IB Computer Science: Option C - Web Science
Identify one characteristic of Hypertext Markup Language (HTML).
*Can be rendered by all internet browsers; * uses of tags to delimit statements
Explain, with the use of three examples, how black hat search engine optimization tries to manipulate page ranking.
*Hidden content; Extra keywords are hidden in places that are not visible to the user, eg text in background colour/off screen/in comment tags etc; *Keyword stuffing; Repeating the keywords many times in the meta-tags; *Use of link farms; Creating/making use of dummy pages that link to your page (to increase the number of inlinks);
The technologies associated with Web 2.0 have often been described as leading to the emergence of social networking. (Describe two different features, associated with these new technologies, which have contributed to this emergence.
*Incorporation of multimedia into web pages; Which allows users to incorporate videos; *Interactive webpages; That allows friends to write on their walls etc; *User-generated content; That allows users to personalize their webpage; *Instant-messaging; That allows (fast) communication between friends;
Outline the different components of a web page.
*Meta data *header *body and can also include *stylesheets *scripts
DISTINGUISH BETWEEN THE INTERNET AND THE WORLD WIDE WEB (WEB).
*internet is the infrastructure which enables computers, servers and other devices to establish communication by means of cables and satellite connection. *world wide web is the uses the internet to access data and enable data exchange between users all over the globe. some of the applications of the wed include: wed pages, email, skip.
Describe how the web is constantly evolving.
*the web was first a platform of data exchange with a limited number of users with applications like : online libraries at universities. *then commercial applications were added to the web like: online shopping. *with web 2.0, users demand for social aspects have been added such as : social platforms like Facebook or Myspace, semantic webs (helps computers understand the meaning behind the webpages and the interaction between the computer and the users). * due to the progress of technology and availability of high speed internet, mobile devices and connected things such as fridges, houses, cars will play a bigger role
• extensible style sheet language transformations (XSLT)
: is a programming language which transform XML documents into different output formats which are required by browsers such as google chrome and internet explorer.
• extensible mark-up language (XML)
: is a tag-based syntax which is used to structure and describe information
• uniform resource locator (URL)
: is the address of a webpage that is usually easy to remember. it consists at least of a second level domain such as "Facebook" and a top level domain such as .com, .de
(HTML)
: is the standards for formatting content that is to be displayed in computer browsers.
Describe the purpose of a URL.
A Uniform Resource Locator (URL) is a reference to a web resource that specifies its location on a computer network and a mechanism for retrieving it. Example "http://www.facebook.com"
Identify two ways that a client-side script may be made available to a web browser.
A client-side script may be made available to a browser by the use of script tags that are embedded in the HTML code; By the use of an external file;
Evaluate the use of client-side scripting and server-side scripting in web pages.
A client-side script will not require access to a remote server so that any processing that is done will be done more quickly and use less bandwidth; This will reduce the load on the server;
Describe how a domain name server functions.
A domain name server (DNS) translates the URL from a clients request (example "http://www.facebook.com") and resolves a physical network address (IP) from it (example: "204.74.112.1")
Protocols and standards are essential features of the successful operation and developmentof the web. Distinguish between the terms protocol and standard.
A protocol is a rule that must be followed (for a certain successful process to take place); Whilst a standard is a set of (technical) specifications that should be followed (to allow for functionality);
Explain the importance of protocols and standards on the web.
A protocol is a set of rules and procedures that both sender and receiver must adhere to in order to allow coherent data transfer; without protocols a lossless data transfer can not be established. Standards such as html allow interoperability between different systems and components.
Define the term protocol.
A set of rules and procedures that both sender and receiver must adhere to in order to allow coherent data transfer;
Describe how web pages can be connected to underlying data sources.
A webpage can be connected to a database server (for example a SQL-Server), from which the webserver can retrieve information that is to be displayed to the user.
Identify two different types of file which, if compressed, could make use of a lossy compression algorithm.
Audio; Video; Picture; (ie files with colour, sound or movement)
It is common for dynamic web pages to make use of a mixture of client-side and server-side scripting. Explain how the interaction of HTML, client-side and server-side scripting have allowed the production of a web page.
Before the web page is generated scripts will be run on the server-side; The handling of inputs; The retrieval of information from databases; The performing of calculations; Scripts will be written in languages such as PHP; Server-side scripts are hidden from users and therefore secure; The server sends data to the browser (client) in HTML; This could also include JavaScript code which will be interpreted by the client's browser; Allowing (in this case) booking details to be entered by the user on the client side; Server driven information can be delivered on the fly using software such as Ajax;
A small company is deciding whether to make use of a private cloud service for storing theircustomer data instead of storing it on their own server. Discuss the security issues that will affect the company's decision.
Cloud storage: *Operations are hidden from the company which could lead to doubts *No company loyalty so not the same level of dedication and care *The cloud operators are professionals in this area - this is what they do *The cloud operators are likely to have the most up-to-date systems Company storage: *Operations are not hidden from the company *Due to company loyalty a (potential) better level of dedication and care *It is a small company so IT department will be small / not of the highest expertise *No need to continue updating security systems Example conclusion: Cloud storage has been around long enough to have demonstrated that it is a very secure method of storing your data, so the security concerns are unfounded and the cost savings make it a sensible decision.
