http-hooks

Adds hooks to allow efficient access to points in the HTTP request and response lifecycle.

background

Some libraries needs to hook into the http (and https) serving beyond what can be done by an express middleware. Instead of having each of these monkey-patch node.js, http-hooks provides a common set of hooks which these libraries can use.

adding to apps

Adding this to the app is as simple as require('http-hooks') in your server code. Then you can add event listeners as described below.

example

require('http-hooks');    // just requiring it installs it

process.on('httpHooks:request', (req, res) => {
    res.on('httpHooks:pre:writeHead', () => {
        res.setHeader('X-Duration', (res.httpHooks.preWriteHead - req.httpHooks.start));
    });
})

process attribute 'httpHooks.version'

• process.httpHooks.version {String}

This is added to mark that the app is protected by http-hooks.

process event 'httpHooks:server'

• process.on('httpHooks:server', (server) => {...})

This is emitted when a new http or https server object is created.

process event 'httpHooks:connection'

• process.on('httpHooks:connection', (con) => {...})

This is emitted for each incoming http or https connection.

process event 'httpHooks:request'

• process.on('httpHooks:request', (req, res) => {...})

This is emitted for each incoming http or https request.

request attribute 'httpHooks.start'

• req.httpHooks.start {Number}

This is the time (number of milliseconds since unix epoch) of when the request started.

response attribute 'httpHooks.preWriteHead'

• res.httpHooks.preWriteHead {Number}

This is the time (number of milliseconds since unix epoch) of just before res.writeHead() is called, and before the httpHooks:pre:writeHead response event.

response attribute 'httpHooks.postWriteHead'

• res.httpHooks.postWriteHead {Number}

This is the time (number of milliseconds since unix epoch) of just after res.writeHead() is called, but before the httpHooks:post:writeHead response event.

response attribute 'httpHooks.preEnd'

• res.httpHooks.preEnd {Number}

This is the time (number of milliseconds since unix epoch) of just before res.end() is called, and before the httpHooks:pre:end response event.

response attribute 'httpHooks.postEnd'

• res.httpHooks.postEnd {Number}

This is the time (number of milliseconds since unix epoch) of just after res.end() is called, but before the httpHooks:post:end response event.

response event 'httpHooks:pre:writeHead'

• res.on('httpHooks:pre:writeHead', (status, reason, headers) => {...})

This is emitted before the response's writeHead() is called. This might be good time to modify outgoing headers using res.setHeader().

response event 'httpHooks:post:writeHead'

• res.on('httpHooks:post:writeHead', (status, reason, headers) => {...})

This is emitted after the response's writeHead() is called. This might be good time to monitor when the first bytes have been sent to the client.

response event 'httpHooks:pre:end'

• res.on('httpHooks:pre:end', (chunk, encoding) => {...})

This is emitted before the response's end() is called. Before emitting this event http-hooks will add a res.httpHooks.preEnd field. This might be a good time to monitor the time it took to generate the page.

Note: Since http-hooks is often loaded early, other libraries which monkey-patch res.end() will run after http-hooks.

response event 'httpHooks:post:end'

• res.on('httpHooks:post:end', (chunk, encoding) => {...})

This is emitted before the response's end() is called. Before emitting this event http-hooks will add a res.httpHooks.postEnd field. This might be a good time to monitor the time it took to send the response.

Note: Since http-hooks is often loaded early, other libraries which monkey-patch res.end() will run after http-hooks.