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Robert Koifman
Published © Apache-2.0

Softnet Free: Empowering IoT with TCP/IP Connectivity

Focus on your application's logic, leave the networking issues to Softnet Free.

IntermediateFull instructions provided1 hour283
Softnet Free: Empowering IoT with TCP/IP Connectivity

Things used in this project

Software apps and online services

Software resources and tutorials on GitHub
Demo server with free registrations

Story

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Code

Test service application

Java
The application has a dependency on two libraries: softnet.jar and asncodec.jar.
The library repos are published at:
https://github.com/Softnet-Free/softnet-java
https://github.com/Softnet-Free/asn1codec-java
package serviceTestApp;

import softnet.*;
import softnet.exceptions.*;
import softnet.service.*;
import softnet.asn.*;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketTimeoutException;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.util.ArrayList;
import java.util.TimeZone;
import java.util.UUID;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

class MyTCPAcceptHandler implements TCPAcceptHandler {
    @Override
    public void accept(RequestContext context, SocketChannel socketChannel, ConnectionMode mode) {
        System.out.println(String.format("The TCP connection is established in '%s' mode", mode));
				
        try {
            int buffer_size = 100;
            ByteBuffer buffer = ByteBuffer.allocate(buffer_size);

            while(socketChannel.read(buffer) != -1) {
                if(buffer.position() == buffer_size)
                    break;
            }															
			
            SequenceDecoder asnInput = ASNDecoder.Sequence(buffer.array());									
            System.out.println(String.format("The client message: '%s'", asnInput.UTF8String()));
			
            ASNEncoder asnEncoder = new ASNEncoder();
            SequenceEncoder asnOutput = asnEncoder.Sequence();
            asnOutput.UTF8String("Hello! I'm a service.");
			
            buffer.clear();
            buffer.put(asnEncoder.getEncoding());
            buffer.flip();
			
            socketChannel.write(buffer);
            socketChannel.shutdownOutput();			
        }
        catch(IOException e) {
            System.out.println(String.format("TCP socket error: %s", e.getMessage()));
        }
        catch(AsnException e) {
            System.out.println(String.format("Input data format error: %s", e.getMessage()));
        }	
        finally {
            try {
                socketChannel.close();
            } catch (IOException e) {}
			
            context.serviceEndpoint.tcpAccept(5, new MyTCPAcceptHandler()); /* The tcpAccept method is called again right after closing the current connection */
        }
    }				
}

class MyUDPAcceptHandler implements UDPAcceptHandler {
    @Override
    public void accept(RequestContext context, DatagramSocket datagramSocket, InetSocketAddress remoteSocketAddress, ConnectionMode mode) {
        System.out.println(String.format("The UDP connection established in '%s' mode", mode));
				 
        try {			
            byte[] buffer = new byte[15];  
            DatagramPacket packet = new DatagramPacket(buffer, 15);  
		    
            datagramSocket.setSoTimeout(5000);
            int rawNumber = 0;
            System.out.println("Sequence numbers of received packets:");
            for(int i=0; i<100; i++) {
                packet.setLength(15);
                datagramSocket.receive(packet);  				
                SequenceDecoder asnInput = ASNDecoder.Sequence(packet.getData());
                int number = asnInput.Int32();
                if(number / 10 != rawNumber) {
                    rawNumber = number / 10;
                    System.out.println();
                }
                System.out.print(String.format("%d,\t", number));
            }
            System.out.println();
        }		
        catch(SocketTimeoutException e) {
            System.out.println();
        }
        catch(IOException e) {
            System.out.println(String.format("UDP socket error: %s", e.getMessage()));
        }
        catch(AsnException e) {
            System.out.println(String.format("Input data format error: %s", e.getMessage()));
        }
        finally {
            datagramSocket.close();
            context.serviceEndpoint.udpAccept(10, new MyUDPAcceptHandler());
        }
    }
}

class GetBookListByAuthor implements RPCRequestHandler {	
    private ArrayList<Book> bookList;
	
    public GetBookListByAuthor(ArrayList<Book> bookList) {
        this.bookList = bookList;
    }
	
