Table of Contents

• HTTP2
  • Core API
    • Server-side example
    • Client-side example
    • Class: Http2Session
      • Http2Session and Sockets
      • Event: 'close'
      • Event: 'connect'
      • Event: 'error'
      • Event: 'frameError'
      • Event: 'goaway'
      • Event: 'localSettings'
      • Event: 'remoteSettings'
      • Event: 'stream'
      • Event: 'timeout'
      • http2session.alpnProtocol
      • http2session.close([callback])
      • http2session.closed
      • http2session.destroy([error,][code])
      • http2session.destroyed
      • http2session.encrypted
      • http2session.goaway([code, [lastStreamID, [opaqueData]]])
      • http2session.localSettings
      • http2session.originSet
      • http2session.pendingSettingsAck
      • http2session.ping([payload, ]callback)
      • http2session.ref()
      • http2session.remoteSettings
      • http2session.setTimeout(msecs, callback)
      • http2session.close(options[, callback])
      • http2session.socket
      • http2session.state
      • http2session.settings(settings)
      • http2session.type
      • http2session.unref()
    • Class: ServerHttp2Session
      • serverhttp2session.altsvc(alt, originOrStream)
      • Specifying alternative services
    • Class: ClientHttp2Session
      • Event: 'altsvc'
      • clienthttp2session.request(headers[, options])
    • Class: Http2Stream
      • Http2Stream Lifecycle
        • Creation
        • Destruction
      • Event: 'aborted'
      • Event: 'close'
      • Event: 'error'
      • Event: 'frameError'
      • Event: 'timeout'
      • Event: 'trailers'
      • http2stream.aborted
      • http2stream.close(code[, callback])
      • http2stream.closed
      • http2stream.destroyed
      • http2stream.pending
      • http2stream.priority(options)
      • http2stream.rstCode
      • http2stream.session
      • http2stream.setTimeout(msecs, callback)
      • http2stream.state
    • Class: ClientHttp2Stream
      • Event: 'continue'
      • Event: 'headers'
      • Event: 'push'
      • Event: 'response'
    • Class: ServerHttp2Stream
      • http2stream.additionalHeaders(headers)
      • http2stream.headersSent
      • http2stream.pushAllowed
      • http2stream.pushStream(headers[, options], callback)
      • http2stream.respond([headers[, options]])
      • http2stream.respondWithFD(fd[, headers[, options]])
      • http2stream.respondWithFile(path[, headers[, options]])
    • Class: Http2Server
      • Event: 'checkContinue'
      • Event: 'request'
      • Event: 'session'
      • Event: 'sessionError'
      • Event: 'streamError'
      • Event: 'stream'
      • Event: 'timeout'
    • Class: Http2SecureServer
      • Event: 'sessionError'
      • Event: 'unknownProtocol'
      • Event: 'stream'
      • Event: 'request'
      • Event: 'timeout'
      • Event: 'checkContinue'
    • http2.createServer(options[, onRequestHandler])
    • http2.createSecureServer(options[, onRequestHandler])
    • http2.connect(authority[, options][, listener])
    • http2.constants
      • Error Codes for RST_STREAM and GOAWAY
    • http2.getDefaultSettings()
    • http2.getPackedSettings(settings)
    • http2.getUnpackedSettings(buf)
    • Headers Object
    • Settings Object
    • Using options.selectPadding
    • Error Handling
    • Invalid character handling in header names and values
    • Push streams on the client
    • Supporting the CONNECT method
  • Compatibility API
    • ALPN negotiation
    • Class: http2.Http2ServerRequest
      • Event: 'aborted'
      • Event: 'close'
      • request.destroy([error])
      • request.headers
      • request.httpVersion
      • request.method
      • request.rawHeaders
      • request.rawTrailers
      • request.setTimeout(msecs, callback)
      • request.socket
      • request.stream
      • request.trailers
      • request.url
    • Class: http2.Http2ServerResponse
      • Event: 'close'
      • Event: 'finish'
      • response.addTrailers(headers)
      • response.connection
      • response.end([data][, encoding][, callback])
      • response.finished
      • response.getHeader(name)
      • response.getHeaderNames()
      • response.getHeaders()
      • response.hasHeader(name)
      • response.headersSent
      • response.removeHeader(name)
      • response.sendDate
      • response.setHeader(name, value)
      • response.setTimeout(msecs[, callback])
      • response.socket
      • response.statusCode
      • response.statusMessage
      • response.stream
      • response.write(chunk[, encoding][, callback])
      • response.writeContinue()
      • response.writeHead(statusCode[, statusMessage][, headers])
      • response.createPushResponse(headers, callback)
  • Collecting HTTP/2 Performance Metrics

HTTP2#

The http2 module provides an implementation of the HTTP/2 protocol. It can be accessed using:

const http2 = require('http2');

Core API#

The Core API provides a low-level interface designed specifically around support for HTTP/2 protocol features. It is specifically not designed for compatibility with the existing HTTP/1 module API. However, the Compatibility API is.

The http2 Core API is much more symmetric between client and server than the http API. For instance, most events, like error and socketError, can be emitted either by client-side code or server-side code.

Server-side example#

The following illustrates a simple, plain-text HTTP/2 server using the Core API:

const http2 = require('http2');
const fs = require('fs');

const server = http2.createSecureServer({
  key: fs.readFileSync('localhost-privkey.pem'),
  cert: fs.readFileSync('localhost-cert.pem')
});
server.on('error', (err) => console.error(err));
server.on('socketError', (err) => console.error(err));

server.on('stream', (stream, headers) => {
  // stream is a Duplex
  stream.respond({
    'content-type': 'text/html',
    ':status': 200
  });
  stream.end('<h1>Hello World</h1>');
});

server.listen(8443);

To generate the certificate and key for this example, run:

openssl req -x509 -newkey rsa:2048 -nodes -sha256 -subj '/CN=localhost' \
  -keyout localhost-privkey.pem -out localhost-cert.pem

Client-side example#

The following illustrates an HTTP/2 client:

const http2 = require('http2');
const fs = require('fs');
const client = http2.connect('https://localhost:8443', {
  ca: fs.readFileSync('localhost-cert.pem')
});
client.on('error', (err) => console.error(err));
client.on('socketError', (err) => console.error(err));

const req = client.request({ ':path': '/' });

req.on('response', (headers, flags) => {
  for (const name in headers) {
    console.log(`${name}: ${headers[name]}`);
  }
});

req.setEncoding('utf8');
let data = '';
req.on('data', (chunk) => { data += chunk; });
req.on('end', () => {
  console.log(`\n${data}`);
  client.close();
});
req.end();

Class: Http2Session#

• Extends: <EventEmitter>

Instances of the http2.Http2Session class represent an active communications session between an HTTP/2 client and server. Instances of this class are not intended to be constructed directly by user code.

Each Http2Session instance will exhibit slightly different behaviors depending on whether it is operating as a server or a client. The http2session.type property can be used to determine the mode in which an Http2Session is operating. On the server side, user code should rarely have occasion to work with the Http2Session object directly, with most actions typically taken through interactions with either the Http2Server or Http2Stream objects.

Http2Session and Sockets#

Every Http2Session instance is associated with exactly one net.Socket or tls.TLSSocket when it is created. When either the Socket or the Http2Session are destroyed, both will be destroyed.

Because the of the specific serialization and processing requirements imposed by the HTTP/2 protocol, it is not recommended for user code to read data from or write data to a Socket instance bound to a Http2Session. Doing so can put the HTTP/2 session into an indeterminate state causing the session and the socket to become unusable.

Once a Socket has been bound to an Http2Session, user code should rely solely on the API of the Http2Session.

Event: 'close'#

The 'close' event is emitted once the Http2Session has been destroyed.

Event: 'connect'#

The 'connect' event is emitted once the Http2Session has been successfully connected to the remote peer and communication may begin.

Note: User code will typically not listen for this event directly.

Event: 'error'#

The 'error' event is emitted when an error occurs during the processing of an Http2Session.

Event: 'frameError'#

The 'frameError' event is emitted when an error occurs while attempting to send a frame on the session. If the frame that could not be sent is associated with a specific Http2Stream, an attempt to emit 'frameError' event on the Http2Stream is made.

When invoked, the handler function will receive three arguments:

• An integer identifying the frame type.
• An integer identifying the error code.
• An integer identifying the stream (or 0 if the frame is not associated with a stream).

If the 'frameError' event is associated with a stream, the stream will be closed and destroyed immediately following the 'frameError' event. If the event is not associated with a stream, the Http2Session will be shut down immediately following the 'frameError' event.

Event: 'goaway'#

The 'goaway' event is emitted when a GOAWAY frame is received. When invoked, the handler function will receive three arguments:

• errorCode <number> The HTTP/2 error code specified in the GOAWAY frame.
• lastStreamID <number> The ID of the last stream the remote peer successfully processed (or 0 if no ID is specified).
• opaqueData <Buffer> If additional opaque data was included in the GOAWAY frame, a Buffer instance will be passed containing that data.

Note: The Http2Session instance will be shut down automatically when the 'goaway' event is emitted.

Event: 'localSettings'#

The 'localSettings' event is emitted when an acknowledgment SETTINGS frame has been received. When invoked, the handler function will receive a copy of the local settings.

