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Friday, 22 May 2015

Placement #22 Complete Java Material ( Theory + Programs )

Complete Java Material ( Theory + Programs ) 

 
  

                            "MATERIAL"

 

Learn  Java

Online Tutorial for Java beginners to learn basic concepts of Core Java. I have divided this tutorial into three sections. First you will learn the fundamentals of Core Java (Class ,Interface etc.) . In the next section Learn By Example you will find many examples for different Core Java modules with running source code. The third part Cheatsheet will help you quickly revise what you learnt in the first two sections.

 



Thursday, 21 May 2015

Placement #21 Operating System Interview [Questions And Answers]

Operating System Interview
[Questions And Answers]




A real time operating system has well defined fixed time constraints. Process must be done within the defined constraints or the system will fail. An example is the operating system for a flight control computer or an advanced jet airplane. Often used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some display systems. Real-Time systems may be either hard or soft real-time. Hard real-time: Secondary storage limited or absent, data stored in short term memory, or read-only memory (ROM), Conflicts with time-sharing systems, not supported by general-purpose operating systems. Soft real-time: Limited utility in industrial control of robotics, Useful in applications (multimedia, virtual reality) requiring advanced operating-system features.
Multi programming: Multiprogramming is the technique of running several programs at a time using timesharing. It allows a computer to do several things at the same time. Multiprogramming creates logical parallelism. The concept of multiprogramming is that the operating system keeps several jobs in memory simultaneously. The operating system selects a job from the job pool and starts executing a job, when that job needs to wait for any i/o operations the CPU is switched to another job. So the main idea here is that the CPU is never idle. Multi tasking: Multitasking is the logical extension of multiprogramming .The concept of multitasking is quite similar to multiprogramming but difference is that the switching between jobs occurs so frequently that the users can interact with each program while it is running. This concept is also known as time-sharing systems. A time-shared operating system uses CPU scheduling and multiprogramming to provide each user with a small portion of time-shared system. Multi threading: An application typically is implemented as a separate process with several threads of control. In some situations a single application may be required to perform several similar tasks for example a web server accepts client requests for web pages, images, sound, and so forth. A busy web server may have several of clients concurrently accessing it. If the web server ran as a traditional single-threaded process, it would be able to service only one client at a time. The amount of time that a client might have to wait for its request to be serviced could be enormous. So it is efficient to have one process that contains multiple threads to serve the same purpose. This approach would multithread the web-server process, the server would create a separate thread that would listen for client requests when a request was made rather than creating another process it would create another thread to service the request. To get the advantages like responsiveness, Resource sharing economy and utilization of multiprocessor architectures multithreading concept can be used.

Wednesday, 20 May 2015

Placement #20 Networking Interview { Questions And Answers }

Networking Interview[Questions And Answers]

http://devdepsoft.blogspot.in/





 [Networking Frequently Asked Questions ,Networking Server FAQ ]


What is an Object server?

With an object server, the Client/Server application is written as a set of communicating objects. Client object communicate with server objects using an Object Request Broker (ORB). The client invokes a method on a remote object. The ORB locates an instance of that object server class, invokes the requested method and returns the results to the client object. Server objects must provide support for concurrency and sharing. The ORB brings it all together. 


What is a Transaction server? 

With a transaction server, the client invokes remote procedures that reside on the server with an SQL database engine. These remote procedures on the server execute a group of SQL statements. The network exchange consists of a single request/reply message. The SQL statements either all succeed or fail as a unit.


What is a Database Server?

 With a database server, the client passes SQL requests as messages to the database server. The results of each SQL command are returned over the network. The server uses its own processing power to find the request data instead of passing all the records back to the client and then getting it find its own data. The result is a much more efficient use of distributed processing power. It is also known as SQL engine.


What are the most typical functional units of the Client/Server applications?

 User interface Business Logic and Shared data.               

                                                     
What are all the Extended services provided by the OS?
Ubiquitous communications Network OS extension Binary large objects (BLOBs) Global directories and Network yellow pages Authentication and Authorization services System management Network time Database and transaction services Internet services Object- oriented services


What are Triggers and Rules? 

Triggers are special user defined actions usually in the form of stored procedures, that are
automatically invoked by the server based on data related events. It can perform complex actions and can use the full power of procedural languages. A rule is a special type of trigger that is used to perform simple checks on data.


