StreamingApiHandler.xml

<aura:component access="global" controller="StreamingApiController">
    <!-- ChannelName, which needs to subscribed -->
    <aura:attribute name="channelName" type="String" required="true"/>
    <!-- Save the reference of cometD, which will be used to disconnect the subscription -->
    <aura:attribute name="cometd" type="Object"/>
    <!-- Save the reference of current subscription, which can be unsubscribe later on -->
    <aura:attribute name="subscription" type="Object"/>
     <!-- This event is fired when a component is destroyed. 
		Handle this event if you need to do custom cleanup when a component is destroyed.-->
    <aura:handler name="destroy" value="{!this}" action="{!c.unsubscribe}"/>
    <!-- Component event, which will be fired once the message is received -->
    <aura:registerEvent name="onStreamEvent" type="c:StreamEvent"/>
    <!-- Must include cometD library -->
    <ltng:require scripts="{!$Resource.cometd + '/cometd.js'}" afterScriptsLoaded="{!c.doInit}" />    
</aura:component>