Give a brief description of the assigned term using different sources research. Explain how the IT System works and how it connects to the Case Study. All useful information regarding the system should posted in the blog for others to read. You will then post atleast one question each after reading the reaserched work, probing them on their findings. Also ensure that you respond to any question addressed to you. Give examples where possible.
Tendo and Vishal : Cascading style Sheets CSS
Claire and Linda Gantt chart/Project management tool
Solomon and Davarl MySQL / SQL languages
Vernon and Martha : Pay per click advertising
Carola and Joan : PHP language
Shelina and Titina : Backup strategies / RAID
Zahara: Denial of service attack
Hasmita :Open Source Software
Prera: JavaScript
Alicai: Search engine optimization / Page ranking
Claire and Linda : Payment options: Paypall, credit card payments / direct account deposit.
A Gantt chart is a type of bar chart that illustrates a project schedule. Gantt charts illustrate the start and finish dates of the terminal elements and summary elements of a project. Terminal elements and summary elements comprise the work breakdown structure of the project. Some Gantt charts also show the relationships between activities. Gantt charts can be used to show current schedule status using percent-complete shadings and a vertical "TODAY" line. This chart is used also in Information Technology to represent data that have been collected.
ReplyDeleteAdvantages and limitations
• Gantt charts have become a common technique for representing the phases and activities of a project so they can be understood by a wide audience all over the world.
• Although a Gantt chart is useful and valuable for small projects that fit on a single sheet or screen, they can become quite unwieldy for projects with more than about 30 activities. Larger Gantt charts may not be suitable for most computer displays.
• Gantt charts communicate relatively little information per unit area of display. That is, projects are often considerably more complex than can be communicated effectively with a Gantt chart.
• Gantt charts only represent part of the triple constraints (cost, time and scope) of projects, because they focus primarily on schedule management. Moreover, Gantt charts do not represent the size of a project or the relative size of work elements, therefore the magnitude of a behind-schedule condition is easily miscommunicated. If two projects are the same number of days behind schedule, the larger project has a larger impact on resource utilization, yet the Gantt does not represent this difference.
• Having too many interrelationships between activities may result in a cluttered or unreadable chart.
• Because the horizontal bars of a Gantt chart have a fixed height, they can misrepresent the time-phased workload (resource requirements) of a project, which may cause confusion especially in large projects
Carol and Joan said
ReplyDeletePHP language is a hypertext Preprocessor that is a widely used.It is a general-purpose scripting language that was originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document. As a general-purpose programming language, PHP code is processed by an interpreter application in command-line mode performing desired operating system and producing program output on its standard output channel. It may also function as a graphical application. PHP is available as a processor for most modern web servers and as a standalone interpreter on most operating systems and computing platforms.
The main implementation of PHP is now produced by the PHP Group and serves as the de facto standard for PHP as there is no formal specification.
PHP is free software released under the PHP License.
http://upload.wikimedia.org/wikipedia/commons/e/ef/Mysqlwb-homepage.png
ReplyDeleteMYSQL
ReplyDeleteCarmen Machado wants to create a website so she needs a programming language so that she can program her website. And for that she will use MySQL
MySQL stands for structured query language.
MySQL is a relational database management system (RDBMS) that runs as a server providing multi-user access to number of databases.
MySQL is a relational database management system (RDBMS) based on SQL (Structured Query Language).
MySQL was developed to manage large volumes of data at very high speed to overcome the problems of existing solutions. MySQL can be used for verity of applications but it is mostly used for the web applications on the internet.
MySQL will help Machado in posting the images and information about the company because she will have a lot of information she will have to use a sequencing language. And also because Machado will have to change her information in the near future then she directly changes the information from the database using MySQL.
MySQL is used in some of the most frequently visited web sites on the internet. And the SQL script can be edited for any errors or addition of any application.
Behind all information on the website a SQL code is written to it.
The advantage of using MySQL is that all applications very well for all applications.
