XHR Streaming vs WebSocket: Which One to Choose?

When it comes to building real-time web applications, developers often face the dilemma of choosing between XHR streaming and WebSocket. While both technologies provide a way to establish and maintain a bidirectional connection between the client and server, they have some important differences that can impact the performance, scalability, and user experience of your application.

What is XHR Streaming?

XHR (XMLHttpRequest) streaming, also known as long-polling, is a technique that allows the client to send a request to the server and keep the connection open until the server sends a response. The server can send multiple responses over the same connection, which allows the client to receive real-time updates without the need for constant polling.

The XHR streaming process works as follows:

1. The client sends an XHR request to the server.
2. The server responds with a partial response or waits until it has new data to send.
3. The client receives the response and processes it.
4. The client sends another XHR request to the server to maintain the connection.
5. The process repeats as long as the connection is open.

XHR streaming has been around for a long time and is supported by all modern browsers. It is relatively easy to implement and works well for applications that require real-time updates but don’t need to send a lot of data or handle a large number of concurrent connections.

What is WebSocket?

WebSocket is a protocol that provides a full-duplex, bidirectional communication channel between the client and server over a single TCP connection. It allows real-time data to be exchanged between the client and server without the need for constant polling or long-polling.

The WebSocket process works as follows:

1. The client sends a WebSocket handshake request to the server.
2. The server responds with a WebSocket handshake response.
3. The WebSocket connection is established.
4. The client and server can exchange data in real-time over the same connection.

WebSocket is a relatively new technology and is not supported by all browsers. However, it has some important advantages over XHR streaming, such as:

• Lower latency and higher throughput: WebSocket uses a binary protocol that is more efficient than HTTP, which results in lower latency and higher throughput.
• Full-duplex communication: WebSocket allows both the client and server to send data at any time, which allows for more natural and efficient communication.
• Scalability: WebSocket can handle a large number of concurrent connections with minimal overhead, which makes it ideal for applications that require real-time communication with many clients.

When to Use XHR Streaming?

XHR streaming is a good choice for applications that require real-time updates but don’t need to send a lot of data or handle a large number of concurrent connections. Some examples of applications that can benefit from XHR streaming are:

• Chat applications: XHR streaming can be used to send real-time messages between users.
• Stock tickers: XHR streaming can be used to display real-time stock prices.
• Notifications: XHR streaming can be used to notify users of new events or updates.

XHR streaming is also a good choice for applications that need to support older browsers that don’t support WebSocket.

When to Use WebSocket?

WebSocket is a good choice for applications that require real-time communication with many clients or need to send a lot of data over the network. Some examples of applications that can benefit from WebSocket are:

• Multiplayer games: WebSocket can be used to provide real-time communication between players.
• Collaborative editing: WebSocket can be used to allow multiple users to edit the same document in real-time.
• Live streaming: WebSocket can be used to stream video or audio in real-time.

WebSocket is also a good choice for applications that require low latency and high throughput, such as financial trading platforms or real-time bidding systems.

How to Choose Between XHR Streaming and WebSocket?

When choosing between XHR streaming and WebSocket, you should consider the following factors:

• Application requirements: What are the real-time communication requirements of your application? Does it need to send a lot of data or handle a large number of concurrent connections?
• Browser support: Do you need to support older browsers that don’t support WebSocket?
• Development resources: Do you have the resources to implement and maintain WebSocket?

Ultimately, the choice between XHR streaming and WebSocket depends on the specific needs of your application. Both technologies have their strengths and weaknesses, and the right choice will depend on your requirements and constraints.

Frequently Asked Questions

What is the difference between XHR and AJAX?

XHR (XMLHttpRequest) is a browser API that allows JavaScript to make HTTP requests to the server and receive responses in various formats, such as HTML, XML, or JSON. AJAX (Asynchronous JavaScript and XML) is a technique that uses XHR to update parts of a web page without the need for a full page reload. XHR is a low-level API, while AJAX is a higher-level concept that uses XHR and other browser APIs to provide a better user experience.

Can WebSocket be used with HTTPS?

Yes, WebSocket can be used with HTTPS (HTTP Secure), which provides encryption and authentication of the communication channel. WebSocket over HTTPS uses the same port (443) as HTTPS and requires a valid SSL/TLS certificate to establish the connection.

What is the alternative to XHR streaming and WebSocket?

Polling is an alternative to XHR streaming and WebSocket that involves the client sending periodic requests to the server to check for updates. While polling is simple to implement, it can result in high network traffic and latency, especially for applications that require real-time updates. Server-Sent Events (SSE) is another alternative that allows the server to push real-time updates to the client over a unidirectional connection. SSE is simpler than WebSocket but also has some limitations, such as the inability to send binary data or handle bidirectional communication.

Can XHR streaming and WebSocket be used together?

Yes, XHR streaming and WebSocket can be used together in the same application to provide real-time updates to clients that support WebSocket and fallback to XHR streaming for older browsers. This approach is called “hybrid polling” and involves using XHR streaming as a fallback mechanism for browsers that don’t support WebSocket.