resilient.js

A reactive HTTP client for node.js and browsers designed for distributed systems, providing fault tolerance capabilities with transparent server fallback, dynamic server discovery (e.g: using Consul), request retry/backoff logic, optional client-side balancing based on empirical server latency and more...

Provides a simple middleware-oriented programmatic API and featured command-line interface. It has been designed to be lightweight (just ~2K SLOC. 9KB gzipped) and dependency free.

To get started, take a look to how does it work, basic usage, examples and API docs.

Resilient is conceptually similar to Ribbon, a Netflix's project and it was inspired by Chaos Engineering.

Features
Installation
Environments
Middleware layer
Framework-specific adapters
Related projects
How does it work?
Basic usage
- Static servers
- Dynamic servers lookup
Middleware Layer
- Types of middleware
- Middleware API
Command-line interface
API
- Client
- Options
- Built-in errors
- Events
FAQ
Contributing
License

Features

Supports callback and promise based async requests.
Reliable failover and error handling with transparent server fallback
Smart network error handling covering multiple failure scenarios
Smart balancer logic based on empirical server score (network latency, errors and succesfull requests)
Transparent request retry cycle attempts on failure (configurable)
Discern best servers based on scoring per read and write operations when balancing
In/out traffic extensible middleware layer
Configurable balancer policy by weight
Configurable timeouts, retry loop, cache TTL, fallback behavior...)
Avoid fallback/retry cycles per custom HTTP responses codes or verbs
Define custom timeouts per HTTP method (e.g permissive for POST/PUT/DELETE, aggressive for GET)
Parallel servers discovering for faster availability
Built-in support for request/response interceptors (via middleware)
Built-in support for servers caching to improve reliability when fallback
Configurable external HTTP client to use as forward request proxy (instead of using the embedded one)
Dynamic servers auto discovering (based on the resilient specification or via middleware)
Able to plug in custom failure strategies to determine if a request was failed or not.
Supports promiscuous errors (handles 400-499 codes as fallback errors)
Supports pre/post request hooks via event bus API
Supports mock/stub working mode via middleware (useful for testing)
Reliable HTTP client (it uses internally request and lil-http for the browser)
Round robin scheduling algorithm for traffic distribution (experimental)
Featured cURL-inspired command-line interface
Lightweight library (just ~2K SLOC, 9KB gzipped)
Dependency free in browser environments (in node.js it only depends on request package)
Cross JS engine. ES5/6 compliant (requires Promise global to be available)

Installation

Via npm

npm install resilient

Via Bower

bower install resilient

Via Component

component install resilient-http/resilient.js

Or loading the script remotely

<script src="//cdn.rawgit.com/resilient-http/resilient.js/0.4.0/resilient.js"></script>

Environments

Runs in any ES5 compliant engine.


+4	+33	+29	+10	+19	+7.1

Middleware

Consul - Example

Framework-specific adapters

angular-resilient - Turn $http into a resilient and fault tolerant client

Related projects

resilient-server - node.js powered dummy HTTP lookup server for testing/development

How to use?

See the basic usage and examples for detailed use cases

How does it work?

The following graph represents from a high-level point of view the internal logic encapsulated in Resilient HTTP client.

Basic usage

If require is available, you must use it to fetch the module. Otherwise it will be available as global exposed as resilient

var Resilient = require('resilient')

Static servers

Define your service servers pool

var servers = [
  'http://api1.server.com',
  'http://api2.server.com',
  'http://api3.server.com'
]

Create a new client and set the servers to balance

var client = Resilient({ service: { basePath: '/api/1.0' }})
client.setServers(servers)

Perform a request (the best available server will be used automatically)

client.get('/users').then(function (res) {
  if (res.status === 200) {
    console.log('Success:', res.data)
  }
})

Dynamic servers lookup

Define the lookup servers pool

var servers = [
  'http://discover1.server.com',
  'http://discover2.server.com',
  'http://discover3.server.com'
]

Create a new client and set the discovering servers

var client = Resilient({ service: { basePath: '/api/1.0' }})
client.discoveryServers(servers)

Finally, perform the request (and that's all, Resilient will take care about everything to reach the best server)

client.get('/users').then(function (res) {
  if (res.status === 200) {
    console.log('Success:', res.data)
  }
})

Note: you could use Consul or other HTTP server using a custom middleware as discovery server. For more information about the Resilient discovery interface, take a look at the documentation

For more usage cases take a look to the examples

Middleware Layer

From version 0.3.x Resilient introduces support for duplex middleware. It essentially provides an interceptor like layer to use external components to augment a specific functionality.

