TP monitor

8/13/2019 TP monitor

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Web serverFrom Wikipedia, the free encyclopedia

The inside and front of a Dell PowerEdgeWeb server

Web servercan refer to either the hardware(the computer or thesoftware(the computer application that helps to deliver Web

contentthat can be accessed through the!nternet"#$%

The most common use of web servers is to hostwebsites,but there are other uses such asgaming, data storage or

runningenterprise applications"

Contents

[hide]

1 Overview

2 History

3 Common features

4 Path translation

5 Kernel-mode and user-mode we servers

! "oad limits

o !#1 Causes of overload

o !#2 $ym%toms of overload

o !#3 &nti-overload te'hni(ues

) *ar+et share

, $ee also

.eferen'es

1/ 0ternal lin+s

[edit]Overview
http://en.wikipedia.org/wiki/Dell_PowerEdgehttp://en.wikipedia.org/wiki/Computer_hardwarehttp://en.wikipedia.org/wiki/Computer_hardwarehttp://en.wikipedia.org/wiki/Softwarehttp://en.wikipedia.org/wiki/Softwarehttp://en.wikipedia.org/wiki/Softwarehttp://en.wikipedia.org/wiki/Web_contenthttp://en.wikipedia.org/wiki/Web_contenthttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Web_server#cite_note-new-0http://en.wikipedia.org/wiki/Web_server#cite_note-new-0http://en.wikipedia.org/wiki/Websitehttp://en.wikipedia.org/wiki/Websitehttp://en.wikipedia.org/wiki/Websitehttp://en.wikipedia.org/wiki/Online_gamehttp://en.wikipedia.org/wiki/Online_gamehttp://en.wikipedia.org/wiki/Enterprise_softwarehttp://en.wikipedia.org/wiki/Enterprise_softwarehttp://en.wikipedia.org/wiki/Enterprise_softwarehttp://en.wikipedia.org/wiki/Web_serverhttp://en.wikipedia.org/wiki/Web_server#Overviewhttp://en.wikipedia.org/wiki/Web_server#Historyhttp://en.wikipedia.org/wiki/Web_server#Common_featureshttp://en.wikipedia.org/wiki/Web_server#Path_translationhttp://en.wikipedia.org/wiki/Web_server#Kernel-mode_and_user-mode_web_servershttp://en.wikipedia.org/wiki/Web_server#Load_limitshttp://en.wikipedia.org/wiki/Web_server#Causes_of_overloadhttp://en.wikipedia.org/wiki/Web_server#Symptoms_of_overloadhttp://en.wikipedia.org/wiki/Web_server#Anti-overload_techniqueshttp://en.wikipedia.org/wiki/Web_server#Market_sharehttp://en.wikipedia.org/wiki/Web_server#See_alsohttp://en.wikipedia.org/wiki/Web_server#Referenceshttp://en.wikipedia.org/wiki/Web_server#External_linkshttp://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=1http://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=1http://en.wikipedia.org/wiki/File:Inside_and_Rear_of_Webserver.jpghttp://en.wikipedia.org/wiki/File:Inside_and_Rear_of_Webserver.jpghttp://en.wikipedia.org/wiki/Dell_PowerEdgehttp://en.wikipedia.org/wiki/Computer_hardwarehttp://en.wikipedia.org/wiki/Softwarehttp://en.wikipedia.org/wiki/Web_contenthttp://en.wikipedia.org/wiki/Web_contenthttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Web_server#cite_note-new-0http://en.wikipedia.org/wiki/Websitehttp://en.wikipedia.org/wiki/Online_gamehttp://en.wikipedia.org/wiki/Enterprise_softwarehttp://en.wikipedia.org/wiki/Web_serverhttp://en.wikipedia.org/wiki/Web_server#Overviewhttp://en.wikipedia.org/wiki/Web_server#Historyhttp://en.wikipedia.org/wiki/Web_server#Common_featureshttp://en.wikipedia.org/wiki/Web_server#Path_translationhttp://en.wikipedia.org/wiki/Web_server#Kernel-mode_and_user-mode_web_servershttp://en.wikipedia.org/wiki/Web_server#Load_limitshttp://en.wikipedia.org/wiki/Web_server#Causes_of_overloadhttp://en.wikipedia.org/wiki/Web_server#Symptoms_of_overloadhttp://en.wikipedia.org/wiki/Web_server#Anti-overload_techniqueshttp://en.wikipedia.org/wiki/Web_server#Market_sharehttp://en.wikipedia.org/wiki/Web_server#See_alsohttp://en.wikipedia.org/wiki/Web_server#Referenceshttp://en.wikipedia.org/wiki/Web_server#External_linkshttp://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=1


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The primary function of a web server is to deliverweb pageson the re&uest to clientsusing the 'ypertet Transfer Protocol

('TTP" This means delivery of 'T)* documentsand any additional content that may be included by a document, such

as images,style sheetsand scripts"

+ user agent, commonly a web browseror web crawler,initiates communication by making a re&uestfor a specific resource usin

'TTP and the server responds with the content of that resource or an error messageif unable to do so" The resource is typically

real file on the servers secondary memory, but this is not necessarily the case and depends on how the web server

isimplemented"

While the primary function is to serve content, a full implementation of 'TTP also includes ways of receiving content from clients

This feature is used for submittingweb forms, includinguploadingof files"

)any generic web servers also support server-side scriptingusing+ctive .erver Pages(+.P,P'P, or otherscripting language

This means that the behaviour of the web server can be scripted in separate files, while the actual server software remains

unchanged" /sually, this function is used to create 'T)* documents dynamically(0on-the-fly0 as opposed to returning static

documents"The former is primarily used for retrieving and1or modifying information from databases" The latter is typically muchfaster and more easilycached"

Web servers are not always used for serving the World Wide Web"They can also be found embeddedin devices such

as printers,routers,webcamsand serving only a local network" The web server may then be used as a part of a system for

monitoring and1or administering the device in &uestion" This usually means that no additional software has to be installed on the

client computer, since only a web browser is re&uired (which now is included with mostoperating systems"

[edit]History

The worlds first web server

!n $232Tim 4erners-*eeproposed a new pro5ect with the goal of easing the echange of information between scientists by using

ahypertetsystem to his employer 6E78" The pro5ect resulted in 4erners-*ee writing two programs in $229:

+ browsercalled WorldWideWeb

The worlds first web server, later known as6E78 httpd,which ran on 8e;T.TEP
http://en.wikipedia.org/wiki/Web_pagehttp://en.wikipedia.org/wiki/Web_pagehttp://en.wikipedia.org/wiki/Web_pagehttp://en.wikipedia.org/wiki/Client_(computing)http://en.wikipedia.org/wiki/Hypertext_Transfer_Protocolhttp://en.wikipedia.org/wiki/Hypertext_Transfer_Protocolhttp://en.wikipedia.org/wiki/HTMLhttp://en.wikipedia.org/wiki/HTMLhttp://en.wikipedia.org/wiki/Imagehttp://en.wikipedia.org/wiki/Imagehttp://en.wikipedia.org/wiki/Style_sheet_(web_development)http://en.wikipedia.org/wiki/Javascripthttp://en.wikipedia.org/wiki/Javascripthttp://en.wikipedia.org/wiki/User_agenthttp://en.wikipedia.org/wiki/Web_browserhttp://en.wikipedia.org/wiki/Web_crawlerhttp://en.wikipedia.org/wiki/Web_crawlerhttp://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Request_messagehttp://en.wikipedia.org/wiki/List_of_HTTP_status_codes#4xx_Client_Errorhttp://en.wikipedia.org/wiki/Secondary_memoryhttp://en.wikipedia.org/wiki/Implementationhttp://en.wikipedia.org/wiki/Implementationhttp://en.wikipedia.org/wiki/Form_(web)http://en.wikipedia.org/wiki/Form_(web)http://en.wikipedia.org/wiki/Uploadhttp://en.wikipedia.org/wiki/Uploadhttp://en.wikipedia.org/wiki/Server-side_scriptinghttp://en.wikipedia.org/wiki/Active_Server_Pageshttp://en.wikipedia.org/wiki/PHPhttp://en.wikipedia.org/wiki/PHPhttp://en.wikipedia.org/wiki/Scripting_languagehttp://en.wikipedia.org/wiki/Scripting_languagehttp://en.wikipedia.org/wiki/Dynamic_web_pagehttp://en.wikipedia.org/wiki/Static_web_pagehttp://en.wikipedia.org/wiki/Static_web_pagehttp://en.wikipedia.org/wiki/Static_web_pagehttp://en.wikipedia.org/wiki/Databasehttp://en.wikipedia.org/wiki/Web_cachehttp://en.wikipedia.org/wiki/World_Wide_Webhttp://en.wikipedia.org/wiki/World_Wide_Webhttp://en.wikipedia.org/wiki/Embedded_systemhttp://en.wikipedia.org/wiki/Printer_(computing)http://en.wikipedia.org/wiki/Printer_(computing)http://en.wikipedia.org/wiki/Router_(computing)http://en.wikipedia.org/wiki/Router_(computing)http://en.wikipedia.org/wiki/Webcamhttp://en.wikipedia.org/wiki/Webcamhttp://en.wikipedia.org/wiki/Local_Area_Networkhttp://en.wikipedia.org/wiki/Operating_systemhttp://en.wikipedia.org/wiki/Operating_systemhttp://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=2http://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=2http://en.wikipedia.org/wiki/Tim_Berners-Leehttp://en.wikipedia.org/wiki/Tim_Berners-Leehttp://en.wikipedia.org/wiki/Hypertexthttp://en.wikipedia.org/wiki/Hypertexthttp://en.wikipedia.org/wiki/CERNhttp://en.wikipedia.org/wiki/Web_browserhttp://en.wikipedia.org/wiki/WorldWideWebhttp://en.wikipedia.org/wiki/CERN_httpdhttp://en.wikipedia.org/wiki/CERN_httpdhttp://en.wikipedia.org/wiki/CERN_httpdhttp://en.wikipedia.org/wiki/NeXTSTEPhttp://en.wikipedia.org/wiki/File:First_Web_Server.jpghttp://en.wikipedia.org/wiki/File:First_Web_Server.jpghttp://en.wikipedia.org/wiki/Web_pagehttp://en.wikipedia.org/wiki/Client_(computing)http://en.wikipedia.org/wiki/Hypertext_Transfer_Protocolhttp://en.wikipedia.org/wiki/Hypertext_Transfer_Protocolhttp://en.wikipedia.org/wiki/HTMLhttp://en.wikipedia.org/wiki/Imagehttp://en.wikipedia.org/wiki/Style_sheet_(web_development)http://en.wikipedia.org/wiki/Javascripthttp://en.wikipedia.org/wiki/User_agenthttp://en.wikipedia.org/wiki/Web_browserhttp://en.wikipedia.org/wiki/Web_crawlerhttp://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Request_messagehttp://en.wikipedia.org/wiki/List_of_HTTP_status_codes#4xx_Client_Errorhttp://en.wikipedia.org/wiki/Secondary_memoryhttp://en.wikipedia.org/wiki/Implementationhttp://en.wikipedia.org/wiki/Form_(web)http://en.wikipedia.org/wiki/Uploadhttp://en.wikipedia.org/wiki/Server-side_scriptinghttp://en.wikipedia.org/wiki/Active_Server_Pageshttp://en.wikipedia.org/wiki/PHPhttp://en.wikipedia.org/wiki/Scripting_languagehttp://en.wikipedia.org/wiki/Dynamic_web_pagehttp://en.wikipedia.org/wiki/Static_web_pagehttp://en.wikipedia.org/wiki/Static_web_pagehttp://en.wikipedia.org/wiki/Databasehttp://en.wikipedia.org/wiki/Web_cachehttp://en.wikipedia.org/wiki/World_Wide_Webhttp://en.wikipedia.org/wiki/Embedded_systemhttp://en.wikipedia.org/wiki/Printer_(computing)http://en.wikipedia.org/wiki/Router_(computing)http://en.wikipedia.org/wiki/Webcamhttp://en.wikipedia.org/wiki/Local_Area_Networkhttp://en.wikipedia.org/wiki/Operating_systemhttp://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=2http://en.wikipedia.org/wiki/Tim_Berners-Leehttp://en.wikipedia.org/wiki/Hypertexthttp://en.wikipedia.org/wiki/CERNhttp://en.wikipedia.org/wiki/Web_browserhttp://en.wikipedia.org/wiki/WorldWideWebhttp://en.wikipedia.org/wiki/CERN_httpdhttp://en.wikipedia.org/wiki/NeXTSTEP


