Polling can be done with many services on the host to update the client on the status of a process that has been started. But, there are times when the lag, (associated with polling) is a nuisance. Server-sent events are updates over a real-time streaming connection, the same as voice communications.
Even for a simple Chat application communications can be interfered with resulting in a person asking a question that was just answered. Or in a game where somebody is reacting to a player who has already moved. Or, sports scores can appear before the announcer has finished reading them. SSEs fix these annoyances by providing real-time communications.
Time sent from server
Server-Sent Events (SSE) provide real-time communication from a server to the client, (note: WebSockets are bidirectional). They are useful to keep the client updated on a process that has begun on the server; or provide streaming updates for information the server can provide such as sports scores, stock updates, or even a chat feed. The benefit of real-time SSE over polling is a reduction of lag time, caused by delays in creating new connections and delays to request new data.
With microservices, the host can safely get information about a process the client has started from the back-end office environment without exposing the back-end to internet traffic. The connection is a private secured connection between the host and the office and the microservice prevents any unauthorized data requests.
Providing the customer a command center view of the status of his request can be a game changer for businesses in several ways. The client does not need to call and use human resources to see the status of his order. It is a nuisance to the client to need to call, although he may still want the information and will choose the service if it is available or the business that provides it.