Background: I have a spring webapp which every 10 seconds polls a RestController API server for various information like employee information and their task information, and a json response object is returned. This employee status and task information is stored in a backend database and served by the rest api calls to the client browsers.
An example call and response is like:
client javascript:
await getEmployeeInfo();
Returns:
{
"employees": [{
"id": "0001",
"name": "john",
"status": "online",
"tasks": ["task1", "task2"]
},
{
"id": "0002",
"name": "pam",
"status": "out-to-lunch",
"tasks": ["task2", "task3"]
}
]
}
Once the above response is received by the client browser, it is then parsed and displayed graphically on a webpage.
What I want to do:
Instead of polling the server for new information every few seconds, I would rather call the getEmployeeInfo() API, receive the information, and have the HTTP connection kept open to receive updates if their are any.
What I don't want to do: Hammer the server by polling every few seconds to receive the latest information from the server, even though there hasn't been any updates since the last poll. I could reduce the polling frequency to reduce server load, but then the realtimeness of the information would suffer.
My Question: What technology could I use that would allow me to stop polling the server and have the server give updated information to browser clients only when an update has actually occurred. I would require something that provided two-way information as the browser client updates and displays information.
CodePudding user response：
Both Websockets and SSE (Server Sent Events) can meet your needs.
More details in 
In your example you will open a web-socket (wss) connection to your backend and then on your frontend you will wait for the backend server to response. Since you are using Spring as a backend and javascript on the frontend you should take a look at: