Flutter WebSockets Tutorial: Integrating WebSockets in Your Flutter App – A Step-by-Step Guide

What is WebSocket in Flutter?

A WebSocket is a protocol that enables bidirectional, real-time communication between a client and a server through a single, persistent TCP connection. Unlike standard HTTP, which establishes a new connection for every request and response, WebSockets in Flutter maintain a continuous connection, allowing for ongoing, real-time data transfer in your Flutter app. This means both the client and server can send and receive messages at any time without the need to re-establish connections continually.

Flutter WebSockets are commonly used in applications that require live updates or continuous interaction—such as online games, real-time chat apps in Flutter, stock market feeds, or collaborative tools. The process begins with an HTTP handshake to initiate the connection. Once established, the communication transitions to the WebSocket protocol, enabling efficient data transfer without the need to repeatedly open and close connections.

Conceptually, WebSocket in Flutter is just a layer on top of TCP.

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How is TCP Different from HTTP in Flutter WebSocket Communication?

HTTP creates a new connection for each request, which places an extra load on the server as it needs to perform a new handshake for every interaction. After a request is fulfilled, the connection is terminated. In contrast, a TCP connection remains open and persistent as long as neither the client nor the server interrupts or ends the communication.

How Does WebSocket Work in Flutter Apps?

WebSocket works by establishing a persistent, two-way connection between a client and a server, allowing both to send and receive data at any time. Here’s how it works:

Handshake

The process begins with the client sending an HTTP request to the server, requesting to upgrade the connection to a WebSocket. This request includes a special header indicating that the client wants to use the WebSocket protocol. The server responds, confirming its agreement to proceed with the upgrade.

Upgrade to WebSocket

Once the server agrees, the connection switches from HTTP to WebSocket. At this point, the connection is persistent, meaning it remains open as long as the client and server need to communicate. From this point on, the data is transmitted using the WebSocket protocol rather than HTTP.

Bi-directional Communication

Once the upgrade is complete, both the client and server can send and receive messages autonomously. This is in contrast to the traditional request-response model of HTTP, where the client always has to initiate communication. WebSockets in Flutter allow for real-time, continuous data flow in both directions.

Data Transfer

Data sent over WebSockets is broken down into smaller frames, which can include text, binary data, or control information. These frames are efficiently transmitted, which helps reduce overhead compared to HTTP.

Connection Persistence

The WebSocket connection remains open as long as both sides want to keep it. This allows for instant communication without the need for repeated handshakes. The connection is only closed when either the client or server decides to end it.

Closing the Connection

When either the client or server wants to terminate the connection, they send a special frame to gracefully close the WebSocket connection. When the connection is closed, the communication concludes, and the resources it utilized are released.

Why Do We Need WebSocket in

Flutter Applications?

WebSockets are essential for real-time, bidirectional communication in applications where frequent updates or constant interaction between the client and server are needed. Traditional methods like HTTP are request-response based, which means the client has to keep making requests to the server to check for updates. This can lead to delays and inefficiency—especially in dynamic applications like real-time chat apps in Flutter, online games, or financial trading platforms.

With Flutter WebSockets, once the connection is established, both the client and server can send messages to each other at any time without the need to repeatedly initiate requests. This makes WebSocket in Flutter ideal for scenarios where instant feedback or data synchronization is crucial, such as live notifications, collaborative editing, or monitoring real-time data streams.

By maintaining a persistent connection, WebSocket-based communication in Flutter reduces the overhead of repeatedly opening and closing connections, providing faster communication, lower latency, and a more efficient way to handle real-time data exchange.

If you’re building a backend to support your Flutter app’s real-time features and need an efficient server solution, Node.js development could help scale your project.

When Should We Use WebSocket in Flutter Apps?

WebSocket in Flutter should be used when your application requires real-time, low-latency communication where both the client and server need to send and receive data continuously or at unpredictable intervals. It’s ideal in scenarios where frequent updates or instant feedback are essential and traditional HTTP polling would be inefficient or slow.

When Should We Avoid Using WebSocket in Flutter?

WebSockets in Flutter are not ideal for scenarios where real-time communication isn’t necessary or when the cost of maintaining an open connection exceeds the advantages.

Low Traffic or Infrequent Updates

If your app only needs occasional or one-time data exchanges (like simple form submissions or infrequent page refreshes), using WebSockets would introduce unnecessary complexity and resource consumption. In these situations, traditional HTTP requests are a better fit.

Static or Simple Content

For websites or applications that serve mostly static content with minimal need for dynamic updates (e.g., blogs or news sites), WebSockets are overkill, and regular HTTP/HTTPS would be more efficient.

Resource Constraints

Devices or environments with limited system memory or processing power (e.g., IoT devices or low-end smartphones) may struggle with maintaining multiple open WebSocket connections in Flutter, especially when the app scales to many users.

Security Concerns

Improper implementation of WebSocket in Flutter apps could lead to vulnerabilities like man-in-the-middle attacks. If the environment or application lacks proper security mechanisms, it’s better to rely on more secure, stateless protocols like HTTPS.

Complexity in Scaling

WebSocket connections are stateful, requiring each client to keep a connection open. In applications with heavy traffic, handling and scaling WebSocket connections can be more challenging than with stateless protocols such as HTTP.

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