What is an Operating System?

- A collection of small and large software that help in the management of the computer hardware resources is called an operating system. 

- As the term suggests it operates or drives the system. 

- The basic common services required by the computer programs are offered by this OS only. 

- Without an OS, the application programs would fail to function. 

- Operating systems are of many types. 

- One such type is the time sharing OS that schedules the tasks to be done so that the processor time, printing, mass storage and so on resources could be utilized efficiently. 

- It is an intermediate thing between the hardware and the user. 

- It is through the OS that you are able to actually communicate with the computer hardware. 

- Functions such as memory allocation and basic input output operations are dependent totally on the OS. 

- Even though the hardware directly executes the application code, it does frequently involve the OS or OS itself interrupts in between. 

- Any device containing a computer do has an OS such as video game consoles, mobile phones, web servers, super computers and so on.

- Some popular OS are:

Ø  Android

Ø  BSD

Ø  Linux

Ø  iOS

Ø  Microsoft windows

Ø  Windows phone

Ø  Mac OS X

Ø  IBM z/ OS

All the OS have relation with UNIX save windows and z/OS.

- Types of Operating systems are:

1. Real time OS
2. Multi – user OS
3. Multi – tasking OS
4. Single  - tasking OS
5. Distributed OS
6. Embedded OS

- It was in 1950 that the basic operating systems came in to existence such as parallel processing, interrupts and run time libraries.

- Assembly language was used for writing the UNIX OS. 

- There are many sub–categories in the Unix like family of the operating systems:

1. System V
2. BSD
3. Linux and so on.

- A number of computer architectures are supported by these Unix – like systems. 

- They come in heavy use in the following fields:

1. Servers in business
2. Work stations in academic
3. Engineering environments

- Few UNIX variants are available for free such as BSD, Linux etc. and are quite popular. 

- The holder of the Unix trademark is the open group and it has certified four Oss as Unix so far. 

- Two of the original system V Unix descendants are IBM’s AIX and HP’s HP – UX and they run only on the hardware provided by their manufacturer. 

- Opposite to these is the sun microsystem’s Solaris OS that can be used on different hardware types (inclusive of the Sparc and x86 servers etc. and PCs). - The POSIX standard was established to the sought the inter-operability of the Unix. 

- This standard is applicable for any OS now, even though originally it was developed especially for the variants of Unix.

- Berkeley Software Distribution or BSD family is a Unix sub–group. 

- It includes the following:

1. FreeBSD
2. NetBSD
3. OpenBSD

- The major use of all of these is in the web servers. 

- Furthermore, they are also capable of functioning as a PC OS. 

- BSD has made a great contribution in the existence of the internet. 

- Most of the protocols were refined and implemented in BSD. 

Explain FitNesse testing tool? What are principles of Fitnesse?

- FitNesse is an automated testing tool that has been developed to serve as a wiki and a web server for the development of software systems and applications. 

- This testing tool is entirely based up on the frame work for integrated testing that has been developed by Ward Cunningham. 

- It has been designed to support acceptance testing more than unit testing. 

- It comes with the feature of facilitating the description of the system functions in detail.

- With FitNesse testing tool, the users using a developed system can enter the input when it has been specially formatted i.e., non – programmers are able to access this format. 

- FitNesse tool interprets this input and automatically creates all the tests. 

- The system then execute these tests and returns the output to the users. 

- The main advantage of following this approach is that a very fast feedback can be obtained from the users. 

- Support in the form of classes called ‘fixtures’ is provided by the developer of the SUT i.e., system under testing. 

- The credit of writing the code for the fitNesse tool goes to Robert C. Martin and his colleagues in java language. 

- Since the program was developed in java, therefore initially it supported only java but now over the time it has got versions in a number of languages such as Python, C++, Delphi, ruby, C# and so on. 

Principles of FitNesse Testing Tool

This software works on certain principles which we shall discuss now:

FitNesse as a testing method: 

- Originally, it was designed as an interface using the fit frame work and it proved to be highly usable. 

- As such it is known to support the regression tests and black box acceptance tests in an agile style.

- This style of testing involves all the functional testers working in collaboration with the software developers in a software development project in an effort of developing a testing suite. 

