Table of Contents

• HTTP/2
  • 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: 'ping'
      • Event: 'remoteSettings'
      • Event: 'stream'
      • Event: 'timeout'
      • http2session.alpnProtocol
      • http2session.close([callback])
      • http2session.closed
      • http2session.connecting
      • 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.socket
      • http2session.state
      • http2session.settings(settings)
      • http2session.type
      • http2session.unref()
    • Class: ServerHttp2Session
      • serverhttp2session.altsvc(alt, originOrStream)
      • Specifying alternative services
      • serverhttp2session.origin(...origins)
    • Class: ClientHttp2Session
      • Event: 'altsvc'
      • Event: 'origin'
      • clienthttp2session.request(headers[, options])
    • Class: Http2Stream
      • Http2Stream Lifecycle
        • Creation
        • Destruction
      • Event: 'aborted'
      • Event: 'close'
      • Event: 'error'
      • Event: 'frameError'
      • Event: 'timeout'
      • Event: 'trailers'
      • Event: 'wantTrailers'
      • http2stream.aborted
      • http2stream.close(code[, callback])
      • http2stream.closed
      • http2stream.destroyed
      • http2stream.endAfterHeaders
      • http2stream.pending
      • http2stream.priority(options)
      • http2stream.rstCode
      • http2stream.sentHeaders
      • http2stream.sentInfoHeaders
      • http2stream.sentTrailers
      • http2stream.session
      • http2stream.setTimeout(msecs, callback)
      • http2stream.state
      • http2stream.sendTrailers(headers)
    • 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: 'stream'
      • Event: 'timeout'
      • server.close([callback])
      • server.setTimeout([msecs][, callback])
    • Class: Http2SecureServer
      • Event: 'checkContinue'
      • Event: 'request'
      • Event: 'session'
      • Event: 'sessionError'
      • Event: 'stream'
      • Event: 'timeout'
      • Event: 'unknownProtocol'
      • server.close([callback])
      • server.setTimeout([msecs][, callback])
    • 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.aborted
      • 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

HTTP/2#

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, connect and stream, can be emitted either by client-side code or server-side code.

Server-side example#

The following illustrates a simple HTTP/2 server using the Core API. Since there are no browsers known that support unencrypted HTTP/2, the use of http2.createSecureServer() is necessary when communicating with browser clients.

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('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));

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.

User code will not create Http2Session instances directly. Server-side Http2Session instances are created by the Http2Server instance when a new HTTP/2 connection is received. Client-side Http2Session instances are created using the http2.connect() method.

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. Its listener does not expect any arguments.

Event: 'connect'#

• session <Http2Session>
• socket <net.Socket>

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'#

• error <Error>

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

Event: 'frameError'#

• type <integer> The frame type.
• code <integer> The error code.
• id <integer> The stream id (or 0 if the frame isn't associated with a stream).

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.

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'#

• 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.

The 'goaway' event is emitted when a GOAWAY frame is received.

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

Event: 'localSettings'#

• settings <HTTP/2 Settings Object> A copy of the SETTINGS frame received.

The 'localSettings' event is emitted when an acknowledgment SETTINGS frame has been received.

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: 'ping'#

• payload <Buffer> The PING frame 8-byte payload

The 'ping' event is emitted whenever a PING frame is received from the connected peer.

Event: 'remoteSettings'#

• settings <HTTP/2 Settings Object> A copy of the SETTINGS frame received.

The 'remoteSettings' event is emitted when a new SETTINGS frame is received from the connected peer.

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

Event: 'stream'#

• stream <Http2Stream> A reference to the stream
• headers <HTTP/2 Headers Object> An object describing the headers
• flags <number> The associated numeric flags
• rawHeaders <Array> An array containing the raw header names followed by their respective values.

The 'stream' event is emitted when a new Http2Stream is created.

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 an unencrypted 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.connecting#

• <boolean>

Will be true if this Http2Session instance is still connecting, will be set to false before emitting connect event and/or calling the http2.connect callback.

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: <HTTP/2 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.

The originSet property is only available when using a secure TLS connection.

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: <HTTP/2 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.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#

Provides miscellaneous information about the current state of the Http2Session.

• Value: <Object>
  • effectiveLocalWindowSize <number> The current local (receive) flow control window size for the Http2Session.
  • effectiveRecvDataLength <number> The current number of bytes that have been received since the last flow control WINDOW_UPDATE.
  • nextStreamID <number> The numeric identifier to be used the next time a new Http2Stream is created by this Http2Session.
  • localWindowSize <number> The number of bytes that the remote peer can send without receiving a WINDOW_UPDATE.
  • lastProcStreamID <number> The numeric id of the Http2Stream for which a HEADERS or DATA frame was most recently received.
  • remoteWindowSize <number> The number of bytes that this Http2Session may send without receiving a WINDOW_UPDATE.
  • outboundQueueSize <number> The number of frames currently within the outbound queue for this Http2Session.
  • deflateDynamicTableSize <number> The current size in bytes of the outbound header compression state table.
  • inflateDynamicTableSize <number> The current size in bytes of the inbound header compression state table.