    @Override
    public int execute(RequestContext context, SequenceDecoder parameters, SequenceEncoder result, SequenceEncoder error) {
        try {
            String author = parameters.UTF8String();
            for (Book book : bookList) {
                if(book.author.equalsIgnoreCase(author)) {
                    SequenceEncoder asnBook = result.Sequence();
                    asnBook.UTF8String(book.title);
                    asnBook.UTF8String(book.author);
                    asnBook.GndTime(book.pubDate);
                    asnBook.Int32(book.pages);
                    asnBook.Real32(book.price);
                }				
            }			
            return 0;
        }
        catch(AsnException e) {
            return -1;
        }
    }
}

class SetTemperature implements RPCRequestHandler {
    @Override
    public int execute(final RequestContext context, SequenceDecoder parameters, SequenceEncoder result, SequenceEncoder error) {
        final UUID taskID = UUID.randomUUID();
		
        try {
            System.out.println(String.format("The 'Set Temperature' task is created. Target temp: %s", parameters.Int32()));		
		
            Thread thread = new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        Thread.sleep(3000);					
                        PrivateEvent notification = new PrivateEvent("TemperatureSet", context.clientId);
                        notification.arguments.OctetString(taskID);
                        context.serviceEndpoint.raiseEvent(notification);					
                    } 
                    catch (InterruptedException e) {}
            }});
            thread.start();
			
            result.OctetString(taskID);
            return 0;
        } 
        catch (AsnException e) {
            e.printStackTrace();
            return -1;
        }
    }
}

class Book {
    public String title;
    public String author;
    public Date pubDate;
    public int pages;
    public float price;
    public Book(String title, String author, Date pubDate, int pages, float price) {
        this.title = title;
        this.author = author;
        this.pubDate = pubDate;
        this.pages = pages;
        this.price = price;
    }
}

public class ServiceApp {	
    public static final String apiVersion = "1.0";	
    private static ServiceEndpoint serviceEndpoint = null;
    private static ArrayList<Book> bookList = new ArrayList<Book>();	
	
    private static void loadBookList() throws ParseException {		
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        TimeZone utcTimeZone = TimeZone.getTimeZone("UTC");
        dateFormat.setTimeZone(utcTimeZone);		
        bookList.add(new Book("The Secrets of Time", "Jane Smith", dateFormat.parse("2018-05-25"), 320, 19.99f));
        bookList.add(new Book("Beyond the Stars", "Jane Smith", dateFormat.parse("2019-02-23"), 288, 15.99f));
        bookList.add(new Book("Echoes of the Past", "John Doe", dateFormat.parse("2021-03-10"), 246, 14.99f));
        bookList.add(new Book("The Mystery of the Hidden Treasure", "Sarah Johnson", dateFormat.parse("2020-11-05"), 368, 17.99f));
        bookList.add(new Book("Lost in the Wilderness", "David Wilson", dateFormat.parse("2019-06-20"), 412, 21.99f));
    }
	
    static void executeEventRaisingDemo() 
    {
        try {			
            ReplacingEvent replacingEvent = new ReplacingEvent("CurrentTemperature");
            replacingEvent.arguments.Int32(1);
            serviceEndpoint.raiseEvent(replacingEvent);
	
            QueueingEvent queueingEvent = new QueueingEvent("CriticalPressure");
            queueingEvent.arguments.Int32(1);
            serviceEndpoint.raiseEvent(queueingEvent);
				
            Thread.sleep(1000);
		
            replacingEvent = new ReplacingEvent("CurrentTemperature");
            replacingEvent.arguments.Int32(2);
            serviceEndpoint.raiseEvent(replacingEvent);
	
            queueingEvent = new QueueingEvent("CriticalPressure");
            queueingEvent.arguments.Int32(2);
            serviceEndpoint.raiseEvent(queueingEvent);
	
            Thread.sleep(1000);
			
            replacingEvent = new ReplacingEvent("CurrentTemperature");
            replacingEvent.arguments.Int32(3);
            serviceEndpoint.raiseEvent(replacingEvent);
			
            queueingEvent = new QueueingEvent("CriticalPressure");
            queueingEvent.arguments.Int32(3);
            serviceEndpoint.raiseEvent(queueingEvent);
        } 
        catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
	
    public static void main(String[] args) {
        // Instead of this account details, specify the details of your service
        String service_uri = "softnet-srv://3cd69efa-70a5-4c4f-9dec-50c47afd5db0@ts.softnet-iot.org";
        String password = "5Ur3pLBXSw";
				
        try {							
            SiteStructure siteStructure = ServiceEndpoint.createStructure(					
                "Test Service",
                "John Doe");
			
            siteStructure.addReplacingEvent("CurrentTemperature");
            siteStructure.addQueueingEvent("CriticalPressure", 600, 3);
            siteStructure.addPrivateEvent("TemperatureSet", TimeSpan.fromMinutes(30));
			            