Note: When using http2session.settings() to submit new settings, the modified settings do not take effect until the 'localSettings' event is emitted.

session.settings({ enablePush: false });

session.on('localSettings', (settings) => {
  /** use the new settings **/
});

Event: 'remoteSettings'#

The 'remoteSettings' event is emitted when a new SETTINGS frame is received from the connected peer. When invoked, the handler function will receive a copy of the remote settings.

session.on('remoteSettings', (settings) => {
  /** use the new settings **/
});

Event: 'stream'#

The 'stream' event is emitted when a new Http2Stream is created. When invoked, the handler function will receive a reference to the Http2Stream object, a Headers Object, and numeric flags associated with the creation of the stream.

const http2 = require('http2');
session.on('stream', (stream, headers, flags) => {
  const method = headers[':method'];
  const path = headers[':path'];
  // ...
  stream.respond({
    ':status': 200,
    'content-type': 'text/plain'
  });
  stream.write('hello ');
  stream.end('world');
});

On the server side, user code will typically not listen for this event directly, and would instead register a handler for the 'stream' event emitted by the net.Server or tls.Server instances returned by http2.createServer() and http2.createSecureServer(), respectively, as in the example below:

const http2 = require('http2');

// Create a plain-text HTTP/2 server
const server = http2.createServer();

server.on('stream', (stream, headers) => {
  stream.respond({
    'content-type': 'text/html',
    ':status': 200
  });
  stream.end('<h1>Hello World</h1>');
});

server.listen(80);

Event: 'timeout'#

After the http2session.setTimeout() method is used to set the timeout period for this Http2Session, the 'timeout' event is emitted if there is no activity on the Http2Session after the configured number of milliseconds.

session.setTimeout(2000);
session.on('timeout', () => { /** .. **/ });

http2session.alpnProtocol#

• Value: <string> | <undefined>

Value will be undefined if the Http2Session is not yet connected to a socket, h2c if the Http2Session is not connected to a TLSSocket, or will return the value of the connected TLSSocket's own alpnProtocol property.

http2session.close([callback])#

• callback <Function>

Gracefully closes the Http2Session, allowing any existing streams to complete on their own and preventing new Http2Stream instances from being created. Once closed, http2session.destroy() might be called if there are no open Http2Stream instances.

If specified, the callback function is registered as a handler for the 'close' event.

http2session.closed#

• Value: <boolean>

Will be true if this Http2Session instance has been closed, otherwise false.

http2session.destroy([error,][code])#

• error <Error> An Error object if the Http2Session is being destroyed due to an error.
• code <number> The HTTP/2 error code to send in the final GOAWAY frame. If unspecified, and error is not undefined, the default is INTERNAL_ERROR, otherwise defaults to NO_ERROR.
• Returns: <undefined>

Immediately terminates the Http2Session and the associated net.Socket or tls.TLSSocket.

Once destroyed, the Http2Session will emit the 'close' event. If error is not undefined, an 'error' event will be emitted immediately after the 'close' event.

If there are any remaining open Http2Streams associated with the Http2Session, those will also be destroyed.

http2session.destroyed#

• Value: <boolean>

Will be true if this Http2Session instance has been destroyed and must no longer be used, otherwise false.

http2session.encrypted#

• Value: <boolean> | <undefined>

Value is undefined if the Http2Session session socket has not yet been connected, true if the Http2Session is connected with a TLSSocket, and false if the Http2Session is connected to any other kind of socket or stream.

http2session.goaway([code, [lastStreamID, [opaqueData]]])#

• code <number> An HTTP/2 error code
• lastStreamID <number> The numeric ID of the last processed Http2Stream
• opaqueData <Buffer> | <TypedArray> | <DataView> A TypedArray or DataView instance containing additional data to be carried within the GOAWAY frame.

Transmits a GOAWAY frame to the connected peer without shutting down the Http2Session.

http2session.localSettings#

• Value: <Settings Object>

A prototype-less object describing the current local settings of this Http2Session. The local settings are local to this Http2Session instance.

http2session.originSet#

• Value: <string[]> | <undefined>

If the Http2Session is connected to a TLSSocket, the originSet property will return an Array of origins for which the Http2Session may be considered authoritative.

http2session.pendingSettingsAck#

• Value: <boolean>

Indicates whether or not the Http2Session is currently waiting for an acknowledgment for a sent SETTINGS frame. Will be true after calling the http2session.settings() method. Will be false once all sent SETTINGS frames have been acknowledged.

http2session.ping([payload, ]callback)#

• payload <Buffer> | <TypedArray> | <DataView> Optional ping payload.
• callback <Function>
• Returns: <boolean>

Sends a PING frame to the connected HTTP/2 peer. A callback function must be provided. The method will return true if the PING was sent, false otherwise.

The maximum number of outstanding (unacknowledged) pings is determined by the maxOutstandingPings configuration option. The default maximum is 10.

If provided, the payload must be a Buffer, TypedArray, or DataView containing 8 bytes of data that will be transmitted with the PING and returned with the ping acknowledgment.

The callback will be invoked with three arguments: an error argument that will be null if the PING was successfully acknowledged, a duration argument that reports the number of milliseconds elapsed since the ping was sent and the acknowledgment was received, and a Buffer containing the 8-byte PING payload.

session.ping(Buffer.from('abcdefgh'), (err, duration, payload) => {
  if (!err) {
    console.log(`Ping acknowledged in ${duration} milliseconds`);
    console.log(`With payload '${payload.toString()}`);
  }
});

If the payload argument is not specified, the default payload will be the 64-bit timestamp (little endian) marking the start of the PING duration.

http2session.ref()#

Calls ref() on this Http2Session instance's underlying net.Socket.

http2session.remoteSettings#

• Value: <Settings Object>

A prototype-less object describing the current remote settings of this Http2Session. The remote settings are set by the connected HTTP/2 peer.

http2session.setTimeout(msecs, callback)#

• msecs <number>
• callback <Function>
• Returns: <undefined>

Used to set a callback function that is called when there is no activity on the Http2Session after msecs milliseconds. The given callback is registered as a listener on the 'timeout' event.

http2session.close(options[, callback])#

• options <Object>
  • errorCode <number> The HTTP/2 error code to return. Note that this is not the same thing as an HTTP Response Status Code. Default: 0x00 (No Error).
  • lastStreamID <number> The Stream ID of the last successfully processed Http2Stream on this Http2Session. If unspecified, will default to the ID of the most recently received stream.
  • opaqueData <Buffer> | <Uint8Array> A Buffer or Uint8Array instance containing arbitrary additional data to send to the peer upon disconnection. This is used, typically, to provide additional data for debugging failures, if necessary.
• callback <Function> A callback that is invoked after the session shutdown has been completed.
• Returns: <undefined>

Attempts to shut down this Http2Session using HTTP/2 defined procedures. If specified, the given callback function will be invoked once the shutdown process has completed.

If the Http2Session instance is a server-side session and the errorCode option is 0x00 (No Error), a "graceful" shutdown will be initiated. During a "graceful" shutdown, the session will first send a GOAWAY frame to the connected peer identifying the last processed stream as 2³¹-1. Then, on the next tick of the event loop, a second GOAWAY frame identifying the most recently processed stream identifier is sent. This process allows the remote peer to begin preparing for the connection to be terminated.

session.close({
  opaqueData: Buffer.from('add some debugging data here')
}, () => session.destroy());

http2session.socket#

• Value: <net.Socket> | <tls.TLSSocket>

Returns a Proxy object that acts as a net.Socket (or tls.TLSSocket) but limits available methods to ones safe to use with HTTP/2.

destroy, emit, end, pause, read, resume, and write will throw an error with code ERR_HTTP2_NO_SOCKET_MANIPULATION. See Http2Session and Sockets for more information.

setTimeout method will be called on this Http2Session.

All other interactions will be routed directly to the socket.

http2session.state#

• Value: <Object>
  • effectiveLocalWindowSize <number>
  • effectiveRecvDataLength <number>
  • nextStreamID <number>
  • localWindowSize <number>
  • lastProcStreamID <number>
  • remoteWindowSize <number>
  • outboundQueueSize <number>
  • deflateDynamicTableSize <number>
  • inflateDynamicTableSize <number>

An object describing the current status of this Http2Session.

http2session.settings(settings)#

• settings <Settings Object>
• Returns <undefined>

Updates the current local settings for this Http2Session and sends a new SETTINGS frame to the connected HTTP/2 peer.

Once called, the http2session.pendingSettingsAck property will be true while the session is waiting for the remote peer to acknowledge the new settings.

Note: The new settings will not become effective until the SETTINGS acknowledgment is received and the 'localSettings' event is emitted. It is possible to send multiple SETTINGS frames while acknowledgment is still pending.

http2session.type#

• Value: <number>

The http2session.type will be equal to http2.constants.NGHTTP2_SESSION_SERVER if this Http2Session instance is a server, and http2.constants.NGHTTP2_SESSION_CLIENT if the instance is a client.

http2session.unref()#

Calls unref() on this Http2Session instance's underlying net.Socket.

Class: ServerHttp2Session#

serverhttp2session.altsvc(alt, originOrStream)#

• alt <string> A description of the alternative service configuration as defined by RFC 7838.
• originOrStream <number> | <string> | <URL> | <Object> Either a URL string specifying the origin (or an Object with an origin property) or the numeric identifier of an active Http2Stream as given by the http2stream.id property.

Submits an ALTSVC frame (as defined by RFC 7838) to the connected client.

const http2 = require('http2');

const server = http2.createServer();
server.on('session', (session) => {
  // Set altsvc for origin https://example.org:80
  session.altsvc('h2=":8000"', 'https://example.org:80');
});

server.on('stream', (stream) => {
  // Set altsvc for a specific stream
  stream.session.altsvc('h2=":8000"', stream.id);
});

Sending an ALTSVC frame with a specific stream ID indicates that the alternate service is associated with the origin of the given Http2Stream.

The alt and origin string must contain only ASCII bytes and are strictly interpreted as a sequence of ASCII bytes. The special value 'clear' may be passed to clear any previously set alternative service for a given domain.

When a string is passed for the originOrStream argument, it will be parsed as a URL and the origin will be derived. For instance, the origin for the HTTP URL 'https://example.org/foo/bar' is the ASCII string 'https://example.org'. An error will be thrown if either the given string cannot be parsed as a URL or if a valid origin cannot be derived.

A URL object, or any object with an origin property, may be passed as originOrStream, in which case the value of the origin property will be used. The value of the origin property must be a properly serialized ASCII origin.

Specifying alternative services#

The format of the alt parameter is strictly defined by RFC 7838 as an ASCII string containing a comma-delimited list of "alternative" protocols associated with a specific host and port.

