Polling vs long polling vs webhooks
Polling, long-polling, and webhooks are three techniques used in applications for getting updates or information, each with its own mechanism and use case.
Polling
Polling is a technique where the client repeatedly requests (polls) a server at regular intervals to get new or updated data.
Characteristics
- Regular Requests
- The client makes requests at fixed intervals (e.g., every 5 seconds).
- Client-Initiated
- The client initiates each request.
Example
A weather app that checks for updated weather information every 15 minutes by sending a request to the weather server.
Pros
- Simple to Implement
- Easy to set up on the client side.
Cons
- Inefficient
- Generates a lot of unnecessary traffic and server load, especially if there are no new updates.
- Delay in Updates
- There's always a delay between the actual update and the client receiving it.
Long polling
Long-polling is an enhanced version of polling where the server holds the request open until new data is available to send back to the client.
Characteristics
- Open Connection
- The server keeps the connection open for a period until there's new data or a timeout occurs.
- Reduced Traffic
- Less frequent requests compared to traditional polling.
Example
A chat application where the client sends a request to the server and the server holds the request until new messages are available. Once new messages arrive, the server responds, and the client immediately sends another request.
Pros
- More Timely Updates
- Clients can receive updates more quickly after they occur.
- Reduced Network Traffic
- Less frequent requests than standard polling.
Cons
- Resource Intensive on the Server
- Holding connections open can consume server resources.
Webhooks
Webhooks are user-defined HTTP callbacks that are triggered by specific events. When the event occurs, the source site makes an HTTP request to the URL configured for the webhook.
Characteristics
- Server-Initiated
- The server sends data when there’s a new update, without the client needing to request it.
- Event-Driven
- Triggered by specific events in the server.
Example
A project management tool where a webhook is set up to notify a team's chat application whenever a new task is created. The creation of the task triggers a webhook that sends data directly to the chat app.
Pros
- Real-Time
- Provides real-time updates.
- Efficient
- Eliminates the need for polling, reducing network traffic and load.
Cons
- Complexity in Handling
- The client needs to be capable of receiving and handling incoming HTTP requests.
- Security Considerations
- Requires secure handling to prevent malicious data reception.
Polling vs long polling vs webhooks
- Initiation and Traffic
- Polling is client-initiated with frequent traffic, long-polling also starts with the client but reduces traffic by keeping the request open, and webhooks are server-initiated, requiring no polling.
- Real-Time Updates
- Webhooks offer the most real-time updates, while polling and long-polling have inherent delays.
The choice between polling, long-polling, and webhooks depends on the application's requirements for real-time updates, server and client capabilities, and efficiency considerations. Polling is simple but can be inefficient, long-polling offers a middle ground with more timely updates, and webhooks provide real-time updates efficiently but require the client to handle incoming requests.