The commoditization of technology has reached its pinnacle with the advent of the recent paradigm of Cloud Computing. Infosys Cloud Computing blog is a platform to exchange thoughts, ideas and opinions with Infosys experts on Cloud Computing

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March 31, 2011

Is cloud computing same as putting things Online?

All those just boarding the cloud train, may have posed this question to themselves or to others who may have a know-how on cloud. Being a Cloud SME myself, I have faced this question several times. This post is an attempt to clear some of the confusion that exists around this specific topic.

To answer this question: There is lot more to the cloud than just on-demand processing power and the pay-per-use model. The IaaS-PaaS-SaaS cloud pyramid seems to be one of the better and widely used models to explain cloud and bring about correlation between the several entities in the cloud eco-system.

From a cloud application perspective the key here would be distinction between the consumer of an app (End consumer view) and the technology on which an app (Developer view) is built on.

For an end consumer, experiencing cloud could be like using any other web app; perceived to be reliable and always available. An application which can be used cheap or even free (this could be optional, would depend on the value of the services being offered and the perceived brand value of the provider).

From a SaaS providers perspective, perceiving cloud is about offering an application that meets with the expected levels of SLA's( reliability, availability etc..) of the consumer under any operating conditions without any additional capital investments from the SaaS providers end.

For classifying cloud apps, taking the SaaS providers view would be more apt rather than the end consumer and some definitions of with that perspective out there..
NIST states, "The capability provided to the consumer is to use the provider's applications running on a cloud infrastructure. The applications are accessible from various client devices through a thin client interface such as a web browser (e.g., web-based email). The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings."
Wiki states, "A cloud application leverages cloud computing in software architecture, often eliminating the need to install and run the application on the customer's own computer, thus alleviating the burden of software maintenance, ongoing operation, and support."

Summarizing, a cloud app is an application which consumes, is governed and managed by the services or infrastructure provided by a cloud platform. The cloud platform are the likes of Azure, EC2, AppEngine, SalesForce's PAAS offering etc. Apps that are build on these platforms are by all means a cloud app each dependent on the services provided by the underlying platforms..

VMware vCloud Director - Networking

While going through vCloud Director(vCD), VMware's private Cloud solution, I came across the networking, it took me some time to grasp the concepts behind it. This blog talks about  the types of network in vCD.

vCloud Director provides an abstraction over the compute, network and storage resource of vSphere layers. From a networking stand point vSphere virtualizes the physical networking devices (Switches and Network Interface Card) as vNetwork Standard switches/portgroups and/or vNetwork Distributed switches/dvPortGroups. vCD further abstracts this  to different layers named

·         External Network

·         Organization Network

·         Vapp Network

External Network

External networks provide external connectivity to vCloud Director and commonly it's an Internet connection. These are created and managed by vCD administrators. Another usecase I can think of is VPN connection to a public cloud or company network.

Organization Network

An organization in vCD is logical entity which represents a group of users. It can be different enterprises or various departments within an enterprise (Finance, marketing etc). An organization will have Vapps which is nothing but a grouping of related virtual machine managed as a single entity. Vapps provide features like starting the virtual machine in particular order and doing operations as single entity.

Organization network provides the communication between Vapps and also provide connectivity to external networks. Based on the connectivity organization networks can be classified as

·         Direct connection  where organization network is directly bridged to external network.

·         Routed connection where connectivity to external network is through a vShield Edge device which provide features like NAT, firewall and DHCP.

·         Isolated connection where there is no connectivity to external network

Vapp Network

Vapp Network defines how communication happens between virtual machines in a Vapp and the connectivity to organization networks. Like organization networks Vapp networks are also classified into three based on the connectivity to organization networks.


·          Direct connection where Vapp network is directly bridged to an organization network.

·         Routed connection where connectivity to organization network is through a vShield Edge device which provide features like NAT, firewall and DHCP.

·         Isolated connection where there is no connectivity to organization network.

A typical scenario to explain these network types is of J2EE application as a Vapp. Various modules like Web Server Virtual machine, Application Server virtual machine and Database server will be part of a Vapp and only Web server needs to talk to the internet. The below diagram shows this network types and their interaction.