Producing a simple and robust protocol allows your system to implemented in range of different manners, using various different technologies. Consider the number of different web browsers and servers on offer. Let us develop a very simple chat protocol. First of all, each message transmitted will have a header. Our header will comprise of a 4 character message type code and an integer detailing the number of bytes or characters in our message body. The header will be split from the message body by a return character.
Simple Chat Application(Client-Server) in Android
Returned by the server if the client's authorization request is successful. Sent by the server to indicate that there has been a error authorization failed etc and the client will be disconnected. Sent by the server to indicate a warning, such as the client has sent an invalid message. Such a protocol may seem a little excessive especially in our example but it provides a robust programmers interface and a solid platform for future extensions.
For example, we may wish to include file sharing, making the message size an important piece of information. We will implement our chat server protocol using LiveCode. Our server will function in a very similar manner to our broadcast server. This time, however, once a client is connected, the will go on the pending list, awaiting authorization. Authorization will be a simple tasks of ensuring the client has a uniques user name. Once authorized, the client will be moved on to the authorized list and be allowed to send and receive messages.
The main handler of interest will be the message received callback. Here, the server must parse the header and if required read the message body. To do this, we will use the "read from for" command, reading the number of characters defined in the message header. Though we could easily develop our client in LiveCode, in this final part of the lesson we will consider Java.
Doing so demonstrates how we can use sockets for inter-application communication and the importance of using a clearly defined protocol. I won't go into to too much detail here, but will note a few key points. Since we will be working with sockets, we'll need to import the Java "net" library. Also, since we will be using input and output streams, we'll need the "io" library.
In order to open a socket, we create a new object of type Socket: Once we have opened our socket, we can then fetch the input and output streams. These streams allow us to read and write data to and from the server. Java provides various wrappers allowing the data read and written to be formatted in various ways: At the simplest level, you may wish to read and write directly to the socket, handling data a byte at a time. Alternatively, you may wish to operate at a higher level, sending data as unicode text. In our example we use a BufferedReader for the input stream as it allows us to read a single line of text - our message header - as well as a fixed block of text - our message body.
Notice that after we write to the output stream, we call the flush method. This ensures that the data is sent immediately, rather than queued up in the stream. Once the client is connected to the server, we start a new thread that listens to the input stream for data from the server. We do this by making our client class implement the Runnable interface, then filling out the run method of our client. The run method will be called once the new thread is created and must continually listen to the input stream whilst the client is connected.
All the main functionality will be wrapped up in a single Client class. Our Client class will have three main public methods available to the user: Note the use of an enumerative type, used to store the clients current connection status, and the ClientUI type used to handle all user interaction. I like the lesson; I think you need a little more explanation of why you are including code example for a Java client--is it because you want to show interoperability with other platforms or because a revTalk version of the client is too difficult to write?
Seems like the whole Java thing is kind of out of context here, but maybe with a bit of explanation it will become obvious why the need. The purpose of this lesson is to demonstrate how to talk to other applications written in other languages. We produced it on request from another user who was looking to do this very task. Go Rev. Hi Sean, thanks for the comment. I have passed your request on to the team who create the lessons. This is a great tutorial but I guess there is something missing and it is about a how the client will get the Host IP address.
Creating a simple Chat Client/Server Solution
Without it the solution is worthless unless both client and server are in the same network. Am I right? If answer is yes any hints as how to do it? Yes I also would be interested how the client get the Host IP. And I would like to connect from mobile phone android to the server on PC - would that work too? And what need to be done from security point of view on server side? Do you have an example for these topics?
I tried the example "Chat Server" shipped with LC Sample Stacks and got troubles to run when seperated into client and server apps. Hope this site is still alive, but maybe not, as Simon didn't got a reply for more than a year now. View in admin portal Edit content on web Edit in desktop. LiveCode Lessons. Search term.
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How to communicate with other applications using sockets Sockets provide the programmer with a facility to allow their applications to communicate over a network. What are Sockets? Creating a Simple Broadcast Server Let us expand on these commands and create a simple broadcast server. When a client attempts to -- connect, the broadcastServerClientConnected message will be sent.
Close all open communication -- channels. Store the client -- in the connected list and begin reading lines of text from them. The -- broadcastServerMessageReceived message will be sent when a line is received.
Java tutorial: Sockets programming
Broadcast that line of -- text to all connected clients. Creating a Broadcast Client. Will send a broadcastClientConnected -- when the client has connected. Output the -- message and continue reading data from the server. Log the error. We will include 5 message types: Sent by the client, requesting authorization.
When a client -- attempts to connect, the chatServerClientConnected message will be sent. Store the client as -- pending and begin reading message headers line of text from the client. Parse the header and -- the read message body if required. Do this by switching accross the message -- type first item in header. Remove the client from the pending -- list if they are pending, or authorised list if they are authorised.
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Java Chat Client Though we could easily develop our client in LiveCode, in this final part of the lesson we will consider Java. Updates the client's current connection status. Opening a Stack from the Server. Hi Bruce, The purpose of this lesson is to demonstrate how to talk to other applications written in other languages. Warm regards, Ben. Very nice tutorial indeed. Shows just how to do it. Could really do with seeing how to transmit bot binary and hex data over a socket. Kind regards Elanor. Add your comment. Subscribe E-Mail me when someone replies to this comment.
Are you human? How can I get the path to the folder a stack file resides in? How can I search delimited data for a matching string? How to count upper and lower case characters Using the flagged property in a field How do I style paragraphs in a field? How do I display a table in a field? JS chat server , with our native Android Client!
If you want to jump straight to the code, its on GitHub.
- Multi-threaded chat Application in Java | Set 1 (Server Side Programming) - GeeksforGeeks.
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Otherwise, read on! To follow along, start by cloning the repository: IO provides an event-oriented API that works across all networks, devices and browsers. Its incredibly robust works even behind corporate proxies! The first step is to install the Java Socket.
In this app, we use onCreate lifecycle callback for that, but it actually depends on your application. Sending data looks as follows. In this case, we send a string but you can do JSON data too with the org.
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- Android Client-Server Using Sockets – Client Implementation.
- Ben Beaumont;