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4etween $22$ and $22


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[edit]%ernelmode and usermode web servers

+ web server can be either implemented into theA.kernel, or inuser space(like other regular applications"

+nin-kernel web server(likeT/;on @8/1*inu or )icrosoft !!.on Windows will usually work faster, because, as part of the

system, it can directly use all the hardware resources it needs, such as non-paged memory, 6P/ time-slices, network adapters,

buffers"

Web servers that run in user-mode have to ask the system the permission to use more memory or more 6P/ resources" 8ot only

do these re&uests to the kernel take time, but they are not always satisfied because the system reserves resources for its own

usage and has the responsibility to share hardware resources with all the other running applications"

+lso, applications cannot access the systems internal buffers, which causes useless buffer copies that create another handicap

for user-mode web servers" +s a conse&uence, the only way for a user-mode web server to match kernel-mode performance is t

raise the &uality of its code to much higher standards, similar to that of the code used in web servers that run in the kernel" This i

a significant issue under Windows, where the user-mode overhead is about si times greater than that under *inu" #?%

[edit]Load limits

+ web server (program has defined load limits, because it can handle only a limited number of concurrent client connections

(usually between ? and 39,999, by default between B99 and $,999 per !P address(and T6P port and it can serve only a certain

maimum number of re&uests per second depending on:

its own settings,

the 'TTP re&uest type,

whether the content is static or dynamic,

whether the content iscached,and

the hardwareandsoftwarelimitations of the A. of the computer on which the web server runs"

When a web server is near to or over its limits, it becomes unresponsive"

[edit]Causes of overload

+t any time web servers can be overloaded because of:

&oo mu!h legitimate web traffi!'Thousands or even millions of clients connecting to the web site in a short interval,

e"g",.lashdot effectC

(istributed (enial of Servi!eattacks" + denial-of-service attack (Do. attack or distributed denial-of-service attack

(DDo. attack is an attempt to make a computer or network resource unavailable to its intended usersC

Computer wormsthat sometimes cause abnormal traffic because of millions of infected computers (not coordinated

among themC

)SS virusescan cause high traffic because of millions of infected browsers and1or web serversC

*nternet bots'Traffic not filtered1limited on large web sites with very few resources (bandwidth, etc"C
http://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=5http://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=5http://en.wikipedia.org/wiki/Operating_systemhttp://en.wikipedia.org/wiki/Operating_systemhttp://en.wikipedia.org/wiki/Operating_systemhttp://en.wikipedia.org/wiki/Kernel_(computing)http://en.wikipedia.org/wiki/User_spacehttp://en.wikipedia.org/wiki/User_spacehttp://en.wikipedia.org/wiki/In-kernel_web_serverhttp://en.wikipedia.org/wiki/In-kernel_web_serverhttp://en.wikipedia.org/wiki/TUX_web_serverhttp://en.wikipedia.org/wiki/TUX_web_serverhttp://en.wikipedia.org/wiki/TUX_web_serverhttp://en.wikipedia.org/wiki/Internet_Information_Serviceshttp://en.wikipedia.org/wiki/Internet_Information_Serviceshttp://en.wikipedia.org/wiki/Web_server#cite_note-1http://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=6http://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=6http://en.wikipedia.org/wiki/IP_addresshttp://en.wikipedia.org/wiki/IP_addresshttp://en.wikipedia.org/wiki/Web_cachehttp://en.wikipedia.org/wiki/Web_cachehttp://en.wikipedia.org/wiki/Web_cachehttp://en.wikipedia.org/wiki/Personal_computer_hardwarehttp://en.wikipedia.org/wiki/Personal_computer_hardwarehttp://en.wikipedia.org/wiki/Computer_softwarehttp://en.wikipedia.org/wiki/Computer_softwarehttp://en.wikipedia.org/wiki/Computer_softwarehttp://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=7http://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=7http://en.wikipedia.org/wiki/Slashdot_effecthttp://en.wikipedia.org/wiki/Slashdot_effecthttp://en.wikipedia.org/wiki/Slashdot_effecthttp://en.wikipedia.org/wiki/Distributed_Denial_of_Servicehttp://en.wikipedia.org/wiki/Distributed_Denial_of_Servicehttp://en.wikipedia.org/wiki/Computer_wormhttp://en.wikipedia.org/wiki/Computer_virus#Cross-site_scripting_virushttp://en.wikipedia.org/wiki/Internet_bothttp://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=5http://en.wikipedia.org/wiki/Operating_systemhttp://en.wikipedia.org/wiki/Kernel_(computing)http://en.wikipedia.org/wiki/User_spacehttp://en.wikipedia.org/wiki/In-kernel_web_serverhttp://en.wikipedia.org/wiki/TUX_web_serverhttp://en.wikipedia.org/wiki/Internet_Information_Serviceshttp://en.wikipedia.org/wiki/Web_server#cite_note-1http://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=6http://en.wikipedia.org/wiki/IP_addresshttp://en.wikipedia.org/wiki/Web_cachehttp://en.wikipedia.org/wiki/Personal_computer_hardwarehttp://en.wikipedia.org/wiki/Computer_softwarehttp://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=7http://en.wikipedia.org/wiki/Slashdot_effecthttp://en.wikipedia.org/wiki/Distributed_Denial_of_Servicehttp://en.wikipedia.org/wiki/Computer_wormhttp://en.wikipedia.org/wiki/Computer_virus#Cross-site_scripting_virushttp://en.wikipedia.org/wiki/Internet_bot


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*nternet+networ,- slowdowns, so that client re&uests are served more slowly and the number of connections increase

so much that server limits are reachedC

Web servers +!omputers- partial unavailability'This can happen because of re&uired or urgent maintenance or

upgrade, hardware or software failures, back-end(e"g",database failures, etc"C in these cases the remaining web servers ge

too much traffic and become overloaded"

[edit]Symptoms of overload

The symptoms of an overloaded web server are:

7e&uests are served with (possibly long delays (from $ second to a few hundred seconds"

The web server returns an'TTP error code,such as B99, B9?, B9>, B9


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[edit]1ar,et share

What Is A Web Server?

A web server is a piece of software that enables a website to be viewed using HTTP. HTTP (HyperText Transfer Protocol) is th

key protocol for the transfer of data on the web. You know when youre using HTTP because the website !"# begins with

$http%&&$ (for exa'ple $http%&&www.uackit.co'$).

You 'ight be thinking $* always thought a web server was a special high+powered co'puter$. ,ell youd be right too. -o'e

high+powered co'puters are referred to as web servers as they have been built with web hosting in 'ind. ut in 'ost cases

when so'eone refers to a web server they are referring to a piece of software that you install on a co'puter.

What Does a Web Server Look Like?

That depends on which web server you choose to install. Heres an exa'ple of /icrosoft *nternet *nfor'ation -ervices (**-) 0

looks like%

The left pane represents the various websites 2TP sites and -/TP virtual servers. ,hen an ite' in the left pane is selected

the contents are displayed in pane on the right hand side.

