How to implement server push messages in php5.2.17?

The company wants to create a page that can display push data from third-party interfaces in real time. Hundreds of people may be using it at the same time, and not only one data needs to be refreshed in real time. I originally wanted to use ajax to do it, but I heard that people Will it put more pressure on the server?
I checked and websocket seems to be more suitable, but I don’t understand what’s going on. . . Many people have mentioned swoole and workman, but both of them require php5.3 or above. Our company's version is only 5.2.17, and they are not allowed to upgrade. I am at a loss now. I really have no idea but to use ajax to top up the account first. . . .