Node.js http2stream.rstCode Method

In this article, we will discuss the http2stram.rstCode method in Node.js with its syntax, parameters, and examples.

What is the http2stram.rstCode method in Node.js?

The HTTP/2 protocol is implemented by the http2 module in Node.js, which enables efficient and multiplexed communication between clients and servers. One of the more advanced capabilities of this module is the ability to work with streams, particularly Http2Stream objects, which represent bidirectional communication streams within an HTTP/2 session.

The http2stream.rstCode() function can be used to reset or end a single HTTP/2 stream with a specific error code. It is particularly useful when we wish to signal that the stream has encountered an error or needs to be terminated before it is completed.

Syntax:

It has the following syntax:

• Parameters: There are no parameters accepted by this procedure.
• Value returned: The RST_STREAM error code is represented by an integer value returned by this function.

Key points:

Purpose:

• Use the rstCode attribute to set or retrieve a stream's reset code. Streams can terminate gracefully or with an error message thanks to this mechanism.

Error codes:

The error codes follow the HTTP/2 protocol and are contained in the http2.constants object. Common error codes include:

• http2.constants.NGHTTP2_NO_ERROR: No error (graceful closure).
• http2.constants.NGHTTP2_CANCEL: It indicates the stream was canceled.
• http2.constants.NGHTTP2_PROTOCOL_ERROR: It indicates a protocol error.

Usage:

• Setting http2stream.rstCode.close() function before running stream ensures that the specified error code is used to end the stream.
• A stream is typically used in error-handling or cleanup scenarios when it needs to be reset.

Read-Only After Closure:

The rstCode property, which is read-only once the stream is closed, reflects the code used to reset the stream.

Example 1:

Let us take an example to illustrate the http2stream.rstCode() function in Node.js.

Output:

 
HTTP/2 server running on port 3000
Error: Command failed: timeout 7 node index.js   

Explanation:

The server in the example responds with a basic "Hello, HTTP/2!" message for other pathways, and then resets the stream with the NGHTTP2_CANCEL code if a client requests the /error path, which indicates that the stream was purposefully cancelled.

Example 2:

Let us take another example to illustrate the http2stream.rstCode() function in Node.js.

Output:

 
HTTP/2 server running on port 3000
Error: Command failed: timeout 7 node index.js   

Explanation:

Simulated Timeout:

• In order to mimic a 5-second timeout for the stream, use a setTimeout() function.
• The NGHTTP2_CANCEL error code is used to reset the stream in the event that the timeout occurs.

Client Communication:

• The server clears the timeout, replies with a status of 200, and finishes the stream with a message if the client submits data before the timeout.

Managing Errors:

• The stream.on('error') listener makes sure that any errors on the stream are properly cleaned up and logged.

In order to test the above code we need to follow the below steps:

Case 1: if the client sends No data (it causes timed out):

• The server resets the stream using the NGHTTP2_CANCEL code if the client doesn't send any data within five seconds of connecting.

An error message stating that the stream was cancelled is sent to the client.

Case 2: If the client sends data before the timed out:

• Data is sent to the server by the client prior to the 5-second timeout.
• The HTTP/2 200 OK status and the message "Stream completed successfully!" are the server's responses.

Then the client receives successful message:

Conclusion:

In conclusion, the http2stream.rstCode() method in Node.js is a useful tool for managing HTTP/2 streams because it allows programmers to end or reset streams with specific error codes. Timeouts, cancellations, and protocol errors are among the scenarios that this feature handles to guarantee dependable and efficient stream management during HTTP/2 sessions. Using rstCode correctly is essential to ensuring smooth communication between the server and clients. It allows for error alerting and graceful termination. The integration of this feature with effective error handling and response methods enables developers to build scalable and reliable apps that fully utilize the advanced capabilities of the HTTP/2 protocol.