*n the above screenshot there is one website (called $3efault ,eb -ite$) one 2TP site (called $3efault 2TP -ite$) and one

-/TP virtual server (called $3efault -/TP 4irtual -erver$).
http://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=10http://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=10http://en.wikipedia.org/w/index.php?title=Web_server&action=edit&section=10


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You can right click on an ite' to display its properties. 2or exa'ple you can right click on $3efault ,eb -ite$ to display (and

configure) the properties of that website.

Do I Need A Web Server?

*f you 'aintain your own web site * reco''end you install a web server on your own develop'ent 'achine. That way you ca

configure your develop'ent environ'ent to be closer to your live environ'ent.

Also if you intend to use server+side technologies such as PHP or 5old2usion you will definitely need a web server.

Web Servers are Easy!

You 'ight also be thinking that web servers are way too advanced for you + that they are only used by professional web

developers and&or hosting co'panies. Please dont think that6

Think of a web server as si'ply another piece of software you can install on your 'achine. 7nce you install it you can

configure it to suit your needs.

And depending on your co'puter set up you 'ay even find that you already have a web server on your 'achine.

8ow having declared that $web servers are easy6$ there are 'any advanced topics regarding web servers. * wont be going

into any detail in this tutorial. You can get a web server up and running on your 'achine with a 'ini'u' of technical

knowledge. Then once youve done that youll start to beco'e fa'iliar with the various options available to you. Then if

reuired you can research the 'ore advanced topics to suit your needs (such as security load issues logging etc)

Web Servers - Advantages

There are 'any advantages to using a web server within your develop'ent environ'ent. 7f course in a production hosting

environ'ent a web server is essential. And depending on your website a web server could indeed be essential in your

develop'ent environ'ent.

,hen * say $develop'ent environ'ent$ *' referring to a copy of your website usually on your local 'achine that you use

perfor' updates before you co''it the' to the live (production) environ'ent.

*n practice you could have 'any copies of your website for different purposes (such as testing training protypes etc) but

lets 9ust call it $develop'ent environ'ent$ for now.

Here are so'e advantages of using a web server within your develop'ent environ'ent%

Your local website behaves 'ore like the live one. 2or exa'ple you can configure directory security test your custo'

error pages etc before co''iting the' to the production environ'ent.

You can use server+side scripting languages such as PHP and 5old2usion.

Allows you to standardi:e your coding. 2or exa'ple you can use root+relative paths for your i'age references and

hyperlinks (i.e. $&directory&i'age.gif$). *n other words your paths can represent the website structure rather than t

directory structure of your co'puter.

;nowledge. The knowledge you gain fro' using your own web server will help you understand how it works in the liv

environ'ent. This will 'ost certainly help you when you need to co''unicate with your hosting provider + youll be

able to use ter'inology that 'akes it easier for the' to understand your reuest&issue.

Viewing HTL i"es Witho#t a Web Server


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,hen so'eone learns how to code HT/# chances are one of the first things they learn to do is how to view their (newly

created) HT/# file. They will learn that you can si'ply double click on the HT/# file and this will launch it in their web

browser. And fro' that point on they can view their web page&website as it was intended to be viewed.

Here are so'e exa'ples of what the !"# could look like when viewing a web page without a web server%

file%&&&5%&3ocu'entsand-ettings&Ho'er-i'pson&/y3ocu'ents&index.ht'l

file%&&&5%&*netpub&wwwroot&index.ht'l

These exa'ples are using the fileprotocol in order to display the files.

Viewing HTL i"es With a Web Server

7ne proble' with the above 'ethod is that youre not viewing the website using the HTTP protocol (youre using

the fileprotocol instead).

8ow this isnt nor'ally a proble' if youre only using client side languages such as HT/# 5-- and client+side ?ava-cript. u

it is a proble' if youre trying to use a server+side language such as PHP 5old2usion etc.

Also even if youre not using a server+side language it could still cause you proble's with developing a website that behaves

exactly how it should on the web.

,hen you view a web page via a web server the !"# begins with $http://$. Also the !"# will consist of either an *P address

a do'ain na'e&host na'e.

Here are so'e exa'ples of what the !"# could look like when viewing a web page via a web server%

http%&&1=@.>.>.1

http%&&localhost

http%&&www.uackit.co'

http%&&dev.uackit.co'

,hen you first set up a web server you can usually navigate to your default web site

using http://localhostor http://127.0.0.1. ,hen you add 'ore websites youll need to create your own !"#s for the' (via a

38- server or Hosts file) then assign that !"# to your websites via your web server.

Web Servers - eat#res

Theres a co''on set of features that youll find on 'ost web servers. ecause web servers are built specifically to host

websites their features are typically focussed around setting up and 'aintaining a websites hosting environ'ent.

/ost web servers have features that allow you to do the following%

5reate one or 'ore websites. (8o * dont 'ean build a set of web pages. ,hat * 'ean is set up the website in the

web server so that the website can be viewed via HTTP)

5onfigure log file settings including where the log files are saved what data to include on the log files etc. (#og files

can be used to analyse traffic etc)

5onfigure website&directory security. 2or exa'ple which user accounts are&arent allowed to view the website which

*P addresses are&arent allowed to view the website etc.

5reate an 2TP site. An 2TP site allows users to transfer files to and fro' the site.

5reate virtual directories and 'ap the' to physical directories


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5onfigure&no'inate custo' error pages. This allows you to build and display user friendly error 'essages on your

website. 2or exa'ple you can specify which page is displayed when a user tries to access a page that doesnt exist

(i.e. a $> error$).

-pecify default docu'ents. 3efault docu'ents are those that are displayed when no file na'e is specified. 2or

exa'ple if you open $http%&&localhost$ which file should be displayedB This is typically $index.ht'l$ or si'ilar but it

doesnt need to be. You could no'inate $index.cf'$ if your website is using 5old2usion. You could also no'inate a =n

choice (in case there is no index.cf' file) and a Crd choice and so on.

E$a%&"e Web Server

Heres an exa'ple of the $Properties$ dialog box fro' /icrosoft **-. This box is displaying the properties for a single website.

To display the box * si'ply right+clicked on the website and selected $Properties$.

You can see that the website has been configured to use the local path of c:\inetpub\wwwroot. ,hat this 'eans is that when

you update your website you need to place your files and folders within that directory. As soon as you do that your changes

will take effect on your website. 7f course if this is your develop'ent environ'ent you can si'ply edit the files straight fro'

that directory.

How Web Servers Work


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henever you view a web page on the internet you are reuesting that page fro' a web server. ,hen you type a !"# into you

browser (for exa'ple $http%&&www.uackit.co'&ht'l&tutorial&index.cf'$) your browser reuests the page fro' the web

server and the web server sends the page back%

The above diagra' is a si'plistic version of what occurs. Heres a 'ore detailed version%

1. Your web browser first needs to know which *P address the website $www.uackit.co'$ resolves to. *f it doesnt

already have this infor'ation stored in its cache it reuests the infor'ation fro' one or 'ore 38- servers (via the

internet). The 38- server tells the browser which *P address the website is located at. 8ote that the *P address was

assigned when the website was first created on the web server.

=. 8ow that the web browser knows which *P address the website is located at it can reuest the full !"# fro' the web

server.

C. The web server responds by sending back the reuested page. *f the page doesnt exist (or another error occurs) it

will send back the appropriate error 'essage.

. Your web browser receives the page and renders it as reuired.

,hen referring to web browsers and web servers in this 'anner we usually refer to the' as a client(web browser) and

a server(web server).

#"ti&"e Websites

A web server can (and usually does) contain 'ore than one website. *n fact 'any hosting co'panies host hundreds or even

thousands of websites on a single web server. Dach website is usually assigned a uniue *P address which distinguishes it fro

other websites on the sa'e 'achine. This *P address is also what the 38- server uses to resolve the do'ain na'e.

*t is also possible to configure 'ultiple websites without using different *P addresses using host headers and&or different port

This can be useful in a develop'ent environ'ent and is uite easy to do.

'age Not o#nd

*f the reuested page isnt found the web server sends the appropriate error code&'essage back to the client.

You can create user friendly error 'essages then configure your web server to display that page instead of the usual error

page. This can add a nice touch to your website. How 'any ti'es have you (or even worse your visitors) encountered a plai

white page with so'e cryptic error 'essage on itB


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*ts very easy to create custo' error pages then configure your web server to use the'.

De(a#"t Do)#%ents

*f youve ever created a website you 'ay have found that if you have an $index$ file (index.ht'l for exa'ple) you dont nee

to specify the na'e of the file. 2or exa'ple the following !"#s both load the sa'e page%

1. http%&&www.uackit.co'&ht'l&tutorial

=. http%&&www.uackit.co'&ht'l&tutorial&index.cf'

*n this exa'ple $index.cf'$ is the default document. You can configure your web server so that any file na'e can be the

default docu'ent. 2or exa'ple you could configure your web server to use $index.cf'$ in the event no filena'e has been

specified or if you use PHP $index.php$. You could even specify different default docu'ents for different directories if you lik

SSL *erti(i)ates

You can apply --# certificates against a website via the web server. 2irst you need to generate the certificate either by yours

(i.e. using a certificate generator) or by a 5ertificate Authority (5A). Then once it has been generated you apply it to your

website via your web server. Applying an --# certificate to a website is a straight forward task.

7nce youve applied an --# certificate against a website you can navigate it using HTTP- (as opposed to HTTP). HTTP-

encrypts any data that is transferred over the internet. This reduces the possibility of so'e 'alicious person being able to rea

your users sensitive infor'ation.

To navigate a website using HTTP- you si'ply replace the HTTP with HTTP- at the start of the !"# in your browsers location

bar ($https%&&www.uackit.co'$)

Web Servers - E$a%&"es

A&a)he HTT' Server

Apache HTTP -erver (also referred to as si'ply $Apache$) has at the ti'e of writing been the 'ost popular web server on th

web since 1EEF. Apache is developed and 'aintained by the Apache -oftware 2oundation which consists of a decentrali:ed

tea' of developers. The software is produced under the Apache licence which 'akes it free and open source.

