Hello, I'm Stephen Cole, a trainer here at Cloud Academy. As a reminder, here's what was covered in part one of this course. Streaming data exists because some data moves faster than others and not all data is created--or used--equally.  

Some data only has value for a short period of time and, by short, I mean measured in seconds.  That's part of the reason why streaming data is a thing today.  It can capture data and use it while it still has value.  

Streaming data works well in the cloud because the cloud has the promise of agility, scalability, and elasticity.  Agility is about changing to meet needs. Being agile is more than adapting to change, it’s also about being able to fit into places that were at one time too big or too small. Scalability means that growth can happen when needed. Elasticity, at least in the cloud, is the opposite of scalability. Even though environments can expand, one of the cloud's key characteristics is that they can return to its original size. This means that environments in the cloud can grow and shrink as needed.

So, if you are no longer using a resource, you can turn it off -- and stop paying for it. This is how I think about it. When I was a kid, my dad would go through the house grumbling about me forgetting to turn the lights out when I left a room.  He'd say things like, "Why am I paying to light up a room nobody is using." This was not far from one of his other remarks, "Close the front door, I'm not paying to heat the whole neighborhood."  Maybe I'm alone in this experience.  I'm not sure.  Still, to me, that's the fundamental principle of elasticity.  It's my dad reminding me that it's a bad idea to pay for something if it isn't being used.

Kinesis Data Streams is one of the features of Amazon Kinesis.  It is a massively scalable and durable real-time data streaming service.  It is not designed for binary data.  For that, use Amazon Kinesis Video Streams.  For data streaming that is near-real time and destined for AWS storage or an HTTP endpoint, use Kinesis Data Firehose.

Kinesis Data Streams  is used to collect data in real time from sources such as website clickstreams, database event streams, financial transactions, social media feeds, IT logs, location tracking events, and IoT devices.

Data collected is available within milliseconds inside a stream and enables applications to do things like analytics, dashboards, anomaly detection, and dynamic pricing in real time.