An example of creating a website using MySQL is shown by the link below
http://upload.wikimedia.org/wikipedia/commons/e/ef/Mysqlwb-homepage.png
Common forms of denial of service attacks are:
ReplyDeleteBuffer Overflow Attacks
The most common kind of DoS attack is simply to send more traffic to a network address than the programmers who planned its data buffers anticipated someone might send. The attacker may be aware that the target system has a weakness that can be exploited or the attacker may simply try the attack in case it might work. A few of the better-known attacks based on the buffer characteristics of a program or system include:
• Sending e-mail messages that have attachments with 256-character file names to Netscape and Microsoft mail programs
• Sending oversized Internet Control Message Protocol (ICMP) packets (this is also known as the Packet Internet or Inter-Network Groper (ping) of death)
• Sending to a user of the Pine e-mail program a message with a "From" address larger than 256 characters
SYN Attack
When a session is initiated between the Transport Control Program (TCP) client and server in a network, a very small buffer space exists to handle the usually rapid "hand-shaking" exchange of messages that sets up the session. The session-establishing packets include a SYN field that identifies the sequence in the message exchange. An attacker can send a number of connection requests very rapidly and then fail to respond to the reply. This leaves the first packet in the buffer so that other, legitimate connection requests can't be accommodated. Although the packet in the buffer is dropped after a certain period of time without a reply, the effect of many of these bogus connection requests is to make it difficult for legitimate requests for a session to get established.
Teardrop Attack
This type of denial of service attack exploits the way that the Internet Protocol (IP) requires a packet that is too large for the next router to handle be divided into fragments. The fragment packet identifies an offset to the beginning of the first packet that enables the entire packet to be reassembled by the receiving system. In the teardrop attack, the attacker's IP puts a confusing offset value in the second or later fragment. If the receiving operating system does not have a plan for this situation, it can cause the system to crash.
Smurf Attack
In this attack, the perpetrator sends an IP ping (or "echo my message back to me") request to a receiving site The ping packet specifies that it be broadcast to a number of hosts within the receiving site's local network. The packet also indicates that the request is from another site, the target site that is to receive the denial of service. (Sending a packet with someone else's return address in it is called spoofing the return address.) The result will be lots of ping replies flooding back to the innocent, spoofed host. If the flood is great enough, the spoofed host will no longer be able to receive or distinguish real traffic.
Viruses
Computer viruses, which replicate across a network in various ways, can be viewed as denial-of-service attacks where the victim is not usually specifically targeted but simply a host unlucky enough to get the virus. Depending on the particular virus, the denial of service can be hardly noticeable ranging all the way through disastrous.
Physical Infrastructure Attacks
Here, someone may simply cut a fiber optic cable. This kind of attack is usually mitigated by the fact that traffic can sometimes quickly be rerouted.
Pay per click (PPC) is an Internet advertising model used on websites, in which advertisers pay their host only when their ad is clicked. With search engines, advertisers typically bid on keyword phrases relevant to their target market. Content sites commonly charge a fixed price per click rather than use a bidding system.
ReplyDeleteCost per click (CPC) is the amount of money an advertiser pays search engines and other Internet publishers for a single click on its advertisement that brings one visitor to its website.
What is Pay Per Click Advertising?
Pay Per Click Advertising enables you to list your site at the top of search engine results by advertising on keywords that best describe your product or service. It's a dynamic marketplace - the higher you bid, the higher your advertisement will be displayed in the list.
You pay only when a searcher clicks on your listing and connects to your site. You don't pay to list, you only pay for clicks or click throughs. This way you only pay for the traffic to your site, there are no other hidden costs.
Pay Per Click is not only available on search engines. Publishers can also include PPC advertisements on their sites. For example, we use Google's PPC Adsense product as you can see in the left-hand column.
It's a smart idea.
An account with a PPC search engine is a great way to drive targeted traffic to your site because you only pay for actual clicks to your site. It allows you to get maximum exposure, while you control the amount you want to spend on your marketing campaign. You can clearly track the effectiveness of your ad campaign.
JAVA SCRIPT
ReplyDeleteJavaScript is an implementation of the ECMAScript language standard and is typically used to enable programmatic access to computational objects within a host environment. It can be characterized as a prototype-based object-oriented[5] scripting language that is dynamic, weakly typed and has first-class functions. It is also considered a functional programming language[6] like Scheme and OCaml because it has closures and supports higher-order functions.[7]
JavaScript is primarily used in the form of client-side JavaScript, implemented as part of a web browser in order to provide enhanced user interfaces and dynamic websites. However, its use in applications outside web pages is also significant.
