 If you recall, we used to come across a term known as ecosystem, particularly in biophysical systems, we would call it a food chain. Likewise, in the cloud computing environment, we have an entire ecosystem. So let's look at the ecosystem from the entities, components, and roles viewpoint. So formally, we start with the definition. So the cloud computing ecosystem is a business ecosystem where everyone's present to make some money. It has various organizations, individuals, systems which interact with each other. The actors which perform certain actions in a cloud ecosystem are either there to provide cloud services or consume cloud services. So formally, the ITUT document defines three players as the cloud service users, cloud service providers, and the cloud service partners also known as the cloud service networks. The diagram and the texts I've taken from the International Telecommunication Union telecom reference document from 2012, that is ITUT focus group on cloud, the technical standard recommendations for standardization. So here we see that on the access side, the cloud service user uses the provider to have access to the partners and the partner associated services. So you see that we have service providers abridging between the service users and the third party networks. Now let's look at the possible roles that we could see for the service users, providers, and the partners could be very obvious. For instance, the cloud service users could be individuals, the government itself, or the enterprises. The cloud service providers could provide the very basic classical form of cloud services like infrastructure, software, platform, network, etc. In addition, the service providers could get together in various relationships known as interworking or internet working of cloud service providers for peering, service brokerage and for federation. We would quickly have a look at all of these. And then the partners or the cloud service networks could include the application developers for a certain cloud service provider, content and software provider, the hardware and equipment provider, sometimes the vendors, sometimes the original equipment manufacturers themselves, the system integrators which could merge, which could combine and offer multiple services like bundled services. And then we have, if you recall from the NIST reference architecture, the auditor as the partner as well. The internet working scenarios for clouds could be peering, federation and brokerage. Let's look at each one of these in turn. So we have two service providers, A and B, which have exposed their APIs for accessing their services. So these two are coming to appear to peer relationship known as peering. So cloud service providers would now connect to each other or interwork with each other using the APIs provided by both. If we extend the same concept for more than two service providers, we could think of it as a federation. So the federated or federation of cloud service providers is when multiple like-minded, mutually trusting service providers join an alliance probably to provide the meta services or super services. Now each cloud service provider connects to the other cloud service provider through a common API. This common API could be on bilateral relationship or could be a centralized common API. And then continuing with this, the best or the most advanced form of internet working is when the service providers come together and depute or delegate a broker. So a broker is essentially another cloud service provider, which plays the role of brokerage of services. So it means all the cloud service providers like A, B and C in this case expose their APIs to the broker cloud service provider, which on behalf of these cloud service providers receives requests from the CSUs or cloud service users and likewise entertains the requests from each of these cloud service providers. So it means now the broker has exposed the services for three cloud service providers being the central entity. Now this particular relationship allows multiple cloud service providers to work as a federation and delegating their exposed services to a broker.