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[dhilipkumar]

What is Green computer ?

             "The computer must be designed to use only non-toxic materials, to be energy efficient, and to have minimal impact on the environment in every stage of its life cycle." Elaborating on the last point, she adds: "A recycling strategy should be considered part of the computer's design, e.g., the computer should be designed for easy disassembly and disposal or made so that it is safe to discard."

The next environmental trend is "green IT". Computers may not produce plumes of smoke but they do consume surprisingly large amounts of electricity.

The computer industry is responsible for almost 2% of global carbon emissions, according to technology research group Gartner, mainly from PCs, servers and cooling systems.

            Google has more than 500000 servers in 40 data centres. It has never revealed how much greenhouse gas it generates, but the global Internet company says it now offsets this through a mixture of renewable energy, increased energy efficiency and other projects.

             Google is not alone in switching to green IT. SA companies are close behind in finding more energy-efficient ways of minimising the effect of technology usage on the environment.

[dhilipkumar]

what is Blu-ray ?


              Blu-ray is an optical disc format designed to display high definition video and store large amounts of data.

Blu-ray is the successor to DVD. The standard was developed collaboratively by Hitachi, LG, Matsushita (Panasonic), Pioneer, Philips, Samsung, Sharp, Sony, and Thomson. It became the default optical disk standard for HD content and optical data storage after winning a format war with HD-DVD, the format promoted by Toshiba and NEC.

The format's name comes from the fact that a blue laser reads from and writes to the disc rather than the red laser of DVD players. The blue laser has a 405 nanometer (nm) wavelength that can focus more tightly than the red lasers used for writable DVD. As a consequence, a Blu-ray disc can store much more data in the same 12 centimeter space. Like the rewritable DVD formats, Blu-ray uses phase change technology to enable repeated writing to the disc.

Blu-ray's standard storage capacity is enough to store a continuous backup copy of most people's hard drives on a single disc. Initially, the format had a 27 gigabyte (GB) single-sided capacity and 50 GB on dual-layer discs. Single-sided Blu-ray discs can store up to 13 hours of standard video data, compared to single-sided DVD's 133 minutes. In July 2008, Pioneer announced that they had found a way to increase capacity to 500 GB by creating 20-layer discs. These discs are not, however, expected to be commercially available in the near future.

                                               

[balaganesh]

Hi Dhilip

your post is good..

Excellent post

 

[dhilipkumar]

   What is RAID?

        RAID (redundant array of independent disks; originally redundant array of inexpensive disks) is a way of storing the same data in different places (thus, redundantly) on multiple hard disks. By placing data on multiple disks, I/O (input/output) operations can overlap in a balanced way, improving performance. Since multiple disks increases the mean time between failures (MTBF), storing data redundantly also increases fault tolerance.

A RAID appears to the operating system to be a single logical hard disk. RAID employs the technique of disk striping, which involves partitioning each drive's storage space into units ranging from a sector (512 bytes) up to several megabytes. The stripes of all the disks are interleaved and addressed in order.

In a single-user system where large records, such as medical or other scientific images, are stored, the stripes are typically set up to be small (perhaps 512 bytes) so that a single record spans all disks and can be accessed quickly by reading all disks at the same time.

In a multi-user system, better performance requires establishing a stripe wide enough to hold the typical or maximum size record. This allows overlapped disk I/O across drives.

There are at least nine types of RAID plus a non-redundant array (RAID-0):

RAID-0: This technique has striping but no redundancy of data. It offers the best performance but no fault-tolerance.

RAID-1: This type is also known as disk mirroring and consists of at least two drives that duplicate the storage of data. There is no striping. Read performance is improved since either disk can be read at the same time. Write performance is the same as for single disk storage. RAID-1 provides the best performance and the best fault-tolerance in a multi-user system.

RAID-2: This type uses striping across disks with some disks storing error checking and correcting (ECC) information. It has no advantage over RAID-3.