An object describing the current status of this Http2Session.

http2session.settings(settings)#

• settings <HTTP/2 Settings Object>

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.

serverhttp2session.origin(...origins)#

• origins <string> | <URL> | <Object> One or more URL Strings passed as separate arguments.

Submits an ORIGIN frame (as defined by RFC 8336) to the connected client to advertise the set of origins for which the server is capable of providing authoritative responses.

const http2 = require('http2');
const options = getSecureOptionsSomehow();
const server = http2.createSecureServer(options);
server.on('stream', (stream) => {
  stream.respond();
  stream.end('ok');
});
server.on('session', (session) => {
  session.origin('https://example.com', 'https://example.org');
});

When a string is passed as an origin, 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 an origin, 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.

Alternatively, the origins option may be used when creating a new HTTP/2 server using the http2.createSecureServer() method:

const http2 = require('http2');
const options = getSecureOptionsSomehow();
options.origins = ['https://example.com', 'https://example.org'];
const server = http2.createSecureServer(options);
server.on('stream', (stream) => {
  stream.respond();
  stream.end('ok');
});

Class: ClientHttp2Session#

Event: 'altsvc'#

• alt <string>
• origin <string>
• streamId <number>

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 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, streamId) => {
  console.log(alt);
  console.log(origin);
  console.log(streamId);
});

Event: 'origin'#

• origins <string[]>

The 'origin' event is emitted whenever an ORIGIN frame is received by the client. The event is emitted with an array of origin strings. The http2session.originSet will be updated to include the received origins.

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

client.on('origin', (origins) => {
  for (let n = 0; n < origins.length; n++)
    console.log(origins[n]);
});

The 'origin' event is only emitted when using a secure TLS connection.

clienthttp2session.request(headers[, options])#

• headers <HTTP/2 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).
  • waitForTrailers <boolean> When true, the Http2Stream will emit the 'wantTrailers' event after the final DATA frame has been sent.

• 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 the options.waitForTrailers option is set, the 'wantTrailers' event is emitted immediately after queuing the last chunk of payload data to be sent. The http2stream.sendTrailers() method can then be called to send trailing headers to the peer.

When options.waitForTrailers is set, the Http2Stream will not automatically close when the final DATA frame is transmitted. User code must call either http2stream.sendTrailers() or http2stream.close() to close the Http2Stream.

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

• :method = 'GET'
• :path = /

Class: Http2Stream#

• Extends: <stream.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'#

• error <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 HTTP/2 Headers Object and flags associated with the headers.

Note that this event might not be emitted if http2stream.end() is called before trailers are received and the incoming data is not being read or listened for.

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

Event: 'wantTrailers'#

The 'wantTrailers' event is emitted when the Http2Stream has queued the final DATA frame to be sent on a frame and the Http2Stream is ready to send trailing headers. When initiating a request or response, the waitForTrailers option must be set for this event to be emitted.

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.constants.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.endAfterHeaders#

• <boolean>

Set the true if the END_STREAM flag was set in the request or response HEADERS frame received, indicating that no additional data should be received and the readable side of the Http2Stream will be closed.

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.sentHeaders#

• Value: <HTTP/2 Headers Object>

An object containing the outbound headers sent for this Http2Stream.

http2stream.sentInfoHeaders#

• Value: <HTTP/2 Headers Object[]>

An array of objects containing the outbound informational (additional) headers sent for this Http2Stream.

http2stream.sentTrailers#

• Value: <HTTP/2 Headers Object>

An object containing the outbound trailers sent for this this HttpStream.

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.close(NGHTTP2_CANCEL));

http2stream.state#

Provides miscellaneous information about the current state of the Http2Stream.

• Value: <Object>
  • localWindowSize <number> The number of bytes the connected peer may send for this Http2Stream without receiving a WINDOW_UPDATE.
  • state <number> A flag indicating the low-level current state of the Http2Stream as determined by nghttp2.
  • localClose <number> true if this Http2Stream has been closed locally.
  • remoteClose <number> true if this Http2Stream has been closed remotely.
  • sumDependencyWeight <number> The sum weight of all Http2Stream instances that depend on this Http2Stream as specified using PRIORITY frames.
  • weight <number> The priority weight of this Http2Stream.

A current state of this Http2Stream.

http2stream.sendTrailers(headers)#

• headers <HTTP/2 Headers Object>

Sends a trailing HEADERS frame to the connected HTTP/2 peer. This method will cause the Http2Stream to be immediately closed and must only be called after the 'wantTrailers' event has been emitted. When sending a request or sending a response, the options.waitForTrailers option must be set in order to keep the Http2Stream open after the final DATA frame so that trailers can be sent.

const http2 = require('http2');
const server = http2.createServer();
server.on('stream', (stream) => {
  stream.respond(undefined, { waitForTrailers: true });
  stream.on('wantTrailers', () => {
    stream.sendTrailers({ xyz: 'abc' });
  });
  stream.end('Hello World');
});

The HTTP/1 specification forbids trailers from containing HTTP/2 pseudo-header fields (e.g. ':method', ':path', etc).