For example, the value 'h2="example.org:81"' indicates that the HTTP/2 protocol is available on the host 'example.org' on TCP/IP port 81. The host and port must be contained within the quote (") characters.

Multiple alternatives may be specified, for instance: 'h2="example.org:81", h2=":82"'

The protocol identifier ('h2' in the examples) may be any valid ALPN Protocol ID.

The syntax of these values is not validated by the Node.js implementation and are passed through as provided by the user or received from the peer.

Class: ClientHttp2Session#

Event: 'altsvc'#

The 'altsvc' event is emitted whenever an ALTSVC frame is received by the client. The event is emitted with the ALTSVC value, origin, and stream ID, if any. If no origin is provided in the ALTSVC frame, origin will be an empty string.

const http2 = require('http2');
const client = http2.connect('https://example.org');

client.on('altsvc', (alt, origin, stream) => {
  console.log(alt);
  console.log(origin);
  console.log(stream);
});

clienthttp2session.request(headers[, options])#

• headers <Headers Object>

• options <Object>

  • endStream <boolean> true if the Http2Stream writable side should be closed initially, such as when sending a GET request that should not expect a payload body.
  • exclusive <boolean> When true and parent identifies a parent Stream, the created stream is made the sole direct dependency of the parent, with all other existing dependents made a dependent of the newly created stream. Default: false
  • parent <number> Specifies the numeric identifier of a stream the newly created stream is dependent on.
  • weight <number> Specifies the relative dependency of a stream in relation to other streams with the same parent. The value is a number between 1 and 256 (inclusive).
  • getTrailers <Function> Callback function invoked to collect trailer headers.

• Returns: <ClientHttp2Stream>

For HTTP/2 Client Http2Session instances only, the http2session.request() creates and returns an Http2Stream instance that can be used to send an HTTP/2 request to the connected server.

This method is only available if http2session.type is equal to http2.constants.NGHTTP2_SESSION_CLIENT.

const http2 = require('http2');
const clientSession = http2.connect('https://localhost:1234');
const {
  HTTP2_HEADER_PATH,
  HTTP2_HEADER_STATUS
} = http2.constants;

const req = clientSession.request({ [HTTP2_HEADER_PATH]: '/' });
req.on('response', (headers) => {
  console.log(headers[HTTP2_HEADER_STATUS]);
  req.on('data', (chunk) => { /** .. **/ });
  req.on('end', () => { /** .. **/ });
});

When set, the options.getTrailers() function is called immediately after queuing the last chunk of payload data to be sent. The callback is passed a single object (with a null prototype) that the listener may use to specify the trailing header fields to send to the peer.

Note: The HTTP/1 specification forbids trailers from containing HTTP/2 pseudo-header fields (e.g. ':method', ':path', etc). An 'error' event will be emitted if the getTrailers callback attempts to set such header fields.

The :method and :path pseudo-headers are not specified within headers, they respectively default to:

• :method = 'GET'
• :path = /

Class: Http2Stream#

• Extends: <Duplex>

Each instance of the Http2Stream class represents a bidirectional HTTP/2 communications stream over an Http2Session instance. Any single Http2Session may have up to 2³¹-1 Http2Stream instances over its lifetime.

User code will not construct Http2Stream instances directly. Rather, these are created, managed, and provided to user code through the Http2Session instance. On the server, Http2Stream instances are created either in response to an incoming HTTP request (and handed off to user code via the 'stream' event), or in response to a call to the http2stream.pushStream() method. On the client, Http2Stream instances are created and returned when either the http2session.request() method is called, or in response to an incoming 'push' event.

Note: The Http2Stream class is a base for the ServerHttp2Stream and ClientHttp2Stream classes, each of which is used specifically by either the Server or Client side, respectively.

All Http2Stream instances are Duplex streams. The Writable side of the Duplex is used to send data to the connected peer, while the Readable side is used to receive data sent by the connected peer.

Http2Stream Lifecycle#

Creation#

On the server side, instances of ServerHttp2Stream are created either when:

• A new HTTP/2 HEADERS frame with a previously unused stream ID is received;
• The http2stream.pushStream() method is called.

On the client side, instances of ClientHttp2Stream are created when the http2session.request() method is called.

Note: On the client, the Http2Stream instance returned by http2session.request() may not be immediately ready for use if the parent Http2Session has not yet been fully established. In such cases, operations called on the Http2Stream will be buffered until the 'ready' event is emitted. User code should rarely, if ever, need to handle the 'ready' event directly. The ready status of an Http2Stream can be determined by checking the value of http2stream.id. If the value is undefined, the stream is not yet ready for use.

Destruction#

All Http2Stream instances are destroyed either when:

• An RST_STREAM frame for the stream is received by the connected peer.
• The http2stream.close() method is called.
• The http2stream.destroy() or http2session.destroy() methods are called.

When an Http2Stream instance is destroyed, an attempt will be made to send an RST_STREAM frame will be sent to the connected peer.

When the Http2Stream instance is destroyed, the 'close' event will be emitted. Because Http2Stream is an instance of stream.Duplex, the 'end' event will also be emitted if the stream data is currently flowing. The 'error' event may also be emitted if http2stream.destroy() was called with an Error passed as the first argument.

After the Http2Stream has been destroyed, the http2stream.destroyed property will be true and the http2stream.rstCode property will specify the RST_STREAM error code. The Http2Stream instance is no longer usable once destroyed.

Event: 'aborted'#

The 'aborted' event is emitted whenever a Http2Stream instance is abnormally aborted in mid-communication.

Note: The 'aborted' event will only be emitted if the Http2Stream writable side has not been ended.

Event: 'close'#

The 'close' event is emitted when the Http2Stream is destroyed. Once this event is emitted, the Http2Stream instance is no longer usable.

The listener callback is passed a single argument specifying the HTTP/2 error code specified when closing the stream. If the code is any value other than NGHTTP2_NO_ERROR (0), an 'error' event will also be emitted.

Event: 'error'#

The 'error' event is emitted when an error occurs during the processing of an Http2Stream.

Event: 'frameError'#

The 'frameError' event is emitted when an error occurs while attempting to send a frame. When invoked, the handler function will receive an integer argument identifying the frame type, and an integer argument identifying the error code. The Http2Stream instance will be destroyed immediately after the 'frameError' event is emitted.

Event: 'timeout'#

The 'timeout' event is emitted after no activity is received for this 'Http2Stream' within the number of milliseconds set using http2stream.setTimeout().

Event: 'trailers'#

The 'trailers' event is emitted when a block of headers associated with trailing header fields is received. The listener callback is passed the Headers Object and flags associated with the headers.

stream.on('trailers', (headers, flags) => {
  console.log(headers);
});

http2stream.aborted#

• Value: <boolean>

Set to true if the Http2Stream instance was aborted abnormally. When set, the 'aborted' event will have been emitted.

http2stream.close(code[, callback])#

• code <number> Unsigned 32-bit integer identifying the error code. Default: http2.constant.NGHTTP2_NO_ERROR (0x00)
• callback <Function> An optional function registered to listen for the 'close' event.
• Returns: <undefined>

Closes the Http2Stream instance by sending an RST_STREAM frame to the connected HTTP/2 peer.

http2stream.closed#

• Value: <boolean>

Set to true if the Http2Stream instance has been closed.

http2stream.destroyed#

• Value: <boolean>

Set to true if the Http2Stream instance has been destroyed and is no longer usable.

http2stream.pending#

• Value: <boolean>

Set to true if the Http2Stream instance has not yet been assigned a numeric stream identifier.

http2stream.priority(options)#

• options <Object>
  • exclusive <boolean> When true and parent identifies a parent Stream, this stream is made the sole direct dependency of the parent, with all other existing dependents made a dependent of this stream. Default: false
  • parent <number> Specifies the numeric identifier of a stream this stream is dependent on.
  • weight <number> Specifies the relative dependency of a stream in relation to other streams with the same parent. The value is a number between 1 and 256 (inclusive).
  • silent <boolean> When true, changes the priority locally without sending a PRIORITY frame to the connected peer.
• Returns: <undefined>

Updates the priority for this Http2Stream instance.

http2stream.rstCode#

• Value: <number>

Set to the RST_STREAM error code reported when the Http2Stream is destroyed after either receiving an RST_STREAM frame from the connected peer, calling http2stream.close(), or http2stream.destroy(). Will be undefined if the Http2Stream has not been closed.

http2stream.session#

• Value: <Http2Session>

A reference to the Http2Session instance that owns this Http2Stream. The value will be undefined after the Http2Stream instance is destroyed.

http2stream.setTimeout(msecs, callback)#

• msecs <number>
• callback <Function>
• Returns: <undefined>

const http2 = require('http2');
const client = http2.connect('http://example.org:8000');
const { NGHTTP2_CANCEL } = http2.constants;
const req = client.request({ ':path': '/' });

// Cancel the stream if there's no activity after 5 seconds
req.setTimeout(5000, () => req.rstStream(NGHTTP2_CANCEL));

http2stream.state#

• Value: <Object>
  • localWindowSize <number>
  • state <number>
  • localClose <number>
  • remoteClose <number>
  • sumDependencyWeight <number>
  • weight <number>

A current state of this Http2Stream.

Class: ClientHttp2Stream#

• Extends <Http2Stream>

The ClientHttp2Stream class is an extension of Http2Stream that is used exclusively on HTTP/2 Clients. Http2Stream instances on the client provide events such as 'response' and 'push' that are only relevant on the client.

Event: 'continue'#

Emitted when the server sends a 100 Continue status, usually because the request contained Expect: 100-continue. This is an instruction that the client should send the request body.