What is meant by Transparency? 

Transparency really means hiding the network and its servers from the users and even the application programmers.


What are TP-Lite and TP-Heavy Monitors? 

TP-Lite is simply the integration of TP Monitor functions in the database engines. TP-Heavy are TP Monitors which supports the Client/Server architecture and allow PC to initiate some very complex multiserver transaction from the desktop.


What are the two types of OLTP?

 TP lite, based on stored procedures. TP heavy, based on the TP monitors.


What is a Web server?

 This new model of Client/Server consists of thin, protable, "universal" clients that talk to superfat servers. In the simplet form, a web server returns documents when clients ask for them by name. The clients and server communicate using an RPC-like protocol called HTTP.


What are Super servers? 

These are fully-loaded machines which includes multiprocessors, high-speed disk arrays for intervive I/O and fault tolerant features.


What is a TP Monitor? 

There is no commonly accepted definition for a TP monitor. According to Jeri Edwards' a TP Monitor is "an OS for transaction processing".


TP Monitor does mainly two things extremely well. They are Process management and Transaction management.? 

They were originally introduced to run classes of applications that could service hundreds and sometimes thousands of clients. TP Monitors provide an OS - on top of existing OS - that connects in real time these thousands of humans with a pool of shared server processes.


What is meant by Asymmetrical protocols? 

There is a many-to-one relationship between clients and server. Clients always initiate the dialog by requesting a service. Servers are passively awaiting for requests from clients.


What are the types of Transparencies?

The types of transparencies the NOS middleware is expected to provide are:- Location transparency Namespace transparency Logon transparency
Replication transparency Local/Remote access transparency Distributed time transparency Failure transparency and Administration transparency.


What is the difference between trigger and rule?

The triggers are called implicitly by database generated events, while stored procedures are called explicitly by client applications.


What are called Transactions?

The grouped SQL statements are called Transactions (or) A transaction is a collection of actions embused with ACID properties.


What are the building blocks of Client/Server?

The client The server and Middleware.


Explain the building blocks of Client/Server?

The client side building block runs the client side of the application. The server side building block runs the server side of the application.
The middleware buliding block runs on both the client and server sides of an application. It is broken into three categories:-
Transport stack Network OS Service-specific middleware.


What are all the Base services provided by the OS? 

Task preemption Task priority Semaphores Interprocess communications (IPC) Local/Remote Interprocess communication Threads Intertask protection Multiuser High performance file system Efficient memory management and Dynamically linked Run-time extensions.


What are the roles of SQL?

 SQL is an interactive query language for ad hoc database queries. SQL is a database programming language. SQL is a data definition and data administration language. SQL is the language of networked database servers SQL helps protect the data in a multi-user networked environment. Because of these multifacted roles it plays, physicists might call SQL as "The grand unified theory of database".


What are the characteristics of Client/Server?

 Service Shared resources Asymmentrical protocols Transparency of location Mix-and-match Message based exchanges Encapsulation of services Scalability Integrity Client/Server computing is the ultimate "Open platform". It gives the freedom to mix-and-match components of almost any level. Clients and servers are loosely coupled systems that interact through a message-passing mechanism.


What is Structured Query Langauge (SQL)? 

SQL is a powerful set-oriented language which was developed by IBM research for the databases that adhere to the relational model. It consists of a short list of powerful, yet highly flexible, commands that can be used to manipulate information collected in tables. Through SQL, we can manipulate and control sets of records at a time.


What is Remote Procedure Call (RPC)?

 RPC hides the intricacies of the network by using the ordinary procedure call mechanism familiar to every programmer. A client process calls a function on a remote server and suspends itself until it gets back the results. Parameters are passed like in any ordinary procedure. The RPC, like an ordinary procedure, is synchoronous. The process that issues the call waits until it gets the results. Under the covers, the RPC run-time software collects values for the parameters, forms a message, and sends it to the remote server. The server receives the request, unpack the parameters, calls the procedures, and sends the reply back to the client. It is a telephone-like metaphor.


What are the main components of Transaction-based Systems? 

Resource Manager Transaction Manager and Application Program.


What are the three types of SQL database server architecture? 

Process-per-client Architecture. (Example: Oracle 6, Informix ) Multithreaded Architecture. (Example: Sybase, SQL server) Hybrid Architecture


What are the Classification of clients? 