Apache is available for a range of operating syste's including !nix #inux 8ovell 8etware ,indows /ac 7- G -olaris and

2ree-3.

Apache HTTP -erver website% http%&&httpd.apache.org

i)roso(t Internet In(or%ation Servi)es +IIS,

**- is at the ti'e of writing the second 'ost popular web server on the web. *t is however gaining 'arket share and if the

current trend continues it wont be long before it overtakes Apache.

**- co'es as an optional co'ponent of 'ost ,indows operating syste's. You can install **- by using Add/Remove Windows

omponentsfro'Add or Remove !ro"ramsin the 5ontrol Panel.

/icrosoft **- website% http%&&www.'icrosoft.co'&iis

S#n ava Syste% Web Server
http://httpd.apache.org/http://www.microsoft.com/iis/http://httpd.apache.org/http://www.microsoft.com/iis/


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ased on the -un 7ne ,eb -erver the -un ?ava -yste' ,eb -erver is designed for 'ediu' to large business applications.

-un ?ava -yste' ,eb -erver is available for 'ost operating syste's.

-un ?ava -yste' ,eb -erver website% http%&&www.sun.co'&software&products&websrvr&ho'ewebsrvr.x'l

Web Server *o%&onents and De&enden)iesWindows *E ./0> out of 1 rated this helpful + "ate this topic

Note The following section applies only to the ,eb server release in ,indows 5D Platfor' uilder wherethe individual libraries that 'ake up the ,eb server can be linked together in custo'i:able ways.

The ,eb server contains seven co'ponents. The following table lists descriptions of these co'ponents aswell as dependencies between the co'ponents. -i:e approxi'ations are based on a retail build of ,indow

5D co'piled for the *ntel xIF+based co'puter. ,ith the exception of Httpasp all of the co'ponents should

be available in /axall and /inco'' configurations.

5o'ponentna'e

3escription Approxi'at

Htt%d .e(uired in all 'onfiurations# 2/ K

Htt%'ore .e(uired in all 'onfiurations#

Htt%%arse .e(uired in all 'onfiurations#

Htt%auth .e(uired for authenti'ation# 2 K

Htt%isa%i Common 'om%onent for s'ri%tin o%tions# his 'om%onent is the ase for6$&P6 etensions7 6$&P6 filters7 and &$P %aes7 and %erforms no stand-aloneo%erations#

3 K

Htt%etn .e(uired for 6$&P6 etensions# his 'om%onent de%ends on Htt%isa%i# 4 K

Htt%filt .e(uired for 6$&P6 filters# his 'om%onent de%ends on Htt%isa%i andHtt%etn#

1/ K

Htt%as% .e(uired for su%%ort of &$P# his 'om%onent de%ends on Htt%isa%i and

Htt%etn# he si8e a%%roimation re%resents only the overhead that is added tothe 9e server when the se%arate 'om%onents of &$P are installed#

1 K

Note The netregd co'ponent 'ust be included to allow the ,eb server to be accessed by its 3o'ain

8a'e -yste' (38-) na'e. ,ithout this co'ponent you 'ust use the *P address of the ,eb server toaccess it. -ee the /icrosoft ,indows 5D Platfor' uilder docu'entation for 'ore infor'ation about the

netregd co'ponent.

*f a file that is reuested by the client browser has a .dll extension and is in a virtual directorywith HSE1LA2S134L1E5E*3TEper'issions and if the Httpextn co'ponent is not part of the ,eb

server the $0>1 J 8ot *'ple'ented$ status code is returned to the client browser.
http://www.sun.com/software/products/web_srvr/home_web_srvr.xmlhttp://msdn.microsoft.com/en-us/library/ms903391.aspx#feedbackhttp://www.sun.com/software/products/web_srvr/home_web_srvr.xmlhttp://msdn.microsoft.com/en-us/library/ms903391.aspx#feedback


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*f a file that is reuested has an .asp extension and the Httpasp co'ponent is not part of the ,eb server if the 'ain A-P+page library has not been set up properly the $0>1 J 8ot *'ple'ented$ status code is

returned to the client browser.

#niform $esour!e Lo!ators +#$Ls-

/7*s, or /niform 7esource *ocators, are the method by which documents or dataare addressed in the World Wide Web" The /7* contains the following information

the internet name of the site containing the resource (document or data the typeof service the resource is served by (eg, 'TTP, @opher, W+!. the !nternetport numberof the service" !f this is omitted the browser assumes a

commonly accepted default value" the location of the resource in the directory structure of the server"

/7*s are more sophisticated than this brief introduction would imply" For more

detail, have a look at the /7* overview document, found at the/7*:http:11www"w>"org1hypertet1WWW1+ddressing1/7*1Averview"html"

2'3 Stru!ture of an #$L

The following is an outline of the most common form of a /7*:

http://www.address.edu:1234/path/sudir/file.ext! ! ! ! !!service ! ! ! !

!"""" host """"""! ! ! ! ! ! !port! ! ! file a#d ! !" resource details "!

2'3'4 Servi!e

The above figure gives a general outline of /7* structure" This outline if followed bmost, but not all, /7*s" .pecific cases are discussed in subse&uent sections"

The first part is the service specifier, (here 'TTP service which specifies theaccess method" .pecifically this is the part beforethe colon" .ome eamples ofservices are:http:, $opher:, wais:and ftp:"

2'3'5 .ddress and "ort number

The second part is usually the internet address of the server, indicated by thedouble forward slash (11" This address can also contain the (optional port number
http://www.w3.org/hypertext/WWW/Addressing/URL/Overview.htmlhttp://www.w3.org/hypertext/WWW/Addressing/URL/Overview.html


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the service listens at" The full name is then specified by a stringlike //www.address.edu:1234/, where :1234means Port number $?>


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From Wikipedia, the free encyclopedia

Se!ure Hyperte%

An Overview of SHTTP
http://en.wikipedia.org/wiki/HTTP_Securehttp://en.wikipedia.org/wiki/HTTP_Securehttp://en.wikipedia.org/wiki/Encryptionhttp://en.wikipedia.org/wiki/World_Wide_Webhttp://en.wikipedia.org/wiki/World_Wide_Webhttp://en.wikipedia.org/wiki/Hypertext_Transfer_Protocolhttp://en.wikipedia.org/wiki/Hypertext_Transfer_Protocolhttp://en.wikipedia.org/wiki/Hypertext_Transfer_Protocolhttp://tools.ietf.org/html/rfc2660http://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#cite_note-0http://en.wikipedia.org/wiki/Web_browserhttp://en.wikipedia.org/wiki/Web_serverhttp://en.wikipedia.org/wiki/Web_serverhttp://en.wikipedia.org/wiki/Electronic_commercehttp://en.wikipedia.org/wiki/Electronic_commercehttp://en.wikipedia.org/wiki/Electronic_commercehttp://en.wikipedia.org/wiki/Netscape_Communications_Corporationhttp://en.wikipedia.org/wiki/Microsofthttp://en.wikipedia.org/wiki/De_factohttp://en.wikipedia.org/wiki/De_factohttp://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocolhttp://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#Differences_from_HTTPShttp://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#See_alsohttp://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#Referenceshttp://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#External_linkshttp://en.wikipedia.org/w/index.php?title=Secure_Hypertext_Transfer_Protocol&action=edit&section=1http://en.wikipedia.org/w/index.php?title=Secure_Hypertext_Transfer_Protocol&action=edit&section=1http://en.wikipedia.org/wiki/Secure_Sockets_Layerhttp://en.wikipedia.org/wiki/Domain_Name_Systemhttp://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#cite_note-1http://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#cite_note-2http://en.wikipedia.org/wiki/HTTP_Securehttp://en.wikipedia.org/wiki/Encryptionhttp://en.wikipedia.org/wiki/World_Wide_Webhttp://en.wikipedia.org/wiki/Hypertext_Transfer_Protocolhttp://tools.ietf.org/html/rfc2660http://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#cite_note-0http://en.wikipedia.org/wiki/Web_browserhttp://en.wikipedia.org/wiki/Web_serverhttp://en.wikipedia.org/wiki/Electronic_commercehttp://en.wikipedia.org/wiki/Netscape_Communications_Corporationhttp://en.wikipedia.org/wiki/Microsofthttp://en.wikipedia.org/wiki/De_factohttp://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocolhttp://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#Differences_from_HTTPShttp://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#See_alsohttp://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#Referenceshttp://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#External_linkshttp://en.wikipedia.org/w/index.php?title=Secure_Hypertext_Transfer_Protocol&action=edit&section=1http://en.wikipedia.org/wiki/Secure_Sockets_Layerhttp://en.wikipedia.org/wiki/Domain_Name_Systemhttp://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#cite_note-1http://en.wikipedia.org/wiki/Secure_Hypertext_Transfer_Protocol#cite_note-2


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Adam Shostack, May 1995

A. ntrod!ction to, and history of, S"HTTP

$-HP was desined y 0# .es'orla and $'hiffman of 06 to se'ure HP 'onne'tions# $-HP %rovides a wide variety of me'hanisms to %rovide for 'onfidentiality7 authenti'ation7 andinterity# $e%aration of %oli'y from me'hanism was an e%li'it oal# he system is not tied to any

%arti'ular 'ry%tora%hi' system7 +ey infrastru'ture7 or 'ry%tora%hi' format# he internet draft isfairly 'lear in its %resentation of the %roto'ol7 althouh im%lementation details are s+et'hy#

