How does long polling work

After getting a response, the Client typically sends a new long-poll request, either immediately or after a pause, to allow for an appropriate latency duration. A timeout is set for each Long-Poll request. After a connection is lost owing to timeouts, the Client must rejoin regularly. How does long polling work? Considerations when using long-polling As long polling is just an improvisation applied to an underlying request-response mechanism, it comes with an additional degree of complexity in its implementation.

As usage grows, how will you orchestrate your real-time backend? Does long polling automatically re-establish connections when mobile devices rapidly switch between WiFi and cellular networks or lose connections and the IP address changes? With long polling, can you manage the message queue and catch up on missed messages?

Does long polling provide load balancing or failover support across multiple servers? Challenges in long polling Message ordering and delivery There is a chance that the communication will be lost if the Client was unable to receive it. If the same Client establishes several connections to the server, message ordering cannot be guaranteed. Performance and scaling Device support and fallbacks.

Conclusion Long polling helps provide frequent updates. Our Weekly Newsletter Subscribe to get well-designed content on data structures and algorithms, machine learning, system design, oops, and mathematics. Coding Interview. Machine Learning. System Design. OOPS Concepts. We Welcome Doubts and Feedback! Full Name. Submit Your Response.

More Content From EnjoyAlgorithms. With these considerations in mind, that's where a real-time communication platform like PubNub comes in. When looking at HTTP long polling with the goal of streaming data, PubNub is a low-latency and low-overhead real-time Web app communication environment, and features the ability to send messages to a single client, client groups and all clients.

Instead of relying solely on HTTP long polling for real-time messaging, a protocol agnostic approach is beneficial. PubNub automatically chooses the best protocols and frameworks depending on environment, latency, etc. Any server or client code wanting to communicate makes a single API call to publish or subscribe to data channels. The code is identical between clients and servers, making implementation much simpler than using HTTP long polling.

In terms of connection management, the network handles network redundancy, routing topology, loading balancing, failover, and channel access. Additionally, PubNub offers core building blocks for building real-time into your application. Learn in-demand tech skills in half the time.

Early Access Courses. Assessments New. Free Trial New. For Business. For Educators. Become an Affiliate. The server architecture must be able to work with many pending connections.

Servers written using Node. Server '. Previous lesson Next lesson. Comments read this before commenting… If you have suggestions what to improve - please submit a GitHub issue or a pull request instead of commenting. If you can't understand something in the article — please elaborate. Chapter Network requests.