[MUSIC] So why are we using a web browser protocol to integrate mobile clients with cloud services? Why do we want to use HTTP to talk to the cloud? Well HTTP provides us a number of nice properties. One is, we've got a uniform interface that we can provide via HTTP to the services or resources that are sitting on the server. And, for example, if a client is a Browser and sends a request over HTTP and that Server rec, receives that request, the request is exactly the same as if a mobile device had sent it. So, if this is a Mobile device that's sending that request, either way on the other side, on the server side, that request still has to conform to the same requirements and specifications of the HTTP protocol. So we can have a common interface. This is one of the big advantages of using HTTP to interact with cloud resources and services. Is we don't have to go and rewrite everything from scratch and figure out a whole new way of having our servers accessible and having mobile devices able to communicate with them. We can reuse what we're already building and providing to our browser based clients and the web is ubiquitous. Everybody's building websites, everybody's supporting web service as it is. Why not reuse this infrastructure for mobile? And so that's one of the big reasons behind using HTTP to support mobile and cloud interactions. Now, we get a number or of other great things as well. There's already all kinds of stuff on the server side from a framework and programmatic perspective that we can use to process HTTP requests. So there's things for doing stuff like sessions or remembering when people request something, who that person is and what they previously requested or what other data is associated with their current login. We also get things like Data marshalling. This is very important when you want to convert from the format of the HTTP request to some other format that you need to process. And there's a huge amount of infrastructure that's already been developed, in terms of libraries and frameworks, that you can use to program if you use HTTP as your underlying protocol for your interaction with the cloud. But there's also a number of other reasons that it's really nice to use HTTP. There's also infrastructure that decides, how do we load balance and distribute requests across our servers? So for example, if you have a million people accessing your, your service simultaneously, how are you going to distribute those requests across those servers? So, Load Balancing infrastructure for HTTP can be reused if we're using HTTP as the communication mechanism with the cloud. So there's such a significant investment both in the existing frameworks and libraries, the load balancing and other management infrastructure that's been developed for HTTP. It's natural to use HTTP as an interaction mechanism with the cloud. Now, as we'll see later in the class, there's some challenges to using HTTP, particularly when things that we would like to do with our mobile services don't fit into the client server model where the client is always the mobile device requesting some resource from the server. So maybe an email comes into the server and your client needs to be notified about it. Well that's difficult to fit into the HTTP model. But we'll talk about how we overcome some of those challenges later in the lessons.