$-HP is a su%erset of HP7 whi'h allows messaes to e en'a%sulated in various ways#0n'a%sulations 'an in'lude en'ry%tion7 sinin7 or *&C ased authenti'ation# his en'a%sulation'an e re'ursive7 and a messae 'an have several se'urity transformations a%%lied to it# $-HP alsin'ludes header definitions to %rovide +ey transfer7 'ertifi'ate transfer7 and similar administrativefun'tions# $-HP a%%ears to e etremely fleile in what it will allow the %rorammer to do# $-HP also offers the %otential for sustantial user involvement in7 and oversiht of7 theauthenti'ation ; en'ry%tion a'tivities#

$-HP does not rely on a %arti'ular +ey 'ertifi'ation s'heme# 6t in'ludes su%%ort for .$&7 in-andout-of-and and +ereros +ey e'hane# Key 'ertifi'ations 'an e %rovided in a messae7 or otaineelsewhere# "i+e $$"7 'lient %uli' +eys are not re(uired#

6


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Content-ransfer-0n'odin e%lains how the 'ontent of the messae is en'oded# )7 , it are selfe%lanatory7 ase-!4 is as defined in .?C-1421#

Content-y%e is a standard header7 and should enerally e a%%li'ationhtt%#

Prearraned-Key-6nfo is information aout the +eys used in the en'a%sulation of this messae# ?ield

are for the ty%e of 'i%her7 a :0K >data e'hane +ey@ used to en'ry%t this messae7 and the identityof the +ey used to en'ry%t the :0K# *&C-6nfo is a messae authenti'ation 'ode to ensure that amessae has not een tam%ered with7 without the e%ense of sinatures#

hese are the only $e'ure HP headers defined in the s%e'# However7 there are also a numer ofnew HP headers defined# hose are $e'urity $'heme7 en'ry%tion identity7 :D-14,5 Dame 'lass7Kereros Dame 'lass7 Certifi'ate 6nfo7 Key &ssin7 and Don'es#

$e'urity $'heme is a holds the %roto'ol name and version# 0n'ry%tion 6dentity names the entity forwhi'h a messae is en'ry%ted7 say in the 'ase of a server with multi%le %uli' +eys# he name 'lass

o%tions >:D-14,5 and Kereros@ allow entities to say how they identify themselves7 and who theyare#

Certifi'ate 6nfo lines allow a sender to send a %uli' +ey 'ertifi'ate in a messae with other %ur%osesavin the troule of a se%arate e%li'it 'ertifi'ate retrieval#

Key assin is the messae used for a'tual +ey e'hanes7 and assinment of symoli' names toe'haned +eys# Key e'hane has many o%tions7 allowin +eys to e en'a%sulated in various waysiven symoli' names7 and have lifetimes assined to them# "ifetimes 'an e s@ are session identifiers7 used to indi'ate the freshness of a session7 and %re'lude re%layatta'+s# & messae may in'lude a numer of non'es7 from 8ero to several# he server will oftenenerate them7 and e%e't a 'lient to res%ond with the same non'e# Don'es are often time ased7 ut$e'ure HP suests that a random value may e used# >Cry%tora%hi'ally stron random numerare diffi'ult to enerate7 however7 it seems that the non'e need not e very stron#@

2. Negotiation

o offer fleiility in the 'ry%tora%hi' enhan'ements used7 'lient and server neotiate aout what

enhan'ements ea'h is willin to use7 unwillin to use7 or will re(uire e used# Deotiations lo'+shave four %arts7 %ro%erty7 value7 dire'tion >always with res%e't to the neotiator@7 and strenth >of

%referen'e@# 6f aents are unale to dis'over a 'ommon set of alorithms7 a%%ro%riate a'tions shoulde ta+en# Continuin to re(uest a refused o%tion is 'onsidered ineffe'tual and ina%%ro%riate#

*# example #e$otiatio# li#e would e:HTTP%5e(%Excha#$e%*l$orithms: recv%re'uired6,*75er%

o mean that messaes to this ma'hine must use Kereros 5 or .$& en'ry%tion to e'hane +eys#


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he modes availale are >re'vEEori@->o%tionalEEre(uiredEErefused@# he +eywords for Kereros-versionOutand refers to any eternal7 or %rearraned +ey# ?or the situation of only a server havin a +ey7and not e%e'tin the 'lient to have any +ey7 the messae isG $HP-Key-0'hane-&lorithmsGori-o%tionalI6nand7 .$&J re'v-re(uiredI.$&

$HP-*essae-:iest-&lorithmsG Can e


19/50

& dis'ussion 'i%her modes is eyond the s'o%e of this %a%er7 ut 'an e found in >?6P$ ,1@ or>$'hneier7 147 'ha%ter ,@# &ain7 C:*? and :0$ are (uestionale alorithms7 ut the authors'hose to allow fleiility# >*att la8e ; Carl 0llison oth %rovided useful overviews of C*:? ;:0$ here aout 3 wee+s a'+# han+s aain@

$HP-Priva'y-0nhan'ementsG Can e any or all of whi'huses name suordination@ one 'ould use the e%ression elow# Dote the use of .?C-14,5 (uotin to

%rote't the 'omma >an .?C-14,5 field se%arator@ and the ed-style (uotin to %rote't the dot >an edmeta'hara'ter@#

;our%5e(%Patter#: 8F%14A7 /+6Perso#a 9ertificate7 6,* 8ata ecurit(7 @#c./

$e'ure HP defines defaults for all these values# hose defaults may e neotiated u%wards ordownwards7 and areG o use PKC$-) or P0* to en'ode messaesJ to e'hane +eys7 and sinmessaes usin .$ *:5 is used as the messae diest7 and >sinle@ :0$7 in various modes7 isused as the ul+ 'i%her#

3. Message Format Options

he format of the ody of a messae is indi'ated y the Content-Priva'y-:omain $HP headerline# here are several a''e%tale Content-Priva'y-:omains7 whi'h are P0*7 PBP7 and PKC$- )#Mnder PKC$-)7 the most interestin o%tion is a self sined sinature 'ertifi'ate in a messae ody#his is %ermitted7 and no assertions are made to its reliaility# his allows im%lementors a reat deaof fleiility# Other PKC$-) o%tions in'lude en'ry%tion >with a %uli' +ey7 or some %rearraned setMsin a domain of P0* or PBP7 the messaes are en'oded with


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& A$e'urity.etry 42/A messae indi'ates that the 'ry%tora%hi' o%tions in use are insuffi'ient7 andsuests that an o%tion re- neotiation miht e in order# 6f the messae was sent under $- HP7 thres%onse will indi'ate what o%tions are desired >or demanded@# his 'an for'e a new %uli' +eyneotiation7 or offer a new non'e for freshness# 6f the 42/ messae is re'eived under HP7 itindi'ates that an $-HP messae should e sent# he %arameters desired are in'luded in theres%onse#

here are limits %la'ed on automati' retries7 e'ause of atta'+s %ossile with HP# he 'lient isonly allowed if the server re(uestin the retry already has the information# $ome a''e%tale times toretry in'ludeG

he retry res%onse was returned en'ry%ted under an inand +ey freshly enerated for theoriinal re(uest#

he retry res%onse was sined y the intended re'i%ient of the oriinal re(uest# he oriinal re(uest used an outand +ey and the res%onse is en'ry%ted under that +ey#

he authors7 a%%ro%riately7 ure 'aution in 'hoosin when to automati'ally res%ond to a re-en'ry%tion re(uest# hey also %rohiit automati' re-tryin a sinature7 and allow for automati'retryin of a *&C authenti'ation failure#

5.Oder servers

here are several issues that 'an o''ur when a 'lient and server do not oth su%%ort $-HP7 orwhen they su%%ort different versions of the %roto'ol# 6f the 'lient doesn


21/50

6n addition7 the 'ost of 'lear tet 'ry%tanalysis of :0$ is sustantially hiher than that of .C4-4/#>.e'all that :0$ is the default 'i%her for $-HP7 and .C4-4/ is the default 'i%her for $$"#@ o

rea+ an .C4-4/ +ey in aout month 'osts aout N125# o rea+ a :0$ +ey in one month 'osts aoN1/7/// >etra%olated from 9iener7 14@

& 5! it :0$ +ey 'osts one million dollars to rea+ in ) hours# >9iener7 14@ his 'ost s'ales u%

and down in a linear fashion# >6#0#7 a 12 million dollar ma'hine will ta+e 14 hours@# & month has )2hours >24 hours 3/ days@7 whi'h is 1/2 %eriods of ) hours# he 'ost of rea+in :0$ in rouhlyone month is thus aout N1/ ///7 as o%%osed to N125 for 4/ it .C4#

'. (eaknesses

he use of in and +ey e'hane is %otentially very %rolemati'J the authors donKahn@ 0%e'tin %rorammers to learn from this mista+es of others >es%e'ially 5/ year oldmista+es@ is a %oor et#

$-HP7 in ein fleile7 may offer a %rorammer enouh ro%e to han themselves# &dmittedly7 itdoes not offer very many ro+en o%tions7 ut it doesn


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+ transaction serverwill consist of a system providing the safety described above, and an environmentwhere programs ca

be written to make use of these features" !t will also have various connection protocolsto allow it to connect to

the databasesinvolved, and to the front endsoftware (for eample the computer of a telesalesperson or the web interface

of an online bank"

& transa'tion server manaes usiness transa'tions# 6t sits in the middle7 etween the 'lient and theserver and a'ts as lue7 holdin essential data %ro'essin a'tivities toether# 6t allows hue amountsof information to remain a''urate and ensures transa'tions are 'om%leted without interru%tion or da'orru%tion# & transa'tion server sits riht in the middle of a system7 manain transa'tions as they8oom around different networ+s# he transa'tion server is res%onsile for maintainin hih

%erforman'e7 availaility and data interity# 6t also ma+es sure that no 'om%uter has too mu'h or toolittle to do#

