GRC 175 Class Lessons

Internet Technologies and Services

 

LECTURE 1      Internet Connections    •   WWW Organizations  

Uniform Resource Locator (URL)

As the web developed on the Internet, it adopted a standardized way of specifying the address of a particular website or file.

Currently, the addressing system uses URLs (Uniform Resource Locators). URLs combine information about the type of protocol being used, the address of the website where the resource is located, the subdirectory location, and, sometimes, the name of the file.

Here is an example:

http://www.macromedia.com/products/ dreamweaver/main.html This URL is composed of the following parts:

http: —The type of Internet protocol used for storage and transmission of information.
//www.macromedia.com — The domain name that identifies the website where the resource is stored.
/products/dreamweaver/ —The directory path to the resource stored on the remote computer.
main.html —The name of the file to be retrieved.

URLs provide a consistent, easily understood method for finding and retrieving information and computer files. It is important to understand that the URL is also a filing system. It is the same format that you will use to name your web page files.

Telnet

Telnet is a protocol that allows the user access to a server on a network.

Although HTTP or FTP allow you to request specific files from remote computers, neither actually let you log on. With Telnet, you log on as a regular user with whatever privileges you may have been granted to the specific application and data on that computer.

Email

SMTP (Simple Mail Transfer Protocol) is a TCP/IP protocol used in sending and receiving e-mail. However, since it is limited in its ability to queue messages at the receiving end, it is usually used with one of two other protocols—

Post Office Protocol 3 (POP3) or Internet Message Access Protocol (IMAP). These protocols let the user save messages in a server mailbox and download them periodically from the server.

Thus, users typically use a program that uses SMTP for sending e-mail and either POP3 or IMAP for receiving messages stored on their local server.

IM

Instant messaging is the ability to exchange messages with another user instantly (synchronous communication). Unlike E-mail, most exchanges are text-only. However, some instant messenger services allow attachments.

Instant messaging is becoming very important in working situations because it keeps you in instant touch with co-workers who may or may not be in the same geographical location as you are.

However, instant messengers are not a secure form of company communication. They should not be used to exchange sensitive company information.

Plug-ins

Plug-ins are programs that add features or services to your browser.

To play audio files or animation files, you usually need something to generate that motion. Plug-ins contain the code that can run these files.

Plug-ins are downloaded and installed on your computer so that they can be accessed by your web browser to play the desired file

Initially, Netscape Navigator launched helper applications to display files it could not read itself.

A plug-in application, on the other hand, is recognized automatically by the browser and displayed right inside the browser window. Most users wait until they need a particular plug-in before they download it.

One of the most popular plug-ins is Adobe Acrobat, which is a document presentation and navigation program that lets you view documents just as they look in print. Two other popular plug-ins are RealNetwork's RealPlayer streaming video player and Macromedia Flash.

Special formats can also be displayed by programs based on ActiveX or Java, which can add any type of new capability to the browser, including the ability to play additional file formats.

Adobe Acrobat
Lets you convert any document to Adobe Portable Document Format (PDF). Adobe PDF files can be opened reliably across a broad range of hardware and software; these PDF files look just like your original files. To view PDF files, you will need Adobe Acrobat Reader. Adobe Acrobat Reader can be downloaded for free at the Adobe website.
http://www.adobe.com/products/acrobat/readstep2.html

QuickTime

Developed by Apple, combines sound, text, animation, and video in a single file. Using the QuickTime player plug-in, which can be downloaded from Apple, the user can view and control multimedia sequences. QuickTime files have the extension .mov.
http://www.apple.com/quicktime/download/

RealPlayer

To access radio and video broadcasts from around the world as well as tap into channels or media guides. RealPlayer is the plug-in required to hear and/or view RealMedia presentations made with RealAudio, RealVideo, and SMIL.
http://www.real.com/player/index.html

Flash Player

Animations that are created with the now unsupported Adobe LiveMotion or Macromedia Flash need to be viewed on your browser using the Flash player plug-in.

This plug-in is necessary to play files with the extension .swf. As long as different browsers are equipped with the necessary plug-ins, SWF animations will look the same regardless of which browser you are using.

This player is becoming ubiquitous because newer versions of Internet Explorer and Netscape Navigator already have the plug-in installed and the user doesn't need to download the plug-in, which can be found at http://www.macromedia.com/software/flashplayer/

SVG (Scalable Vector Graphics)

SVG is a type of graphics file,like EPS. SVG images require a plug-in in order for the user to view it on his/her web browser. The SVG plug-in will enable you to view any SVG artwork. Adobe has a plug-in for SVG files that can be used across different platforms (PC, Macintosh, Unix).
http://www.adobe.com/svg/

Browsers

A web browser is a software application that displays files, retrieved from a local or remote computer, based on the instructions included in the file. A browser is a client program that uses HTTP to make requests of web servers. The first web browser was Mosaic, introduced in 1993. Today, the two most popular browsers are Netscape Navigator and Microsoft Internet Explorer. Both of these are graphical browsers, which means that they can display graphics as well as text. In addition, most modern browsers can display multimedia information, including sound and video, though they require plug-ins for some formats.
All browsers are not equal. Each browser interprets the markup in a slightly different manner and often introduces markup that is proprietary to that browser. As new markup standards are introduced, new versions of browsers are required to render the new markup. As a result, browsers in use at any given time vary greatly, not only from type to type but also from version to version. This means that the same file can and usually does have varying displays from one user to another - something any web designer needs to keep in mind.

Leading Browsers

Internet Explorer
Microsoft refined a version of Mosaic (see below) and released it as Internet Explorer. Some of the tags were proprietary, but Microsoft is not the only company to include proprietary elements and technology in their browsers.

With Netscape and Microsoft running neck and neck in a race to achieve dominance in this area, both innovation and problems occurred.

No one knows this issue as well as the working web designer, who must constantly work to leverage what he or she knows against the limitations of a given browser, a given browser version, and proprietary versus recommended elements and attributes

Netscape Navigator
Netscape's browser was developed in 1995 by a team led by Marc Andreessen, the creator of Mosaic, the first graphical browser and the software that gave birth to "the world wide web."

Netscape began its practice of releasing beta software to the public over the Internet and using early adopters to help with beta testing.

Netscape went through several versions of its browser. The new browser introduced a variety of elements and attributes considered at that time proprietary, unauthorized extensions.

However, many of these elements and attributes have become part of HTML, although many have been left out in more recent versions.

At the time, however, it was the extended capabilities allowed by the browser that made it so exciting.

Netscape is committed to upholding the recommendations set forth by the W3C concerning language support.

Netscape 6.0 wss considered to be one of the most advanced browsers in terms of recommended support for HTML 4.01

Opera

Mozilla

Some sources that keep track of how many (what percentage) of users are using each of the popular browers.
http://www.w3schools.com/browsers_stats.asp
http://www.thecounter.com/stats/

However, you should read this disclaimer about browser stats.

LECTURE 1      Internet Connections    •   WWW Organizations