What are some alternatives?
When comparing iKnode and PubNub, you can also consider the following products
Backendless - Backendless is a mobile Backend as a Service (mBaaS) platform.
Firebase - Firebase is a cloud service designed to power real-time, collaborative applications for mobile and web.
convertigo - Convertigo offers mobile backend as a service for creating and deploying business mobile applications.
Pusher - Pusher is a hosted API for quickly, easily and securely adding scalable realtime functionality via WebSockets to web and mobile apps.
Parse (Updated) - Parse with five new products, live from F8
Socket.io - Realtime application framework (Node.JS server)