            ServiceURI serviceURI = new ServiceURI(service_uri);
            serviceEndpoint = ServiceEndpoint.create(siteStructure, apiVersion, serviceURI, password);
            serviceEndpoint.setPersistenceL1();
			
            serviceEndpoint.addEventListener(new ServiceEventAdapter()
            {
                @Override
                public void onConnectivityChanged(ServiceEndpointEvent e)
                {
                    ServiceEndpoint serviceEndpoint = e.getEndpoint();
                    EndpointConnectivity connectivity = serviceEndpoint.getConnectivity();
                    System.out.println(String.format("Endpoint connectivity status: %s, Error: %s, Message: %s", connectivity.status, connectivity.error, connectivity.message));
                }

                @Override
                public void onStatusChanged(ServiceEndpointEvent e)
                {
                    ServiceEndpoint serviceEndpoint = e.getEndpoint();
                    ServiceStatus serviceStatus = serviceEndpoint.getStatus();
                    System.out.println(String.format("Service status: %s", serviceStatus));
                    
                    if(serviceStatus == ServiceStatus.Online) {
                        executeEventRaisingDemo();
                    }
                }
            });
						
            serviceEndpoint.tcpListen(5, null, 2);
            serviceEndpoint.tcpAccept(5, new MyTCPAcceptHandler());			
			
            /*
            serviceEndpoint.udpListen(10, 2);			
            serviceEndpoint.udpAccept(10, new MyUDPAcceptHandler());
            */
            
            /*
            loadBookList();
            serviceEndpoint.registerProcedure("getBookListByAuthor", new GetBookListByAuthor(bookList), 2);
            */
            
            /*
            serviceEndpoint.registerProcedure("setTemperature", new SetTemperature(), 1);            
            */
            
            serviceEndpoint.connect();
            System.in.read(); /* waits until pressing the Enter key */
        }		
        catch(java.lang.Throwable e) {
            e.printStackTrace();
        }
        finally {
            if(serviceEndpoint != null)
                serviceEndpoint.close();
            System.out.println("The service app is closed!");
        }
    }
}

Test client application

Java
The application has a dependency on two libraries: softnet.jar and asncodec.jar.
The library repos are published at:
https://github.com/Softnet-Free/softnet-java
https://github.com/Softnet-Free/asn1codec-java
package clientTestApp;

import softnet.*;
import softnet.asn.*;
import softnet.exceptions.*;
import softnet.client.*;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.TimeZone;

public class ClientApp {
    static ClientSEndpoint clientSEndpoint = null;
	
    public static void executeTcpDemo() 
    {
        clientSEndpoint.tcpConnect(5, new TCPResponseHandler() {
            @Override
            public void onSuccess(ResponseContext context, SocketChannel socketChannel,	ConnectionMode mode) {
                System.out.println(String.format("The TCP connection is established in '%s' mode", mode));

                try {								
                    ASNEncoder asnEncoder = new ASNEncoder();
                    SequenceEncoder asnOutput = asnEncoder.Sequence();
                    asnOutput.UTF8String("Hello! I'm a client.");
					
                    int buffer_size = 100;
                    ByteBuffer buffer = ByteBuffer.allocate(buffer_size);
                    buffer.put(asnEncoder.getEncoding());
                    buffer.flip();
					
                    socketChannel.write(buffer);
                    socketChannel.shutdownOutput();
					
                    System.out.println("The hello message is sent to the service!");

                    buffer.clear();
                    while(socketChannel.read(buffer) != -1) {
                        if(buffer.position() == buffer_size)
                            break;
                    }							
					
                    buffer.flip();
                    SequenceDecoder asnInput = ASNDecoder.Sequence(buffer.array());									
                    System.out.println(String.format("The service's response: '%s'", asnInput.UTF8String()));
						
                    socketChannel.close();
                }
                catch(IOException e) {
                    System.out.println(String.format("TCP socket error: %s", e.getMessage()));
                }
                catch(AsnException e) {
                    System.out.println(String.format("Input data format error: %s", e.getMessage()));
                }	
                finally {
                    try {
                        socketChannel.close();
                    } catch (IOException e) {}
                }
            }