RAID-3: This type uses striping and dedicates one drive to storing parity information. The embedded error checking (ECC) information is used to detect errors. Data recovery is accomplished by calculating the exclusive OR (XOR) of the information recorded on the other drives. Since an I/O operation addresses all drives at the same time, RAID-3 cannot overlap I/O. For this reason, RAID-3 is best for single-user systems with long record applications.

RAID-4: This type uses large stripes, which means you can read records from any single drive. This allows you to take advantage of overlapped I/O for read operations. Since all write operations have to update the parity drive, no I/O overlapping is possible. RAID-4 offers no advantage over RAID-5.

RAID-5: This type includes a rotating parity array, thus addressing the write limitation in RAID-4. Thus, all read and write operations can be overlapped. RAID-5 stores parity information but not redundant data (but parity information can be used to reconstruct data). RAID-5 requires at least three and usually five disks for the array. It's best for multi-user systems in which performance is not critical or which do few write operations.

RAID-6: This type is similar to RAID-5 but includes a second parity scheme that is distributed across different drives and thus offers extremely high fault- and drive-failure tolerance.

RAID-7: This type includes a real-time embedded operating system as a controller, caching via a high-speed bus, and other characteristics of a stand-alone computer. One vendor offers this system.

RAID-10: Combining RAID-0 and RAID-1 is often referred to as RAID-10, which offers higher performance than RAID-1 but at much higher cost. There are two subtypes: In RAID-0+1, data is organized as stripes across multiple disks, and then the striped disk sets are mirrored. In RAID-1+0, the data is mirrored and the mirrors are striped.

[dhilipkumar]

What is VHDL?

                 VHDL (VHSIC Hardware Description Language) is a computer programming language designed to illustrate the behavior of field-programmable gate arrays and application-specific integrated circuits of digital systems in electronic design. VHDL describes the performance of electronic components in many areas such as; microprocessors, custom chips and simple logic gates. VHDL is used to describe precise aspects of electrical circuit behavior in order to create a VHDL simulation model. Incorporated with schematics, block diagrams and system-level VHDL descriptions, the VHDL simulation model can be used as the foundation for building larger circuits.

           Additionally, VHDL functions as a general-purpose programming language. VHDL has similarities to the C and C++ programming language structure. VHDL differs in that it includes features that allow simultaneous events description and provides a solid set of control and data representation features. VHDL is primarily used to detail the performance specification of a circuit in the form of a test bench. These circuit stimuli and comparable expected outputs substantiate the functionality of a circuit over the course of a period of time.

           An information technology professional interested in learning more about VHDL can participate in the informative tutorials provided in this section.

[dhilipkumar]

what is AJAX:

        “Asynchronous JavaScript And XML”, otherwise known as AJAX, is a programming language that allows a web page to receive miniscule amounts of data from a web server without reloading the complete web page. Ajax works together with JavaScript. AJAX permits Web pages to be dynamic, interactive and behave as local applications. This combination of features is known as “rich client” applications. AJAX is similar to Dynamic HTML and allows synchronous and asynchronous access to remote services by using the XMLHTTPRequest object.

          Before AJAX technology was developed, a request from the user for the retrieval of data would cause the entire Web page to be refreshed, resulting in very slow loading time and minimal interaction between the user and the web page. With the advent and success of AJAX, websites utilize the “remote scripting” of AJAX to better the functionality and waiting time of interactive and dynamic websites. The server exchanges small amounts of data without the user’s knowledge, increasing the speed, usability and navigation of web pages.

It is necessary for any IT professional programmer or developer to be familiar with the Ajax programming language. Online Training explaining the uses of Ajax, critique of Ajax, Challenges, Framework, basic overview of Web Services, XML, security aspects and the power of Ajax are discussed through tutorials in this section.
 

[dhilipkumar]

What is N-Tier?

