TWO KINDS OF APPLICATIONS:
SYSTEM SOFTWARE:
APPLICATION SOFTWARE:
[System Software] is a program designed to manage all the hardware resources and also runs the applications programs in a Computer. It is mainly of two types are the Operating system and utility software that is installed with the Operating system. The Operating system and utility programs are written in such a way to function independently because they are not user oriented. It always runs in the background and executes all the operations in a Computer. But there are some system software’s that are used by the end-users like a Device manager which is found on Control panel. Operating systems like Windows, Mac, Linux, and UNIX are the best examples that manage all the programs in a Computer. Since there are other systems software’s that help the OS to perform all the tasks like BIOS (Basic Input/output system) that manages data flow between OS and other attached devices such as keyboard, mouse, hard drives etc. Boot program loads the Operating system to RAM, an Assembler takes basic instructions and converts them to machine language to perform operations and a Device manager controls all the devices attached to Computer. The utility software’s like disk derangement, system restore, compilers and debuggers are also installed on the Operating system software. # [Application Software] is a program or a group of program designed for the end-user to perform a specific task in a Computer. The user directly interacts with the application programs for performing a task in a system. Some of the applications software’s are browsers, e-mail clients, word processors, spreadsheet, database programs and many more that has various built-in functions to be used. Furthermore the Applications Software’s are also broadly categorized for better productivity. Some of them are:-
Application suites are packed with multiple programs with user interfaces, features and functions to interact with the users. Some of them are Microsoft Office, Adobe Creativity suite, Security suite, Gaming apps and many more.
Enterprise Software : labels the organization requirements and also manages data flow in a huge environment. It may be an automated billing system, e-mail marketing, business intelligence and Content management.
Enterprise Infrastructure : Software provides the capabilities required to support enterprise software systems. It is mainly used for businesses, society or Organization for network security, surveillance system, transportation, sewage, communication, electricity and water that need high investment for the systems.
Educational Software : includes all the contents of different subjects that can be used by a student or any individuals. There are several websites providing educational software about various topics and vast database makes it an easy to use application.
Multimedia Software : is used for development of media in our day to day life. There are various audio, video and image editing tools, printing media that can be used to maximize the growth of a business.
Content Access Software : is used to access the contents in a website for publishing digital contents and entertainment.
Information Software : is used for addressing the needs of an individual by creating and managing information for individual projects within the department. It may be the word processors, spreadsheets, e-mail or blog clients etc.
How Does a Web Application Work?*
Defining web applications
In computer system, a web application is a client-side and server-side software application in which the client runs or request in a web browser. Common web applications include email, online retail sales, online auctions, wikis, instant messaging services and more. Many companies are shifting their focus to web applications that can be delivered as Software-as-a-Service (SaaS), such as moving to Microsoft 365.
How a web application works step-by-step
Step 1: The user accesses a web application via a web browser or mobile application, triggering a request to the web server over the Internet. Note that there may be security measures (i.e. firewalls or cloud access security brokers) and load balancers.
Step 2: The web server forwards the request to the web application server. The web application server performs the requested task – such as querying the database or processing the data – then generates the results of the requested data.
Step 3: The web application server sends the results back to the web server.
Step 4: the web server delivers the requested information to the client (desktop, mobile device, tablet, etc.) and the information appears on the user’s display.
Internetworking
TCP/IP - Transport Control Protocol/Internet Protocol
A set of rules for communication between computers where each device (host) is assigned a unique IP address which is valid on a particular network. An IP address is made up of 4 "octets" ranging between 0 and 255, and separated by a period or dot. (Ex. 128.241.171.241)
An IP address can be assigned statically or dynamically. This option is found in the TCP/IP protocol settings within Network Properties. See Demo: TCP/IP Settings
DHCP - Dynamic Host Configuration Protocol
If you get your IP address dynamically, then DHCP is used. Simply put, the PC requests an IP address and the DHCP server on the network "leases" one out of its available pool of addresses. You can find out information about your currently assigned address, DHCP server, DNS servers (see below), and more using the WINIPCFG command (Windows 95/98), or IPCONFIG (Windows NT/2000/XP). See Demo: WINIPCFG
# DNS - Domain Name System Every device on the Internet is assigned an IP address, but navigating to them using their 12-digit IP address would be very cumbersome. DNS allows a domain name to be used as a pseudonym for a specific IP address. (i.e. www.mistupid.com). When you type in a web site name, your system looks up the name on an assigned DNS server and resolves it to its IP address. It can then access the web site. The PING command can be used to check if a domain name is resolving to an IP address, and if that IP address can be reached from your machine.
Network Protocols are a set of rules governing exchange of information in an easy, reliable and secure way. Before we discuss the most common protocols used to transmit and receive data over a network, we need to understand how a network is logically organized or designed. The most popular model used to establish open communication between two systems is the Open Systems Interface (OSI) model proposed by ISO.
OSI Model
OSI model is not a network architecture because it does not specify the exact services and protocols for each layer. It simply tells what each layer should do by defining its input and output data. It is up to network architects to implement the layers according to their needs and resources available.