Non-GUI clients - Two types are:- Non-GUI clients that do not need multi-tasking (Example: Automatic Teller Machines (ATM), Cell phone) Non-GUI clients that need multi-tasking (Example: ROBOTs) GUI clients OOUI clients


What are called Non-GUI clients, GUI Clients and OOUI Clients? 

Non-GUI Client: These are applications, generate server requests with a minimal amount of human interaction. GUI Clients: These are applicatoins, where occassional requests to the server result from a human interacting with a GUI (Example: Windows 3.x, NT 3.5) OOUI clients : These are applications, which are highly-iconic, object-oriented user interface that provides seamless access to information in very visual formats. (Example: MAC OS, Windows 95, NT 4.0)


What is Message Oriented Middleware (MOM)? 

MOM allows general purpose messages to be exchanged in a Client/Server system using message queues. Applications communicate over networks by simply putting messages in the queues and getting messages from queues. It typically provides a very simple high level APIs to its services. MOM's messaging and queuing allow clients and servers to communicate across a network without being linked by a private, dedicated, logical connection. The clients and server can run at different times. It is a post-office like metaphor.


What is meant by Middleware?

 Middleware is a distributed software needed to support interaction between clients and servers. In short, it is the software that is in the middle of the Client/Server systems and it acts as a bridge between the clients and servers. It starts with the API set on the client side that is used to invoke a service and it covers the transmission of the request over the network and the resulting response. It neither includes the software that provides the actual service - that is in the servers domain nor the user interface or the application login - that's in clients domain.


What are the functions of the typical server program?

It waits for client-initiated requests. Executes many requests at the same time. Takes care
of VIP clients first. Initiates and runs background task activity. Keeps running. Grown bigger and faster.


What is meant by Symmentric Multiprocessing (SMP)? 

It treats all processors as equal. Any processor can do the work of any other processor. Applications are divided into threads that can run concurrently on any available processor. Any processor in the pool can run the OS kernel and execute user-written threads.


What are General Middleware?

 It includes the communication stacks, distributed directories, authentication services, network time, RPC, Queuing services along with the network OS extensions such as the distributed file and print services.


Placement #19 Unix Interview { Questions And Answers }

Unix Interview Questions And Answers 

http://devdepsoft.blogspot.in/

 [Unix Frequently Asked Questions ,Unix FAQ ]


How are devices represented in UNIX? 

All devices are represented by files called special files that are located in/dev directory. Thus, device files and other files are named and accessed in the same way. A 'regular file' is just an ordinary data file in the disk. A 'block special file' represents a device with characteristics similar to a disk (data transfer in terms of blocks). A 'character special file' represents a device with characteristics similar to a keyboard (data transfer is by stream of bits in sequential order).

What is 'inode'? 

All UNIX files have its description stored in a structure called 'inode'. The inode contains info about the file-size, its location, time of last access, time of last modification, permission and so on. Directories are also represented as files and have an associated inode. In addition to descriptions about the file, the inode contains pointers to the data blocks of the file. If the file is large, inode has indirect pointer to a block of pointers to additional data blocks (this further aggregates for larger files). A block is typically 8k. Inode consists of the following fields: File owner identifier File type File access permissions File access times Number of links File size Location of the file data

Brief about the directory representation in UNIX ? 

A Unix directory is a file containing a correspondence between filenames and inodes. A directory is a special file that the kernel maintains. Only kernel modifies directories, but processes can read directories. The contents of a directory are a list of filename and inode number pairs. When new directories are created, kernel makes two entries named '.' (refers to the directory itself) and '..' (refers to parent directory). System call for creating directory is mkdir (pathname, mode).

What are the Unix system calls for I/O? 

open(pathname,flag,mode) - open file creat(pathname,mode) - create file close(filedes) - close an open file read(filedes,buffer,bytes) - read data from an open file write(filedes,buffer,bytes) - write data to an open file lseek(filedes,offset,from) - position an open file dup(filedes) - duplicate an existing file descriptor dup2(oldfd,newfd) - duplicate to a desired file descriptor
fcntl(filedes,cmd,arg) - change properties of an open file ioctl(filedes,request,arg) - change the behaviour of an open file The difference between fcntl anf ioctl is that the former is intended for any open file, while the latter is for device-specific operations.


