To send a notification first create a `Device` object. Pass it the device token as either a hexadecimal string, or alternatively as a `Buffer` object containing the token in binary form.
As of version 1.2.0 it is also possible to use a set of methods provided by Notification object (`setAlertText`, `setActionLocKey`, `setLocKey`, `setLocArgs`, `setLaunchImage`) to aid the creation of the alert parameters. For applications which provide Newsstand capability there is a new boolean parameter `note.newsstandAvailable` to specify `content-available` in the payload.
**\*N.B.:** If you wish to send notifications containing emoji or other multi-byte characters you will need to set `note.encoding = 'ucs2'`. This tells node to send the message with 16bit characters, however it also means your message payload will be limited to 127 characters.
If the enhanced binary interface is enabled and an error occurs - as defined in Apple's documentation - when sending a message, then subsequent messages will be automatically resent* and the connection will be re-established. If an `errorCallback` is also specified in the connection options then it will be invoked with 2 arguments `(err, notification)`. Alternatively it is possible to specify an error callback function on a notification-by-notification basis by setting the ```.errorCallback``` property on the notification object to the callback function before sending.
**\*N.B.:** As of v1.2.5 a new events system has been implemented to provide more feedback to the application on the state of the connection. At present the ```errorCallback``` is still called in the following cases in addition to the new event system. It is strongly recommended that you migrate your application to use the new event system as the existing overloading of the ```errorCallback``` method will be deprecated and removed in future versions.
If a notification fails to be sent because a connection error occurs then the `errorCallback` will be called for each notification waiting for the connection which failed. In this case the first parameter will be an Error object instead of an error number.
`errorCallback` will be called in 3 situations with the parameters shown.
1. The notification has been rejected by Apple (or determined to have an invalid device token or payload before sending) for one of the reasons shown in Table 5-1 [here][errors] `errorCallback(errorCode, notification)`
1. A notification has been rejected by Apple but it has been removed from the cache so it is not possible to identify which. In this case subsequent notifications may be lost. **If this happens you should consider increasing your `cacheLength` value to prevent data loss**`errorCallback(255, null)`
1. A connection error has occurred before the notification can be sent. `errorCallback(Error object, notification)`
**\*N.B.:** The `cacheLength` option for the connection specifies the number of sent notifications which will be cached, on a FIFO basis for error handling purposes. If `cacheLength` is not set to a large enough value, then in high volume environments, a notification - possibly including some subsequent notifications - may be removed from the cache before Apple returns an error associated with it. In this case the `errorCallback` will still be called, but with a `null` notification and error code 255. If this happens you should consider increasing `cacheLength` to prevent losing notifications. All the notifications still residing in the cache will be resent automatically.
The following events have been introduced as of v1.2.5 to allow closer monitoring and information about the internal processes in node-apn. If the events are not useful to you they can all be safely ignored (with the exception of ```error``` which indicates a failure to load the security credentials) and no action needs to be taken on your part when events are emitted. The ```disconnected``` event, for instance, is provided for informational purposes, the library will automatically re-establish the connection as necessary. The events are emitted by the connection itself so you should use ```apnsConnection.on('error', errorHandler)``` to attach listeners.
####Events (arguments):
- ```error (error)```: emitted when an error occurs during initialisation of the module, usually due to a problem with the keys and certificates.
- ```transmitted (notification)```: emitted when a notification has been sent to Apple - not a guarantee that it has been accepted by Apple, an error relating to it make occur later on. A notification may also be sent several times if an earlier notification caused an error requiring retransmission.
- ```timeout```: emitted when the connectionTimeout option has been specified and no activity has occurred on a socket for a specified duration. The socket will be closed immediately after this event.
- ```connected```: emitted when the connection to Apple is successfully established. No action is required as the connection is managed internally.
- ```disconnected```: emitted when the connection to Apple has been closed, this could be for numerous reasons, for example an error has occurred or the connection has timed out. No action is required.