Event: 'headers'#

The 'headers' event is emitted when an additional block of headers is received for a stream, such as when a block of 1xx informational headers is received. The listener callback is passed the Headers Object and flags associated with the headers.

stream.on('headers', (headers, flags) => {
  console.log(headers);
});

Event: 'push'#

The 'push' event is emitted when response headers for a Server Push stream are received. The listener callback is passed the Headers Object and flags associated with the headers.

stream.on('push', (headers, flags) => {
  console.log(headers);
});

Event: 'response'#

The 'response' event is emitted when a response HEADERS frame has been received for this stream from the connected HTTP/2 server. The listener is invoked with two arguments: an Object containing the received Headers Object, and flags associated with the headers.

For example:

const http2 = require('http2');
const client = http2.connect('https://localhost');
const req = client.request({ ':path': '/' });
req.on('response', (headers, flags) => {
  console.log(headers[':status']);
});

Class: ServerHttp2Stream#

• Extends: <Http2Stream>

The ServerHttp2Stream class is an extension of Http2Stream that is used exclusively on HTTP/2 Servers. Http2Stream instances on the server provide additional methods such as http2stream.pushStream() and http2stream.respond() that are only relevant on the server.

http2stream.additionalHeaders(headers)#

• headers <Headers Object>
• Returns: <undefined>

Sends an additional informational HEADERS frame to the connected HTTP/2 peer.

http2stream.headersSent#

• Value: <boolean>

Boolean (read-only). True if headers were sent, false otherwise.

http2stream.pushAllowed#

• Value: <boolean>

Read-only property mapped to the SETTINGS_ENABLE_PUSH flag of the remote client's most recent SETTINGS frame. Will be true if the remote peer accepts push streams, false otherwise. Settings are the same for every Http2Stream in the same Http2Session.

http2stream.pushStream(headers[, options], callback)#

• headers <Headers Object>
• options <Object>
  • exclusive <boolean> When true and parent identifies a parent Stream, the created stream is made the sole direct dependency of the parent, with all other existing dependents made a dependent of the newly created stream. Default: false
  • parent <number> Specifies the numeric identifier of a stream the newly created stream is dependent on.
• callback <Function> Callback that is called once the push stream has been initiated.
• Returns: <undefined>

Initiates a push stream. The callback is invoked with the new Http2Stream instance created for the push stream.

const http2 = require('http2');
const server = http2.createServer();
server.on('stream', (stream) => {
  stream.respond({ ':status': 200 });
  stream.pushStream({ ':path': '/' }, (pushStream) => {
    pushStream.respond({ ':status': 200 });
    pushStream.end('some pushed data');
  });
  stream.end('some data');
});

Setting the weight of a push stream is not allowed in the HEADERS frame. Pass a weight value to http2stream.priority with the silent option set to true to enable server-side bandwidth balancing between concurrent streams.

http2stream.respond([headers[, options]])#

• headers <Headers Object>
• options <Object>
  • endStream <boolean> Set to true to indicate that the response will not include payload data.
  • getTrailers <function> Callback function invoked to collect trailer headers.
• Returns: <undefined>

const http2 = require('http2');
const server = http2.createServer();
server.on('stream', (stream) => {
  stream.respond({ ':status': 200 });
  stream.end('some data');
});

When set, the options.getTrailers() function is called immediately after queuing the last chunk of payload data to be sent. The callback is passed a single object (with a null prototype) that the listener may use to specify the trailing header fields to send to the peer.

const http2 = require('http2');
const server = http2.createServer();
server.on('stream', (stream) => {
  stream.respond({ ':status': 200 }, {
    getTrailers(trailers) {
      trailers['ABC'] = 'some value to send';
    }
  });
  stream.end('some data');
});

Note: The HTTP/1 specification forbids trailers from containing HTTP/2 pseudo-header fields (e.g. ':status', ':path', etc). An 'error' event will be emitted if the getTrailers callback attempts to set such header fields.

http2stream.respondWithFD(fd[, headers[, options]])#

• fd <number> A readable file descriptor.
• headers <Headers Object>
• options <Object>
  • statCheck <Function>
  • getTrailers <Function> Callback function invoked to collect trailer headers.
  • offset <number> The offset position at which to begin reading.
  • length <number> The amount of data from the fd to send.

Initiates a response whose data is read from the given file descriptor. No validation is performed on the given file descriptor. If an error occurs while attempting to read data using the file descriptor, the Http2Stream will be closed using an RST_STREAM frame using the standard INTERNAL_ERROR code.

When used, the Http2Stream object's Duplex interface will be closed automatically.

const http2 = require('http2');
const fs = require('fs');

const fd = fs.openSync('/some/file', 'r');

const server = http2.createServer();
server.on('stream', (stream) => {
  const stat = fs.fstatSync(fd);
  const headers = {
    'content-length': stat.size,
    'last-modified': stat.mtime.toUTCString(),
    'content-type': 'text/plain'
  };
  stream.respondWithFD(fd, headers);
});
server.on('close', () => fs.closeSync(fd));

The optional options.statCheck function may be specified to give user code an opportunity to set additional content headers based on the fs.Stat details of the given fd. If the statCheck function is provided, the http2stream.respondWithFD() method will perform an fs.fstat() call to collect details on the provided file descriptor.

The offset and length options may be used to limit the response to a specific range subset. This can be used, for instance, to support HTTP Range requests.

When set, the options.getTrailers() function is called immediately after queuing the last chunk of payload data to be sent. The callback is passed a single object (with a null prototype) that the listener may use to specify the trailing header fields to send to the peer.

const http2 = require('http2');
const fs = require('fs');

const fd = fs.openSync('/some/file', 'r');

const server = http2.createServer();
server.on('stream', (stream) => {
  const stat = fs.fstatSync(fd);
  const headers = {
    'content-length': stat.size,
    'last-modified': stat.mtime.toUTCString(),
    'content-type': 'text/plain'
  };
  stream.respondWithFD(fd, headers, {
    getTrailers(trailers) {
      trailers['ABC'] = 'some value to send';
    }
  });
});
server.on('close', () => fs.closeSync(fd));

Note: The HTTP/1 specification forbids trailers from containing HTTP/2 pseudo-header fields (e.g. ':status', ':path', etc). An 'error' event will be emitted if the getTrailers callback attempts to set such header fields.

http2stream.respondWithFile(path[, headers[, options]])#

• path <string> | <Buffer> | <URL>
• headers <Headers Object>
• options <Object>
  • statCheck <Function>
  • onError <Function> Callback function invoked in the case of an Error before send.
  • getTrailers <Function> Callback function invoked to collect trailer headers.
  • offset <number> The offset position at which to begin reading.
  • length <number> The amount of data from the fd to send.

Sends a regular file as the response. The path must specify a regular file or an 'error' event will be emitted on the Http2Stream object.

When used, the Http2Stream object's Duplex interface will be closed automatically.

The optional options.statCheck function may be specified to give user code an opportunity to set additional content headers based on the fs.Stat details of the given file:

If an error occurs while attempting to read the file data, the Http2Stream will be closed using an RST_STREAM frame using the standard INTERNAL_ERROR code. If the onError callback is defined, then it will be called. Otherwise the stream will be destroyed.

Example using a file path:

const http2 = require('http2');
const server = http2.createServer();
server.on('stream', (stream) => {
  function statCheck(stat, headers) {
    headers['last-modified'] = stat.mtime.toUTCString();
  }

  function onError(err) {
    if (err.code === 'ENOENT') {
      stream.respond({ ':status': 404 });
    } else {
      stream.respond({ ':status': 500 });
    }
    stream.end();
  }

  stream.respondWithFile('/some/file',
                         { 'content-type': 'text/plain' },
                         { statCheck, onError });
});

The options.statCheck function may also be used to cancel the send operation by returning false. For instance, a conditional request may check the stat results to determine if the file has been modified to return an appropriate 304 response:

const http2 = require('http2');
const server = http2.createServer();
server.on('stream', (stream) => {
  function statCheck(stat, headers) {
    // Check the stat here...
    stream.respond({ ':status': 304 });
    return false; // Cancel the send operation
  }
  stream.respondWithFile('/some/file',
                         { 'content-type': 'text/plain' },
                         { statCheck });
});

The content-length header field will be automatically set.

The offset and length options may be used to limit the response to a specific range subset. This can be used, for instance, to support HTTP Range requests.

The options.onError function may also be used to handle all the errors that could happen before the delivery of the file is initiated. The default behavior is to destroy the stream.

When set, the options.getTrailers() function is called immediately after queuing the last chunk of payload data to be sent. The callback is passed a single object (with a null prototype) that the listener may use to specify the trailing header fields to send to the peer.

const http2 = require('http2');
const server = http2.createServer();
server.on('stream', (stream) => {
  function getTrailers(trailers) {
    trailers['ABC'] = 'some value to send';
  }
  stream.respondWithFile('/some/file',
                         { 'content-type': 'text/plain' },
                         { getTrailers });
});

Note: The HTTP/1 specification forbids trailers from containing HTTP/2 pseudo-header fields (e.g. ':status', ':path', etc). An 'error' event will be emitted if the getTrailers callback attempts to set such header fields.

Class: Http2Server#

• Extends: <net.Server>

In Http2Server, there is no 'clientError' event as there is in HTTP1. However, there are 'socketError', 'sessionError', and 'streamError', for errors emitted on the socket, Http2Session, or Http2Stream.

Event: 'checkContinue'#

• request <http2.Http2ServerRequest>
• response <http2.Http2ServerResponse>

If a 'request' listener is registered or http2.createServer() is supplied a callback function, the 'checkContinue' event is emitted each time a request with an HTTP Expect: 100-continue is received. If this event is not listened for, the server will automatically respond with a status 100 Continue as appropriate.

Handling this event involves calling response.writeContinue() if the client should continue to send the request body, or generating an appropriate HTTP response (e.g. 400 Bad Request) if the client should not continue to send the request body.

Note that when this event is emitted and handled, the 'request' event will not be emitted.

Event: 'request'#

• request <http2.Http2ServerRequest>
• response <http2.Http2ServerResponse>

Emitted each time there is a request. Note that there may be multiple requests per session. See the Compatibility API.

Event: 'session'#

The 'session' event is emitted when a new Http2Session is created by the Http2Server.

