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Apns4erl

This lib is intended to allow you to write an APNs provider for Apple Push Notificaion services (APNs) in Erlang.

Copyright (c) 2010 Inaka Labs SRL support@inaka.net, released under the MIT license

Contact Us

For questions or general comments regarding the use of Apns4erl, please use our public hipchat room.

If you find any bugs or have a problem while using Apns4erl, please open an issue in this repo (or a pull request :)).

And you can check all of our open-source projects at inaka.github.io

Example

Using apns4erl is quite simple. First, setup something similar to this in your sys.config:

    {apns, [
      {apple_host, "gateway.sandbox.push.apple.com"},
      {apple_port, 2195},
      {cert_file, "/etc/certs/mycert_dev.pem"},
      {key_file, undefined},
      {cert_password, undefined},
      {timeout, 30000},
      {expires_conn, 300}
      {feedback_port, 2196},
      {feedback_host, "feedback.sandbox.push.apple.com"},
      {feedback_timeout, 18000000}
    ]}

NOTE: The apple_host to use will depend on your environment (production or development). Remember to always use the correct certificate, device tokens, and apns hostname for production or development environments.

NOTE 2: To generate the .pem file, from the .cer an .p12 files provided by Apple, you can use this script

Then, once you've started the apns application, you can connect to the APNS network using:

      apns:connect(
        %% your connection identifier:
        my_connection_name,
        %% called in case of a "hard" error:
        fun ?MODULE:handle_apns_error/2,
        %% called if the device uninstalled the application:
        fun ?MODULE:handle_apns_delete_subscription/1
      ).

As a result, you will get a tuple:

  • {ok, Pid}
  • {error, {already_started, Pid}}
  • {error, Reason}

Pid is the Pid of the apns_connection process spawned to handle the connection.

CAUTION: It is highly recommended to pass a fully qualified function for callbacks, using the fun M:F/A syntax. If you pass in a local fun using fun F/A, any subsequent code upgrades to the module where that local fun was defined, will cause the code server to kill processes that are holding on to references to the old code (eg. the apns connection processes, thus killing the apns4erl application).

To send a notification

apns:send_message(my_connection_name, "this_is_a_valid_device_token", "hello world").

That's it!

A little more about what's going on

Actually, send_message/3, send_message/4, send_message/5, send_message/6, send_message/7, and send_message/8 are calling send_message/2, which takes a #apns_msg record as its 2nd argument. Thus, you can also create the message customized with your own needs, by using a #apns_msg record:

    -include_lib("apns/include/apns.hrl").

    apns:send_message(my_connection_name, #apns_msg{
      alert  = "alert" ,
      badge  = 1,
      sound  = "sound" ,
      category = "EMAIL_ACTION",
      expiry = 1348000749,
      device_token = "this_is_a_valid_device_token"
    }).

Feedback Channel and Getting Errors

Notice how we are passing 2 funs to the connect function. These are used as callbacks:

If there was an error while sending a message, the first fun will be called.

If there were no errors, but Apple reported that the user removed the application from the device, the 2nd fun will be used (this is effectively the feedback channel).

    handle_apns_error(MsgId, Status) ->
      error_logger:error_msg("error: ~p - ~p~n", [MsgId, Status]).

    handle_apns_delete_subscription(Data) ->
      error_logger:info_msg("delete subscription: ~p~n", [Data]).

Passing Keys and Certificates Directly

By default, the private key and certificate to use to connect to Apple's servers are loaded out of the PEM-encoded files specified in cert_file and key_file. However, if you prefer to store these elsewhere and load them manually, you can pass DER-encoded binaries when connecting:

    CertBin = <<"-----BEGIN CERTIFICATE-----"...>>, % perhaps from a database
    KeyBin = <<"-----BEGIN RSA PRIVATE KEY-----"...>>,
    [{'Certificate', CertDER, not_encrypted}] = public_key:pem_decode(CertBin),
    [{'RSAPrivateKey', KeyDER, not_encrypted}] = public_key:pem_decode(KeyBin),
    Connection = #apns_connection{cert_file=undefined,
                                  cert=CertDER,
                                  key={'RSAPrivateKey', KeyDER}},
    apns:connect(Connection).

If you store your key and certificate as DER binaries, you can pass them directly without any decoding.