From a high-level point of view it's conceptually similar to an evented API approach, which is commonly used in a event-driven environment with JavaScript, but in this case it's slightly different in terms of flow control nature and relies more in data mutation compared to events.

The significant feature in Resilient middleware layer is that it provides bidirectional control flow for both incoming and outgoing HTTP traffic. This allows you to perform multiple actions before and after a request of a specific type is made by Resilient. This might be considered also as a sort hooks in aspect-oriented programming.

Types of middleware

Since Resilient is divided in two communication live cycle layers, one for the discovery servers and the other one for the service end servers, middleware can be created for both layers:

service - Default. Use this type in middleware which are oriented for final servers communication, such as request transformers, autorization...
discovery - Use this type in middleware which are oriented only for lookup communication, for instance used as adapter for a lookup server which is not compatible with the Resilient lookup protocol.

Note: the middleware type should be defined a static member of the middleware returned function, using the type property.

Middleware API

Required interface for middleware:

Function([ params ])
  -> Function(options, resilient)
    -> Object{ in: Function(err, res, next), out: Function(option, next) }

For non-duplex middleware you can use the following interface as well:

Function([ params ])
  -> Function(options, resilient)
    -> Function(err, res, next)

An example of a simple middleware implementation:

function testMiddleware(params) {
  // Middleware-specific params
  params = params || {}

  // Do whatever you need here with the params

  // Resilient will pass the Options
  function middleware(options, resilient) {
    // Do whatever you need here with Resilient client options
    // such as defining servers

    return {
      'in': function (err, res, next) {
        // Do something here with the err/response

        next() // Don't forget to call next
      },
      'out': function (options, next) {
        // Do something here with the out HTTP request options

        next() // Don't forget to call next
      }
    }
  }

  middleware.type = 'discovery' // Default to: service

  return middleware
}

An example of middleware usage:

var client = Resilient({
  discovery: {
    servers: ['http://server1', 'http://server2']
  }
})

client.use(testMiddleware({
  custom: 'options',
  key: 'api-key',
  timeout: 3000
}))

client.get('/').then(function (res) {
  console.log(res)
}).catch(function (err) {
  console.error(err)
})

Command-line interface

For better approach you should install Resilient as global package: npm install -g resilient

Resilient command-line HTTP client
Usage: resilient [url] [options]

Examples:
  resilient http://httpbin.org/user-agent
  resilient --status http://httpbin.org/status/201
  resilient --info http://httpbin.org/status/204
  resilient http://httpbin.org/post -x POST \
            -d '{"hello":"world"}' -h "Content-Type: application/json"
  resilient /api/users -s http://server1.net,http://server2.net
  resilient /api/users -z http://discover1.net,http://discover2.net
  resilient --discover -z http://discover1.net,http://discover2.net --discovery-timeout 500

Options:
  --version, -v            Show the Resilient client version
  --path, -p               Request path
  --servers, -s            Define the service servers (comma separated)
  --method, -x             HTTP method
  --header, -h             Define custom request header
  --data, -d               Value data to send as HTTP request body
  --file, -f               File path to send as HTTP request body
  --retry, -r              Request retry attempts                                       [default: 0]
  --timeout, -t            Request timeout in miliseconds
  --discover, -k           Get an updated list of servers asking for discovery servers
  --discovery-servers, -z  Define the discovery service servers (comma separated)
  --discovery-retry, -R    Discovery servers retry attempts                             [default: 0]
  --discovery-timeout, -T  Discovery servers request maximum timeout in miliseconds
  --info, -i               Show response headers and info
  --info-headers, -I       Show only the response status and headers
  --status, -c             Print the response status code
  --debug, -D              Enable debug mode
  --help, -H               Show help