Event: 'sessionError'#

The 'sessionError' event is emitted when an 'error' event is emitted by an Http2Session object associated with the Http2Server.

Event: 'streamError'#

If a ServerHttp2Stream emits an 'error' event, it will be forwarded here. The stream will already be destroyed when this event is triggered.

Event: 'stream'#

The 'stream' event is emitted when a 'stream' event has been emitted by an Http2Session associated with the server.

const http2 = require('http2');
const {
  HTTP2_HEADER_METHOD,
  HTTP2_HEADER_PATH,
  HTTP2_HEADER_STATUS,
  HTTP2_HEADER_CONTENT_TYPE
} = http2.constants;

const server = http2.createServer();
server.on('stream', (stream, headers, flags) => {
  const method = headers[HTTP2_HEADER_METHOD];
  const path = headers[HTTP2_HEADER_PATH];
  // ...
  stream.respond({
    [HTTP2_HEADER_STATUS]: 200,
    [HTTP2_HEADER_CONTENT_TYPE]: 'text/plain'
  });
  stream.write('hello ');
  stream.end('world');
});

Event: 'timeout'#

The 'timeout' event is emitted when there is no activity on the Server for a given number of milliseconds set using http2server.setTimeout().

Class: Http2SecureServer#

• Extends: <tls.Server>

Event: 'sessionError'#

The 'sessionError' event is emitted when an 'error' event is emitted by an Http2Session object associated with the Http2SecureServer.

Event: 'unknownProtocol'#

The 'unknownProtocol' event is emitted when a connecting client fails to negotiate an allowed protocol (i.e. HTTP/2 or HTTP/1.1). The event handler receives the socket for handling. If no listener is registered for this event, the connection is terminated. See the Compatibility API.

Event: 'stream'#

The 'stream' event is emitted when a 'stream' event has been emitted by an Http2Session associated with the server.

const http2 = require('http2');
const {
  HTTP2_HEADER_METHOD,
  HTTP2_HEADER_PATH,
  HTTP2_HEADER_STATUS,
  HTTP2_HEADER_CONTENT_TYPE
} = http2.constants;

const options = getOptionsSomehow();

const server = http2.createSecureServer(options);
server.on('stream', (stream, headers, flags) => {
  const method = headers[HTTP2_HEADER_METHOD];
  const path = headers[HTTP2_HEADER_PATH];
  // ...
  stream.respond({
    [HTTP2_HEADER_STATUS]: 200,
    [HTTP2_HEADER_CONTENT_TYPE]: 'text/plain'
  });
  stream.write('hello ');
  stream.end('world');
});

Event: 'request'#

• request <http2.Http2ServerRequest>
• response <http2.Http2ServerResponse>

Emitted each time there is a request. Note that there may be multiple requests per session. See the Compatibility API.

Event: 'timeout'#

Event: 'checkContinue'#

• request <http2.Http2ServerRequest>
• response <http2.Http2ServerResponse>

If a 'request' listener is registered or http2.createSecureServer() is supplied a callback function, the 'checkContinue' event is emitted each time a request with an HTTP Expect: 100-continue is received. If this event is not listened for, the server will automatically respond with a status 100 Continue as appropriate.

Handling this event involves calling response.writeContinue() if the client should continue to send the request body, or generating an appropriate HTTP response (e.g. 400 Bad Request) if the client should not continue to send the request body.

Note that when this event is emitted and handled, the 'request' event will not be emitted.

http2.createServer(options[, onRequestHandler])#

• options <Object>
  • maxDeflateDynamicTableSize <number> Sets the maximum dynamic table size for deflating header fields. Default: 4Kib
  • maxSessionMemory <number> Sets the maximum memory that the Http2Session is permitted to use. The value is expressed in terms of number of megabytes, e.g. 1 equal 1 megabyte. The minimum value allowed is 1. Default: 10. This is a credit based limit, existing Http2Streams may cause this limit to be exceeded, but new Http2Stream instances will be rejected while this limit is exceeded. The current number of Http2Stream sessions, the current memory use of the header compression tables, current data queued to be sent, and unacknowledged PING and SETTINGS frames are all counted towards the current limit.
  • maxHeaderListPairs <number> Sets the maximum number of header entries. Default: 128. The minimum value is 4.
  • maxOutstandingPings <number> Sets the maximum number of outstanding, unacknowledged pings. The default is 10.
  • maxSendHeaderBlockLength <number> Sets the maximum allowed size for a serialized, compressed block of headers. Attempts to send headers that exceed this limit will result in a 'frameError' event being emitted and the stream being closed and destroyed.
  • paddingStrategy <number> Identifies the strategy used for determining the amount of padding to use for HEADERS and DATA frames. Default: http2.constants.PADDING_STRATEGY_NONE. Value may be one of:
    • http2.constants.PADDING_STRATEGY_NONE - Specifies that no padding is to be applied.
    • http2.constants.PADDING_STRATEGY_MAX - Specifies that the maximum amount of padding, as determined by the internal implementation, is to be applied.
    • http2.constants.PADDING_STRATEGY_CALLBACK - Specifies that the user provided options.selectPadding callback is to be used to determine the amount of padding.
    • http2.constants.PADDING_STRATEGY_ALIGNED - Will attempt to apply enough padding to ensure that the total frame length, including the 9-byte header, is a multiple of 8. For each frame, however, there is a maximum allowed number of padding bytes that is determined by current flow control state and settings. If this maximum is less than the calculated amount needed to ensure alignment, the maximum will be used and the total frame length will not necessarily be aligned at 8 bytes.
  • peerMaxConcurrentStreams <number> Sets the maximum number of concurrent streams for the remote peer as if a SETTINGS frame had been received. Will be overridden if the remote peer sets its own value for. maxConcurrentStreams. Default 100
  • selectPadding <Function> When options.paddingStrategy is equal to http2.constants.PADDING_STRATEGY_CALLBACK, provides the callback function used to determine the padding. See Using options.selectPadding.
  • settings <Settings Object> The initial settings to send to the remote peer upon connection.
• onRequestHandler <Function> See Compatibility API
• Returns: <Http2Server>

Returns a net.Server instance that creates and manages Http2Session instances.

const http2 = require('http2');

// Create a plain-text HTTP/2 server
const server = http2.createServer();

server.on('stream', (stream, headers) => {
  stream.respond({
    'content-type': 'text/html',
    ':status': 200
  });
  stream.end('<h1>Hello World</h1>');
});

server.listen(80);

http2.createSecureServer(options[, onRequestHandler])#

• options <Object>
  • allowHTTP1 <boolean> Incoming client connections that do not support HTTP/2 will be downgraded to HTTP/1.x when set to true. Default: false. See the 'unknownProtocol' event. See ALPN negotiation.
  • maxDeflateDynamicTableSize <number> Sets the maximum dynamic table size for deflating header fields. Default: 4Kib
  • maxSessionMemory <number> Sets the maximum memory that the Http2Session is permitted to use. The value is expressed in terms of number of megabytes, e.g. 1 equal 1 megabyte. The minimum value allowed is 1. Default: 10. This is a credit based limit, existing Http2Streams may cause this limit to be exceeded, but new Http2Stream instances will be rejected while this limit is exceeded. The current number of Http2Stream sessions, the current memory use of the header compression tables, current data queued to be sent, and unacknowledged PING and SETTINGS frames are all counted towards the current limit.
  • maxHeaderListPairs <number> Sets the maximum number of header entries. Default: 128. The minimum value is 4.
  • maxOutstandingPings <number> Sets the maximum number of outstanding, unacknowledged pings. The default is 10.
  • maxSendHeaderBlockLength <number> Sets the maximum allowed size for a serialized, compressed block of headers. Attempts to send headers that exceed this limit will result in a 'frameError' event being emitted and the stream being closed and destroyed.
  • paddingStrategy <number> Identifies the strategy used for determining the amount of padding to use for HEADERS and DATA frames. Default: http2.constants.PADDING_STRATEGY_NONE. Value may be one of:
    • http2.constants.PADDING_STRATEGY_NONE - Specifies that no padding is to be applied.
    • http2.constants.PADDING_STRATEGY_MAX - Specifies that the maximum amount of padding, as determined by the internal implementation, is to be applied.
    • http2.constants.PADDING_STRATEGY_CALLBACK - Specifies that the user provided options.selectPadding callback is to be used to determine the amount of padding.
    • http2.constants.PADDING_STRATEGY_ALIGNED - Will attempt to apply enough padding to ensure that the total frame length, including the 9-byte header, is a multiple of 8. For each frame, however, there is a maximum allowed number of padding bytes that is determined by current flow control state and settings. If this maximum is less than the calculated amount needed to ensure alignment, the maximum will be used and the total frame length will not necessarily be aligned at 8 bytes.
  • peerMaxConcurrentStreams <number> Sets the maximum number of concurrent streams for the remote peer as if a SETTINGS frame had been received. Will be overridden if the remote peer sets its own value for maxConcurrentStreams. Default: 100
  • selectPadding <Function> When options.paddingStrategy is equal to http2.constants.PADDING_STRATEGY_CALLBACK, provides the callback function used to determine the padding. See Using options.selectPadding.
  • settings <Settings Object> The initial settings to send to the remote peer upon connection.
  • ...: Any tls.createServer() options can be provided. For servers, the identity options (pfx or key/cert) are usually required.
• onRequestHandler <Function> See Compatibility API
• Returns <Http2SecureServer>

Returns a tls.Server instance that creates and manages Http2Session instances.

const http2 = require('http2');

const options = {
  key: fs.readFileSync('server-key.pem'),
  cert: fs.readFileSync('server-cert.pem')
};