- FitNesse testing revolves around the notion of black box testing.

- This involves considering the system to be a black box and testing it in the terms of the output that is automatically generated by the tool in accordance with the given inputs. 

- The responsibility of the functional tester is to design tests in a sense of functionality and expressing the same in the fitNesse tool. 

- On the other hand, the responsibility of the software developer is to connect the tool to the SUT so that tests can be executed and the actual output can be compared to the expected one. 

- The idea that drives this tool is forcing the functional testers and software developers to come up with a common language for an improved collaboration which will eventually lead to an improved mutual understanding of the SUT.

Fitnesse as a testing tool:

- Fitnesse defines the tests as inputs and outputs coupled together. 

- These inputs and outputs coupled together are expressed as variations of a decision table. 

- It supports a number of variations that range from tables that execute queries to tables for literal decision and to tables that express the testing scripts. 

- A free form table is the most generic variation that the designers can interpret in any way they like. 

- However, some sort of table is always used to express the tests. 

- The primary focus of FitNesse is on the easy creation of the tests, thus allowing the testers to maintain a high quality for the tests rather focusing on how the tests are to be executed. 

- Three factors are involved in the creation of the tests through fitNesse:

a)   Easy creation of the tables.

b)   Easy translation of the tables in to calls to SUT.

c)   Maintaining flexibility in the documentation of the tests. 

Explain how the data is secured in HTTPS?

HTTP secure or HTTPS can be thought of as an extended version of the regular HTTP. This communication protocol is the widely used one next to the regular HTTP when it comes to having a secure communication path between the user and the server over a computer network. 

The HTTPS finds quite a wide deployment over the internet when compared to deployment over intranet. If we understand it deeply we will come to know that in actual it is not a protocol in itself as it seems so from outside. 

It is actually a regular hyper text transfer protocol (HTTP) simply layered over SSL/ TSL protocol. The SSL/ TSL protocol thus lends its security capabilities to the standard HTTP communications when HTTP is layered up on SSL/ TSL. 

In this article we discuss how the data is secured in HTTPS. As we mentioned above that it is quite deployed in the internet services and it is so because it provides a quite convenient means to authenticate the web site as well as the web server associated with it (with which the connection is being established).

How data is secured in HTTPS

Such an authentication is of much importance as it provides the protection against the man in middle attacks which usually occurs because of eavesdropping between our communications with the server. 

- Moreover, HTTPS provides bidirectional encryption of the communications or the data that is exchanged between the clients and the servers. 

- The ability of the bidirectional encryption by virtue of which it protects against tampering and eavesdropping which otherwise would forge the contents of the communications between the clients and the servers, makes it much necessary. 

- HTTPS comes with a reasonable guarantee that you get to communicate only with the web site which you intended to communicate with and with none else.  - Furthermore, a way to prevent the forgery of the contents of the communication that takes place between the users and the clients cannot be hampered or forged by any of the third parties is ensured by the http secure. 

- In HTTPS, the entire HTTP is levied up on the top of the TSL or SSL thus enabling the total encryption of the HTTP communications content.

- This communications content includes:

1. Request URL which states the particular web page that was requested.
2. Query parameters
3. Headers
4. Cookies containing the identity information about the user and so on. 

Negative Points of HTTPS

Though the HTTPS has got many advantages, its minus point cannot be unseen.

-HTTPS cannot protect the disclosure of the communication content.

-This happens so because the addresses of the host web sites and port numbers form a necessary part of the TCP/ IP protocols that underlie the https. -To be seen practically, it means that the identity of the server can still be inferred by the eavesdroppers even on a correctly configured web server as well as the amount and duration of the communication.

-In the early years, the HTTPS was common to be used in the money transactions over the World Wide Web and other sensitive transitions like e- mails.

-In the recent years it has been known for the following:

1. Authenticating the web pages,
2. Providing security to the accounts,
3. Maintaining the privacy of the user communications, web browsing and identity.

The HTTPS has also come to the rescue of the wi- fi since it is highly prone to attacks being un- encrypted. The importance of https is often more realized when the connections are made over tor or anonymity network.