Transaction Server A$$%ications

ransa'tion servers are est suited to se'ure7 hih-s%eed a%%li'ations su'h asG

0-'ommer'e $to'+ mar+et tradin &irline reservations Credit-'ard verifi'ation Online an+in transa'tions

9hen a transa'tion server sees that one 'om%uter has een sent too mu'h wor+7 it automati'ally

divides the wor+ amon all availale 'om%uters7 %oolin resour'es to %revent any one ma'hine from'rashin#

9hen it u%dates dataases7 a transa'tion server also %erforms what


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24/50

his 'on'e%tual drawin shows the transa'tion server sittin etween the'entral server and three 'lients# 6n the model it


25/50

.hort for transactionprocessing monitor,a program that monitors atransactionas it passes from one stage in a process to another" The

TP monitors purpose is to ensure that the transaction processes completely or, if an error occurs, to take appropriate actions"TP monitors are especially important in three-tierarchitectures that employload balancingbecause a transaction may be forwarded to aof severalservers"!n fact, many TP monitors handle all the load balancing operations, forwarding transactions to different servers basedon their availability"

Previous

Term 8etTerm

(hat ty$e of network do

need

How wi%% (A/

o$timi2ation he%$ my

network

How do de$%oy

(ire%ess )A/

(hat are /etwork

To$o%o3ies

TP monitor(hat wire%ess networkin3

standard do !se

How do sec!re my

wire%ess network

(hat a$$%iances wi%%

sec!re my network

How &o O$timi2e

My (ire%ess )A/

2ro#&ware6 Shared Tho#ghts7 Shared edia7 and Shared ode"s

?a'es Patrick ,illia's

patrickKclockwerks.co'

#*- CI0T

;nowledge /anage'ent -yste's

April == =>>C

-chool of *nfor'ation

The !niversity of Texas at Austin

Lroupware ackground M 3efinitionsTypes of Lroupware Applications

5o'ponents of Lroupware ApplicationsThe "ole of Lroupware in ;nowledge /anage'ent

Lroupware 3esign and *'ple'entation *ssuesAwareness

5hallenges of Lroupware -yste's5auses of Lroupware -uccess

5auses of Lroupware 2ailureThe 2uture of Lroupware

"eferences
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protected]://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#1http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#2http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#3http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#4http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#5http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#6http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#7http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#8http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#9http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#10http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#11http://www.webopedia.com/TERM/I/in-app_billing.htmlhttp://www.webopedia.com/TERM/windows_server_2012.htmlhttp://www.webopedia.com/_email/email_a_colleague.htmlhttp://www.webopedia.com/TERM/T/transaction_processing.htmlhttp://www.webopedia.com/TERM/T/three_tier.htmlhttp://www.webopedia.com/TERM/L/load_balancing.htmlhttp://www.webopedia.com/TERM/S/server.htmlhttp://www.webopedia.com/TERM/windows_server_2012.htmlhttp://www.webopedia.com/TERM/windows_server_2012.htmlhttp://www.webopedia.com/TERM/I/in-app_billing.htmlhttp://www.webopedia.com/TERM/I/in-app_billing.htmlhttp://www.webopedia.com/DidYouKnow/Hardware_Software/Networking/what_type_of_network_do_i_need.htmlhttp://www.webopedia.com/DidYouKnow/Hardware_Software/Networking/what_type_of_network_do_i_need.htmlhttp://www.webopedia.com/DidYouKnow/Hardware_Software/Networking/how_will_wan_optimization_help_my_network.htmlhttp://www.webopedia.com/DidYouKnow/Hardware_Software/Networking/how_will_wan_optimization_help_my_network.htmlhttp://www.webopedia.com/DidYouKnow/Hardware_Software/Networking/how_will_wan_optimization_help_my_network.htmlhttp://www.webopedia.com/DidYouKnow/Hardware_Software/Networking/wireless_lan_network_deployment.htmlhttp://www.webopedia.com/DidYouKnow/Hardware_Software/Networking/wireless_lan_network_deployment.htmlhttp://www.webopedia.com/DidYouKnow/Hardware_Software/Networking/mesh_topology.htmlhttp://www.webopedia.com/DidYouKnow/Hardware_Software/Networking/mesh_topology.htmlhttp://www.webopedia.com/quick_ref/WLANStandards.asphttp://www.webopedia.com/quick_ref/WLANStandards.asphttp://www.webopedia.com/DidYouKnow/Hardware_Software/Security/wireless_network_security.htmlhttp://www.webopedia.com/DidYouKnow/Hardware_Software/Security/wireless_network_security.htmlhttp://www.webopedia.com/quick_ref/network_appliance.asphttp://www.webopedia.com/quick_ref/network_appliance.asphttp://www.webopedia.com/DidYouKnow/Hardware_Software/Networking/wireless_lan_network_optimization.htmlhttp://www.webopedia.com/DidYouKnow/Hardware_Software/Networking/wireless_lan_network_optimization.htmlmailto:[email protected]://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#1http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#2http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#3http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#4http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#5http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#6http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#7http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#8http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#9http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#10http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#11


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Lroupware produces shared thoughts shared 'edia and shared 'odels. 5ollective thought is

'oved into a higher level when the traditional group interaction is eclipsed by the use of such

collaborative tools. Dfficient sharing of ideas can be transfor'ed into shared understanding and

into shared priorities. (1EEI p. E1)

These definitions place e'phasis on groupware as the uintessential knowledge 'anage'ent

technology. However the vastness of the concept of groupware provides little structure or direction to

those seeking knowledge 'anage'ent solutions for their organi:ations. 5lases and ,ehner further

identify the ability $to acuire knowledge entities and to opti'i:e the storage navigation and

distribution of these separable units of knowledge in databases$ as the 'ost significant tasks for the

co'puter support of knowledge 'anage'ent (=>>= p. =). ardra' spotlights what 'ay be the

proble' in engineering these capabilities% $because we do have a pretty good idea of what is 'eant

by co'puter support ... confusion lies in understanding the nature of what we 'ean by cooperative

wor#$ (1EEI p. IE).

This paper will pri'arily focus on the conceptual fra'ework of groupware the $what we 'ean by

cooperative work$ di'ensions including the driving forces of such work na'ely awareness shared

context and identity. The successful groupware and knowledge 'anage'ent solutions available in the

'arketplace today reflect the i'portance these concepts representN the sheer volu'e of products

reflect the diversity in groupware needs and definitions at play. The uestion addressed here is not

what belongs in a groupware solution but rather how people use groupware and why. ,hat are the

li'itations and challenges of hu'ans working together in a virtual spaceB Are physical world

'etaphors helpful or do they do 'ore har' than goodB

*t is 'ost i'portant to note that groupware workgroup co'puting 5-5,++ whatever na'e is applied

to co'puter+'ediated collaboration++ has been at the center of co'puter technology since the

beginning. The ideas e'bodied by current software products proposing knowledge 'anage'ent and

groupware solutions are based on goals that have been a part of the co'puting world since its

inception% to aug'ent hu'an ability and intellect.

Types of Lroupware Applicationsack to top
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As 'entioned above the variety of groupware applications is rivaled only by the nu'ber of discreet

definitions of what groupware should do. *'portant concepts in differentiating types of groupware

applications include workflow focused co''unication focused what+you+see+is+what+*+see

(,Y-*,*-) synchronous (real+ti'e) and asynchronous (content repositories). Lroupware

applications 'ay represent a co'bination of any or all of these criteria.

-calia and -ack'ary describe three categories of groupware based on the level of co'plexity% e'ail

and electronic bulletin boards co'puter conferences and group decision support syste's which

$pro'ote discussion and analysis of proble's and i'prove the speed and uality of the decision+

'aking process$ (1EEF). ,hile these categories do highlight a clear hierarchy of groupware uses

actual groupware syste's generally exhibit foggier boundaries.

3epending on the situation the ideal 'ix of groupware di'ensions can differ greatly. ,hilesynchronous groupware applications often atte'pt to replicate the dyna'ics of face+to+face

co''unication (such as videoconferencing) the task+centered virtual environ'ent 'ay not reuire

such a feature. Lreenspan Loldberg ,ei'er and asso note that $being able to share 'aps

drawings text etc. is often 'ore i'portant than seeing the others face$ (=>>> p. =0=). ;raut

Lergle and 2ussell suggest that $the benefit of visual infor'ation co'es fro' allowing collaborators

to share the work area rather than fro' seeing one another$ (=>>= p. C1).

2urther'ore Lutwin and Lreenberg note that with relaxed+,Y-*,*- syste's in which the user sees

a blend of both private and group view 'aintaining awareness of others in the workspace can be a

considerable proble' (=>>= p. 10). Lutwin "ose'an and Lreenberg explain this awareness

proble' with a basic rule of groupware present in 'uch of the literature% $increasing individual control

reduces the group focus inherent in ,Y-*,*- environ'ents$ (1EEF p. =0E).

-uccessful groupware applications reuire that the co'bination of these di'ensions be tailored to the

task to be co'pleted in the 5-5, environ'ent. 7ne+to+'any co''unication 'ay be well suited to

one+way strea'ing video while the group editing of a docu'ent de'ands the co''on focus of a

strict ,Y-*,*- environ'entN an application supporting a coordination 'eeting a'ong geographically+

dispersed executives working with a co''on client 'ay reuire a co'bination of videoconferencing

and shared workspace features.


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5o'ponents of Lroupware Applicationsack to top

#ococo and Yen identify perhaps the 'ost i'portant ele'ent of collaborative syste's often

overlooked as a functional co'ponent% people (1EII p. EC). The authors focus on both facilitators

and decision 'akers as the co''on link a'ong all other co'ponents of the groupware syste'. /anyargue that within the fra'ework of groupware users can and should serve in design roles as well.

