Law-Connect

Connect middleware for Law.

Purpose

Law-Connect provides a piece of Connect middleware to route HTTP requests to Law services. It provides configurable routing on URI path and HTTP method, as well as a resource helper which expands into standard CRUD routes (modeled after the Rails resources[1]).

[1] http://guides.rubyonrails.org/routing.html#crud-verbs-and-actions

Usage

Law-Connect provides a standard Connect middleware.We expect the user to have a collection of already-configured Law services (services), a collection of route definitions (routeDefs), and an optional object (options )of parameters that control how error information is exposed in responses.

Lifecycle

Law-Connect simply provides a constructor for a piece of Connect middleware. It expects a fully wired-up services object (the output of law.create).

Example

connect = require 'connect'
lawAdapter = require 'law-connect'

// Given a Connect application...
app = connect()

// The `connect.json`, `connect.urlencoded`, `connect.multipart` middleware must be `use`'d before Law-Connect
app.use connect.json() // required!
app.use connect.urlencoded() // required!
app.use connect.multipart() // required!

// Given a wired-up `services` object, e.g. the result of:
//   services = law.create {services, jargon, policy}
routeDefs = load './routeDefs'

// Hide most Error information in responses
options =
  includeDetails: false
  includeStack: false

// Apply the middleware!
app.use lawAdapter({services, routeDefs, options})

Error handling and HTTP status codes

Errors are passed in the first callback argument, according to the Node convention used within Law. Errors within Law are subtypes of a LawError subtype of Error, created with the tea-error library. Thus LawError and subtypes enrich Error with a toJSON method and the ability to construct instances with additional properties containing information about the error context.

By default, all error response bodies include:

• The error message
• All custom, service-specific properties attached to the LawError instance.
• The error stack trace (stack)

If a Law service returns an error, the HTTP response presently defaults to using a status code of 500 Internal Server Error.

If there was no Law service that could be matched with the request, the middleware will return a 501 Not Implemented HTTP response.

Otherwise, the default response is 200 OK. Specific HTTP codes can be specified by Law services by including a statusCode property in the results argument of the callback, which will always be treated as metadata (and thus not included in the response body).

Configuration

Service Definitions

Regular route definitions are of the form:

[
  {
    path: '/something'
    method: 'get'
    serviceName: 'indexThings'
  }
  {
    path: '/something/:id'
    method: 'get'
    serviceName: 'showThing'
  }
]

The values of the serviceName property should resolve to a wired-up Law service when the adapter is constructed. If not, a default noService service will respond with a 501 error indicating that no service is implemented.

The resource syntax uses the format:

[
  {
    resource: 'photos'
    prefix: 'api'
    id: 'special_field'
  }
]

The presence of the resource key indicates that the route definition should be automatically expanded into several regular route definitions. The value of resource should be the collection name (plural).

The prefix and id keys are optional. prefix will namespace all of the routes under the provided string. id configures what named argument will be passed in for the instance routes.

Regular route definitions and resource route definitions can be freely interspersed within a single route definition array, and resources definitions will be expanded in-place.

Options

Optional configuration can be passed via the options property of the arguments object. The current properties, which all default to true, are:

• includeDetails: Include context details attached as properties to any subtypes of LawError.
• includeMessage: Include the Error.message property.
• includeStack: Include the stack trace via the Error.stack property.

License

(MIT License)

Copyright (c) 2013 Torchlight Software info@torchlightsoftware.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.