 N-Tier applications are useful, in that they are able to readily implement Distributed Application Design and architecture concepts. These types of applications also provide strategic benefits to solutions at the enterprise level. It is true that two tier, client server applications may seem deceptively simple from the outset – they are easy to implement and easy to use for Rapid Prototyping. At the same time, these applications can be quite a pain to maintain and secure over time.

N-Tier applications, on the other hand, are advantageous, particularly in the business environment, for a number of reasons.

N-Tier applications typically come loaded with the following components:

Security. N-Tier applications come with logging mechanisms, monitoring devices, as well as Appropriate Authentication, ensuring that the device and system is always secure.

Availability + Scalability. N-Tier applications tend to be more reliable. They come loaded with fail over mechanisms like fail over clusters to ensure redundancy.

Manageability. N-Tier applications are designed with the following capabilities in mind: deployment, monitoring, and troubleshooting. N-Tier devices ensure that one has the sufficient tools at one’s disposal in order to handle any errors that may occur, log those errors, and provide guidance towards correcting those errors.

Maintenance. Maintenance in N-Tier applications is easy, as the applications adopt coding and deployment standards, as well as data abstraction, modular application design, and frameworks that enable reliable maintenance strategies.

Data abstraction. N-Tier applications make it so that one can easily adjust the functionality without altering other applications.

[dhilipkumar]

Data Modeling

      Information systems and computer sciences use data modeling to manage and organize large quantities of structured and unstructured data. A data model describes the information to be stored in vast data management systems like relational databases. Data models do not include unstructured data such as email messages, word processing documents, digital video, audio or image files. Furthermore, data modeling establishes implicit and explicit constrains and limitations of the structured data. A data model is formally known as data model theory.

A professional Information Technologies engineer may work as a Data Modeling Analyst for businesses using enterprise data management tools and technologies. A Data Modeling Analyst or Data Model Manager will be familiar with process modeling, understanding data modeling concepts, data modeling tools, entity relationship diagramming, dimensional data modeling and physical or logical data modeling.

Data Modeling Analysts use data modeling functions to supply an accurate representation of the enterprise. Secondly, data modeling is used to accurately reflect the data of the organization. Based on this information, a database is created.

Tutorials on Data Management in Data Modeling explain the basic concepts behind data modeling, its uses with enterprise management, terminology related to data modeling, the history of data modeling and instructions on various models within data modeling.

[Cognitive]

Thanks for your informative article...Proud Acumen...continue.....

[dhilipkumar]

What is 3x Protocol

3x is the second revision of the Evolution-Data Optimized (EV-DO) set of mobile telecommunications standards made by the Third Generation Partnership Project 2 (3GPP2). It is also known as TIA-856 Rev B or EV-DO Rev B, antecedent to EV-DO Rev 0 and EV-DO Rev A.

It is one of several types of the CDMA2000 set of standards, its full designation being CDMA2000 3xRTT, where "3xRTT" stands for "three times Radio Transmission Technology" (three times because it has three carriers, in comparison to 1xRTT which has only one carrier).

The 3x protocol, like all other EV-DO standards, is a form of 3G technology. In order to maximize its rate of data transmission, 3x makes use of varied multiplexing techniques like frequency division duplex (FDD) and code division multiple access (CDMA). To achieve higher rates of data transmission, 3x may make use of two 3.75 MHz channels, or multiple 1.25 MHz channels.

Since 3x is a multi-carrier version of Rev A, it is also sometimes referred to as "Multi-Carrier" or "MC." Its multi-carrier specification gives it a number of improvements over its predecessor. It has an increased maximum downlink rate of 14.7 Mbps (4.9 Mbps per carrier for 3 carriers is expected for typical transmission).

Expected peak rates for a 3x network with two channels are 6.2 Mbps for forward link throughput and 3.6 Mbps for reverse link throughput.

For one with three channels, expected peak rates are 9.3 Mbps for forward link throughput and 5.4 Mbps for reverse link throughput.

Interference from adjacent sectors was reduced and rate was improved by hybrid frequency re-use.

Latency was reduced by using statistical multiplexing across channels, enabling new services like video telephony, web browsing, gaming and remote console sessions.