Apart fro' the users of a syste' the basic co'ponents of groupware applications include ob9ects and

concepts of a fa'iliar variety. The basic regions of 5-5, applications include% e'ail docu'ent

'anage'ent workflow infor'ation sharing access to shared data sources collaborative tools

(8ewning 1EE@ p. 0F) networking co''unications tools concurrent processing windowing

environ'ents (Lrudin 1EE1) 'e'os databases custo'er files (#ococo M Yen 1EEI p. I>) contact

'anage'ent utilities (,hittaker ?ones M Terveen =>>= p. =1F) awareness tools such as 'iniature

views and radar (Lutwin M Lreenberg 1EEIb p. 01F) shared whiteboards docu'ent 'arkup

discussion groups (,erbach =>>=) and public and private calendars (;yng 1EE1).

The "ole of Lroupware in ;nowledge /anage'entack to top

*n ter's of knowledge 'anage'ent groupware fulfills a nu'ber of specific roles. #otus 8otes the

standard conception of a groupware application supports two of these specific knowledge

'anage'ent rolesN it enables both co''unication and group 'e'ory (,hittaker 1EEF p. >E).

Lroupware syste's not only facilitate and provide a foru' for organi:ational co''unication but

collect and store this co''unication as well. These dual roles represent 5lases and ,ehners $'ost

significant tasks$ 'entioned above and reflect their $'ore 'odest approach$ of 5-5, to $aug'ent

organi:ational 'e'ory$ (=>>= p. =).

*n addition to knowledge generation and storage Lutwin and Lreenberg note a general knowledge

'anage'ent role that all groupware syste's should support providing users with infor'ation about

their collaborators (=>>= p. 1F). This is a 'ore i''ediate real+ti'e need within a virtual

environ'ent and Lutwin and Lreenberg have pursued a great deal of research on awareness in

virtual work environ'ents that will be addressed later in this paper.

Lroupware can also set the pace for knowledge workflow in an organi:ation. 3ix states that the ability
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for a groupware syste' to 'atch the pace of the cooperative task is para'ount to its success and

that $different tasks have different paces$ and reuire appropriate 'eans of notification (1EE@ p.

101). -i'ilarly groupware syste's can also control co''unication and disruption% $the flip side to

initiative is interruption. *f other people or things have the responsibility for telling you when things

happen they 'ay tell you when you least want the' to6$ (3ix 1EE@ p. 101). A groupware solution

should be able to 'anage pace and co''unication relative to the tasks it is e'ployed to aug'ent.

Additionally groupware can be utili:ed to 'anage conflict. ;yng states that groupware is often

responsible for identifying conflict preserving a record of it until $procedures can be set up to handle

it$ (;yng 1EE1).

-tructured conversational interaction such as that available in the threaded discussions of #otus 8otes

(,hittaker 1EEF p. 1>) can serve to facilitate conversation and bring out conflict but they can alsoi'pede the conversation and knowledge generation%

"ather than facilitating conversation atte'pts to 'aintain conversational focus by i'posing a

rigid topic structure 'ay inhibit interaction. Providing prior topics 'ay actually serve as a filter on

conversations% if users are uncertain of the structure of the database or its $rules of conduct$

they 'ay choose not to participate. (,hittaker 1EEF p. 1F)

All of the roles described above also support coordination a'ong 'e'bers of an organi:ation which

'ay be the 'ost i'portant facet of groupware for knowledge 'anage'ent. Dffective groupware

syste's 'ust add di'ension to relationships a'ong people in different locations not 'erely atte'pt

to replicate physical interaction. -uch syste's cultivate shared awareness such as #ococo and Yens

$shared thoughts shared 'edia and shared 'odels$ (1EEI p. E1) allowing users to%

Coordinate with ea'h otherso'ial networ+s@

:evelo% and raod'ast new +nowlede $hare and mani%ulate diital oQe'ts 0asily orient themselves amon 'owor+ers in the virtual environment

These categories illustrate the i'portance of users taking active role in groupware for it success as a

knowledge 'anage'ent solution. *t has already been noted that people the'selves 'ay be the 'ost

i'portant co'ponents of groupware syste's. The philosophy driving knowledge 'anage'ent today

holds that people are the assets and 'ust be encouraged to i'part their value to others. *t is no


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surprise that the issues facing knowledge workers and groupware developers often reflect

psychological and sociological concerns.

Lroupware 3esign and *'ple'entation *ssuesack to top

5-5, is based on collective hu'an activity and as such its use and value 'ay be directly

affected by group+interaction patterns group+develop'ent processes participant attitudes and

all the 'yriad social factors that are found in any work group. (-calia M -ack'ary 1EEF)

As people can be considered the pri'ary co'ponent of groupware syste's so can they be considered

the genesis of 'ost proble's facing successful groupware i'ple'entation. -calia and -ack'ary shed

light on a truis' that can 'ake or break an organi:ations adoption of a groupware solution for

knowledge 'anage'ent. ,asserschaff and entley recogni:e that individual user buy+in is an

i'portant factor in syste' success and discuss $the need for groupware syste's to recogni:e and

support individual differences$ and highlight $the tension in 'any existing syste's which seek to

support these differences only to the extent that they do not li'it the syste's ability to 'aintain a

co''on context for the groups work$ (1EE@ p. C=C).

Lronback ;yng and /orgensen (1EEC) state that $users do not 'ake explicit distinctions between

working in cooperative or individual 'odes they 9ust want to carry out their work$ supporting their

view that 5-5, $should be provided as open building blocks that can be s'oothly integrated with

existing types of applications.$

The state'ents above reflect the 'ultitude of issues a designer 'ust face in the develop'ent of

groupware design and i'ple'entation. The factors at play that influence user perception of a

groupware syste' can basically be approached in ter's of awareness.

Awarenessack to top

3ourish and elotti state that $awareness infor'ation is always reuired to coordinate group

activities whatever the task do'ain$ (1EE= p. 1>@). 5-5, is no exceptionN in the groupware
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environ'ent awareness is 'anifested in a nu'ber of ways% as workspace awareness in feedthrough

and through shared context. Lutwin and Lreenberg provide a description of the i'pact of awareness

in a virtual environ'ent versus face+to+face co''unication%

,hile staying aware of others is so'ething that we take for granted in the everyday world

'aintaining this awareness has proven to be difficult in real+ti'e distributed syste's where

infor'ation resources are poor and interaction 'echanis's are foreign. As a result working

together through a groupware syste' often see's inefficient and clu'sy co'pared to face+to+

face work. (=>>= p. 11)

,hile perhaps clu'sy 'ethods of working in successful groupware syste's 'axi'i:e what Lutwin

and Lreenberg call $workspace awareness$ which they define as $the up+to+the+'o'ent

understanding of another persons interaction in the shared workspace$(=>>= p. 1@). y providing

an understanding of what other users are doing and how the environ'ent is changing this

awareness 3ourish and elotti hold provides users with the context for their own activities (1EE= p.

1>@).

,orkspace awareness is not an easy aspect of a groupware syste' to 'anage as $how it happened$

is rooted in the $occurrence of actions in ti'e i'plicitly noted and understood while they happen but

so hard to reconstruct afterwards$ (3ix 1EE@ p. 1E). ecause these reconstructions are difficult

constant workspace awareness is necessary. A constant strea' of workspace awareness infor'ation

is referred to as $feedthrough$ or shared feedback. *n addition to providing the user with infor'ation

about the changes decisions and locations of other users feedthrough helps users to understand

that their own actions are visible as well.

Lutwin and Lreenberg present an exa'ple of feedthrough in a shared workspace in which a graphical

interface button reacts to one users 'ouse behavior in 'anner that is visible to everyone in the

workspace (1EEI p. =11). *n 'ore co'plex tasks such as browsing or selecting fro' a 'enu only

relevant infor'ation is trans'itted to other users such as the specific 'enu choice. The benefits of

workspace awareness and feedthrough are best su''ed up by Lutwin and Lreenberg in another

paper% $,orkspace awareness is used in collaboration to coordinate activity to si'plify verbal

co''unication to provide appropriate assistance and to 'anage 'ove'ent between individual and

shared work$ (1EEIb p. 011).

*dentity within a groupware syste' is another kind of awareness. 2irst of all identity 'akes the

processes of workspace awareness and feedthrough possible by supplying actors for the actions.


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-econdly where workspace awareness and feedthrough provide a running co''entary of other users

actions identity is often engaged as a 'eans of deter'ining what actions user can and cannot

undertake in the group environ'ent. This is called $role restriction.$

,hile $role restriction$ 'ay see' like a feature that suppresses the activity of users 3ourish and

elotti fra'e it as a 'eans of facilitating activity. $7ne of the efforts of role support... is to reduce

uncertainty about the actions an individual 'ight take and hence provide greater awareness a'ong

participants of others likely activities$ (1EE= p. 1>E).

"ole restriction is also useful as a 'eans of access control (entley Appelt ushbach et al. 1EE@)

and can be an effective 'eans of 'otivation as well. *dentity i'plies accountability which greatly

i'pacts 'otivation and user 'otivation is para'ount to the success of a groupware syste'.

5hallenges of Lroupware -yste'sack to top

Lrudin (1EE1) describes the general challenge of designing effective groupware%$...our effortless

interactions with others 'ake it easy to overlook the co'plexity of workplaces and the poorly

understood nature of collaboration in general.$ This echoes ardra's clai' about learning $what we

'ean by cooperative work.$ The challenges facing groupware designers are diverse and 'any and

a'ong these proble's are 'any opportunities to explore ardra's dile''a.

Lutwin and Lreenberg identify three challenges to groupware designers in supporting awareness

deciding $what infor'ation to gather and distribute how to present the infor'ation to the group and

when the infor'ation will be the 'ost useful$ (=>>= p. 1C). Additionally they detail three proble's

in 'aintaining this necessary awareness%

2irst the input and output devices used in groupware syste's generate only a fraction of the

perceptual infor'ation that is available in a face+to+face workspace. -econd a users interaction

with a co'putational workspace generates 'uch less infor'ation than actions in a physical

workspace. Third groupware syste's often do not present even the li'ited awareness

infor'ation that is available to the syste'. (=>>= p. 10).

