node-coap is an highly experimental client and server library for CoAP modelled after the http module.
What is CoAP?
Constrained Application Protocol (CoAP) is a software protocol intended to be used in very simple electronics devices that allows them to communicate interactively over the Internet. - Wikipedia
This library follows the draft-18 of the standard. Moreover, it supports the observe-11 specification.
It does not parse the protocol but it use CoAP-packet instead.
If you need a command line interface for CoAP, check out coap-cli.
node-coap is an OPEN Open Source Project, see the Contributing section to find out what this means.
This has been tested only on node v0.10.
$ npm install coap --save
The following example opens a UDP server and sends a CoAP message to it:
const coap = require('coap')
, server = coap.createServer()
server.on('request', function(req, res) {
res.end('Hello ' + req.url.split('/')[1] + '\n')
})
// the default CoAP port is 5683
server.listen(function() {
var req = coap.request('coap://localhost/Matteo')
req.on('response', function(res) {
res.pipe(process.stdout)
res.on('end', function() {
process.exit(0)
})
})
req.end()
})
or on IPv6:
const coap = require('coap')
, server = coap.createServer({ type: 'udp6' })
server.on('request', function(req, res) {
res.end('Hello ' + req.url.split('/')[1] + '\n')
})
// the default CoAP port is 5683
server.listen(function() {
var req = coap.request('coap://[::1]/Matteo')
req.on('response', function(res) {
res.pipe(process.stdout)
res.on('end', function() {
process.exit(0)
})
})
req.end()
})
coap.request()coap.createServer()IncomingMessageOutgoingMessageObserveReadStreamObserveWriteStreamcoap.registerOption()coap.registerFormat()coap.Agentcoap.globalAgentcoap.globalAgentIPv6Execute a CoAP request. url can be a string or an object.
If it is a string, it is parsed using require('url').parse(url).
If it is an object:
host: A domain name or IP address of the server to issue the request
to.
Defaults to 'localhost'.hostname: To support url.parse() hostname is preferred over
hostport: Port of remote server. Defaults to 5683.method: A string specifying the CoAP request method. Defaults to
'GET'.confirmable: send a CoAP confirmable message (CON), defaults to
true.observe: send a CoAP observe message, allowing the streaming of
updates from the server.pathname: Request path. Defaults to '/'. Should not include query stringquery: Query string. Defaults to ''. Should not include the path,
e.g. 'a=b&c=d'observe: send a CoAP observe message, allowing the streaming of
updates from the server.agent: Controls Agent behavior. Possible values:
undefined (default): use globalAgent, a single socket for all
concurrent requests.Agent object: explicitly use the passed in Agent.false: opts out of socket reuse with an Agent, each request uses a
new UDP socket.coap.request() returns an instance of IncomingMessage.
If you need
to add a payload, just pipe into it.
Otherwise, you must call end to submit the request.
If hostname is a IPv6 address then the payload is sent through a
IPv6 UDP socket, dubbed in node.js as 'udp6'.
function (response) { }
Emitted when a response is received.
response is
an instance of IncomingMessage.
If the observe flag is specified, the 'response' event
will return an instance of
ObserveReadStream.
Which represent the updates coming from the server, according to the
observe spec.
Returns a new CoAP Server object.
The requestListener is a function which is automatically
added to the 'request' event.
function (request, response) { }
Emitted each time there is a request.
request is an instance of IncomingMessage and response is
an instance of OutgoingMessage.
If the observe flag is specified, the response variable
will return an instance of ObserveWriteStream.
Each write(data) to the stream will cause a new observe message sent
to the client.
Begin accepting connections on the specified port and hostname. If the
hostname is omitted, the server will accept connections directed to any
IPv4 or IPv6 address by passing null as the address to the underlining socket.
To listen to a unix socket, supply a filename instead of port and hostname.
This function is asynchronous.
Closes the server.
This function is synchronous, but it provides an asynchronous callback for convenience.
An OutgoingMessage object is returned by coap.request or
emitted by the coap.createServer 'response' event.
It may be used to access response status, headers and data.
It implements the Writable Stream interface, as well as the following additional methods and properties.
The CoAP code ot the message.
It is HTTP-compatible, as it can be passed 404.
Sets a single option value.