API

resilient([ options ])

Creates a new resilient client with custom config

Options

The options object supports three different configuration levels

Resilient({
  service: { ... },
  balancer: { ... },
  discovery: { ... }
})

Service

Specific configuration options for the end service servers pool of the Resilient client.

servers array<string> - A list of valid servers URIs to reach for the given service. Default null. It's recommended to use discovery servers instead of static service servers
retry number - Number of times to retry if all requests failed. Use Infinity for infinitive attemps. Default 0
waitBeforeRetry number - Number of milisenconds to wait before start the request retry cycle. Default to 50
discoverBeforeRetry boolean - Force to refresh service servers list asking to the discovery servers on each retry attempt. You must define the discovery servers in order to use this feature. Default true
promiscuousErrors boolean - Enable promiscuous error handling mode. Client HTTP status errors (400-499) will be treated as failed request, retrying it until it has a valid status (when retry option is enabled). Default false
omitRetryWhen array<object> - A collection of rules per method and status code to match in order to omit a request retry cycle. See the usage example. Default null
omitFallbackWhen array<object> - A collection of rules per method and status code to match in order to omit a request server fallback. See usage example. Default null
omitRetryOnMethods array<string> - Omit a retry cycle attempt if the request method is on the given array. Default null
omitFallbackOnMethods array<string> - Omit fallback to the next best available server if current HTTP method is on the given array. If you use this option, retry cycles will be disabled as well for the given methods. Default null
omitRetryOnErrorCodes array<number> - Omit a retry cycle attempt if the latest request response status code is one of the given array. Default null
omitFallbackOnErrorCodes array<number> - Omit fallback to the next best available server if the latest request response status code is one of the given array. Default null
timeouts object - Define custom request timeout values in miliseconds per HTTP method, useful to differ read/write requests. This option has priority over the timeout option. Default: null

Specific shared configuration options for the HTTP client for final service requests

path string - Server request path as part of the final URL
basePath string - Server resource base path to share between all requests
method string - Request HTTP method. Default to GET
data mixed - Payload data to send as body request
headers object - Map of strings representing HTTP headers to send to the server
params object - Map of strings representing the query params
timeout number - Request maximum timeout in miliseconds before to abort it. Default to 10 seconds
auth object - Authentication credentials to the server. Object must have both user and password properties

Browser specific options

withCredentials boolean - Whether to set the withCredentials flag on the XHR object. See MDN for more information
responseType string - Define how to handle the response data. Allowed values are: text, arraybuffer, blob or document

Node.js specific options

See all HTTP options supported for node.js here

Balancer

enable boolean - Enable/disable the smart client balancer. Default to true.
random boolean - Use random balance strategy using Math.random(). Default to false.
balanceStrategy function - Custom balance strategy function. Interface to be implemented: function (servers []Server) => []Server. Default to null.
disableWeight boolean - Disable emphirical built-in weight calculus based on server stats for balancing (latency, errors, success).
roundRobin boolean - Enable round robin schedule algorithm (experimental). Default: false.
roundRobinSize number - Round robin round size. Useful to increase requests distribution across different servers. Default to 3 servers.
weight object - Balacer calculus percentage weight used for best available server scoring policy:
- success number - Percentage weight for success request. Default to 15.
- error number - Percentage weight for failed request. Default to 50.
- latency number - Percentage weight for request average latency. Default to 35.

