Module 13 - Types of Software

Database Server

A database is a structured data repository. A database management system is software that responds to user queries to create, manipulate, and retrieve records from the database. There are numerous database management system packages available. A database server permits database access across a network. The database server will perform such tasks as data analysis, data manipulation, security, and archiving. The database server may or may not store the database itself. By separating the server from the database, one can use different mechanisms to store the database, for instance a storage area network to support load balancing. MySQL is a very popular, open source database server. MySQL is actually an umbrella name for a number of different database products. MySQL Community is the database server. There is also a proxy server for a MySQL database, a cluster server for high-speed transactional database interaction, and a tool to support GUI construction.

File Server

A file server is in essence a computer with a large hard disk storing files that any or many users of the network may wish to access. The more complex file servers are used to not only store data files but also to store software to be run over the network. File servers used to be very prominent in computer networks because hard disk storage was prohibitively expensive. Today, with 1 TB of hard disk space costing $100, many organizations have forgone the use of file servers. The file server is still advantageous for most organizations because it supports file sharing, permits easy backup of user files, allows for encryption of data storage, and allows remote access to files. There are many different file servers available with NFS (the Network File System) being the most popular in the Unix/Linux world.

Proxy Server

A proxy server is used in an organization to act as a giant cache of web pages that anyone in the organization has recently retrieved. The idea is that if many people within the organization tend to view the same pages, caching these pages locally permits future accesses to obtain the page locally rather than remotely. Another function of the proxy server is to provide a degree of anonymity since the IP address recorded by the web server in response to the request is that of the proxy server and not the individual client. Proxy servers can also be used to block certain content from being returned; for example, rejecting requests going to specific servers (e.g., Facebook) and rejecting responses that contain certain content (e.g., the word "porn"). Squid is the most commonly used proxy server although Apache can also serve as a proxy server. Squid, like Apache, is open source. Among the types of things a system administrator or web administrator might configure with Squid are the number and size of the caches, and the Squid firewall to permit or prohibit access of various types.

FTP Server

An FTP server is like a webserver in that it hosts files and allows clients to access those files. However, with FTP, access is in the form of uploading files and downloading files. Any files downloaded are saved to disk unlike the web service where most files are loaded directly into the client's web browser. FTP access either requires that the user has an account (unlike HTTP), or requires that the user log in as an anonymous user. The anonymous user has access to public files (often in a special directory called /pub). FTP is an older protocol than HTTP and has largely been replaced by HTTP with the exception of file uploading. An FTP server is available in Linux, ftpd. This service is text-based. An extension to FTP is FTPS, a secure form of FTP. Although SFTP is another secure way to handle file transfer, it is not based on the FTP protocol. One can also run SSH and then use ftp from inside of SSH. Popular FTP client tools for performing FTP include WS-FTP and FileZilla, both of which are GUI programs that send commands to an FTP server. FileZilla can also operate as an FTP server, as can Apache.

E-mail Server

An e-mail server provides e-mail service. Its job is to accept e-mail requests from clients, send messages out to other e-mail servers, receive e-mails from other servers, and alert the user that e-mail has arrived. The Linux and Unix operating systems have a built-in e-mail service, sendmail. Clients are free to use any number of different programs to access their e-mail. In Windows, there are a large variety of e-mail servers available including Eudora, CleanMail, and Microsoft Windows Server. Unlike FTP and Web servers, which have a limited number of protocols to handle (primarily FTP, FTPS, HTTP, and HTTPS), there are more e-mail protocols that servers have to handle: IMAP, POP3, SMTP, HTTP, MAPI, and MIME.

Intranet

Applications intended for Internet Usage will work internally as easily as they work externally

Device Drivers

Device drivers provide specific interfaces between the OS running a computer and hardware. There are literally hundreds of thousands of drivers available (according to driverguide.com, more than 1.5 million), and there is no need to fill a user's hard disk drive with all of them when most will never be used. Many popular device drivers are preloaded into the operating system, whereas others must be loaded off of the Internet or CD-ROM when a new hardware device has been purchased.

Server

Examples include: web servers and email servers; Works with hardware to provide a network service

Commonly used OS

Linux; MAC OS, Microsoft, Unix,

Layers of an OS

OS utilities; services; shells; OS Kernel; Device drivers

Daemons or services

Operating system - System software that runs in the background all of the time; They wait for an event to arise before they take action.

Server Software

Print service, ftp server, webserver, e-mail server, database server, and file server

Application

Programs users run to accomplish a task; Examples include: spreadsheet software and database software; run by the end user

Services or daemons

Services, or daemons, are operating system programs that are usually started when the operating system is loaded and initialized, but they run in the background. This means that the program, while it is active, does not take up any CPU time until it is called upon to do so. The operating system will, when a particular event arises, invoke the needed service or daemon to handle the event. There are numerous services in any operating system.

Utility Programs

System utilities are programs that allow the user to monitor and improve system performance. Utilities greatly range in function. For example, utilities exist to defragment the hard disk and to scan files for viruses and other forms of malware. Usually, system utilities must be installed separately as they may not come with the operating system (often, these require purchasing and so many users may ignore their availability).