Explain one advantage of the use of a peer-2-peer (P2P) network for obtaining and downloading music and movie files.
Easier to set up; Less time will need to be spent in configuring the network; Other advantages could deal with the increased range of available files and the lower (or even zero) costs involved (depending upon the network).
With specific references to one protocol and one standard, discuss the consequences if they did not exist.
For example: TCP; If there was no transport protocol; Packets would be lost; HTML; If there was no standard scripting language for displaying webpages; Different web browsers may not display all pages;
Outline the principal difference between HTML and HTTP.
HTML is a programming/scripting/markup language; HTTP is a protocol/standard;
Explain the differences between a static web page and a dynamic web page.
HTML web pages are remaining with the same content and layout until the web designer is changing them. web pages, that make use of PHP, ASP.NET, Java change their appearance and content depending on user input.
Identify one characteristic of XML.
It does not contain a fixed set of tags, therefore new ones can be added;
When a user enters a URL into the search bar of the browser the URL will normally be sent to a domain name server. Identify the two possible actions that this domain name server will then take.
It will (successfully) map the URL to an IP address in its own database; If it cannot, it will pass the request to (a more authoritative) name server; Returns NXDOMAIN when the requested domain is known to be unassigned/invalid;
Music is distributed across the web in a variety of different ways such as peer-2-peer (P2P) networks. Discuss two factors that would affect the decision to use either lossless or lossy compression when transferring files across the Internet.
Lossless compression is used when loss of data is unacceptable when transferring files such as audio files; Lossy compression may not significantly affect the final version of the file when it is decompressed; Lossy compression will reduce file size; Reduced file size may be an important requirement such as in the use of MP3 music files; Lossy compression results in faster file transfer; Which is important when Internet connections are slow or files are large; If lossy compression is used the original file cannot be reinstated;
The organizers of the theatre want to ensure their web pages appear higher up the ranking of search engines. Suggest whether the use of meta-tags can help achieve this aim.
Meta tags contain keywords/descriptions related to the web page's content; They are embedded in HTML code can be read by search engines; This can help their ranking; Search engines have become more sophisticated; They no longer place a high value on the content of meta tags; As they are not always a reliable guide to the web page's content; Search engines now use other parameters; e.g. Some will place more value on the number of links pointing to a web page;
C.3.3 With the use of examples, outline the difference between interoperability and open standards.
Open standards are a freely available set of specifications; For example, the use of (freely available) HTML;
Describe why the use of meta-tags might not always return the results expected by a search query.
The keyword in a meta-tag might have different meanings; eg "star"; So a webpage about astronomy might be listed by a search engine when the search query/user was searching for a famous actor; Even though the page was indexed correctly;
Describe, with the use of examples, how the use of open standards allows interoperability to occur.
The use of open standards implies that anyone can use them; They are standards that are agreed from the beginning; therefore ensuring interoperability; For example, the Internet backbone relies on the IP protocol which is an agreed standard, allowing the transfer of information to occur;
Outline the principles of searching algorithms used by search engines.
Web search engines get their information by web crawling from site to site.
One of the characteristics of XML code is its ability to describe data. By making direct reference to the XML code above, outline one way in which this characteristic is shown.
can use easily identifiable field names for data; As in the name or species field;
Identify the characteristics of: • internet protocol (IP)
has the task of delivering packets from the source host to the destination host solely based on the IP addresses in the packet headers. For this purpose, IP defines packet structures that encapsulate the data to be delivered. It also defines addressing methods that are used to label the datagram with source and destination information.
• JavaScript:
is a programming language is commonly used for web applications
HTTP(S) • hypertext transfer protocol:
is a protocol that describes the data exchange in the world wide web. (which port to uses and how the data should be formatted)
Explain the functions of a browser.
is a software application for retrieving, presenting, and traversing information resources on the World Wide Web.
• file transfer protocol (FTP).
is built on a client-server model architecture and uses separate control and data connections between the client and the server
Describe the function of the common gateway interface (CGI).
is making executable programs that are installed on a server available to a client.
• cascading style sheet (CSS):
is the central source for formatting instructions of content and layout of a webpage.
Describe the different types of web page.
personal pages, blogs, search engine pages, forums, social media platforms, newspages, media sources, trading pages, costumer service platforms, information pages of authorities
• transmission control protocol ( TCP)
provides reliable, ordered, and error-checked delivery of a stream of octets between applications running on hosts communicating over an IP network
Identify the characteristics of the following: • uniform resource identifier (URI) • URL.
string of characters used to identify a resource. commonly informally termed a web address could have the form http://www.example.com/index.html, which indicates a protocol (http), a hostname (www.example.com), and a file name (index.html). Example "http://www.facebook.com"
Describe one reason why a client-side script may be used in preference to a server-side script.
will not require access to a remote server so that any processing that is done will be done more quickly and use less bandwidth; This will reduce the load on the server;