// Create a secure HTTP/2 server
const server = http2.createSecureServer(options);

server.on('stream', (stream, headers) => {
  stream.respond({
    'content-type': 'text/html',
    ':status': 200
  });
  stream.end('<h1>Hello World</h1>');
});

server.listen(80);

http2.connect(authority[, options][, listener])#

• authority <string> | <URL>
• options <Object>
  • maxDeflateDynamicTableSize <number> Sets the maximum dynamic table size for deflating header fields. Default: 4Kib
  • maxSessionMemory <number> Sets the maximum memory that the Http2Session is permitted to use. The value is expressed in terms of number of megabytes, e.g. 1 equal 1 megabyte. The minimum value allowed is 1. Default: 10. This is a credit based limit, existing Http2Streams may cause this limit to be exceeded, but new Http2Stream instances will be rejected while this limit is exceeded. The current number of Http2Stream sessions, the current memory use of the header compression tables, current data queued to be sent, and unacknowledged PING and SETTINGS frames are all counted towards the current limit.
  • maxHeaderListPairs <number> Sets the maximum number of header entries. Default: 128. The minimum value is 1.
  • maxOutstandingPings <number> Sets the maximum number of outstanding, unacknowledged pings. The default is 10.
  • maxReservedRemoteStreams <number> Sets the maximum number of reserved push streams the client will accept at any given time. Once the current number of currently reserved push streams exceeds reaches this limit, new push streams sent by the server will be automatically rejected.
  • maxSendHeaderBlockLength <number> Sets the maximum allowed size for a serialized, compressed block of headers. Attempts to send headers that exceed this limit will result in a 'frameError' event being emitted and the stream being closed and destroyed.
  • paddingStrategy <number> Identifies the strategy used for determining the amount of padding to use for HEADERS and DATA frames. Default: http2.constants.PADDING_STRATEGY_NONE. Value may be one of:
    • http2.constants.PADDING_STRATEGY_NONE - Specifies that no padding is to be applied.
    • http2.constants.PADDING_STRATEGY_MAX - Specifies that the maximum amount of padding, as determined by the internal implementation, is to be applied.
    • http2.constants.PADDING_STRATEGY_CALLBACK - Specifies that the user provided options.selectPadding callback is to be used to determine the amount of padding.
    • http2.constants.PADDING_STRATEGY_ALIGNED - Will attempt to apply enough padding to ensure that the total frame length, including the 9-byte header, is a multiple of 8. For each frame, however, there is a maximum allowed number of padding bytes that is determined by current flow control state and settings. If this maximum is less than the calculated amount needed to ensure alignment, the maximum will be used and the total frame length will not necessarily be aligned at 8 bytes.
  • peerMaxConcurrentStreams <number> Sets the maximum number of concurrent streams for the remote peer as if a SETTINGS frame had been received. Will be overridden if the remote peer sets its own value for maxConcurrentStreams. Default: 100
  • selectPadding <Function> When options.paddingStrategy is equal to http2.constants.PADDING_STRATEGY_CALLBACK, provides the callback function used to determine the padding. See Using options.selectPadding.
  • settings <Settings Object> The initial settings to send to the remote peer upon connection.
  • createConnection <Function> An optional callback that receives the URL instance passed to connect and the options object, and returns any Duplex stream that is to be used as the connection for this session.
  • ...: Any net.connect() or tls.connect() options can be provided.
• listener <Function>
• Returns <ClientHttp2Session>

Returns a ClientHttp2Session instance.

const http2 = require('http2');
const client = http2.connect('https://localhost:1234');

/** use the client **/

client.close();

http2.constants#

Error Codes for RST_STREAM and GOAWAY#

Value	Name	Constant
0x00	No Error	http2.constants.NGHTTP2_NO_ERROR
0x01	Protocol Error	http2.constants.NGHTTP2_PROTOCOL_ERROR
0x02	Internal Error	http2.constants.NGHTTP2_INTERNAL_ERROR
0x03	Flow Control Error	http2.constants.NGHTTP2_FLOW_CONTROL_ERROR
0x04	Settings Timeout	http2.constants.NGHTTP2_SETTINGS_TIMEOUT
0x05	Stream Closed	http2.constants.NGHTTP2_STREAM_CLOSED
0x06	Frame Size Error	http2.constants.NGHTTP2_FRAME_SIZE_ERROR
0x07	Refused Stream	http2.constants.NGHTTP2_REFUSED_STREAM
0x08	Cancel	http2.constants.NGHTTP2_CANCEL
0x09	Compression Error	http2.constants.NGHTTP2_COMPRESSION_ERROR
0x0a	Connect Error	http2.constants.NGHTTP2_CONNECT_ERROR
0x0b	Enhance Your Calm	http2.constants.NGHTTP2_ENHANCE_YOUR_CALM
0x0c	Inadequate Security	http2.constants.NGHTTP2_INADEQUATE_SECURITY
0x0d	HTTP/1.1 Required	http2.constants.NGHTTP2_HTTP_1_1_REQUIRED

The 'timeout' event is emitted when there is no activity on the Server for a given number of milliseconds set using http2server.setTimeout().

http2.getDefaultSettings()#

• Returns: <Settings Object>

Returns an object containing the default settings for an Http2Session instance. This method returns a new object instance every time it is called so instances returned may be safely modified for use.

http2.getPackedSettings(settings)#

• settings <Settings Object>
• Returns: <Buffer>

Returns a Buffer instance containing serialized representation of the given HTTP/2 settings as specified in the HTTP/2 specification. This is intended for use with the HTTP2-Settings header field.

const http2 = require('http2');

const packed = http2.getPackedSettings({ enablePush: false });

console.log(packed.toString('base64'));
// Prints: AAIAAAAA

http2.getUnpackedSettings(buf)#

• buf <Buffer> | <Uint8Array> The packed settings.
• Returns: <Settings Object>

Returns a Settings Object containing the deserialized settings from the given Buffer as generated by http2.getPackedSettings().

Headers Object#

Headers are represented as own-properties on JavaScript objects. The property keys will be serialized to lower-case. Property values should be strings (if they are not they will be coerced to strings) or an Array of strings (in order to send more than one value per header field).

For example:

const headers = {
  ':status': '200',
  'content-type': 'text-plain',
  'ABC': ['has', 'more', 'than', 'one', 'value']
};

stream.respond(headers);

Note: Header objects passed to callback functions will have a null prototype. This means that normal JavaScript object methods such as Object.prototype.toString() and Object.prototype.hasOwnProperty() will not work.

const http2 = require('http2');
const server = http2.createServer();
server.on('stream', (stream, headers) => {
  console.log(headers[':path']);
  console.log(headers.ABC);
});

Settings Object#

The http2.getDefaultSettings(), http2.getPackedSettings(), http2.createServer(), http2.createSecureServer(), http2session.settings(), http2session.localSettings, and http2session.remoteSettings APIs either return or receive as input an object that defines configuration settings for an Http2Session object. These objects are ordinary JavaScript objects containing the following properties.

• headerTableSize <number> Specifies the maximum number of bytes used for header compression. Default: 4,096 octets. The minimum allowed value is 0. The maximum allowed value is 2³²-1.
• enablePush <boolean> Specifies true if HTTP/2 Push Streams are to be permitted on the Http2Session instances.
• initialWindowSize <number> Specifies the senders initial window size for stream-level flow control. Default: 65,535 bytes. The minimum allowed value is 0. The maximum allowed value is 2³²-1.
• maxFrameSize <number> Specifies the size of the largest frame payload. Default: 16,384 bytes. The minimum allowed value is 16,384. The maximum allowed value is 2²⁴-1.
• maxConcurrentStreams <number> Specifies the maximum number of concurrent streams permitted on an Http2Session. There is no default value which implies, at least theoretically, 2³¹-1 streams may be open concurrently at any given time in an Http2Session. The minimum value is
  1. The maximum allowed value is 2³¹-1.
• maxHeaderListSize <number> Specifies the maximum size (uncompressed octets) of header list that will be accepted. The minimum allowed value is 0. The maximum allowed value is 2³²-1. Default: 65535.

All additional properties on the settings object are ignored.

Using options.selectPadding#

When options.paddingStrategy is equal to http2.constants.PADDING_STRATEGY_CALLBACK, the HTTP/2 implementation will consult the options.selectPadding callback function, if provided, to determine the specific amount of padding to use per HEADERS and DATA frame.

The options.selectPadding function receives two numeric arguments, frameLen and maxFrameLen and must return a number N such that frameLen <= N <= maxFrameLen.

const http2 = require('http2');
const server = http2.createServer({
  paddingStrategy: http2.constants.PADDING_STRATEGY_CALLBACK,
  selectPadding(frameLen, maxFrameLen) {
    return maxFrameLen;
  }
});

Note: The options.selectPadding function is invoked once for every HEADERS and DATA frame. This has a definite noticeable impact on performance.

Error Handling#

There are several types of error conditions that may arise when using the http2 module:

Validation Errors occur when an incorrect argument, option, or setting value is passed in. These will always be reported by a synchronous throw.

State Errors occur when an action is attempted at an incorrect time (for instance, attempting to send data on a stream after it has closed). These will be reported using either a synchronous throw or via an 'error' event on the Http2Stream, Http2Session or HTTP/2 Server objects, depending on where and when the error occurs.

Internal Errors occur when an HTTP/2 session fails unexpectedly. These will be reported via an 'error' event on the Http2Session or HTTP/2 Server objects.

Protocol Errors occur when various HTTP/2 protocol constraints are violated. These will be reported using either a synchronous throw or via an 'error' event on the Http2Stream, Http2Session or HTTP/2 Server objects, depending on where and when the error occurs.

Invalid character handling in header names and values#

The HTTP/2 implementation applies stricter handling of invalid characters in HTTP header names and values than the HTTP/1 implementation.

Header field names are case-insensitive and are transmitted over the wire strictly as lower-case strings. The API provided by Node.js allows header names to be set as mixed-case strings (e.g. Content-Type) but will convert those to lower-case (e.g. content-type) upon transmission.

Header field-names must only contain one or more of the following ASCII characters: a-z, A-Z, 0-9, !, #, $, %, &, ', *, +, -, ., ^, _, ` (backtick), |, and ~.