These are the seven layers of the OSI model −
Physical layer −It is the first layer that physically connects the two systems that need to communicate. It transmits data in bits and manages simplex or duplex transmission by modem. It also manages Network Interface Card’s hardware interface to the network, like cabling, cable terminators, topography, voltage levels, etc.
Data link layer − It is the firmware layer of Network Interface Card. It assembles datagrams into frames and adds start and stop flags to each frame. It also resolves problems caused by damaged, lost or duplicate frames.
Network layer − It is concerned with routing, switching and controlling flow of information between the workstations. It also breaks down transport layer datagrams into smaller datagrams.
Transport layer − Till the session layer, file is in its own form. Transport layer breaks it down into data frames, provides error checking at network segment level and prevents a fast host from overrunning a slower one. Transport layer isolates the upper layers from network hardware.
Session layer − This layer is responsible for establishing a session between two workstations that want to exchange data.
Presentation layer − This layer is concerned with correct representation of data, i.e. syntax and semantics of information. It controls file level security and is also responsible for converting data to network standards.
Application layer − It is the topmost layer of the network that is responsible for sending application requests by the user to the lower levels. Typical applications include file transfer, E-mail, remote logon, data entry, etc.
OSI Model It is not necessary for every network to have all the layers. For example, network layer is not there in broadcast networks.
When a system wants to share data with another workstation or send a request over the network, it is received by the application layer. Data then proceeds to lower layers after processing till it reaches the physical layer.
At the physical layer, the data is actually transferred and received by the physical layer of the destination workstation. There, the data proceeds to upper layers after processing till it reaches application layer.
At the application layer, data or request is shared with the workstation. So each layer has opposite functions for source and destination workstations. For example, data link layer of the source workstation adds start and stop flags to the frames but the same layer of the destination workstation will remove the start and stop flags from the frames.
Let us now see some of the protocols used by different layers to accomplish user requests.
TCP/IP TCP/IP stands for Transmission Control Protocol/Internet Protocol. TCP/IP is a set of layered protocols used for communication over the Internet. The communication model of this suite is client-server model. A computer that sends a request is the client and a computer to which the request is sent is the server.
TCP/IP TCP/IP has four layers −
Application layer − Application layer protocols like HTTP and FTP are used.
Transport layer − Data is transmitted in form of datagrams using the Transmission Control Protocol (TCP). TCP is responsible for breaking up data at the client side and then reassembling it on the server side.
Network layer − Network layer connection is established using Internet Protocol (IP) at the network layer. Every machine connected to the Internet is assigned an address called IP address by the protocol to easily identify source and destination machines.
Data link layer − Actual data transmission in bits occurs at the data link layer using the destination address provided by network layer.
TCP/IP is widely used in many communication networks other than the Internet.
FTP As we have seen, the need for network came up primarily to facilitate sharing of files between researchers. And to this day, file transfer remains one of the most used facilities.The protocol that handles these requests is File Transfer Protocol or FTP.
FTP Using FTP to transfer files is helpful in these ways −
Easily transfers files between two different networks
Can resume file transfer sessions even if connection is dropped, if protocol is configure appropriately
Enables collaboration between geographically separated teams
PPP Point to Point Protocol or PPP is a data link layer protocol that enables transmission of TCP/IP traffic over serial connection, like telephone line.
Point to Point Protocol To do this, PPP defines these three things −
A framing method to clearly define end of one frame and start of another, incorporating errors detection as well.
Link control protocol (LCP) for bringing communication lines up, authenticating and bringing them down when no longer needed.
Network control protocol (NCP) for each network layer protocol supported by other networks.
Same-origin policy
In computing, the same-origin policy (sometimes abbreviated as SOP) is an important concept in the web application security model. Under the policy, a web browser permits scripts contained in a first web page to access data in a second web page, but only if both web pages have the same origin. An origin is defined as a combination of URI scheme, host name, and port number. This policy prevents a malicious script on one page from obtaining access to sensitive data on another web page through that page's Document Object Model.
This mechanism bears a particular significance for modern web applications that extensively depend on HTTP cookies[1] to maintain authenticated user sessions, as servers act based on the HTTP cookie information to reveal sensitive information or take state-changing actions. A strict separation between content provided by unrelated sites must be maintained on the client-side to prevent the loss of data confidentiality or integrity.
It is very important to remember that the same-origin policy applies only to scripts. This means that resources such as images, CSS, and dynamically-loaded scripts can be accessed across origins via the corresponding HTML tags[2] (with fonts being a notable exception[3]). Attacks take advantage of the fact that the same origin policy does not apply to HTML tags.
http://www.example.com/dir/page2.html Success Same scheme, host and port http://www.example.com/dir2/other.html Success Same scheme, host and port http://username:password@www.example.com/dir2/other.html Success Same scheme, host and port http://www.example.com:81/dir/other.html Failure Same scheme and host but different port https://www.example.com/dir/other.html Failure Different scheme http://en.example.com/dir/other.html Failure Different host http://example.com/dir/other.html Failure Different host (exact match required) http://v2.www.example.com/dir/other.html Failure Different host (exact match required) http://www.example.com:80/dir/other.html Depends Port explicit. Depends on implementation in browser.
