Cloud Architecture & Design

This is the layer where all the required hardwares are stored. These hardwares will be your individual machines, clusters, networking components, storage components etc. These are our data centers

Features of Physical Layer

1. Physical Layer consists of thousands of nodes grouped together (i.e. the data centres):
   These could be a centralized cluster in the data center or could be a B2B cloud where there are many nodes, but all these thousands of nodes form this lower layer of the cloud stack.
   They are responsible for providing the physical hardware to the devices and they are responsible for communication between the devices.
2. Responsible for communication between the hardware devices and higher layers
   They are responsible for providing the lower layer of the devices and they are responsible for communication between the devices and higher layers such as (IaaS, Paas & Saas).

Virtualization Layer (ie., Xen VMWare)  sits on top of the physical Layer   and has a set of Virtual Machines generated by this.

Features of Virtualization Layer:

• Key enabling technology
• Pool of Virtual Machines (Vms) are created from the underneath physical resource.

Basically, this layer is a key enabling technology, that creates a pool of virtual machines which can be used in one form or the other by the consumer.

This layer of Virtual Machines forms the first service model which is called Infrastructure as a Service (IaaS).

The Service Layers include:

Infrastructure as a Service (IaaS)
Platform as a Service (PaaS)
Software as a Service (SaaS)

1. Infrastructure as a Service (IaaS)
   The layers of Virtual Machines (VMs) forms the first service model which is known as  Infrastructure as a Service (IaaS) model.
   When consumer use this service of Infrastructure, they will be given these Virtual Machines, and the consumers can install their own Operating System, softwares etc.
   In these Virtual Machines which  behave as if the underneath hardware  (ie., physical Layer) is being accessed through the Virtual Machine.
   So, the consumers actually rent for Infrastructure (which is the underneath physical Layer), but in reality they rent the Virtual Machines which represent the underlying hardware.
   In other words, the consumers pay for the Infrastructure, but utilize the service of Virtual Machines which represent the physical Layer.
2. Platform as a Service (PaaS)
   Next in the stack comes the Platform Layer, where all the software relevant to creating the middlewares are kept such as Java, SQL Server, C#, PHP, Python, System Compilers, System Softwares etc.
   Everything is available on this platform layer of the stack as the service.
   This is provided to the users as Platform as a Service (PaaS), where these softwares are borrowed by the consumers.
   So, consumers  don’t borrow the Infrastructure (as in the case of IaaS),  but they borrow the platform (i.e. PaaS)  which contains certain softwares as per their requirement on top of the specification of hardware, as per the requirement given by the virtual machine, and they can use that platform.
3. Software as a Service (SaaS)
   Finally, the Application Layer, where all the application software (ie., gmail, facebook, twitter, google drive etc.) will be installed in the cloud stack, which the organization can utilize.
   Here, lots of applications will be provided as a service to the consumers, which is called SaaS.
   Hence, when we want Infrastructure, we can use IaaS, when we want Platform, we can use PaaS and when we want application, we can use SaaS.
   Also, lower service layer supports the upper service layer i.e. SaaS needs PaaS, IaaS and Physical layer, while  PaaS needs IaaS and Physical Layer.

(i.e. create the cloud stack and  resources that form part of the tack)

• Manages the cloud stack
• Makes services available
• Service Management
• Security & Privacy

• Browses service catalog (ie., see what are the services available and when the catalog is available, browse through the catalog)
• Request Service based on their requirements (i.e. based on requirement  request service)
• Set up contract and Service Level Agreement (SLA) : i.e. a contract between the Provider and Consumer which has to be respected by both the parties
• Use the Services
• Makes Payment

• Negotiates (Mediates) between Cloud Provider and Consumers.
• Service Intermediation (i.e. lets the consumers know what are the services available and what are not available).

• conduct independent assessment of cloud services
  (i.e. whether services are good enough, whether quality is good, whether the price charged is correct etc.)
• Security Audit
  (i.e. is your data being maintained the way it has been set up in SLA)
• Privacy Audit
  (i.e. is my data safe. Can be resolved by having independent Auditor auditing Cloud Environment)

Provides Connectivity and transport of cloud service from cloud provider to cloud consumers (i.e. transport the messages that are relevant  to provide the service)