How do you change File Access Permissions?
Every file has following attributes: owner's user ID ( 16 bit integer ) owner's group ID ( 16 bit integer ) File access mode word 'r w x -r w x- r w x' (user permission-group permission-others permission) r-read, w-write, x-execute To change the access mode, we use chmod(filename,mode). Example 1: To change mode of myfile to 'rw-rw-r--' (ie. read, write permission for user - read,write permission for group - only read permission for others) we give the args as: chmod(myfile,0664) . Each operation is represented by discrete values 'r' is 4 'w' is 2 'x' is 1 Therefore, for 'rw' the value is 6(4+2). Example 2: To change mode of myfile to 'rwxr--r--' we give the args as: chmod(myfile,0744).


What are links and symbolic links in UNIX file system? 

A link is a second name (not a file) for a file. Links can be used to assign more than one name to a file, but cannot be used to assign a directory more than one name or link filenames on different computers. Symbolic link 'is' a file that only contains the name of another file.Operation on the symbolic link is directed to the file pointed by the it.Both the limitations of links are eliminated in symbolic links. Commands for linking files are: Link ln filename1 filename2 Symbolic link ln -s filename1 filename2

What is a FIFO?

  FIFO are otherwise called as 'named pipes'. FIFO (first-in-first-out) is a special file which is said to be data transient. Once data is read from named pipe, it cannot be read again. Also, data can be read only in the order written. It is used in interprocess communication
where a process writes to one end of the pipe (producer) and the other reads from the other end (consumer).


How do you create special files like named pipes and device files?

 The system call mknod creates special files in the following sequence. 1. kernel assigns new inode, 2. sets the file type to indicate that the file is a pipe, directory or special file, 3. If it is a device file, it makes the other entries like major, minor device numbers. For example: If the device is a disk, major device number refers to the disk controller and minor device number is the disk.

Discuss the mount and unmount system calls ?

The privileged mount system call is used to attach a file system to a directory of another file system; the unmount system call detaches a file system. When you mount another file system on to your directory, you are essentially splicing one directory tree onto a branch in another directory tree. The first argument to mount call is the mount point, that is , a directory in the current file naming system. The second argument is the file system to mount to that point. When you insert a cdrom to your unix system's drive, the file system in the cdrom automatically mounts to /dev/cdrom in your system.

How does the inode map to data block of a file?

Inode has 13 block addresses. The first 10 are direct block addresses of the first 10 data blocks in the file. The 11th address points to a one-level index block. The 12th address points to a two-level (double in-direction) index block. The 13th address points to a three-level(triple in-direction)index block. This provides a very large maximum file size with efficient access to large files, but also small files are accessed directly in one disk read.





Placement #18 AMCAT {100% Genuine Materials}


AMCAT {100% Genuine Materials}



                                            Material 

 

 

Why AMCAT

  1. The AMCAT is a computer adaptive test which measures job applicants on critical areas like communication skills, logical reasoning, quantitative skills and job specific domain skills thus helping recruiters identify the suitability of a candidate.

  1. Post the test, AMCAT also helps match candidates with suitable jobs based on their performance on the test.

  1. AMCAT's comprehensive feedback report helps you identify your strong and weak areas so that you can work to improve in highlighted areas or apply for specific industries/jobs where your strengths are better suited.

  1. The AMCAT is fast emerging as an industry benchmark with 700+ companies using it as a compulsory testing mechanism for entry level roles. We work alongside industry leading names like Accenture, Snapdeal, Axis Bank, Tata Motors, ITC and many more. Our client list covers multiple industries like IT Services, Banking & Financial Services, Automobiles, Telecom etc.

  1. There are thousands of small companies which are looking for good talent and provide great opportunities for growth. AMCAT works with more than 500 small and medium enterprises, helping you identify opportunities in companies which you would not typically approach.

  1. Apart from industry, leading job search providers like LinkedIn and Monster.com accept the AMCAT test as an employability certification.

  1. Some key numbers about the AMCAT:

    1. Since inception, more than 2 million students have successfully taken the AMCAT.

    1. Every month, more than 1.5 lakh interview calls go out based on a student's AMCAT score.

 


Monday, 18 May 2015

Placement #16 SUCCESSFUL INTERVIEWING



SUCCESSFUL INTERVIEWING