Kernel

The core components of the operating system are referred to as the kernel. The kernel is loaded when the computer is first booted. Included in the kernel are the components that handle process management, resource management, and memory management. Without these, you would not be able to start a new program or have that program run efficiently. The kernel sits on top of the hardware and is the interface between hardware and software.

Benefits of GUI

The graphical user interface (GUI) is a simpler way to issue commands. The GUI uses the mouse to point and click on a desktop. The GUI uses the touch screen to swipe, tap, and pinch on smart phones or tablets.

Webserver

The role of a web server is to respond to HTTP requests. HTTP requests most typically come from web browsers, but other software and users can also submit requests. HTTP is the hypertext transfer protocol. Most HTTP requests are for HTML documents (or variants of html), but could include just about any web-accessible resource. HTTP is similar to FTP in that a file is transferred using the service, but unlike FTP, the typical request is made by clicking on a link in a web browser—and thus, the user does not have to know the name of the server or the name or path of the resource. These are all combined into an entity known as a URL. The open source Apache server is the most popular web server used today. Aside from servicing requests, Apache can execute scripts to generate dynamic pages, use security mechanisms to ensure that requests are not forms of attacks, log requests so that analysts can find trends in the public's browser behavior of the website, and many other tasks.

Shell

The shell is an interface for the user, often personalized for that given user. The shell provides access to the kernel. For instance, a GUI shell will translate mouse motions into calls to kernel routines (e.g., open a file, start a program, move a file). Desktop elements include shortcut icons, the theme of the windows, menus and background, the appearance of toolbars and programs on the start menu, and desktop gadgets.

In Linux, the account is called root.

To change to the root, you use the su command (switch user). Typically, su is used to change from one user account to another by saying su username. The OS then requires the password for username. If you do su without the username, then you are requesting to change to root. Because you can run su from the command line prompt, you do not have to log out. In fact, you can open numerous windows, some of which are controlled as you, the user, and some as root.

Main Role of an Admin account

To limit access to the system software so that they cannot be changed by anyone who has access to the network

cloud computing

allows anytime access anywhere

OS

an operating system (OS) is a program. Its primary task is to allow a computer user to easily access the hardware and software of a computer system. Beyond this, we might say that an OS is required to maintain the computer's environment. An OS is about control and convenience. The OS supports control in that it allows the user to control the actions of the software, and through the software, to control (or access) hardware. The OS supports convenience in that it provides access in an easy-to-use manner. Early OSs were not easy to use, but today's OSs use a graphical user interface (GUI), and commands can be issued by doing things such as dragging, pointing, clicking, and double clicking with the mouse. In some OSs such as Linux and Unix, there are two ways to issue commands: through the GUI and by typing in commands at a command line prompt. In actuality, both Windows and Mac OS also have command line prompts available, but most users never bother with them. Linux and Unix users, however, will often prefer the command line over the GUI.

operating system

are executed based on a scheduler. For instance, your antiviral software might run once every 24 hours, while a program that checks a website for any updates might run once per week. Yet other pieces, often called utilities, are run on demand of the user. For instance, the user might run a disk defragmentation utility to improve hard disk performance. Antiviral software is another utility, although as stated above, it may be executed based on a scheduler.

Application software

consists of programs that end users run to accomplish tasks. The types of application software are as varied as there are careers because each career has its own support software. Productivity software consists of the applications that are useful to just about everyone. Productivity software includes the word processor, presentation software (e.g., PowerPoint), spreadsheet program, database management systems, calendar program, address book, and data organizer. Drawing software may also be grouped here although drawing software is more specific toward artists and graphic designers. Another type of application software is based around Internet usage. Software in this class includes the e-mail client, web browser, and FTP client. There are also computer games and entertainment software (e.g., video players, DVD players, CD players); though not considered productivity software, they are used by just about everyone. Productivity software is sometimes referred to as horizontal software because the software can be used across all divisions within an organization. Vertical software applies instead to software used by select groups with an organization or to a specific discipline. For example, there are classes of software used by musicians such as music sequencers, samplers, and digital recorders. Programmers use development platforms that provide not only a language compiler but also programming support in the form of debugging assistance, code libraries, tracking changes, and code visualization. Filmmakers and artists use video editing, photographic editing and manipulation, and sound editing software. There is a large variety of accounting software available from specialized tax software to digital ledgers.

System Software

consists of programs that make up the operating system. System software is software that directly supports the computer system itself. Such software is often started automatically rather than by request of the end user. Some pieces of the operating system run in the background all of the time. These are often known as daemons or services. - Directly supports the computer system.

Operating System

directly supports the computer system; typically started automatically

Software

refers to the programs that we run on a computer; because programs do not exist in any physical, tangible form; When stored in memory, they exist as electrical current and, when stored on disk, they exist as magnetic charges. Thus, we differentiate software from hardware, whose components we can point to or pick up and touch. We generally categorize software as either system software or application software.

Local applications

will limit those who could access the application to the owner of the local computer

server software

works with hardware to provide a network service. This type of software includes web servers, e-mail servers, and database servers, to name a few.