Using invalid characters within an HTTP header field name will cause the stream to be closed with a protocol error being reported.

Header field values are handled with more leniency but should not contain new-line or carriage return characters and should be limited to US-ASCII characters, per the requirements of the HTTP specification.

Push streams on the client#

To receive pushed streams on the client, set a listener for the 'stream' event on the ClientHttp2Session:

const http2 = require('http2');

const client = http2.connect('http://localhost');

client.on('stream', (pushedStream, requestHeaders) => {
  pushedStream.on('push', (responseHeaders) => {
    // process response headers
  });
  pushedStream.on('data', (chunk) => { /* handle pushed data */ });
});

const req = client.request({ ':path': '/' });

Supporting the CONNECT method#

The CONNECT method is used to allow an HTTP/2 server to be used as a proxy for TCP/IP connections.

A simple TCP Server:

const net = require('net');

const server = net.createServer((socket) => {
  let name = '';
  socket.setEncoding('utf8');
  socket.on('data', (chunk) => name += chunk);
  socket.on('end', () => socket.end(`hello ${name}`));
});

server.listen(8000);

An HTTP/2 CONNECT proxy:

const http2 = require('http2');
const { NGHTTP2_REFUSED_STREAM } = http2.constants;
const net = require('net');
const { URL } = require('url');

const proxy = http2.createServer();
proxy.on('stream', (stream, headers) => {
  if (headers[':method'] !== 'CONNECT') {
    // Only accept CONNECT requests
    stream.close(NGHTTP2_REFUSED_STREAM);
    return;
  }
  const auth = new URL(`tcp://${headers[':authority']}`);
  // It's a very good idea to verify that hostname and port are
  // things this proxy should be connecting to.
  const socket = net.connect(auth.port, auth.hostname, () => {
    stream.respond();
    socket.pipe(stream);
    stream.pipe(socket);
  });
  socket.on('error', (error) => {
    stream.close(http2.constants.NGHTTP2_CONNECT_ERROR);
  });
});

proxy.listen(8001);

An HTTP/2 CONNECT client:

const http2 = require('http2');

const client = http2.connect('http://localhost:8001');

// Must not specify the ':path' and ':scheme' headers
// for CONNECT requests or an error will be thrown.
const req = client.request({
  ':method': 'CONNECT',
  ':authority': `localhost:${port}`
});

req.on('response', (headers) => {
  console.log(headers[http2.constants.HTTP2_HEADER_STATUS]);
});
let data = '';
req.setEncoding('utf8');
req.on('data', (chunk) => data += chunk);
req.on('end', () => {
  console.log(`The server says: ${data}`);
  client.close();
});
req.end('Jane');

Compatibility API#

The Compatibility API has the goal of providing a similar developer experience of HTTP/1 when using HTTP/2, making it possible to develop applications that support both HTTP/1 and HTTP/2. This API targets only the public API of the HTTP/1. However many modules use internal methods or state, and those are not supported as it is a completely different implementation.

The following example creates an HTTP/2 server using the compatibility API:

const http2 = require('http2');
const server = http2.createServer((req, res) => {
  res.setHeader('Content-Type', 'text/html');
  res.setHeader('X-Foo', 'bar');
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('ok');
});

In order to create a mixed HTTPS and HTTP/2 server, refer to the ALPN negotiation section. Upgrading from non-tls HTTP/1 servers is not supported.

The HTTP2 compatibility API is composed of Http2ServerRequest and Http2ServerResponse. They aim at API compatibility with HTTP/1, but they do not hide the differences between the protocols. As an example, the status message for HTTP codes is ignored.

ALPN negotiation#

ALPN negotiation allows supporting both HTTPS and HTTP/2 over the same socket. The req and res objects can be either HTTP/1 or HTTP/2, and an application must restrict itself to the public API of HTTP/1, and detect if it is possible to use the more advanced features of HTTP/2.

The following example creates a server that supports both protocols:

const { createSecureServer } = require('http2');
const { readFileSync } = require('fs');

const cert = readFileSync('./cert.pem');
const key = readFileSync('./key.pem');

const server = createSecureServer(
  { cert, key, allowHTTP1: true },
  onRequest
).listen(4443);

function onRequest(req, res) {
  // detects if it is a HTTPS request or HTTP/2
  const { socket: { alpnProtocol } } = req.httpVersion === '2.0' ?
    req.stream.session : req;
  res.writeHead(200, { 'content-type': 'application/json' });
  res.end(JSON.stringify({
    alpnProtocol,
    httpVersion: req.httpVersion
  }));
}

The 'request' event works identically on both HTTPS and HTTP/2.

Class: http2.Http2ServerRequest#

A Http2ServerRequest object is created by http2.Server or http2.SecureServer and passed as the first argument to the 'request' event. It may be used to access a request status, headers, and data.

It implements the Readable Stream interface, as well as the following additional events, methods, and properties.

Event: 'aborted'#

The 'aborted' event is emitted whenever a Http2ServerRequest instance is abnormally aborted in mid-communication.

Note: The 'aborted' event will only be emitted if the Http2ServerRequest writable side has not been ended.

Event: 'close'#

Indicates that the underlying Http2Stream was closed. Just like 'end', this event occurs only once per response.

request.destroy([error])#

• error <Error>

Calls destroy() on the Http2Stream that received the Http2ServerRequest. If error is provided, an 'error' event is emitted and error is passed as an argument to any listeners on the event.

It does nothing if the stream was already destroyed.

request.headers#

• <Object>

The request/response headers object.

Key-value pairs of header names and values. Header names are lower-cased. Example:

// Prints something like:
//
// { 'user-agent': 'curl/7.22.0',
//   host: '127.0.0.1:8000',
//   accept: '*/*' }
console.log(request.headers);

See Headers Object.

Note: In HTTP/2, the request path, hostname, protocol, and method are represented as special headers prefixed with the : character (e.g. ':path'). These special headers will be included in the request.headers object. Care must be taken not to inadvertently modify these special headers or errors may occur. For instance, removing all headers from the request will cause errors to occur:

removeAllHeaders(request.headers);
assert(request.url);   // Fails because the :path header has been removed

request.httpVersion#

• <string>

In case of server request, the HTTP version sent by the client. In the case of client response, the HTTP version of the connected-to server. Returns '2.0'.

Also message.httpVersionMajor is the first integer and message.httpVersionMinor is the second.

request.method#

• <string>

The request method as a string. Read-only. Example: 'GET', 'DELETE'.

request.rawHeaders#

• <Array>

The raw request/response headers list exactly as they were received.

Note that the keys and values are in the same list. It is not a list of tuples. So, the even-numbered offsets are key values, and the odd-numbered offsets are the associated values.

Header names are not lowercased, and duplicates are not merged.

// Prints something like:
//
// [ 'user-agent',
//   'this is invalid because there can be only one',
//   'User-Agent',
//   'curl/7.22.0',
//   'Host',
//   '127.0.0.1:8000',
//   'ACCEPT',
//   '*/*' ]
console.log(request.rawHeaders);

request.rawTrailers#

• <Array>

The raw request/response trailer keys and values exactly as they were received. Only populated at the 'end' event.

request.setTimeout(msecs, callback)#

• msecs <number>
• callback <Function>

Sets the Http2Stream's timeout value to msecs. If a callback is provided, then it is added as a listener on the 'timeout' event on the response object.

If no 'timeout' listener is added to the request, the response, or the server, then Http2Streams are destroyed when they time out. If a handler is assigned to the request, the response, or the server's 'timeout' events, timed out sockets must be handled explicitly.

Returns request.

request.socket#

• <net.Socket> | <tls.TLSSocket>

Returns a Proxy object that acts as a net.Socket (or tls.TLSSocket) but applies getters, setters, and methods based on HTTP/2 logic.

destroyed, readable, and writable properties will be retrieved from and set on request.stream.

destroy, emit, end, on and once methods will be called on request.stream.

setTimeout method will be called on request.stream.session.

pause, read, resume, and write will throw an error with code ERR_HTTP2_NO_SOCKET_MANIPULATION. See Http2Session and Sockets for more information.

All other interactions will be routed directly to the socket. With TLS support, use request.socket.getPeerCertificate() to obtain the client's authentication details.

request.stream#

• <http2.Http2Stream>

The Http2Stream object backing the request.

request.trailers#

• <Object>

The request/response trailers object. Only populated at the 'end' event.

request.url#

• <string>

Request URL string. This contains only the URL that is present in the actual HTTP request. If the request is:

GET /status?name=ryan HTTP/1.1\r\n
Accept: text/plain\r\n
\r\n

Then request.url will be:

'/status?name=ryan'

To parse the url into its parts require('url').parse(request.url) can be used. Example:

$ node
> require('url').parse('/status?name=ryan')
Url {
  protocol: null,
  slashes: null,
  auth: null,
  host: null,
  port: null,
  hostname: null,
  hash: null,
  search: '?name=ryan',
  query: 'name=ryan',
  pathname: '/status',
  path: '/status?name=ryan',
  href: '/status?name=ryan' }

To extract the parameters from the query string, the require('querystring').parse function can be used, or true can be passed as the second argument to require('url').parse. Example:

$ node
> require('url').parse('/status?name=ryan', true)
Url {
  protocol: null,
  slashes: null,
  auth: null,
  host: null,
  port: null,
  hostname: null,
  hash: null,
  search: '?name=ryan',
  query: { name: 'ryan' },
  pathname: '/status',
  path: '/status?name=ryan',
  href: '/status?name=ryan' }

Class: http2.Http2ServerResponse#

This object is created internally by an HTTP server--not by the user. It is passed as the second parameter to the 'request' event.

The response implements, but does not inherit from, the Writable Stream interface. This is an EventEmitter with the following events:

Event: 'close'#

Indicates that the underlying Http2Stream was terminated before response.end() was called or able to flush.

Event: 'finish'#

Emitted when the response has been sent. More specifically, this event is emitted when the last segment of the response headers and body have been handed off to the HTTP/2 multiplexing for transmission over the network. It does not imply that the client has received anything yet.