            @Override
            public void onError(ResponseContext context, SoftnetException exception) {
                System.out.println(String.format("The TCP connection request failed with an error: %s", exception.getMessage()));	
            }
        }, null);
    }
	
    public static void executeUdpDemo()
    {
        clientSEndpoint.udpConnect(10, new UDPResponseHandler() {
            @Override
            public void onSuccess(ResponseContext context, DatagramSocket datagramSocket, InetSocketAddress remoteSocketAddress, ConnectionMode mode) 
            {
                System.out.println(String.format("The UDP connection is established in '%s' mode", mode));
                try {			
                    int rawNumber = 0;
                    System.out.println("Sequence numbers of sent packets:");
                    for(int i=0; i<100; i++) {
                        ASNEncoder asnEncoder = new ASNEncoder();
                        asnEncoder.Sequence().Int32(i);
                        byte[] buffer = asnEncoder.getEncoding();
                        DatagramPacket packet = new DatagramPacket(buffer, buffer.length, remoteSocketAddress);
                        datagramSocket.send(packet);  				
                        if(i / 10 != rawNumber) {
                            rawNumber = i / 10;
                            System.out.println();
                        }
                        System.out.print(String.format("%d,\t", i));									
                        Thread.sleep(200);
                    }
                    System.out.println();
                }
                catch(IOException e) {
                    System.out.println(String.format("UDP socket error: %s", e.getMessage()));
                }
                catch(InterruptedException e) { }
                finally {
                    datagramSocket.close();
                }
            }

            @Override
            public void onError(ResponseContext context, SoftnetException exception) {
                System.out.println(String.format("The UDP connection request failed with an error: %s", exception.getMessage()));	
            }			
        });
    }
	
    public static void executeRpcDemo()
    {		
        final String author = "Jane Smith";
		
        RemoteProcedure remoteProcedure = new RemoteProcedure("getBookListByAuthor");		
        remoteProcedure.arguments.UTF8String(author);
		
        clientSEndpoint.call(remoteProcedure, new RPCResponseHandler() {
            @Override
            public void onSuccess(ResponseContext context, SequenceDecoder result)
            {
                System.out.println();
                try {
                    if(result.count() > 0) {
                        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
                        TimeZone utcTimeZone = TimeZone.getTimeZone("UTC");
                        dateFormat.setTimeZone(utcTimeZone);
						
                        System.out.println(String.format("Books found by %s:", author));
                        System.out.println();
						
                        while(result.hasNext()) {
                            SequenceDecoder asnBook = result.Sequence();
                            String title = asnBook.UTF8String();
                            asnBook.skip();
                            java.util.Date pubDate = asnBook.GndTimeToDate();
                            int pages = asnBook.Int32();
                            float price = asnBook.Real32();
							
                            System.out.println(String.format("Title: %s", title));
                            System.out.println(String.format("Pub.Date: %s", dateFormat.format(pubDate)));
                            System.out.println(String.format("Pages: %d", pages));
                            System.out.println(String.format("Price: %f", price));
                            System.out.println();
                        }
                    }
                    else {
                        System.out.println("No books found for your request");
                    }
                }
                catch(AsnException e) {
                    System.out.println("The respone from the service has an invalid format");
                }
            }

            @Override
            public void onError(ResponseContext context, int errorCode, SequenceDecoder error) {
                System.out.println(String.format("The service returned an error code: %d", errorCode));
            }

            @Override
            public void onError(ResponseContext context, SoftnetException exception) {
                System.out.println(String.format("The RPC request failed with an error: %s", exception.getMessage()));
            }
        });
    }
	
    public static void executeEventReceivingDemo()
    {
        clientSEndpoint.subscribeToREvent("CurrentTemperature", new RemoteEventListener() {
            @Override
            public void accept(ClientEndpoint clientEndpoint, RemoteEvent remoteEvent) {
                try {
                    System.out.println(String.format("Received event: '%s'. Event number: %d. Age: %d seconds", 
                    remoteEvent.name, remoteEvent.arguments.Int32(), remoteEvent.age));
                }
                catch(AsnException e) {
                    System.out.println("Data format error");
                }
            }

            @Override
            public void acceptError(ClientEndpoint clientEndpoint, SoftnetException exception) {
                System.out.println(String.format("Event subscription error: %s", exception.getMessage()));
            }
        });
		
        clientSEndpoint.subscribeToQEvent("CriticalPressure", new RemoteEventListener() {
            @Override
            public void accept(ClientEndpoint clientEndpoint, RemoteEvent remoteEvent) {
                try {
                    System.out.println(String.format("Received event: '%s'. Event number: %d. Age: %d seconds.", 
                    remoteEvent.name, remoteEvent.arguments.Int32(), remoteEvent.age));
                }
                catch(AsnException e) {
                    System.out.println("Data format error");
                }
            }