Discovery

Specific configuration for discovery servers requests, behavior and logic

servers array<string> - A list of valid server URIs to use as discovery servers
cacheEnabled boolean - Enable/disable discovery servers cache in case of global fallback. Useful to improve client reliability. Default true
cacheExpiration number - Maximum cache time to live. Default to 10 minutes
retry number - Number of times to retry if all requests failed. Use Infinity for infinitive attemps. Default 3
waitBeforeRetry number - Number of milisenconds to wait before start the request retry cycle. Default to 1000
parallel boolean - Discover servers in parallel. This will improve service availability and decrement server lookup delays. Default true
refreshInterval number - Servers list time to live in miliseconds. Default to 2 minutes
enableRefreshServers boolean - Enable/disable discovery servers auto refresh. This option requires refreshServers or enableSelfRefresh has been defined. Default true
refreshServers array - Servers list of refresh servers. This will enable automatically update discovery servers list asking for them selves to the following list of servers on each interval. Default null
refreshServersInterval number - Discovery servers list time to live in miliseconds. Default to 5 minutes
enableSelfRefresh boolean - Enable/disable self-discovery using the discovery servers pools. This requires the refreshPath option has been defined. Default false
forceRefreshFirst boolean - Enable/disable forcing to refresh the server on the first request. This requires the refreshPath and enableRefreshServers options has been defined. Default true
refreshPath string - Discovery refresh servers lookup path. Example: /app/name. This options requires you define enableSelfRefresh to true. Default null
refreshOptions object - Custom HTTP options for discovery servers refresh. By default inherits from discovery options
promiscuousErrors boolean - Enable promiscuous error handling mode. Client HTTP status errors (400-499) will be treated as failed request, retrying it until it has a valid status (when retry option is enabled). Default false
omitRetryWhen array<object> - A collection of rules per method and status code to match in order to omit a request retry cycle. See the usage example. Default null
omitFallbackWhen array<object> - A collection of rules per method and status code to match in order to omit a request server fallback. See usage example. Default null
omitRetryOnMethods array<string> - Omit a retry cycle attempt if the request HTTP method is on the given array. Default null
omitFallbackOnMethods array<string> - Omit fallback to the next best available server if the HTTP method is on the given array. If you use this option, retry cycles will be disabled as well for the given methods. Default null
omitRetryOnErrorCodes array<number> - Omit a retry cycle attempt if the latest request response status code is one of the given array. Default null
omitFallbackOnErrorCodes array<number> - Omit fallback to the next best available server if the latest request response status code is one of the given array. Default null
timeouts object - Define custom request timeout values in miliseconds per HTTP method, useful to differ read/write requests. This option has priority over the timeout option. Default: null

Specific shared configuration options for the HTTP client for discovering processes

path string - Server request path as part of the final URL
basePath string - Server resource base path to share between all requests
timeout number - Server discovery network timeout in miliseconds. Default 2 seconds
auth object - Authentication credentials required for the discovery server. Object must have both user and password properties
params object - Map of strings representing the query params
headers object - Map of strings representing HTTP headers to send to the discovery server
method string - Request HTTP method. Default to GET
data mixed - Optional data to send as payload to discovery servers. Default null

For node.js, see all HTTP options supported here

Request callback arguments

error Error|ResilientError - Response error, if happends. Otherwise null
response Object|http.IncomingMessage - Response object

Response

Browser

data mixed - Body response. If the MIME type is JSON-compatible, it will be transparently parsed
status number - HTTP response status code
headers object - Response headers
xhr object - Original XHR instance
error mixed - Error info, usually an Error instance (in case that an error happens)

Node.js

See http.IncomingMessage

Error

It could be an Error or plain Object instance with the following members

message string - Human readable error message description
status number - Internal error code or server HTTP response status
code number - Optional error code (node.js only)
stack string - Optional stack error trace
request object - Original response object in case that a custom Resilient error happends. Optional
error Error - Original throwed Error instance (node.js only). Optional
xhr XMLHttpRequest - XHR native instance (browser only)

Built-in error codes

1000 - All requests failed. No servers available
1001 - Cannot update discovery servers. Empty or invalid response body
1002 - Missing discovery servers. Cannot resolve the server
1003 - Cannot resolve servers. Missing data
1004 - Discovery server response is invalid or empty
1005 - Missing servers during retry process
1006 - Internal state error (usually caused by an unexpected exception)
1007 - Error injected via middleware