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 HTTP/2 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 HTTP/2 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 HTTP/2 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 <HTTP/2 Headers Object>

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 <HTTP/2 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.
  • err <Error>
  • pushStream <ServerHttp2Stream> The returned pushStream object.
  • headers <HTTP/2 Headers Object> Headers object the pushStream was initiated with.
• Returns: <undefined>

Initiates a push stream. The callback is invoked with the new Http2Stream instance created for the push stream passed as the second argument, or an Error passed as the first argument.

const http2 = require('http2');
const server = http2.createServer();
server.on('stream', (stream) => {
  stream.respond({ ':status': 200 });
  stream.pushStream({ ':path': '/' }, (err, pushStream, headers) => {
    if (err) throw err;
    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.

Calling http2stream.pushStream() from within a pushed stream is not permitted and will throw an error.

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

• headers <HTTP/2 Headers Object>
• options <Object>
  • endStream <boolean> Set to true to indicate that the response will not include payload data.
  • waitForTrailers <boolean> When true, the Http2Stream will emit the 'wantTrailers' event after the final DATA frame has been sent.

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

When the options.waitForTrailers option is set, the 'wantTrailers' event will be emitted immediately after queuing the last chunk of payload data to be sent. The http2stream.sendTrailers() method can then be used to sent trailing header fields to the peer.

When options.waitForTrailers is set, the Http2Stream will not automatically close when the final DATA frame is transmitted. User code must call either http2stream.sendTrailers() or http2stream.close() to close the Http2Stream.

const http2 = require('http2');
const server = http2.createServer();
server.on('stream', (stream) => {
  stream.respond({ ':status': 200 }, { waitForTrailers: true });
  stream.on('wantTrailers', () => {
    stream.sendTrailers({ ABC: 'some value to send' });
  });
  stream.end('some data');
});

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

• fd <number> A readable file descriptor.
• headers <HTTP/2 Headers Object>
• options <Object>
  • statCheck <Function>
  • waitForTrailers <boolean> When true, the Http2Stream will emit the 'wantTrailers' event after the final DATA frame has been sent.
  • 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 server = http2.createServer();
server.on('stream', (stream) => {
  const fd = fs.openSync('/some/file', 'r');

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

The file descriptor is not closed when the stream is closed, so it will need to be closed manually once it is no longer needed. Note that using the same file descriptor concurrently for multiple streams is not supported and may result in data loss. Re-using a file descriptor after a stream has finished is supported.

When the options.waitForTrailers option is set, the 'wantTrailers' event will be emitted immediately after queuing the last chunk of payload data to be sent. The http2stream.sendTrailers() method can then be used to sent trailing header fields to the peer.

When options.waitForTrailers is set, the Http2Stream will not automatically close when the final DATA frame is transmitted. User code must call either http2stream.sendTrailers() or http2stream.close() to close the Http2Stream.

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

const server = http2.createServer();
server.on('stream', (stream) => {
  const fd = fs.openSync('/some/file', 'r');

  const stat = fs.fstatSync(fd);
  const headers = {
    'content-length': stat.size,
    'last-modified': stat.mtime.toUTCString(),
    'content-type': 'text/plain'
  };
  stream.respondWithFD(fd, headers, { waitForTrailers: true });
  stream.on('wantTrailers', () => {
    stream.sendTrailers({ ABC: 'some value to send' });
  });

  stream.on('close', () => fs.closeSync(fd));
});

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

• path <string> | <Buffer> | <URL>
• headers <HTTP/2 Headers Object>
• options <Object>
  • statCheck <Function>
  • onError <Function> Callback function invoked in the case of an Error before send.
  • waitForTrailers <boolean> When true, the Http2Stream will emit the 'wantTrailers' event after the final DATA frame has been sent.
  • 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 the options.waitForTrailers option is set, the 'wantTrailers' event will be emitted immediately after queuing the last chunk of payload data to be sent. The http2stream.sendTrilers() method can then be used to sent trailing header fields to the peer.

When options.waitForTrailers is set, the Http2Stream will not automatically close when the final DATA frame is transmitted. User code must call either http2stream.sendTrailers() or http2stream.close() to close the Http2Stream.

const http2 = require('http2');
const server = http2.createServer();
server.on('stream', (stream) => {
  stream.respondWithFile('/some/file',
                         { 'content-type': 'text/plain' },
                         { waitForTrailers: true });
  stream.on('wantTrailers', () => {
    stream.sendTrailers({ ABC: 'some value to send' });
  });
});

Class: Http2Server#

• Extends: <net.Server>

Instances of Http2Server are created using the http2.createServer() function. The Http2Server class is not exported directly by the http2 module.

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: '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(). Default: 2 minutes.

server.close([callback])#

• callback <Function>

Stops the server from accepting new connections. See net.Server.close().

Note that this is not analogous to restricting new requests since HTTP/2 connections are persistent. To achieve a similar graceful shutdown behavior, consider also using http2session.close() on active sessions.

server.setTimeout([msecs][, callback])#

• msecs <number> Default: 120000 (2 minutes)
• callback