Session Socket Server

A simple Node JS based socket server useful for session based persistence and data transfer.

Server

Startup

1. There is a folder called node-server that contains all the server code.
2. This requires that the PC that is going to run the server software to have Node JS installed. You can find Node JS here: https://nodejs.org/en/
3. There are two executable scripts in the node-server folder to easily start an instance of the server.
   • ServerStart_Mac.command can be used on Macs.
   • StartServer_Win.bat can be used on Windows.
   • You can also start the server by using the command node main.js while in the node-server folder in your operating system's repsective command line.
4. If the server started correctly you should see something like this in your operating system's command-line:

   > ryancook@ryan-macbook:~/Git/seesion-socket-server/node-server$ node main.js
   > new session beginning...
   > Server is listening on 192.168.0.66:5556
   

Messaging

Messages to and from the server should pre-append a 4 letter message type indicator. The following are the currently supported message types:

4-Letter Type	Description
JOIN	Client requesting to join the session.
JRES	Server response confirming join acceptance.
RDAT	Client requesting current session data.
GDAT	Server response with current session data.
UDAT	Update to a specified piece of session data. Client can send to server and server broadcasts to other clients.
KEEP	Client telling Server that it is still connected.
QUIT	Client telling Server that it has disconnected.
EVNT	Generic event that is sent to all connected clients. Up to implementor to decide how to use.

Session Data

The server stores session data in a simple Javascript object. Session data is indexed by a string identifier and the value is JSON.

For instance if you wanted to store the state of a toggle button, it could look like this:

id: toggle_button_a
value:

{
    "isOn": true
}  

Or maybe you want to store a more complex blob like a transformation

id: object_001_transform
value:

{
    "position": {
        "x" : 10,
        "y" : 2,
        "z" : 5
    },
    "rotation": { 
        "x" : 0,
        "y" : 0,
        "z" : 0
    },
    "scale": { 
        "x" : 1,
        "y" : 1,
        "z" : 1
    }
}  

What you store and how you store it is really up to you.

NOTE: Keep in mind that this server updates and emits session data in full.

So in the case of the transform data example above, even if we just wanted to change the x postion to 11, the full session data blob needs to be updated and will be sent in full to all connected clients.

Clients

Joining the Session

1. Create a socket that listens to the server ip and port as the end point.
2. Send the message JOIN to the server.
3. Wait for the response JRES from the server to confirm that the connection has been accepted.

Get Current Session Data

1. Send RDAT message to the server.
2. Wait for GDAT response from server.
3. Strip GDAT from received response and you are left with the raw JSON string of all the current session data.

Contribute

If you wish to contribute to this project feel free to open up a pull request and I will review it for inclusion.

Same goes for bug fixes, if you find any, feel free to open up an Issue here on the GitHub repo or fix it yourself and create a pull request so we may all benefit.