Events

Resilient client has a built-in support for internal states event dispacher and notifier to the public interface

This could be really useful while using an interceptor pattern in order to detect different states and data changes. You can intercept and change any both request and response objects subscribing to the pre/post request hooks. Note that mutation is required, you should modify the object by reference and do not lose it

// subscribe to every outgoing request before be dropped to the network
resilientClient.on('request:start', function handler(options, resilient) {
  // mutate the options, adding an aditional header
  options.headers['API-Token'] = 'awesome!'
  // unsubscribe example
  resilientClient.off('request:start', handler)
})

request:start

Arguments: options<Object>, resilient<Resilient>

Fired before a request is created

You can intercept and modify the request options on the fly, but you must mutate the options object

request:outgoing

Arguments: options<Object>, resilient<Resilient>

Fired every time before a HTTP request is sent via network

You can intercept and modify the request options on the fly, but you must mutate the options object

request:incoming

Arguments: error<Error>, response<Object|http.IncomingMessage>, options<Object>, resilient<Resilient>

Fired every time a HTTP response is received from a server

request:finish

Arguments: error<Error>, response<Object|http.IncomingMessage>, resilient<Resilient>

Fired after a request was completed

You can intercept and modify the error/response on the fly, but you must mutate the object

request:retry

Arguments: options<Object>, servers<Servers>

Fired when a request performs a retry attempt cycle, that means all the previous requests has failed

request:fallback

Arguments: options<Object>, response<Object>

Fired when any request (service or discovery) to a given server fails and therefore tries to perform the next server fallback

servers:refresh

Arguments: servers<Array>, resilient<Resilient>

Fired every time that service servers list is updated from discovery servers

servers:cache

Arguments: servers<Array>, resilient<Resilient>

Fired every time that servers cache is updated

discovery:refresh

Arguments: servers<Array>, resilient<Resilient>

Fired every time that discovery servers are updated form refresh servers

Methods

resilient#send(path, options, callback)

Performs a custom request with the given options. It's recommended using as generic interface to make multi verb requests

resilient#get(path, options, callback)

Return Client

Creates a GET request with optional custom options

resilient#post(path, options, callback)

Return Client

Creates a POST request with optional custom options Return Client

resilient#put(path, options, callback)

Return Client

Creates a PUT request with optional custom options

resilient#delete(path, options, callback)

Alias: del | Return Client

Creates a DELETE request with optional custom options

resilient#patch(path, options, callback)

Return Client

Creates a PATCH request with optional custom options

resilient#head(path, options, callback)

Return Client

Creates a HEAD request with optional custom options

resilient#options([ type|options, options ])

Getter/setter accessor for resilient options, optionally per type. See supported options

resilient#serviceOptions([ options ])

Getter/setter accessor for service-level config options

resilient#discoveryOptions([ options ])

Getter/setter accessor for discovery-level config options

resilient#balancer([ options ])

Return: object

Getter/Setter accessor for balancer-level config options

resilient#httpOptions(type)

Return: object

Get a map of HTTP specific options

resilient#addFailStrategy(strategy)

Alias: failStrategy

Add a custom failure evaluator function strategy in order to determine if Resilient should handle the request as failed or success status, retrying it accordingly if required.

Strategies should return a boolean value indicating if the request failed (true) or not (false).

Use example:

var resilient = require('resilient')

var client = resilient()

client.addFailStrategy(function limitReached(err, res) {
  return !err
    && +res.headers['x-ratelimit-remaining'] === 0
})

resilient#areServersUpdated()

Return: boolean

Returns true if servers are up-to-date. Otherwise false

resilient#servers([ type = 'service' ])

Return: Servers

Return a Servers instance with the current used servers per type. Allowed types are: service and discovery

resilient#serversURL([ type = 'service' ])

Return: array<string>

Return an array of server URLs for the given type. Allowed types are: service and discovery

resilient#resetScore([ type = 'service' ])

Return: Resilient Alias: resetStats

Reset servers stats score based on network latency and percentage of success and failed requests