All the options are in binary format, except for
'Content-Format', 'Accept' and 'ETag'.
See registerOption
to know how to register more.
Use an array of buffers if you need to send multiple options with the same name.
If you need to pass a custom option, pass a string containing a
a number as key and a Buffer as value.
Example:
message.setOption("Content-Format", "application/json");
or
message.setOption("555", [new Buffer('abcde',
new Buffer('ghi')]);
setOption is also aliased as setHeader for HTTP API
compatibility.
Also, 'Content-Type' is aliased to 'Content-Format' for HTTP
compatibility.
See the spec for all the possible options.
An IncomingMessage object is created by coap.createServer or
coap.request
and passed as the first argument to the 'request' and 'response' event
respectively. It may be used to access response status, headers and data.
It implements the Readable Stream interface, as well as the following additional methods and properties.
The full payload of the message, as a Buffer.
All the CoAP options, as parsed by CoAP-packet.
All the options are in binary format, except for
'Content-Format', 'Accept' and 'ETag'.
See registerOption() to know how to register more.
See the spec for all the possible options.
All the CoAP options that can be represented in a human-readable format.
Currently they are only 'Content-Format', 'Accept' and
'ETag'.
See to know how to register more.
Also, 'Content-Type' is aliased to 'Content-Format' for HTTP
compatibility.
The CoAP code of the message.
The method of the message, it might be
'GET', 'POST', 'PUT', 'DELETE' or null.
It is null if the CoAP code cannot be parsed into a method, i.e. it is
not in the '0.' range.
The URL of the request, e.g.
'coap://localhost:12345/hello/world?a=b&b=c'.
The sender informations, as emitted by the socket.
See the dgram docs for details
An ObserveReadStream object is created by coap.request to handle
observe requests.
It is passed as the first argument to the 'response' event.
It may be used to access response status, headers and data as they are
sent by the server.
Each new observe message from the server is a new 'data' event.
It implements the Readable Stream and IncomingMessage interfaces, as well as the following additional methods, events and properties.
Closes the stream.
An ObserveWriteStream object is
emitted by the coap.createServer 'response' event as a response
object.
It may be used to set response status, headers and stream changing data
to the client.
Each new write() call is a new message being sent to the client.
It implements the Writable Stream and OutgoingMessage interfaces, as well as the following additional methods and properties.
Emitted when the client is not sending 'acks' anymore for the sent messages.
Register a new option to be converted to string and added to the
message.headers.
toBinary is a function that accept a string and returns a Buffer.
toString is a function that accept a Buffer and returns a String.
Register a new format to be interpreted and sent in CoAP
Content-Format option.
Each format is identified by a number, see the Content-Format
registry.
These are the defaults formats:
registerFormat('text/plain', 0)
registerFormat('application/link-format', 40)
registerFormat('application/xml', 41)
registerFormat('application/octet-stream', 42)
registerFormat('application/exi', 47)
registerFormat('application/json', 50)
An Agent encapsulate an UDP Socket. It uses a combination of messageId
and token to distinguish between the different exchanges.
The socket will auto-close itself when no more exchange are in place.
By default, no UDP socket are open, and it is opened on demand to send the messages.
Opts is an optional object with the following optional properties:
type: 'udp4' or 'udp6' if we want an Agent on an IPv4 or IPv6
UDP socket.The default Agent for IPv4.
The default Agent for IPv6.
node-coap is an OPEN Open Source Project. This means that:
Individuals making significant and valuable contributions are given commit-access to the project to contribute as they see fit. This project is more like an open wiki than a standard guarded open source project.
See the CONTRIBUTING.md file for more details.
The maximum packet size is 1280, as the blockwise is not supported yet.
node-coap is only possible due to the excellent work of the following contributors:
| Matteo Collina | GitHub/mcollina | Twitter/@matteocollina |
|---|
Copyright (c) 2013-2014 node-coap contributors (listed above).
node-coap is licensed under an MIT +no-false-attribs license. All rights not explicitly granted in the MIT license are reserved. See the included LICENSE file for more details.
FAQs
A CoAP library for node modelled after 'http'
The npm package coap receives a total of 8,578 weekly downloads. As such, coap popularity was classified as popular.
We found that coap demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
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