- ```socketError (error)```: emitted when the connection socket experiences an error. This is useful for debugging but no action should be necessary.
- ```transmissionError (error code, notification)```: emitted when a message has been received from Apple stating that a notification was invalid. If we still have the notification in cache it will be passed as the second argument, otherwise null.
- ```cacheTooSmall (difference)```: emitted when Apple returns a notification as invalid but the notification has been expunged from the cache - usually due to high throughput. The parameter estimates how many notifications have been lost. You should experiment with increasing the cache size or enabling ```autoAdjustCache``` if you see this frequently. Note: With ```autoAdjustCache``` enabled this event will still be emitted when an adjustment is triggered.
Using the `Feedback` object it is possible to periodically query the server for the list. You should provide a function `feedback` which will accept two arguments, the `time` returned by the server (epoch time) and a `Buffer` object containing the device token. You can also set the query interval in seconds. The default options are shown below.
This will automatically start a timer to check with Apple every `interval` seconds. You can cancel the interval by calling `feedback.cancel()`. If you do not wish to have the service automatically queried then set `interval` to 0 and use `feedback.start()`.
**Important:** In a development environment you must set `address` to `feedback.sandbox.push.apple.com`.
More information about the feedback service can be found in the [feedback service documentation][fs].
If you are using a development certificate you may wish to name them differently to enable fast switching between development and production. The filenames are configurable within the module options, so feel free to name them something more appropriate.
If you experience difficulties sending notifications or using the feedback service you can enable debug messages within the library by running your application with `DEBUG=apn` or `DEBUG=apnfb` set as an environment variable.
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[errors]:https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/CommunicatingWIthAPS/CommunicatingWIthAPS.html#//apple_ref/doc/uid/TP40008194-CH101-SW4 "The Binary Interface and Notification Formats"
[fs]:https://developer.apple.com/library/ios/#documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/CommunicatingWIthAPS/CommunicatingWIthAPS.html#//apple_ref/doc/uid/TP40008194-CH101-SW3 "Communicating With APS"
* Introduced a new event model. The connection class is now an event emitter which will emit events on connection state changes. This should largely replace the existing, somewhat inadequate error handling in previous versions. Please see the section above for more details or the message on commit d0a1d17961
* Fixed a bug relating to rejecting unauthorized hosts
* Added support for PFX files instead of separate Certificate and Key Files
* Added a batched feedback feature which can callback with an array of all devices instead of calling the method for each device separately
* Added support for error callbacks on a per notification basis.
* Changed the socket behaviour to enable the TCP Nagle algorithm as recommended by Apple
* Fixed lots of small bugs around connection handling which should make high volume applications more stable. Node should no longer crash completely on EPIPE errors.
* Added connection socket timeout after a period of inactivity, configured by ```options.connectionTimeout```. The socket will then be re-established automatically if further notifications are sent.
* Added cache autoadjustment. If ```options.autoAdjustCache = true``` and a notification error occurs after the notification is purged from the cache the library will attempt to increase the cache size to prevent it happening in future.
* Change in the error handling logic. When a notification errors and it cannot be found in the cache, then all notifications in the cache will be resent instead of being discarded.
*`errorCallback` will also be invoked for connection errors.
* New methods on `Notification` to aid settings the alert properties.
*`content-available` can now be set for Newsstand applications by setting the `newsstandAvailable` property on the Notification object.
*`Notification` objects now have a `.clone(device)` method to assist you in sending the same notification to multiple devices.
* Included some js-doc tags in the source.
* Device object now provides a `.toString()` method to return the hex representation of the device token.
* Feature: Certificate and Key data can be passed directly when creating a new connection instead of providing a file name on disk. (See: `certData` and `keyData` options)
* Deliver whole write buffer if the socket is ready.
* Fixed some global memory leaks.
* Tidied up some code formatting glitches flagged by jslint
* Fixes #9, Addresses an issue if the socket disconnects with queued notifications it would be reinitialised before its teardown is completed leaving the system in an undefined state.
