web technologies unit-v

8/9/2019 Web Technologies Unit-V

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IIMC Prasanth Kumar K

WEB T ECHNLOGIESUNIT-V

. Explain Ne wsg roup a nd its terminology.

Newsgroup: A newsgroup is a discussion group in which computer users throughout the worldparticipate. Users interested in a particular topic may subscribe to the same newsgroup. Boundaries such

as age, gender and background generally do not play a role in the discussion, since users usually only seemessages from each other. Someone can email a message called an article to the newsgroup at anytime. The message then becomes available for others to read. They can respond to the article sharingtheir opinions or expertise. This in turn may stimulate others to respond. In this way, a question or anopinion c an create a lively and lengthy discussion.

Newsgroup Terminology: Most of the terminology for newsgroups is borrowed fromnewspaper news.

Article: A message writt en and sent to a newsgroup.Post: A synonym for article.Posting: The process of sending an article to a newsgroup.Follow-up: An a rticle that is posted in response to a previous news group a rticle.Thread: A collection of one or more fellow-up articles together with the original posting.Subscribe: The procedure user follows to add a newsgroup to the list of those read on regular basis. Oncesubscribed, user will receive the new postings of the newsgroup.Unsubscribe: The process of removing a newsgroup from the list of those user read. User must have beensubscribed in order to unsubscribe.Newsreader: A program that servers as the user interface for newsgroups. Newsreaders allow users toread, post, subscribe and unsubscribe from newsgroups among other things. User should select anewsreader t hat also displays threads.News client: A synonym for newsreader.Expired news: News that is removed from a system usually after a short period of time.News server: A computer that saves forwards and manages news articles. Normally, each organizationruns its own news server and limits ac cess to its customers or user community.

News feed: A news feed that provides recent articles to a new client. The term also encompasses theprocess of delivering t he news articles t hemse lves.Way-station: A news server that functions as news feed for at least two and usually many more othersites.Network News T ransfe r Protoc ol(NNTP): The protoc ol used for distributing news articles.News administrator: A person who is in charge of running a news server. The news system is distributedand each site that receives and posts news must have a site administrator. This person is in charge of determining what news will be received by this site. Administrators can also add or delete newsgroups.The email address for this person is usually newsmaster@domain , where domain is replaced by theappropriate site name.News moderator: A person associated with a specific newsgroup who reads and critically evaluates allarticles submitted for posting to the newsgroup and then decides whether or not each article should beposted.

Moderated newsg roup: A newsgroup that has a moderator.Unmoderated newsgroup: A newsgroup that has no moderator. Because a good moderator can filter outpoor irrelevant posts, moderated newsgroup posts sometime have more valuable content thanunmoderated newsgroup articles.Cross-post : The process of simultaneously submitting the sa me article to two or more newsgroups.Digest: A c ollection of related articles usually edited t hat is posted as an article to a newsgroup.Kill-files: A filter based on names or topics that user specifies so that user is not even shown thosemessages.


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. Explain Ma il List Fundame ntals.

A mailing list is a group of users with a shared interest whose email addresses are collected inan electronic list that can be user to send email to each member on the list. The key to a mailing list is aprogram called a list server which receives and distributed postings and automatically managessubscriptions.

Mailing list provide a forum in which users from all over the world can ask questions and have

them answered by others with similar interests.

To participate in a mailing list, user has to know how to use email. There is no need to learnnew software. For a mailing list, a user posts message to a spec ial mailing list program called t he listserver which has email addresses of all the users subscribed to the list. The list management programthen distributes the message to eac h member on the list via email.

Mailing List Terminology: Much of the terminology used with newsgroups carries over tomailing lists . Terms like article, c ross-post, follow-up, post, posting, subscribe, thread and unsubsc ribe canall be used in the mailing list.

Additional terms are:

Subscriber: A person whose email address is on an elect ronic mailing list. They will receive all posts t o thelist. Note that for the majority of mailing lists, subscription is free.List owner: The person in-charge of a mailing list. While most mailing lists have only one person whohandles the ad ministrative duties, so metimes a couple of people may split the responsibilities.List administrator: Synonym to List owner.List coordinator: Synonym to List owner. List manager: Synonym to List owner.Lurker: A person who is subscr ibed to and reads a mailing list but does not post messages. Such a personis said to lurk.Closed list: A mailing list for which the list owner either accepts or rejects subscriptions. List membershipis filtered. It is not possible to subscribe automatically to a closed list. Only postings from subscribers areaccepted.

Private list: Synonym to Closed List.Newbie: A person who only recently joined a mailing list.Open list: A mailing list to which anyone subscribes. Such a list typically accepts posts even from userswho are not subscribers.Edited list: A mailing list in which posts to the lists may be edited by the list owner or moderator.Digested list: A mailing list in which postings are grouped by topic and sent out as batches instead of individually. Sometimes, when user subscribes, we have a choice of getting either individual postings ordigests.

