Module 14: Creating a WhatsApp Clone
Transcript
next we’ll jump to the websocket package which is the last package first we need to configure the websocket we do this by implementing the websocket configurer and using the annotations on the class to indicate its purpose we define the socket so we can define the packet size to 8k we can set a larger size but generally keeping packets small is a good practice the app socket class is bound to the slash socket url in this line of code this is the thread used to process the websocket connections we can allocate more thread resources based on need let’s go to the app socket the app is an implementation of text websocket handler which handles text messages since all our messages are json this makes more sense i cache the currently active connections here this isn’t a good approach in the long term a better approach would be redis for this sort of caching but for an initial app this can work fine we need access to the user service so we can send message to a group or user the method sends this method sends json to a websocket based on the user token and returns true if it is successful we get the sessions for the given client if he has a web service session we create a text message with js the json we loop over all the websocket connections one by one if a connection is open we send the message there and return otherwise we add the socket to the remove queue we don’t want to remove in the middle of the loop to prevent an exception we remove all the defunct websockets from the queue in this line for all the classes we’re sending via socket in work we return force this method handles the incoming text packets we need to parse the json into a map if m has a type of pro it’s probably an init method if init messages allows us to add a websocket to our cache of connections so we can push a message back into the websocket when we need to send a server note notification otherwise we test if this is a user typing event in which case we need to send a typing message onward finally we send the message as json to the users in the group or to the specific user this invokes the code we saw in the user service class when combination when a connection is closed we loop over the existing list and purge it of the dead connection for simplicity we don’t support partial messages which shouldn’t be necessary for a small 8k messages with that the class is done