After this event, no more events will be emitted on the response object.

response.addTrailers(headers)#

• headers <Object>

This method adds HTTP trailing headers (a header but at the end of the message) to the response.

Attempting to set a header field name or value that contains invalid characters will result in a TypeError being thrown.

response.connection#

• <net.Socket> | <tls.TLSSocket>

See response.socket.

response.end([data][, encoding][, callback])#

• data <string> | <Buffer>
• encoding <string>
• callback <Function>

This method signals to the server that all of the response headers and body have been sent; that server should consider this message complete. The method, response.end(), MUST be called on each response.

If data is specified, it is equivalent to calling response.write(data, encoding) followed by response.end(callback).

If callback is specified, it will be called when the response stream is finished.

response.finished#

• <boolean>

Boolean value that indicates whether the response has completed. Starts as false. After response.end() executes, the value will be true.

response.getHeader(name)#

• name <string>
• Returns: <string>

Reads out a header that has already been queued but not sent to the client. Note that the name is case insensitive.

Example:

const contentType = response.getHeader('content-type');

response.getHeaderNames()#

• Returns: <Array>

Returns an array containing the unique names of the current outgoing headers. All header names are lowercase.

Example:

response.setHeader('Foo', 'bar');
response.setHeader('Set-Cookie', ['foo=bar', 'bar=baz']);

const headerNames = response.getHeaderNames();
// headerNames === ['foo', 'set-cookie']

response.getHeaders()#

• Returns: <Object>

Returns a shallow copy of the current outgoing headers. Since a shallow copy is used, array values may be mutated without additional calls to various header-related http module methods. The keys of the returned object are the header names and the values are the respective header values. All header names are lowercase.

Note: The object returned by the response.getHeaders() method does not prototypically inherit from the JavaScript Object. This means that typical Object methods such as obj.toString(), obj.hasOwnProperty(), and others are not defined and will not work.

Example:

response.setHeader('Foo', 'bar');
response.setHeader('Set-Cookie', ['foo=bar', 'bar=baz']);

const headers = response.getHeaders();
// headers === { foo: 'bar', 'set-cookie': ['foo=bar', 'bar=baz'] }

response.hasHeader(name)#

• name <string>
• Returns: <boolean>

Returns true if the header identified by name is currently set in the outgoing headers. Note that the header name matching is case-insensitive.

Example:

const hasContentType = response.hasHeader('content-type');

response.headersSent#

• <boolean>

Boolean (read-only). True if headers were sent, false otherwise.

response.removeHeader(name)#

• name <string>

Removes a header that has been queued for implicit sending.

Example:

response.removeHeader('Content-Encoding');

response.sendDate#

• <boolean>

When true, the Date header will be automatically generated and sent in the response if it is not already present in the headers. Defaults to true.

This should only be disabled for testing; HTTP requires the Date header in responses.

response.setHeader(name, value)#

• name <string>
• value <string> | <string[]>

Sets a single header value for implicit headers. If this header already exists in the to-be-sent headers, its value will be replaced. Use an array of strings here to send multiple headers with the same name.

Example:

response.setHeader('Content-Type', 'text/html');

or

response.setHeader('Set-Cookie', ['type=ninja', 'language=javascript']);

Attempting to set a header field name or value that contains invalid characters will result in a TypeError being thrown.

When headers have been set with response.setHeader(), they will be merged with any headers passed to response.writeHead(), with the headers passed to response.writeHead() given precedence.

// returns content-type = text/plain
const server = http2.createServer((req, res) => {
  res.setHeader('Content-Type', 'text/html');
  res.setHeader('X-Foo', 'bar');
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('ok');
});

response.setTimeout(msecs[, callback])#

• msecs <number>
• callback <Function>

Sets the Http2Stream's timeout value to msecs. If a callback is provided, then it is added as a listener on the 'timeout' event on the response object.

If no 'timeout' listener is added to the request, the response, or the server, then Http2Streams are destroyed when they time out. If a handler is assigned to the request, the response, or the server's 'timeout' events, timed out sockets must be handled explicitly.

Returns response.

response.socket#

• <net.Socket> | <tls.TLSSocket>

Returns a Proxy object that acts as a net.Socket (or tls.TLSSocket) but applies getters, setters, and methods based on HTTP/2 logic.

destroyed, readable, and writable properties will be retrieved from and set on response.stream.

destroy, emit, end, on and once methods will be called on response.stream.

setTimeout method will be called on response.stream.session.

pause, read, resume, and write will throw an error with code ERR_HTTP2_NO_SOCKET_MANIPULATION. See Http2Session and Sockets for more information.

All other interactions will be routed directly to the socket.

Example:

const http2 = require('http2');
const server = http2.createServer((req, res) => {
  const ip = req.socket.remoteAddress;
  const port = req.socket.remotePort;
  res.end(`Your IP address is ${ip} and your source port is ${port}.`);
}).listen(3000);

response.statusCode#

• <number>

When using implicit headers (not calling response.writeHead() explicitly), this property controls the status code that will be sent to the client when the headers get flushed.

Example:

response.statusCode = 404;

After response header was sent to the client, this property indicates the status code which was sent out.

response.statusMessage#

• <string>

Status message is not supported by HTTP/2 (RFC7540 8.1.2.4). It returns an empty string.

response.stream#

• <http2.Http2Stream>

The Http2Stream object backing the response.

response.write(chunk[, encoding][, callback])#

• chunk <string> | <Buffer>
• encoding <string>
• callback <Function>
• Returns: <boolean>

If this method is called and response.writeHead() has not been called, it will switch to implicit header mode and flush the implicit headers.

This sends a chunk of the response body. This method may be called multiple times to provide successive parts of the body.

Note that in the http module, the response body is omitted when the request is a HEAD request. Similarly, the 204 and 304 responses must not include a message body.

chunk can be a string or a buffer. If chunk is a string, the second parameter specifies how to encode it into a byte stream. By default the encoding is 'utf8'. callback will be called when this chunk of data is flushed.

Note: This is the raw HTTP body and has nothing to do with higher-level multi-part body encodings that may be used.

The first time response.write() is called, it will send the buffered header information and the first chunk of the body to the client. The second time response.write() is called, Node.js assumes data will be streamed, and sends the new data separately. That is, the response is buffered up to the first chunk of the body.

Returns true if the entire data was flushed successfully to the kernel buffer. Returns false if all or part of the data was queued in user memory. 'drain' will be emitted when the buffer is free again.

response.writeContinue()#

Sends a status 100 Continue to the client, indicating that the request body should be sent. See the 'checkContinue' event on Http2Server and Http2SecureServer.

response.writeHead(statusCode[, statusMessage][, headers])#

• statusCode <number>
• statusMessage <string>
• headers <Object>

Sends a response header to the request. The status code is a 3-digit HTTP status code, like 404. The last argument, headers, are the response headers.

For compatibility with HTTP/1, a human-readable statusMessage may be passed as the second argument. However, because the statusMessage has no meaning within HTTP/2, the argument will have no effect and a process warning will be emitted.

Example:

const body = 'hello world';
response.writeHead(200, {
  'Content-Length': Buffer.byteLength(body),
  'Content-Type': 'text/plain' });

Note that Content-Length is given in bytes not characters. The Buffer.byteLength() API may be used to determine the number of bytes in a given encoding. On outbound messages, Node.js does not check if Content-Length and the length of the body being transmitted are equal or not. However, when receiving messages, Node.js will automatically reject messages when the Content-Length does not match the actual payload size.

This method may be called at most one time on a message before response.end() is called.

If response.write() or response.end() are called before calling this, the implicit/mutable headers will be calculated and call this function.

When headers have been set with response.setHeader(), they will be merged with any headers passed to response.writeHead(), with the headers passed to response.writeHead() given precedence.

// returns content-type = text/plain
const server = http2.createServer((req, res) => {
  res.setHeader('Content-Type', 'text/html');
  res.setHeader('X-Foo', 'bar');
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('ok');
});

Attempting to set a header field name or value that contains invalid characters will result in a TypeError being thrown.

response.createPushResponse(headers, callback)#

Call http2stream.pushStream() with the given headers, and wraps the given newly created Http2Stream on Http2ServerRespose.

The callback will be called with an error with code ERR_HTTP2_STREAM_CLOSED if the stream is closed.

Collecting HTTP/2 Performance Metrics#

The Performance Observer API can be used to collect basic performance metrics for each Http2Session and Http2Stream instance.

const { PerformanceObserver } = require('perf_hooks');

const obs = new PerformanceObserver((items) => {
  const entry = items.getEntries()[0];
  console.log(entry.entryType);  // prints 'http2'
  if (entry.name === 'Http2Session') {
    // entry contains statistics about the Http2Session
  } else if (entry.name === 'Http2Stream') {
    // entry contains statistics about the Http2Stream
  }
});
obs.observe({ entryTypes: ['http2'] });

The entryType property of the PerformanceEntry will be equal to 'http2'.

The name property of the PerformanceEntry will be equal to either 'Http2Stream' or 'Http2Session'.

If name is equal to Http2Stream, the PerformanceEntry will contain the following additional properties:

• timeToFirstByte <number> The number of milliseconds elapsed between the PerformanceEntry startTime and the reception of the first DATA frame.
• timeToFirstHeader <number> The number of milliseconds elapsed between the PerformanceEntry startTime and the reception of the first header.

If name is equal to Http2Session, the PerformanceEntry will contain the following additional properties:

• pingRTT <number> The number of milliseconds elapsed since the transmission of a PING frame and the reception of its acknowledgment. Only present if a PING frame has been sent on the Http2Session.
• streamCount <number> The number of Http2Stream instances processed by the Http2Session.
• streamAverageDuration <number> The average duration (in milliseconds) for all Http2Stream instances.
• framesReceived <number> The number of HTTP/2 frames received by the Http2Session.
• type <string> Either 'server' or 'client' to identify the type of Http2Session.