. Explain about Chat Room s and Chat Room Ent rance.

Chat Room : A chat room is a forum through which users can interactively discuss their favoritesubject with people located anywhere on the internet. A chat room is a virtual room in which two or morepeople with a common interest (entertainment, literature, movies, music, politics, religion and so on) canshare ideas and have a real-t ime conversation .

The chat room is actually a channel or path that allows communication between two or morecomputers on the internet. The communication occurs in real time and is similar to a conference call ormeeting. However, messages a re typed on the keyboard and the conversation appears on t he monit ors of all the users o n that c hannel.

Chat Room E ntra nce: When signing into a char room for the first time, user is asked to selecta username and password. Unless the c hat room is moderated and the moderators wants the user to use


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the real name, the user may create any username (or nickname) liked, providing it is not already in use.The user also needs to create a password. T he user is asked to fill a form containing such data as name,password, date of birth, occupation, e mail address, etc . This information can be used for authenticat ionand also for advertising purposes.

Once a user is signed in with a chat service, he can select a room to which he wants to go. The numberof participants in each room is displayed either via a number or list of the rooms oc cupants.

When a chat room is active, a scrolling window displays the conversation as lines of text, eachline preceded by the nickname of t he person who spoke. A second area c alled message box is p rovidedin which the user can type his own message. Leve l of privacy is the choice of the user like whether todisplay their pictures or URL in the chat rooms. Third area is provided to display the list of users orusernames of all people in the chat room. Selecting someone from the list allows user to send a privatemessage to t hem opening a p rivate chat window.

In a chat room, message box a lso provides to select emoticons such as s mile or wink, toaccompany t he message. Several butt ons allow user to submit the message, go to another chat room, orrefresh the sc reen if t he user have been idle for a pe riod of t ime.

. Explain about Multi-User Dime nsion.

Multi-User Dimension (MUD): It is a real-time interactive game that takes place in an imaginaryenvironment where multiple co mputers users can play simultaneously. It is a 3D World. MUDs originatedin 1979 when Richard Bartle and Roy Trubahaw wrote a game program that allowed multiple users to playand interact at the same t ime.

To participate in a MUD, user needs to c onnect Telnet to a server running a MUD. Using asearch engine, user can easily generate a list of currently available MUDs. User can connect to a MUD byusing t elnet command and specifying the MUDs network address and port number.

Some examples are: MAcMOOSE (Macintosh) TinyTalk (UNIX) MUSHClient (PC Winsock)

When user connects to a MUD for the first time, user should read the welcome screen. Thewelcome screen permits to either create a character by placing a name and password or by connectingwith existing name and password. The introductory screen provides other useful information about thegame such as the rules and where to find help. It also provides information about the background story of the ga me. Before starting to play, new players should try to bec ome fa miliar with the commands.

Commands used are: Emote indicate an action, such as a sigh or laugh. Help provide help. Look Describe the contents of the room Page talk to someone in another room Say speak to everyone in the room. Who List who is playing.

. Explain about Mu ltime dia Audio and Video formats.

Audio: The term audio refers to a sound. A number of audio formats exist and audio can be included in aweb page.

A large number of audio file formats are in use. They are: AIFF (.aif, .aiff and .aifc) which stands for Audio Interchange File Format. This format was

developed by Apple.


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AU(.au and .snd) stands for Unix Audio and Unix Sound. This format was developed by SunMicrosystems.

MIDI (.midi and .mid) stands for Musical Instrument Digital Interface. This format was developedby MIDI Manufacture Assoc iation(MMA).

RealAudio (.ra and .ram). T his format was developed by Progress ive Networks. WA V(.wav) stands for Wave format. It is developed by Microsoft.

Audio and Web Pages: 1. One approach to include an audio file in a web page involves object tag,

and its c orresponding ending tag

To include the WAV audio file called mymusic.wav using the object tag, we can use the followingcode:

The DATA attribute specifies the source file and the TYPE attribute specifies the objects MIME type.

2. Microsoft Internet Explorer supports the background sound tag .To include the audiofile , we can use the following code:

The BGSOUND tag also supports t he LOOP att ribute. LOOP can be assigned a natural numb erindicating the number of times the audio file is to be played or it can take a value of infinite indicatingthat t he sound should be played endlessly.

Movies and Video : Online video in essence is a motion picture. A video may or may not includesound. Because of video consists of many images frames plus audio, video files are much larger thanaudio files. This means that downloading a video file takes a long time than audio.

