Emitter Python SDK

This repository contains a Python client for Emitter (see also Emitter GitHub). Emitter is an open-source real-time communication service for connecting online devices. At its core, emitter.io is a distributed, scalable and fault-tolerant publish-subscribe messaging platform based on MQTT protocol and featuring message storage.

This library provides a nicer high-level MQTT interface fine-tuned and extended with specific features provided by Emitter. The code uses the Eclipse Paho MQTT Python Client for handling all the network communication and MQTT protocol.

• Installation
• Examples
• API reference
• ToDo
• License

Installation

This SDK is available as a pip package. Install with:

pip install emitter-io

Examples

These examples show you the whole communication process.

• Python 2: sample-python2.py
• Python 3: sample-python3.py

API reference

• Client()
  • .connect()
  • .disconnect()
  • .keyban()
  • .keygen()
  • .link()
  • .me()
  • .on_connect
  • .on_disconnect
  • .on_error
  • .on_keyban
  • .on_keygen
  • .on_me
  • .on_message
  • .on_presence
  • .presence()
  • .publish()
  • .publish_with_link()
  • .subscribe()
  • .subscribe_with_group()
  • .unsubscribe()
• EmitterMessage()
  • .as_string()
  • .as_object()
  • .as_binary()

---

Client()

The Client class represents the client connection to an Emitter server.

---

Emitter#connect(host="api.emitter.io", port=443, secure=True, keepalive=30)

emitter = Client()

emitter.connect()

Connects to an Emitter server.

• host is the address of the Emitter broker. (Optional | Str | Default: "api.emitter.io")
• port is the port of the emitter broker. (Optional | Int | Default: 443)
• secure whether the connection should be secure. (Optional | Bool | Default: True)
• keepalive is the time the connection is kept alive (Optional | Int | Default: 30)

If you don't want a secure connection, set the port to 8080, unless your broker is configured differently.

To handle connection events, see the .on_connect property.

---

Emitter#disconnect()

emitter.disconnect()

Disconnects from the connected Emitter server.

To handle disconnection events, see the .on_disconnect property.

---

Emitter#keyban(master_key, target_key, ban)

instance.keyban("MEj8QNnzy6pKtE887hpXbD0KyKXi4w4f", "ftibXtPMKXI5p2FjhyINf8tvl2GAHaNG", True)

Sends a request to ban/unban a channel key.

• master_key is your master key to use for the operation. (Required | Str)
• target_key is the key ban or unban. (Required | Str)
• ban is whether to ban or unban the key. (Required | Bool)

To handle keyban responses, see the .on_keyban property. It will take a minute for the change to take effect.

---

Emitter#keygen(key, channel, permissions, ttl=0)

instance.keygen("Z5auMQhNr0eVnGBAgWThXus1dgtSsvuQ", "channel/", "rwslpex")

Sends a key generation request to the server.

• key is your master key to use for the operation. (Required | Str)
• channel is the channel name to generate a key for. (Required | Str)
• permissions are the permissions associated to the key. (Required | Str)
  • r for read
  • w for write
  • s for store
  • l for load
  • p for presence
  • e for extend
  • x for execute
• ttl is the time to live of the key. 0 means it never expires (Optional | Int | Default: 0)

To handle keygen responses, see the .on_keygen property. Requesting a keygen with an extendable channel creates a private channel.

---

Emitter#link(key, channel, name, private, subscribe, options={})

instance.link("5xZjIQp6GA9fpxso1Kslqnv8d4XVWChb",
              "channel",
              "a0",
              True,
              {Client.with_ttl(604800), Client.without_echo()}) // one week

Sends a link creation request to the server. This allows for the creation of a link between a short 2-character name and an actual channel. This function no longer allows the creation of a private channel. For this, use .keygen.

• key is the key to the channel. (Required | Str)
• channel is the channel name. (Required | Str)
• name is the short name for the channel. (Required | Str)
• subscribe whether or not to subscribe to the channel. (Required | Bool)
• options a set of options. Currently available options are:
  • with_at_most_once() to send with QoS0.
  • with_at_least_once() to send with QoS1.
  • with_retain() to retain this message.
  • with_ttl(ttl) to set a time to live for the message.
  • without_echo() to tell the broker not to send the message back to this client.

---

Emitter#me()

instance.me()

Requests information about the connection. Information provided in the response contains the id of the connection, as well as the links that were established with .link() requests.

To handle the responses, see the .on_me property.

---

Emitter#on_connect

Property used to get or set the connection handler, that handle events emitted upon successful (re)connection. No arguments provided.

---

Emitter#on_disconnect

Property used to get or set the disconnection handler, that handle events emitted after a disconnection. No arguments provided.

---

Emitter#on_error

Property used to get or set the error handler, that handle events emitted when an error occurs following any request. The event comes with a status code and a text message describing the error.

{"status": 400,
 "message": "the request was invalid or cannot be otherwise served"}

---

Emitter#on_keyban

Property used to get or set the handler for .keyban() requests. Here is a sample of the message received after such a request:

{"status": 200,
 "banned": True}

---

Emitter#on_keygen

ToDo: Description!

---

Emitter#on_me

Property used to get or set the handler that handle responses to .me() requests. Information provided in the response contains the id of the connection, as well as the links that were established with .link() requests.

{"id": "74W77OC5OXDBQRUUMSHROHRQPE",
 "links": {"a0": "test/",
           "a1": "test/"}}

---

Emitter#on_message

Emitted when the client receives a message packet. The message object will be of EmitterMessage class, encapsulating the channel and the payload.

---

Emitter#on_presence

Emitted either when a presence call was made requesting a status, using the Emitter#presence() function, or when a user subscribed/unsubscribed to the channel and updates were previously requested using again a call to the Emitter#presence() function. Example arguments below.

