*http://stackoverflow.com/questions/15666048/service-vs-provider-vs-factory
http://stackoverflow.com/questions/13937318/convert-angular-http-get-function-to-a-service
SERVICE DESCRIPTION
- $http Allows promise-based access to HTTP requests (API Reference: ng.$http). You can read more about promises in Promises instead of Callbacks (Please note: this chapter has not yet been released).
- $resource Provides a higher-level abstraction for accessing REST-style services (API Reference: ng.$resource)
- $document Is a jQuery (lite)-wrapped reference to window.document (API Reference: ng.$document)
- $window Is a jQuery (lite)-wrapped reference to window (API Reference: ng.$window)
- $timeout This is a wrapped version of window.setTimeout. In tests, you can use $timeout.flush() to synchronously execute all scheduled timeouts. (API Reference: ng.$timeout)
- $parse Parses Angular expressions (for example, for binding with ng-model or similar) and provides accessor functions (API Reference: ng.$parse)
- $cacheFactory Usually used by other services whenever they need a scoped cache of elementes (API Reference: ng.$cacheFactory)
- $filter Provides programmatic access to a filter function (API Reference: ng.$filter)