCount == obj.MaxApplications
            error('hApplication:MaxAppLimit', ...
                'Number of applications that can be configured has reached the limit %d', ...
                obj.MaxApplications);
        end
        
        obj.ApplicationsCount = obj.ApplicationsCount + 1;
        appIdx = obj.ApplicationsCount;
        % Fill the application context
        obj.Applications{appIdx}.App = app;
        obj.Applications{appIdx}.TimeLeft = 0;
        obj.Applications{appIdx}.DestinationID = metaData.DestinationNode;
        obj.Applications{appIdx}.PriorityID = metaData.PriorityID;
    end
    
    function receivePacket(~, ~, ~)
        %receivePacket Receive and terminate packet
    end
end
end