{"time": 1577833210,
 "event": "status",
 "channel": "<channel name>",
 "who": [{"id": "ABCDE12345FGHIJ678910KLMNO", "username": "User1"},
         {"id": "PQRST12345UVWXY678910ZABCD"}]}
{"time": 1577833220,
 "event": "subscribe",
 "channel": "<channel name>",
 "who": {"id": "ABCDE12345FGHIJ678910KLMNO", "username": "User1"}}
{"time": 1577833230,
 "event": "unsubscribe",
 "channel": "<channel name>",
 "who": {"id": "ABCDE12345FGHIJ678910KLMNO"}}

• time is the time of the event as Unix time.
• event is the event type: subscribe when an remote instance subscribed to the channel, unsubscribe when an remote instance unsubscribed from the channel and status when Emitter#presence() is called the first time.
• channel is the channel name.
• who in case of the event is (un)subscribe one dict with the user id, when the event is status, it is a list with the users. When more than 1000 users at the moment subscribed to the channel, 1000 randomly selected are displayed.
  • id is an internal generated id of the remote instance.
  • username is a custom chosen name by the remote instance. Please note that it is optional and check always if this parameter exists.

---

Emitter#presence(key, channel, status=False, changes=False, optional_handler=None)

instance.presence(""5xZjIQp6GA9fpxso1Kslqnv8d4XVWChb"",
                  "channel",
                  True,
                  True)

Sends a presence request to the server.

• key is the channel key to use for the operation. (Required | Str)
• channel is the channel name of which you want to call the presence. (Required | Str)
• status is whether the broker should send a full status of the channel. (Optional | Bool | Default: False)
• changes is whether to subscribe to presence changes on the channel. (Optional | Bool | Default: False)
• optional_handler is the handler to insert in the handler trie. (Optional | callable | Default: None)

Note: if you do not provide a handler here, make sure you did set the default handler for all presence messages using the .on_presence property.

---

Emitter#publish(key, channel, message, options={})

emitter.publish("5xZjIQp6GA9fpxso1Kslqnv8d4XVWChb",
                 "channel",
                 "Hello Emitter!",
                 {Client.with_ttl(604800), Client.without_echo()}) // one week

Publishes a message to a particual channel.

• key is the channel key to use for the operation. (Required | Str)
• channel is the channel name to publish to. (Required | Str)
• message is the message to publish (Required | String)
• options a set of options. Currently available options are:
  • with_at_most_once() to send with QoS0.
  • with_at_least_once() to send with QoS1.
  • with_retain() to retain this message.
  • with_ttl(ttl) to set a time to live for the message.
  • without_echo() to tell the broker not to send the message back to this client.

---

Emitter#publish_with_link(link, message)

instance.publishWithLink("a0",
                         "Hello Emitter!")

Sends a message through the link.

• link is the 2-character name of the link. (Required | Str)
• message is the message to send through the link. (Required | Str)

---

Emitter#subscribe(key, channel, optional_handler=None, options={})

instance.subscribe("5xZjIQp6GA9fpxso1Kslqnv8d4XVWChb",
                   "channel",
                   options={Client.with_last(5)})

Subscribes to a particular channel.

• key is the channel key to use for the operation. (Required | Str)
• channel is the channel name to subscribe to. (Required | Str)
• optional_handler is the handler to insert in the handler trie. (Optional | callable | Default: None)
• options a set of options. Currently available options are:
  • with_last(x) to receive the last x messages stored on the channel.

TODO

• with_from
• with_until

Note: if you do not provide a handler here, make sure you did set the default handler for all messages using the .on_message property.

---

Emitter#subscribe_with_group(key, channel, share_group, optional_handler=None, options={})

instance.subscribe("5xZjIQp6GA9fpxso1Kslqnv8d4XVWChb",
                   "channel",
                   "sg")

Subscribes to a particular share group for a channel. A message sent to that channel will be forwarded to only one member of the share group, chosen randomly. For more information about share groups, see Emitter: Load-balance Messages using Subscriber Groups (on YouTube).

• key is the channel key to use for the operation. (Required | Str)
• channel is the channel name to subscribe to. (Required | Str)
• share_group is the name of the group to join. (Required | Str)
• optional_handler is the handler to insert in the handler trie. (Optional | callable | Default: None)
• options a set of options.

Note: if you do not provide a handler here, make sure you did set the default handler for all messages using the .on_message property.

---

Emitter#unsubscribe(key, channel)

instance.unsubscribe("5xZjIQp6GA9fpxso1Kslqnv8d4XVWChb",
                     "channel")

Unsubscribes from a particual channel.

• key is the channel key to use for the operation. (Required | Str)
• channel is the channel name to unsubscribe from. (Required | Str)

This deletes handlers for that channel from the trie.

---

EmitterMessage()

The EmitterMessage class represents a message received from the Emitter server. It contains two properties:

• channel is the channel name the message was published to. (Str)
• binary is the buffer associated with the payload. (Binary Str)

---

EmitterMessage#asString()

message.asString()

Returns the payload as a utf-8 String.

---

EmitterMessage#asObject()

message.asObject()

Returns the payload as a JSON-deserialized dictionary.

---

EmitterMessage#asBinary()

message.asBinary()

Returns the payload as a raw binary buffer.

ToDo

There are some points where the Python libary can be improved:

• Complete the keygen entry in the README (see the ToDo markings)
• Describe how to use the trie of handlers for regular messages and presence.
• Add with_from and with_until.
• asObject should return an actual object instead of a dictionary.

License

Eclipse Public License 1.0 (EPL-1.0)

Copyright (c) 2016-2019 Misakai Ltd.