A large number of video formats are currently in use. Some of the most popular are: AV I (.avi) which stands for Audio Video Interleaved. This format is developed by Microsft. MPEG (.mpeg or .mpg) which stands for Motion Picture Experts Group or Moving Picture

Experts Group. This format was developed by the Motion Picture Experts Group. QuickTime (.qt or .mov) . This stands for QuickTime or Movie. This format was developed by

Apple.

Video and Web Pages:

To include the AVI file c alled mymovie.av i using the object t ag, we can use the following code:

Please install Plug-in to use.

Values specified in the parameter tag are passed directly to the corresponding plug-in and arenot processed by the browser. For example, the browser uses the DATA attribute to load the


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appropriate file, the TYPE attribute to obtain the MIME type of the file and the HEIGHT and WIDTHatt ributes to layout the required amount of space on the screen for the multimedia e lement.

However, the value true assigned to the parameter autostart is passed directly to the plug-initself. This tells the plug-in to start playing the movie as soon as it is loaded.

. De fine Virtual Realty in 3D Modeling.Or

Explain VRML a nd QTVR.

Virtual Reality involves a three-dimensional simulation of a real or imagined environment usingcomputers. A lot of applications are suited to 3D displays from engineering designs to medical researchand imaging to on-line art galleries to games. If an object such as a cube is being displayed in a virtualrealty setting, we can examine the cube from various points of view (top, bottom, right and left).Software for creating 3D solid figures and line drawings has been available for some time. However, thefirst step was creation of static images. Initially, users were not able to interact with the object beingrendered. Adding dynamic use r interact ion has g reatly enhanced the interest in 3D modeling.

Virtual Reality is becoming another exciting extension of the web. The development of 3D world andobjects and 3D browsers in which to view them is bringing us closer to Web-based virtual reality. Evenwhile 2D graphical browsers were being introduced and accepted, 3D specifications were already in theplann ing stages.

V RML (Virtual Reality Modeling Language): Initially called Virtual Reality MarkUp Language, the VRML 1.0 specification, was originally

established by Silicon Graphics to use simple text based files to create virtual reality environments. Thefirst release of VRML produced environments that were static and non-interactive. The current version isVRML97 and the specification that defines it is VRML 2.0. This collaborative effort extends thecapabilities of VRML 1.0 by supporting interaction, motion, and sound. A VRML world does not have tomodel so mething geographic; any object c an be modeled as a VRML world.

A VRML file is a plaintext or compressed text file. Such files are identified by a file extension of .wrl, .wrl.gz, .wrz and they have a MIME type of model/ vrml . Where HTML files are rendered as pages

by a browser, VRML files are rendered as worlds (wrl stands for world). The z at the end of the fileextension .gz and .wrz denotes a zip or compressed file.

Viewing a VRML world requires a special VRML viewer or a plug-in. If user doesnt havenecessary viewer, then user can try to open a VRML file. Browser will complain and ask the user toinstal l the appropriate plug-in.

The latest version of internet explorer and Netscape come bundled with viewers that supportVRML. Other browsers require downloading an appropriate plug-in.

Virtual World Creation Tools: As with an HTML file, a text editor is all that is required tocreate a VRML file, since it just consists of plaintext. Since VRML files contain information that describescameras, colors, even handlers, lighting, 3D object s and textures, these files are quite co mplex. Becauseof this many VRML authors use modeling software to help them create their VRML files. Modelingsoftware offers WYSIWYG tools for authoring V RML worlds.

Converters that permit to convert 3D and CAD (Computer-Aided Design) file formats to theVRML file format are also available. Other converters can convert VRML 1.0 to VRML 2.0.

Virtual Real ity and Web Pages : Once we have a VRML file, there are several ways to includeit in a 2D web presentat ion.

1. One approach involves providing a hyperlink to the VRML file from HTML documents using ananchor tag.


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3D World

2. The other approach is include VRML file in HTML document as follows:

Please install Plug-in to use.

3. A VRML world can also be included in a frame.

Displays the virtual world artgallery.wrl in its own frame named 3D Pictures.

QTVR (QucikTime Virtual Real ity) :Another virtual reality implementation found on the web uses QuickTime Virtual Reality

(QTVR) also called QuickTime VR. This technology was designed by Apple and was introduced in1995. While a Mac is necessary to create the virtual-reality style 3D objects, any Mac PC can beused to view them.

A 3D panorama (scene) created by QTVR is actually called QuickTime movie (fileextension . mov) that represents a 360 degree image. A QuickTime VR movie c an be included in awebpage in the same way as a VRML file. Navigating through the movie gives users theimpression that they are in 3D world. Creating a panorama involves working with photographs or3D Computer-generated images. It requires a great deal of technical skill.

To view QTVR, we need a QTVR plug-in. The QTVR plug-in interprets and responds tothe movements as user navigates t hrough a sc ene or manipulates an object .

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