Services such as high-definition video streaming were also enabled by bundling multiple channels together.

Talk time and standby time are also increased. 3x also provided ample support for services that required different data rates for uploading and downloading, such as delivery of broadband multimedia content, transferring of files, and web browsing.

[dhilipkumar]

WHAT IS COM+:


        COM+ is an extension of Component Object Model (COM), Microsoft's strategic building block approach for developing application programs. COM+ is both an object-oriented programming architecture and a set of operating system services. It adds to COM a new set of system services for application components while they are running, such as notifying them of significant events or ensuring they are authorized to run. COM+ is intended to provide a model that makes it relatively easy to create business applications that work well with the Microsoft Microsoft Transaction Server (MTS) in a Windows NT or subsequent system. It is viewed as Microsoft's answer to the Sun Microsystems-IBM-Oracle approach known as Enterprise JavaBeans (EJB).


Among the services provided by COM+ are:

#     An event registry that allows components to publish the possibility of an event and other components            to subscribe to be notified when the event takes place. For example, when a sales transaction is completed, it could trigger an event that would allow other programs to be notified for subsequent processing.
#     The interception of designated system requests for the purpose of ensuring security
#     The queues of asynchronously received requests for a service

How COM+ Works Briefly

A "component" is a building block program that is self-describing. This means that it can be run with a mix of other components and each will be able to understand the capabilities and characteristics of the other components. Practically, this means that a new application can be built by reusing components already known to exist and without having to compile the application. It also makes it relatively easy to distribute different components of an application among different computers in a network. Microsoft's Distributed Component Object Model (DCOM) adds interfaces to do this.

In addition to its self-description, a component consists of one or more classes that describe objects and the methods or actions that can be performed on an object. A class (or coclass in COM+ terminology) has properties described in an interface (or cointerface). The class and its interface are language-neutral.

Associated with the class are one or more methods and fields that are implemented in a specific language such as C++ or Java or a visual programming environment. When you instantiate a class, you create an object (something real that can be executed in the computer). Sometimes the term "class" is also used for the instantiated object (which can be confusing).

Using COM, objects (or classes) and their methods and associated data are compiled into binary executable modules, that are, in fact, files with a dynamic link library (DLL) or EXE file name suffix. A module can contain more than one class.

[dhilipkumar]

Save Time, Money and Manpower While Eliminating Redundancies from Your Data Backups


You already know about exponential data growth, in fact you are probably experiencing it in your own environment. Digital information is doubling every 18 months. For some, that growth is even faster. Your information assets are invaluable to your company, so managing and protecting those assets is a critical priority. Data loss can impact revenue, your customers, and your reputation. In fact, some businesses can even fail due to a data loss or a prolonged period of downtime. That's why many companies are looking for solutions that protect data today and manage ever higher volumes in the future.

View this TechRepublic Webcast, co-sponsored by PC Connection and HP, featuring moderator James Hilliard and guest speaker David Fairfield, Business Continuity Product Line Manager for HP, to get expert tips and advice on defending your network against the internal security threats that are introduced every day by your own end users. These key topics and more are addressed:

-> Review customer business challenges (Explosive data growth, security, efficient utilization of resources)

-> Highlight the cost implications of experiencing lost data

-> Define what potential data protection strategy fits your customer needs

-> Provide a summary of the the benefits of Data Deduplication and how this will help your customers with more efficient storage utilization and faster access to lost data

[dhilipkumar]

What is 4G


        4G is the short term for fourth-generation wireless, the stage of broadband mobile communications that will supercede the third generation (3G). While neither standards bodies nor carriers have concretely defined or agreed upon what exactly 4G will be, it is expected that end-to-end IP and high-quality streaming video will be among 4G's distinguishing features. Fourth generation networks are likely to use a combination of WiMAX and WiFi.
Technologies employed by 4G may include SDR (Software-defined radio) receivers, OFDM (Orthogonal Frequency Division Multiplexing), OFDMA (Orthogonal Frequency Division Multiple Access), MIMO (multiple input/multiple output) technologies, UMTS and TD-SCDMA. All of these delivery methods are typified by high rates of data transmission and packet-switched transmision protocols. 3G technologies, by contrast, are a mix of packet and circuit-switched networks.

