Notable Aspects:

• Each server in the cluster stores the session object data in its RAM and does not write it to disk for obvious reasons
• No code change or new code has to be incorporated by the programmer and all that is needed is to change a configuration setting in order to activate velocity caching
• Distributed caching means multiple web servers can each run an instance of the same application which helps in load balancing
• Both web server (IIS) and cache server (Appfabric) can be deployed on a single application server running on Windows Server OS
• Turning on the high-availability feature helps mitigate situations when a server in the cluster goes down by storing a synchronous secondary copy of the data item on a different server

Comments (5)

Lava A9 Dual Sim Phone is a handsome instrument with an assortment of useful features and applications at an affordable price. The phone looks solid with a hard metal body and a smooth keypad which gives an elegant appearance to the phone. Lava A9 comes with a 3.2MP camera that lets you take pictures and shoot videos but the image quality is very poor and doesn't live up to the expectations of a 3.2MP camera. The zooming option is also limited and the camera is a big let down in A9. There is 64MB internal phone memory and the phone will support up to 8GB Micro SD Cards. Listening to music on this phone is not a pleasant experience on the loud speaker but the audio quality is slightly better while hearing it on the ear phone. FM reception is also not satisfactory.

Having said the above glitches in the phone, Lava A9 is otherwise an excellent phone with an impressive profile. The phone comes with both EDGE and GPRS support enabling you to connect with the internet through the pre-installed Opera Mini web browser. Nimbuzz is a refreshingly new application that comes pre-installed with Lava A9 with which you can make calls or chat with your friends over the internet sans the conventional call charges. The phone with a user friendly interface has all the features we expect including bluetooth, java games, Ebook reader, Email support, MP3/MP4 Player, etc. Apart from the usual audio and video recorder the phone also lets you record streaming FM audio in any of the three formats WAV/AWB/AMR. You can also search your contacts with phone number as the search criterion which is handy at some situations. You can also integrate the phone with your PC with the help of Lava A9 PC Suite that can be downloaded from LavaMobiles.com website. Apart from the camera and loud speaker anomalies, LAVA A9 is a good looking phone with powerful features and provides value for money.

Comments (18)

I had a chance to handle this phone after my friend bought it last week. As far as the design is concerned, holding the phone in my palms was a bit awkward considering the width (56.5 mm) of the phone but it is an advantage when it comes to a bigger screen experience. The phone with a plastic body is light weight but still sturdy and looks plain and simple. From the design perspective there is a dedicated keypad lock/unlock button on the right side. Virtual keypad means minimum buttons on the front panel and maximum screen size. The capacitive touchscreen performs well and the interface is intelligently designed for easy navigation of menu items. The menu icons can be docked on the left side for quick access or pulled out from the menu which spans 3 pages that can be easily flicked through. The 2MP camera shoots well in good lighting conditions and the single finger image zoom option is handy while viewing pictures. The phone has a gamut of applications and widgets to integrate with the internet and the social networking world. The sound quality is good and watching videos in a wide screen is comforting as well.

Comments (6)

In software engineering profession everyday new challenges and problems turn up in the blink of an eye and as engineers we are obliged to resolve them ASAP. One of the biggest challenges in the IT industry today is handling data that is vast and increasing everyday. Data is normally stored in databases in the form of tables and a common situation while handling databases is to transfer data from one table to another.

Case I: If both tables reside in the same database server

Consider the case where you want copy the data from Table_1 under Schema_1 into Table_2 under Schema_2. A simple sql command to do this operation would be

INSERT INTO DB_Name.Schema_2.Table_2
SELECT * FROM DB_Name.Schema_1.Table_1 WHERE [condition]

If you want to insert only certain columns you can slightly tweak the command accordingly

INSERT INTO DB_Name.Schema_2.Table_2(COL1, COL2, ....COLn)
SELECT COL1, COL2, ....COLn FROM DB_Name.Schema_1.Table_1 WHERE [condition]

Case II: Load a table from a file

Consider the situation where you want to load a table from a delimited file. This can be done using the BULK INSERT command in Transact-SQL. In order to perform this operation you need access to the file present in the database server. CSV (Comma-seperated values) is a common format used to store the data from a table or spreadsheet. To load a database table from a .csv file use the following command

BULK INSERT Table_Name
FROM 'C:\Program Files\File.csv'
WITH
(
FIELDTERMINATOR = ',',
ROWTERMINATOR = '\n'
)

Bulk insert command provides a slew of options to load a table from a simple delimited text file or even from an xml file.

