Sunday, January 9, 2011

Java on CLOUD Computing



Cloud computing is Internet-based computing, whereby shared servers provide resources, software, and data to computers and other devices on demand, as with the electricity grid. Cloud computing is a natural evolution of the widespread adoption of virtualization, service-oriented architecture and utility computing.

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1)      The fundamental concept of cloud computing is that the computing is "in the cloud" i.e. that the processing (and the related data) is not in a specified, known or static place(s).
2)      Cloud computing customers do not own the physical infrastructure, instead avoiding capital expenditure by renting usage from a third-party provider. They consume resources as a service and pay only for resources that they use.
3)      The cloud is becoming increasingly associated with small and medium enterprises (SMEs) as in many cases they cannot justify or afford the large capital expenditure of traditional IT.
4)      Device and location independence enable users to access systems using a web browser regardless of their location or what device they are using (e.g., PC, mobile). As infrastructure is off-site (typically provided by a third-party) and accessed via the Internet, users can connect from anywhere.

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Benefits:
1)      Reduced Cost: Pricing on a utility computing basis is fine-grained with usage-based options. So, Cloud technology is paid incrementally, saving organizations money.
2)      Increased Storage: Organizations can store more data than on private computer systems.
3)      Highly Automated: Fewer IT skills are required for implementation (in-house), so, No longer do IT personnel need to worry about keeping software up to date.
4)      Flexibility: Cloud computing offers much more flexibility than past computing methods.
5)      More Mobility: Employees can access information wherever they are, rather than having to remain at their desks.
6)      Allows IT to Shift Focus: No longer having to worry about constant server updates and other computing issues, government organizations will be free to concentrate on innovation.
7)      Maintenance: Maintenance of cloud computing applications is easier, since they don't have to be installed on each user's computer. They are easier to support and to improve since the changes reach the clients instantly.
8)      Multi-tenancy: It enables sharing of resources and costs across a large pool of users thus allowing for:
Ø      Centralization of infrastructure in locations with lower costs (such as real estate, electricity, etc.).
Ø      Peak-load capacity increases (users need not engineer for highest possible load-levels).
Ø      Utilization and efficiency improvements for systems that are often only 10–20% utilized.

9)      Reliability: Reliability is improved if multiple redundant sites are used, which makes well designed cloud computing suitable for business continuity and disaster recovery. Nonetheless, many major cloud computing services have suffered outages, and IT and business managers can at times do little when they are affected.
10)  Security: could improve due to centralization of data, increased security-focused resources, etc., but concerns can persist about loss of control over certain sensitive data, and the lack of security for stored kernels.  Security is often as good as or better than under traditional systems, in part because providers are able to devote resources to solving security issues that many customers cannot afford. Providers typically log accesses, but accessing the audit logs themselves can be difficult or impossible. Furthermore, the complexity of security is greatly increased when data is distributed over a wider area and / or number of devices.
11)  Maintenance: Maintenanceof cloud computing applications is easier, since they don't have to be installed on each user's computer. They are easier to support and to improve since the changes reach the clients instantly.
12)  Metering: It means that cloud computing resources usage should be measurable and should be metered per client and application on a daily, weekly, monthly, and yearly basis.

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Expenditure:

Cloud computing users avoid capital expenditure (CapEx) on hardware, software, and services when they pay a provider only for what they use. Consumption is usually billed on a utility (resources consumed, like electricity) or subscription (time-based, like a newspaper) basis with little or no upfront cost. Other benefits of this approach are low barriers to entry, shared infrastructure and costs, low management overhead, and immediate access to a broad range of applications. In general, users can terminate the contract at any time (thereby avoiding return on investment risk and uncertainty), and the services are often covered by service level agreements (SLAs) with financial penalties.

Although companies might be able to save on upfront capital expenditures, they might not save much and might actually pay more for operating expenses. In situations where the capital expense would be relatively small, or where the organization has more flexibility in their capital budget than their operating budget, the cloud model might not make great fiscal sense. Other factors having an impact on the scale of potential cost savings include the efficiency of a company's data center as compared to the cloud vendor's, the company's existing operating costs, the level of adoption of cloud computing, and the type of functionality being hosted in the cloud.
Among the items that some cloud hosts charge for are instances (often with extra charges for high-memory or high-CPU instances), data transfer in and out, storage (measured by the GB-month), I/O requests, PUT requests and GET requests, IP addresses, and load balancing. In some cases, users can bid on instances, with pricing dependent on demand for available instances.
Currently cloud computing in case of java is provided by three major brands which are:
a)    Google App Engine
b)    Aptana Cloud
c)    Stax for EC2

In my later posting, we will discuss about the differences between these 3 cloud computing brands and their implementations.

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