#ococo and Yen identify a wholly organi:ational and hardware+based set of challenges%


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The pri'ary li'itations of groupware include the organi:ational environ'ent of the user the

existing architecture of the users hardware syste' the budgetary constraints of the

organi:ation and the infrastructure in place in the locations that will be linked. (1EEI p. EC)

Providing an idea of syste's reuire'ent issues facing a co'plex groupware i'ple'entation /ills

(1EEE) describes a set of groupware needs faced by the 3efense Advanced "esearch Pro9ects Agency

(3A"PA) to account for collaboration across heterogeneous bandwidth and devices collaboration using

natural 'odes of interaction ready access to infor'ation affecting collaboration collaboration without

continuous activity and the ability to evaluate effectiveness before deploy'ent. These pri'ary

reuire'ents see' al'ost prohibitive to the design of a syste'.

These three distinct sets of challenges are only the beginning. *n designing for specific groupware

environ'ents developers 'ust also deal with the custo'i:ation paradox that appears in 'uch of the

5-5, literature% the 'ore a syste' is tailored to an individual the less useful it is to the group and

vice versa (;yng 1EE1N Lutwin M Lreenberg 1EEI).

5auses of Lroupware -uccessack to top

3espite the see'ingly insur'ountable challenges that oppose the designers of groupware syste'sresearchers have identified several factors that contribute to the success of groupware applications.

;line (=>>1) identified six clusters of user satisfaction issues ($ase of use% &rainin"% &echnical

'upport% onsultation% Wor# (eeds )et% and'*stem apabilities) which can be viewed as a road'ap

for building a user+centric syste'.

Additionally 3ix finds that several cultural factors can have a substantial i'pact on groupware

success% a strong core of initial users full integration of existing infor'ation use of existing

standards and new standards that are si'ple and public (1EE@ p. 1C@).

;yng feels it is i'perative that users have a considerable hand in the design of the syste' in which

they $apply their co'petence in the application do'ain to the design process... 'oving fro'

evaluating to creating$ (1EE1).


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5lases and ,ehner prescribe that conflict be leveraged to 'axi'i:e the flow of different perspectives

throughout the groupware develop'ent process%

,e hold that different perspectives(between software designers as well as between software

designers and anticipated or actual actors at work) involved in design ... 'ay beco'e potential

driving factors for the develop'ent of 5-5, syste's. (=>>= p. >)

To su''ari:e the strongest advice the authors offer to the designers of groupware is no surprise%

focus on users and user needs. This advice is 'ore difficult to 'anage in the context of the challenges

addressed in the previous section.

5auses of Lroupware 2ailureack to top

7bviously groupware syste's fail when they do not 'easure up to the previously discussed

challenges. However 'uch of the 5-5, literature deals with the specific reasons specific syste's

have failed.

5ockburn and ?ones include a'ong their identified causes of groupware failure situations that reuire

too 'uch effort on the part of the user including the effort inherent in collaboration itself the effort

of 'eeting new syste' reuire'ents the effort i'posed by reduced flexibility and the effort i'posed

by difficult integration (1EE0). *'plicating users reluctant to share infor'ation or have their work

'onitored by others #ococo and Yen find that organi:ational culture plays a 'a9or role in the failure

of groupware syste's (1EEI p. E). The link between these two perspectives on groupware failure

see's to be an expectation on the part of the user that 5-5, should be entirely analogous to face+

to+face co''unication. However 'any of the conveniences offered by groupware rely on

transactions unnecessary in physical workspaces. Those unwilling to provide infor'ation on their work

activities or to extend the'selves a little further to learn a new way of working will derail 5-5,

efforts. 8ewnings conception that groupware should concentrate on $i'proving intragroup

co''unication rather than accelerating the pace of an individuals work$ 'ay be the approach

necessary to co'bat this attitude.


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The 2uture of Lroupwareack to top

Lroupware and 5-5, have been uietly shadowing the entire field of co'puter technology for the

last few decades. ased on the rise of connectivity at the end of the =>th century and current trends

in co'puting it is likely the 5-5, will re'ain in the spotlight and serve to unite so'e of the 'oredisparate fields of co'puting in the future. *t is conceivable that the concept of groupware will eclipse

that of the *nternet and -e'antic ,eb as users beco'e 'ore able to define and interact within their

own co''unities. Lrudin states that intelligent agents are $often envisaged as furthering an

individuals interests in group and organi:ational settings$ (1EE1). This begs the uestion of which

direction 5-5, will take in the future% will groupware increase our awareness of the groups to which

we belong or will groupware operate in the background of our interpersonal relationships only

interrupting us when per'issions are needed or rules are violatedB

*n ter's of traditional groupware and the i''ediate future #ococo and Yen predict that as 'ore and

'ore syste's are connected across the internet that $users will be 'ore de'anding of the

infor'ation available fro' this foru' to enable the' to be 'ore productive and efficient as an

individual and in tea's$ (1EEI p. 1>>). ,hittaker ?ones M Terveen envision syste's to exploit and

'anage contacts based on algorith's like one they have developed (=>>= p. ==). Lutwin and

Lreenbergs research suggests that new and richer 'ethods of 'aintaining awareness should be

developed to increase the effectiveness of people interacting in virtual workspaces (1EEIb p. 01@).

O4ect #roker

&n OQe't ro+er is a middleware entity that mat'hes u% 'lient a%%li'ations with taret oQe'ts#& taret oQe't is a software entity that %rovides some servi'e to a 'lient software a%%li'ation# 6t may

e lo'ated on the same ma'hine as the 'lient7 or half a world away# he 'lient doesn%arameters@ it wishes to %rovide for the

o%eration# hen the OQe't ro+er sear'hes its re%ository for an oQe't that 'an %erform the re(uesteservi'e# he oQe't that will %erform the servi'e is 'alled the taret oQe't# he OQe't ro+er %assethe re(uest and the %arameters from the 'lient to the taret7 and if a%%ro%riate7 %asses the results a'from the taret to the 'lient# he 'omination of availale o%erations and asso'iated %arameters is'alled an Ainterfa'e#A &s lon as the 'lient and the taret aree on the interfa'e7 Qust aout anythinelse 'an 'hane in the system and it will still wor+#
http://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#tophttp://c2.com/cgi/fullSearchhttp://www.ischool.utexas.edu/~i385tkms/blog/archives/patrick/groupwarepaper.html#tophttp://c2.com/cgi/fullSearch


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Ab5ect re&uest brokerFrom Wikipedia, the free encyclopedia

his arti'le needs attention from an e6$ert on the s!4ect# Please add a reasonor a talk%arameter to thtem%late to e%lain the issue with the arti'le#9i+iProQe't Com%utinor theCom%utin Portalmay e alto hel% re'ruit an e%ert#(November 2008)

his arti'le does notciteany references or so!rces# Please hel%im%rove this arti'ley addin 'itationto reliale sour'es#Mnsour'ed material may e'hallenedand removed# (June 2010)

!ndistributed computing, an ob=e!t re/uest bro,er +O$B-is a piece of middlewaresoftware that allows programmers to make

program calls from one computer to another via a network" A74s promote interoperability of distributed ob5ect systems because

they enable users to build systems by piecing together ob5ects from different vendors, so that they communicate with each other

via the A74"

A74s handle the transformation of in-process data structures to and from the byte se&uence, which is transmitted over the

network" This is called marshallingorseriali=ation"

.ome A74s, such as6A74+-compliant systems, use an !nterface Description *anguage (!D* to describe the data that is to be

transmitted on remote calls"

!n addition to marshalling data, A74s often epose many more features, such asdistributed transactions,directory servicesor

real-time scheduling"

!n ob5ect-oriented languages, the A74 takes the form of an ob5ect with methods enabling connection to the ob5ects being served

+fter an ob5ect connects to the A74, the methods of that ob5ect become accessible for remote invocations" The A74 re&uires

some means of obtaining the network address of the ob5ect that has now become remote" The typical A74 also has many other

methods"

[edit]*mplementations

6A74+- the 6ommon Ab5ect 7e&uest 4roker +rchitecture"

!ce - the !nternet 6ommunications Engine

"8ET 7emoting- ob5ect remoting library within )icrosofts"8ET Framework

Windows 6ommunication Foundation

A74epress- 7eal-time and Enterprise A74s by Ab5ective !nterface .ystems

Arbi- +n Enterprise-level 6A74+ A74 from!A8+ Technologies

D6A)- the Distributed 6omponent Ab5ect )odel from)icrosoft

7)!- the 7emote )ethod !nvocation Protocol from .un )icrosystems

7P6- 7emote Procedure 6all

.+8'G+ Haradhi- 'igh Performance A74s by .ankhya Technologies

.impleA74- a small, non-6A74+ A74

A74it- an open-source 6A74+ A74 used as middleware for @8A)E

AmniA74- a 6A74+-compliant A74 released under the @P*
http://en.wikipedia.org/wiki/Wikipedia:WikiProject_Computinghttp://en.wikipedia.org/wiki/Wikipedia:WikiProject_Computinghttp://en.wikipedia.org/wiki/Wikipedia:WikiProject_Computinghttp://en.wikipedia.org/wiki/Portal:Computinghttp://en.wikipedia.org/wiki/Portal:Computinghttp://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Verifiabilityhttp://en.wikipedia.org/w/index.php?title=Object_request_broker&action=edithttp://en.wikipedia.org/w/index.php?title=Object_request_broker&action=edithttp://en.wikipedia.org/w/index.php?title=Object_request_broker&action=edithttp://en.wikipedia.org/wiki/Wiki

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