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Chapter 267. PubNub Component
Available as of Camel version 2.19
Camel PubNub component can be used to communicate with the PubNub data stream network for connected devices. This component uses pubnub java library.
Use cases includs:
- Chat rooms: Sending and receiving messages
- Locations and Connected cars: dispatching taxi cabs
- Smart sensors: Receiving data from a sensor for data visualizations
- Health: Monitoring heart rate from a patient’s wearable device
- Multiplayer gamings
- Interactive media: audience-participating voting system
Maven users will need to add the following dependency to their pom.xml for this component:
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-pubnub</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>267.1. URI format
pubnub:channel[?options]
Where channel is the PubNub channel to publish or subscribe to.
267.2. Options
The PubNub component has no options.
The PubNub endpoint is configured using URI syntax:
pubnub:channel
with the following path and query parameters:
267.2.1. Path Parameters (1 parameters):
| Name | Description | Default | Type |
|---|---|---|---|
| channel | Required The channel used for subscribing/publishing events | String |
267.2.2. Query Parameters (14 parameters):
| Name | Description | Default | Type |
|---|---|---|---|
| uuid (common) | UUID to be used as a device identifier, a default UUID is generated if not passed. | String | |
| bridgeErrorHandler (consumer) | Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. | false | boolean |
| withPresence (consumer) | Also subscribe to related presence information | false | boolean |
| exceptionHandler (consumer) | To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored. | ExceptionHandler | |
| exchangePattern (consumer) | Sets the exchange pattern when the consumer creates an exchange. | ExchangePattern | |
| operation (producer) | The operation to perform. PUBLISH: Default. Send a message to all subscribers of a channel. FIRE: allows the client to send a message to BLOCKS Event Handlers. These messages will go directly to any Event Handlers registered on the channel. HERENOW: Obtain information about the current state of a channel including a list of unique user-ids currently subscribed to the channel and the total occupancy count. WHERENOW: Obtain information about the current list of channels to which a uuid is subscribed to. GETSTATE: Used to get key/value pairs specific to a subscriber uuid. State information is supplied as a JSON object of key/value pairs SETSTATE: Used to set key/value pairs specific to a subscriber uuid GETHISTORY: Fetches historical messages of a channel. | String | |
| pubnub (advanced) | Reference to a Pubnub client in the registry. | PubNub | |
| synchronous (advanced) | Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported). | false | boolean |
| authKey (security) | If Access Manager is utilized, client will use this authKey in all restricted requests. | String | |
| cipherKey (security) | If cipher is passed, all communicatons to/from PubNub will be encrypted. | String | |
| publishKey (security) | The publish key obtained from your PubNub account. Required when publishing messages. | String | |
| secretKey (security) | The secret key used for message signing. | String | |
| secure (security) | Use SSL for secure transmission. | true | boolean |
| subscribeKey (security) | The subscribe key obtained from your PubNub account. Required when subscribing to channels or listening for presence events | String |
267.3. Spring Boot Auto-Configuration
The component supports 2 options, which are listed below.
| Name | Description | Default | Type |
|---|---|---|---|
| camel.component.pubnub.enabled | Enable pubnub component | true | Boolean |
| camel.component.pubnub.resolve-property-placeholders | Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders. | true | Boolean |
267.4. Message headers when subscribing
| Name | Description |
|---|---|
|
| The Timestamp for the event. |
|
| The channel for which the message belongs. |
267.5. Message body
The message body can contain any JSON serializable data, including: Objects, Arrays, Ints and Strings. Message data should not contain special Java V4 classes or functions as these will not serialize. String content can include any single-byte or multi-byte UTF-8
Object serialization when sending is done automatically. Just pass the full object as the message payload. PubNub will takes care of object serialization.
When receiving the message body utilize objects provided by the PubNub API.
267.6. Examples
267.6.1. Publishing events
Default operation when producing. The following snippet publish the event generated by PojoBean to the channel iot.
from("timer:mytimer")
// generate some data as POJO.
.bean(PojoBean.class)
.to("pubnub:iot?publishKey=mypublishKey");267.6.2. Fire events aka BLOCKS Event Handlers
See https://www.pubnub.com/blocks-catalog/ for all kind of serverless functions that can be invoked. Example of geolocation lookup
from("timer:geotimer")
.process(exchange -> exchange.getIn().setBody(new Foo("bar", "TEXT")))
.to("pubnub:eon-maps-geolocation-input?operation=fire&publishKey=mypubkey&subscribeKey=mysubkey");
from("pubnub:eon-map-geolocation-output?subscribeKey=mysubkey)
// geolocation output will be logged here
.log("${body}");267.6.3. Subscribing to events
The following snippet listens for events on the iot channel. If you can add the option withPresens, you will also receive channel Join, Leave asf events.
from("pubnub:iot?subscribeKey=mySubscribeKey")
.log("${body}")
.to("mock:result");267.6.4. Performing operations
herenow : Obtain information about the current state of a channel including a list of unique user-ids currently subscribed to the channel and the total occupancy count of the channel
from("direct:control")
.to("pubnub:myChannel?publishKey=mypublishKey&subscribeKey=mySubscribeKey&operation=herenow")
.to("mock:result");wherenow : Obtain information about the current list of channels to which a uuid is subscribed
from("direct:control")
.to("pubnub:myChannel?publishKey=mypublishKey&subscribeKey=mySubscribeKey&operation=wherenow&uuid=spyonme")
.to("mock:result");setstate : Used to set key/value pairs specific to a subscriber uuid.
from("direct:control")
.bean(StateGenerator.class)
.to("pubnub:myChannel?publishKey=mypublishKey&subscribeKey=mySubscribeKey&operation=setstate&uuid=myuuid");gethistory : Fetches historical messages of a channel.
from("direct:control")
.to("pubnub:myChannel?publishKey=mypublishKey&subscribeKey=mySubscribeKey&operation=gethistory");There is a couple of examples in test directory that shows some of the PubNub features. They require a PubNub account, from where you can obtain a publish- and subscribe key.
The example PubNubSensorExample already contains a subscribe key provided by PubNub, so this is ready to run without a account. The example illustrates the PubNub component subscribing to a infinite stream of sensor data.
267.7. See Also
- Configuring Camel
- Component
- Endpoint
- Getting Started
- RSS