            @Override
            public void acceptError(ClientEndpoint clientEndpoint, SoftnetException exception) {
                System.out.println(String.format("Event subscription error: %s", exception.getMessage()));
            }
    	});		
    }
	
    static void subscribeToTemperatureSet()
    {
        clientSEndpoint.subscribeToPEvent("TemperatureSet", new RemoteEventListener() {
            @Override
            public void accept(ClientEndpoint clientEndpoint, RemoteEvent remoteEvent) {
                try {
                    /* Print the task ID and current time */
                    SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm:ss");
                    System.out.println(String.format("The 'Set Temperature' task completed. Task ID: %s. Time: %s", 
                    remoteEvent.arguments.OctetStringToUUID().toString(), timeFormat.format(new Date())));
                }
                catch(AsnException e) {
                    System.out.println("Data format error");
                }
            }

            @Override
            public void acceptError(ClientEndpoint clientEndpoint, SoftnetException exception) {
                System.out.println(String.format("Event subscription error: %s", exception.getMessage()));
            }
        });		
    }
	
    public static void executeAsyncCommDemo()
    {
        RemoteProcedure remoteProcedure = new RemoteProcedure("setTemperature");
        /* set the temperature to 30 degrees Celsius */ 
        remoteProcedure.arguments.Int32(30);
		
        clientSEndpoint.call(remoteProcedure, new RPCResponseHandler() {
            @Override
            public void onSuccess(ResponseContext context, SequenceDecoder result) {
                /* Print the task ID and current time */
                try {
                    SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm:ss");
                    System.out.println(String.format("The 'Set Temperature' task created. Task ID: %s. Time: %s", 
                        result.OctetStringToUUID().toString(), timeFormat.format(new Date())));
                } 
                catch (AsnException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onError(ResponseContext context, int errorCode, SequenceDecoder error) {
                System.out.println(String.format("The service returned an error code: %d", errorCode));
            }

            @Override
            public void onError(ResponseContext context, SoftnetException exception) {
                System.out.println(String.format("The RPC request failed with an error: %s", exception.getMessage()));
            }
        });
    }
		
    public static void main(String[] args) {
        // Instead of this account details, specify the details of your client
        String client_uri = "softnet-s://hj1syian@ts.softnet-iot.org";
        String password = "ZW81jj8NQd";
		
        try {
            ClientURI clientURI = new ClientURI(client_uri);
	
            clientSEndpoint = ClientSEndpoint.create(
                "Test Service", 
                "John Doe",
                clientURI, 
                password,
                "Test Client");
			
            clientSEndpoint.addEventListener(new ClientEventAdapter() {
                @Override
                public void onConnectivityChanged(ClientEndpointEvent e) {
                    ClientEndpoint client = e.getEndpoint();
                    EndpointConnectivity connectivity = client.getConnectivity();
                    System.out.println(String.format("Endpoint connectivity status: %s, Error: %s, Message: %s", connectivity.status, connectivity.error, connectivity.message));
                }

                @Override
                public void onStatusChanged(ClientEndpointEvent e) {
                    ClientEndpoint client = e.getEndpoint();
                    System.out.println(String.format("Client status: %s", client.getStatus()));					
                }
				
                @Override
                public void onServiceOnline(RemoteServiceEvent e) {
                    System.out.println(String.format("Remote service online! Hostname: %s, API version: %s", e.service.getHostname(), e.service.getVersion()));
                    
                    executeTcpDemo();
                    //executeUdpDemo();
                    //executeRpcDemo();
                    //executeAsyncCommDemo();
                }		
            });
            
            //clientSEndpoint.setPersistenceL2();
            //executeEventReceivingDemo();
            
            // subscribeToTemperatureSet();
                        
            clientSEndpoint.connect();
            System.in.read(); /* waits until pressing the Enter key */
        }	
        catch(java.lang.Throwable e) {
            e.printStackTrace();
        }
        finally	{
            if(clientSEndpoint != null)
                clientSEndpoint.close();
            System.out.println("The client app is closed!");
        }
    }		
}

Credits

Robert Koifman
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