Each App has a default channel (without name) which stores all incoming events. This "default" one is used when channel is not specified.

You may create additional Channels for the App. Creating multiple Channels is advanced usage. You don't need to create any in order to use Apache PredictionIO. The Channel is associated with one App only and must have unique name within the same App.

Creating multiple Channels allows you more easily to identify, manage and use specific event data if you may collect events from different multiple sources (eg. mobile, website, or third-party webhooks service) for the your application.

(More usage details coming soon...)

Create a new Channel

For example, to create a new channel "myChannel" for app "myApp", run following pio command:

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pio app channel-new myApp myChannel

you should see something like the following outputs:

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[INFO] [App$] Updated Channel meta-data.
[INFO] [HBLEvents] The table predictionio_eventdata:events_5_2 doesn't exist yet. Creating now...
[INFO] [App$] Initialized Event Store for the channel: myChannel.
[INFO] [App$] Created new channel:
[INFO] [App$]     Channel Name: myChannel
[INFO] [App$]       Channel ID: 2
[INFO] [App$]           App ID: 5

Now "myChannel" is created and ready for collecting data.

Collect data through Channel

The Event API support optional channel query parameter. This allows you to import and query events of the specified channel. When the channel parameter is not specified, the data is collected through the default channel.

URL: http://localhost:7070/events.json?accessKey=yourAccessKeyString&channel=yourChannelName

Query parameters:

For SDK usage, one EventClient should be responsible for collecting data of one specific channel. The channel name is specified when the EventClient object is instantiated.

For example, the following code import event to "YOUR_CHANNEL" of the corresponding App.

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$ curl -i -X POST http://localhost:7070/events.json?accessKey=YOUR_ACCESS_KEY&channel=YOUR_CHANNEL \
-H "Content-Type: application/json" \
-d '{
  "event" : "my_event",
  "entityType" : "user",
  "entityId" : "uid",
  "targetEntityType" : "item",
  "targetEntityId" : "iid",
  "properties" : {
    "someProperty" : "value1",
    "anotherProperty" : "value2"
  },
  "eventTime" : "2004-12-13T21:39:45.618Z"
}'

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from predictionio import EventClient
from datetime import datetime
import pytz

# Create a EventClient for "YOUR_CHANNEL"
client = EventClient('YOUR_ACCESS_KEY', "http://localhost:7070",
  channel='YOUR_CHANNEL') # default channel if not specified

event_properties = {
    "someProperty" : "value1",
    "anotherProperty" : "value2",
    }
event_response = client.create_event(
    event="my_event",
    entity_type="user",
    entity_id="uid",
    target_entity_type="item",
    target_entity_id="iid",
    properties=event_properties,
    event_time=datetime(2014, 12, 13, 21, 38, 45, 618000, pytz.utc))

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(coming soon)

You can also follow the EventAPI debug receipts to query the events of specific channel by adding the channel query parameter in the URL.

Delete a Channel (including all imported data)

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pio app channel-delete <app name> <channel name>

Delete the data-only of a Channel

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pio app data-delete <app name> --channel <channel name>

Accessing Channel Data in Engine

To acccess channel data, simply specify the channel name when use the PEventStore or LEventStore API. Data is read from from the default channel if channelName is not specified.

For example, read data from default channel:

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    val eventsRDD: RDD[Event] = PEventStore.find(
      appName = dsp.appName,
      entityType = Some("user"),
      eventNames = Some(List("rate", "buy")), // read "rate" and "buy" event
      // targetEntityType is optional field of an event.
      targetEntityType = Some(Some("item")))(sc)

For examlpe, read data from the channel "CHANNEL_NAME"

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    val eventsRDD: RDD[Event] = PEventStore.find(
      appName = dsp.appName,
      channelName = Some("CHANNEL_NAME"), // ADDED
      entityType = Some("user"),
      eventNames = Some(List("rate", "buy")), // read "rate" and "buy" event
      // targetEntityType is optional field of an event.
      targetEntityType = Some(Some("item")))(sc)