This score is the average calculus of the total amount of sent requests from the client to each server. This score is used in the scheduling algorithm in order to determinate the best available server (in the case that the balance option is enabled)

Allowed types are: service and discovery

resilient#discoveryServers([ servers ])

Return: Servers

Setter/Getter for discovery servers list

resilient#discoverServers([ options, ] cb)

Return: Resilient

Pass to the callback an up-to-date list of servers asking to discovery servers

Passed arguments to the callback are:

error object - Error, if it happend
servers array - Array of string with the current service servers URL

resilient#latestServers([ options, ] cb)

Return: Resilient Alias: getUpdatedServers

Pass to the callback an up-to-date list of servers, with or without discovery servers configured

Passed arguments to the callback are:

error object - Error, if it happend
servers array - Array of string with the current service servers URL

resilient#updateServers([ options, ] cb)

Force to update the servers list from discovery servers, if they are defined, optionally passing a callback to handle the result

Passed arguments to the callback are:

error object - Error, if it happend
servers array - Array of string with the current service servers URL

resilient#use(middleware)

Register a new middleware. See the middleware documentation or examples for more information

resilient#useHttpClient(fn)

Use a custom HTTP client as proxy instead of the embedded resilient native HTTP client.

Useful to define use proxy for custom frameworks or libraries in your existent project when you need to deal with some complex HTTP pre/post hooks logic and exploit custom HTTP client features

If defined, all the outgoing requests through Resilient client will be proxied to it.

Arguments passed to the client function:

options object - Resilient HTTP service options
callback function - Request status handler. Expected arguments are: error, response

Note: error and response objects must be compatible with the current interface

resilient#restoreHttpClient()

Restore the native resilient HTTP client

resilient#mock(mockFn)

Define a mock/fake HTTP client error/response object for all outgoing requests

resilient.mock(function (options, cb) {
  if (options.url === 'http://discovery.server.me') {
    // fake response
    cb(null, { status: 200, data: ['http://server.net'] })
  } else {
    // fake unavailable status
    cb(null, { status: 503 })
  }
})

See also the useHttpClient() method for custom request proxy forward, also useful for testing with stubs/fakes

resilient#unmock()

Disable the mock/fake mode

resilient#on(event, handler)

Subscribe to an event. See supported events

resilient#off(event, handler)

Unsubscribe a given event and its handler. See supported events

resilient#once(event, handler)

Subscribe to an event with a given handler just once time. After fired, the handler will be removed

See supported events

resilient#cache.flush()

Force to flush servers cache

resilient#client()

Return: Client Alias: http

Returns an HTTP client-only interface. Useful to provide encapsulation from public usage and avoid resilient-specific configuration methods to be called from the public API.

This is a restricted API useful to provide for high-level developers

resilient.VERSION

Type: string

Current semver library version

resilient.CLIENT_VERSION

Type: string

Current semver HTTP client library version

It uses request in node.js and lil-http in the browser

resilient.defaults

Type: object

Default config options

resilient.Options(options)

Create a new options store

resilient.Client(resilient)

Creates a new resilient HTTP client with public API

Useful to provide encapsulation to the resilient API and expose only the HTTP client (the common interface the developers want to consum)

resilient.request(options [, cb])

Use the plain HTTP client (request in node.js and lil-http in the browser)

FAQ

It's required to have discovery servers in my infraestructure in order to use Resilient?

Definitely not. Discovery servers only will be used in the case that you configure them in your Resilient client. In that case Resilient will simply use the the static service servers to communicate with your backend

Can I use Resilient as a simple HTTP client without balancing?

Yes. If your perform a request with a full URI schema, Resilient will treat it as plain request without applying any internal logic:

var client = Resilient({
  service: {
    servers: ['http://server1.me', 'http://server2.me']
  }
})

// direct plain request (no balancing, no discovery, no fallback...)
client.get('http//custom.server/hello', function (err, res) {
  // ...
})

// resilient powered request (with balancing, fallback, discovery server, cache...)
client.get('/hello', function (err, res) {
  // ...
})

Can I use a custom HTTP client instead of the embedded one?