Case III: If both tables reside in different database servers

The bcp Utility is an excellent command line tool to transfer table data between two different database servers swiftly across a network. You can use bcp to extract table data by querying the table and store it in a delimited file. You can then load the other table from this delimited file easily using a simple bcp command. You don't even have to login to the servers to access the files.

bcp DB1.SCHEMA1.TABLE1 out FILEPATH -n -S[server_name\instance_name] -T -e[error_filepath]
bcp DB2.SCHEMA2.TABLE2 in FILEPATH -n -S[server_name\instance_name] -T -e[error_filepath]

-n uses the native (database) data types
-S should be added before server name
-T using a trusted connection
-e should be added before filepath for error file that logs the failed rows

The first command extracts the rows from TABLE1 and stores in the appropriate FILEPATH (eg. C:\Program Files\File.csv) in the database server. The second command loads TABLE2 with the data present in the File.csv. You have to run the first command to create the file first and then run the second command to load the data into the table. Instead of selecting the entire table you can also include your own select query within the bcp command. BCP offers a legion of options to transfer data between tables in different modes and formats.

Alternately you can also make use of Data Transformation Services (DTS)/ SQL Server Integration Services (SSIS) package in order to consolidate data from heterogeneous data sources.

Useful Resources:

bcp Utility - http://msdn.microsoft.com/en-us/library/ms162802.aspx
bulk insert - http://msdn.microsoft.com/en-us/library/ms188365.aspx

Comments (8)

Virtual Memory is a cost effective solution to slake the thirst of memory hungry applications for a seamless experience with your operating system. To understand the concept of virtual memory you need a little knowledge about the memory organization and working. There are basically two types of memory you need to know. Random Access Memory (RAM) is faster but costly. Memory like hard disk is slower but relatively cheaper. Virtual memory is a stratagem to utilize the hard drive memory to achieve enhanced performance from the random access memory.

Whenever you run multiple programs/applications in your desktop, you will be working on only a portion of a particular application at an instant. Therefore it is a waste of resource to load the entire memory required for a particular application into the limited size random access main memory. In a virtual memory environment each page of a process is brought to main memory only when it is needed on demand.


Data is stored in any memory in the form of binary digits. The operating system handles memory management in the form of chunks of memory called pages. A page is nothing but a contiguous block of memory. One process might require multiple pages of memory but only a few pages might be active at a time. Virtual memory uses a technique called demand paging to effectively use the available RAM memory. Every page has an address which may be a virtual or logical address. The main memory is divided into equal size chunks called page frames and each page frame has a unique physical address. So whenever a page needs to be accessed, the operating system has to translate the virtual address into a physical address and this is done by a Memory Management Unit (MMU) with the help of mapping in a page table. The virtual address corresponding to a page is mapped to a physical address corresponding to a page frame in main memory. Whenever a page is not in memory the operating system fetches the page from hard disk in response to a page fault exception. The operating system usually makes a prediction based on past history using intelligent algorithms regarding those pages that are least likely to be needed again and places them in the hard disk.

Comments (25)

Assisted GPS is an improved version of conventional GPS and it has revolutionized mobile navigation systems across the globe. The A-GPS system relies upon an assistance server to accurately resolve the location of a device. A-GPS system is commonly used in mobile phones to provide real time navigation services. The Global Positioning System works on the principle of trilateration to determine the coordinates of a point on earth. In this principle a satellite is considered to be at the center of a sphere and the mathematical treatment of three such spheres/satellites gives the intersections of the spheres which are used to determine the coordinates. By including one more sphere/satellite in the analysis the point can be located more precisely. The distance between the point on earth and the satellite is computed by transmitting a packet of data tagged with the sent time and by subtracting this from the time the packet was received, we get the time of transit. Assuming the packet traveled at the speed of light, we can estimate the distance of the satellite which serves as the radius of the sphere.
The standalone GPS system is susceptible to atmospheric conditions and multipath errors which tend to prolong the time to first fix. This is not appropriate for real time navigation and emergency applications. A-GPS offers a solution to this problem with an architecture that makes use of data connectivity to an Assistance server located at a place with strong signal connectivity with the satellites. There are two possibilities here.

• The assistance server may transmit orbital parameters and atomic time information to the mobile phone via the network. The GPS receiver in the mobile phone correlates this data with the fragmentary data received directly from the satellites thereby increasing its sensitivity and resulting in a quicker time to first fix.
• The mobile phone with limited processing capabilities can delegate the processing function to the more sophisticated assistance server by sending the weak fragmentary data to the processing server that has good satellite signal and receive the position information from the server through the network.

A-GPS is a feasible option to provide navigational services in an urban environment with tall buildings and high radio interference. On the flipside the service provider will charge the subscriber for network data traffic using GPRS/3G.

Comments (6)