When fully implemented, 4G is expected to enable pervasive computing, in which simultaneous connections to multiple high-speed networks provide seamless handoffs throughout a geographical area. Network operators may employ technologies such as cognitive radio and wireless mesh networks to ensure connectivity and efficiently distribute both network traffic and spectrum.

The high speeds offered by 4G will create new markets and opportunities for both traditional and startup telecommunications companies. 4G networks, when coupled with cellular phones equipped with higher quality digital cameras and even HD capabilities, will enable vlogs to go mobile, as has already occurred with text-based moblogs. New models for collaborative citizen journalism are likely to emerge as well in areas with 4G connectivity.

A Japanese company, NTT DoCoMo, is testing 4G communication at 100 Mbps for mobile users and up to 1 Gbps while stationary. NTT DoCoMo plans on releasing their first commercial network in 2010. Other telecommunications companies, however, are moving into the area even faster. In August of 2006, Sprint Nextel announced plans to develop and deploy a 4G broadband mobile network nationwide in the United States using WiMAX. The United Kingdom's chancellor of the exchequer announced a plan to auction 4G frequencies in fall of 2006.

4G technologies are sometimes referred to by the acronym "MAGIC," which stands for Mobile multimedia, Anytime/any-where, Global mobility support, Integrated wireless and Customized personal service.

[dhilipkumar]

what is Bluejacking:


                 Bluejacking is the practice of sending messages between mobile users using a Bluetooth wireless connection. People using Bluetooth-enabled mobile phones and PDAs can send messages, including pictures, to any other user within a 10-meter or so range. Because such communications don't involve the carrier, they are free of charge, which may contribute to their appeal.

                 Bluetooth was created to enable wireless communications between various devices; the user can set a device to be inaccessible, accessible to a specific device (through a process known as pairing), or discoverable, that is, accessible to all devices in range. Although Bluejacking is, in and of itself, a legitimate activity, it has enabled a number of less innocent practices, including bluesnarfing attacks, which involves theft of data from a mobile device, and reportedly a fad known as toothing, the practice of sending an invitation to nearby mobile device users for the purpose of setting up a quick sexual liaison.

[dhilipkumar]

                          GPS (Global Positioning System) messaging is a wireless messaging system for location-specific rather than recipient-specific messages. Somewhat like electronic sticky notes, the messages are sent and received by people with GPS locators in their wireless devices; messages are linked to the location of the sender and accessed by any equipped mobile user entering that location. GPS messaging is sometimes called mid-air messaging, because that's where the messages seem to be located. Hewlett-Packard has a prototype GPS messaging system running in its lab in Bristol, England.
GPS messaging is said to have enormous potential for both emergency situations and the less urgent, albeit ongoing, concerns of users. For example, tourists could leave messages outside a restaurant -- either praising it or complaining about it -- that other tourists would pick up when they were in that location, or highway workers could warn people about upcoming traffic hazards by leaving a message that they would receive when they approached a dangerous area. A project called the Nebraska GPS-Messaging and Satellite Voice Communication Demonstration and Field Test recently explored the use of GPS messaging for law enforcement, emergency response, and highway maintenance applications.

Here's how one version works: You upload a message (or perhaps an audio clip or an image); the message is tagged with your current geographic coordinates and stored on a Web page that is linked to those specific coordinates. Then, when anyone with a capable wireless device enters that location, they can access the message, either as text or image on a screen, or as an audio message through an earpiece. When you move from one location to another, the GPS receiver in your device checks the Web site for messages linked to your location and downloads any that are there. In effect, any GPS-resolvable space could have its own Web site that users would enter geographically.

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