Of course you can do it. In browser environments this is a common premise, for example you need to use the custom HTTP client of the framework you are using in your application, or a custom library like zepto or jQuery that provides a simple AJAX interface

You can do that defining a function middleware to act as proxy pattern to intercept and wrap all the HTTP traffic via the Resilient client

var client = Resilient({})
// example using Zepto.js AJAX interface
client.useHttpClient(function httpProxy(options, cb) {
  options.success = function (data, status, xhr) {
    cb(null, { status: xhr.status, data: data, xhr: xhr })
  }
  options.error = function (xhr) {
    cb({ status: xhr.status, xhr: xhr })
  }
  $.ajax(options)
})

For more information, see the API method documentation

Can I use streams?

Not yet. There are plans to support it in future versions.

Can I use Resilient in production projects?

Resilient was used in both web and node.js production applications.

The library is, indeed, relatively young and it will evolve with new features in future versions (in fact a full core and logic redesign is required), but the API consistency in not compromised between patch minor releases.

How can I create custom middleware?

You can see the middleware documentation or see an example

Contributing

Wanna help? Cool! It will be appreciated :)

You must add new test cases for any new feature or refactor you do, always following the same design/code patterns that already exist

Development

Only node.js is required for development

Clone the repository

$ git clone https://github.com/resilient-http/resilient.js.git && cd resilient.js

Install development dependencies

$ npm install

Install browser dependencies

$ bower install

Generate browser bundle source

$ make browser

Run tests (in both node.js and headless browser)

$ make test

Run tests in real browsers

$ make test-browser

Name		Name	Last commit message	Last commit date
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bin		bin
examples		examples
features		features
lib		lib
test		test
.editorconfig		.editorconfig
.gitignore		.gitignore
.npmignore		.npmignore
.travis.yml		.travis.yml
History.md		History.md
Makefile		Makefile
README.md		README.md
bower.json		bower.json
component.json		component.json
karma.conf.js		karma.conf.js
package.json		package.json
resilient.js		resilient.js
resilient.min.js		resilient.min.js
resilient.min.js.map		resilient.min.js.map

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Contents

Features

Installation

Environments

Middleware

Framework-specific adapters

Related projects

How to use?

How does it work?

Basic usage

Static servers

Dynamic servers lookup

Middleware Layer

Types of middleware

Middleware API

Command-line interface

API

resilient([ options ])

Options

Service

Balancer

Discovery

Request callback arguments

Response

Browser

Node.js

Error

Built-in error codes

Events

request:start

request:outgoing

request:incoming

request:finish

request:retry

request:fallback

servers:refresh

servers:cache

discovery:refresh

Methods

resilient#send(path, options, callback)

resilient#get(path, options, callback)

resilient#post(path, options, callback)

resilient#put(path, options, callback)

resilient#delete(path, options, callback)

resilient#patch(path, options, callback)

resilient#head(path, options, callback)

resilient#options([ type|options, options ])

resilient#serviceOptions([ options ])

resilient#discoveryOptions([ options ])

resilient#balancer([ options ])

resilient#httpOptions(type)

resilient#addFailStrategy(strategy)

resilient#areServersUpdated()

resilient#servers([ type = 'service' ])

resilient#serversURL([ type = 'service' ])

resilient#resetScore([ type = 'service' ])

resilient#discoveryServers([ servers ])

resilient#discoverServers([ options, ] cb)

resilient#latestServers([ options, ] cb)

resilient#updateServers([ options, ] cb)

resilient#use(middleware)

resilient#useHttpClient(fn)

resilient#restoreHttpClient()

resilient#mock(mockFn)

resilient#unmock()

resilient#on(event, handler)

resilient#off(event, handler)

resilient#once(event, handler)

resilient#cache.flush()

resilient#client()

resilient.VERSION

resilient.CLIENT_VERSION

resilient.defaults

resilient.Options(options)

Packages