Features of java script:
a) Imperative and structured: JavaScript supports all the structured programming syntax in C (e.g., if statements, while loops, switch statements, etc.). One partial exception is scoping: C-style block-level scoping is not supported (instead, JavaScript has function-level scoping). JavaScript 1.7, however, supports block-level scoping with the let keyword. Like C, JavaScript makes a distinction between expressions and statements. One syntactic difference from C is automatic semicolon insertion, in which the semicolons that terminate statements can be omitted.
b) Dynamic
-dynamic typing:As in most scripting languages, types are associated with values, not variables. For example, a variable x could be bound to a number, then later rebound to a string. JavaScript supports various ways to test the type of an object, including duck typing.
-object based:JavaScript is almost entirely object-based. JavaScript objects are associative arrays, augmented with prototypes (see below). Object property names are string keys: obj.x = 10 and obj["x"] = 10 are equivalent, the dot notation being syntactic sugar. Properties and their values can be added, changed, or deleted at run-time.
-run-time evaluation:JavaScript includes an eval function that can execute statements provided as strings at run-time.
c)Functional
first-class functions
Functions are first-class; they are objects themselves. As such, they have properties and methods, such as length and call();[24] and they can be assigned to variables, passed as arguments, returned by other functions, and manipulated like any other object.
nested functions
ReplyDelete'Inner' or 'nested' functions are functions defined within another function. They are created each time the outer function is invoked.
closures
JavaScript allows nested functions to be created, with the lexical scope in force at their definition, and has a () operator to invoke them now or later. This combination of code that can be executed outside the scope in which it is defined, with its own scope to use during that execution, is called a closure in computer science.
d)Prototype-based
prototypes
JavaScript uses prototypes instead of classes for inheritance. It is possible to simulate many class-based features with prototypes in JavaScript.
functions as object constructors
Functions double as object constructors along with their typical role. Prefixing a function call with new creates a new object and calls that function with its local this keyword bound to that object for that invocation. The constructor's prototype property determines the object used for the new object's internal prototype.
functions as methods
Unlike many object-oriented languages, there is no distinction between a function definition and a method definition. Rather, the distinction occurs during function calling; a function can be called as a method. When a function is called as a method of an object, the function's local this keyword is bound to that object for that invocation.
e)Miscellaneous
run- time environment
JavaScript typically relies on a run-time environment (e.g. in a web browser) to provide objects and methods by which scripts can interact with "the outside world". In fact, it relies on the environment to provide the ability to include/import scripts.
variadic functions
An indefinite number of parameters can be passed to a function. The function can access them through formal parameters and also through the local arguments object.
array and object literals
Like many scripting languages, arrays and objects (associative arrays in other languages) can each be created with a succinct shortcut syntax.
regular expressions
JavaScript also supports regular expressions in a manner similar to Perl, which provide a concise and powerful syntax for text manipulation that is more sophisticated than the built-in string functions.
f)Vendor-specific extensions
JavaScript is officially managed by Mozilla Foundation, and new language features are added periodically. However, only some non-Mozilla JavaScript engines support these new features:
• property getter and setter functions (also supported by WebKit, Opera,[29] ActionScript, and Rhino)[30]
• conditional catch clauses
• iterator protocol adopted from Python
• shallow generators/coroutines also adopted from Python
• array comprehensions and generator expressions also adopted from Python
• proper block scope via new let keyword
• array and object destructuring (limited form of pattern matching)
• concise function expressions (function(args) expr)
• ECMAScript for XML (E4X), an extension that adds native XML support to ECMAScript
nested functions
ReplyDelete'Inner' or 'nested' functions are functions defined within another function. They are created each time the outer function is invoked.
closures
JavaScript allows nested functions to be created, with the lexical scope in force at their definition, and has a () operator to invoke them now or later. This combination of code that can be executed outside the scope in which it is defined, with its own scope to use during that execution, is called a closure in computer science.
d)Prototype-based
prototypes
JavaScript uses prototypes instead of classes for inheritance. It is possible to simulate many class-based features with prototypes in JavaScript.
functions as object constructors
Functions double as object constructors along with their typical role. Prefixing a function call with new creates a new object and calls that function with its local this keyword bound to that object for that invocation. The constructor's prototype property determines the object used for the new object's internal prototype.
functions as methods
Unlike many object-oriented languages, there is no distinction between a function definition and a method definition. Rather, the distinction occurs during function calling; a function can be called as a method. When a function is called as a method of an object, the function's local this keyword is bound to that object for that invocation.
e)Miscellaneous
run- time environment
JavaScript typically relies on a run-time environment (e.g. in a web browser) to provide objects and methods by which scripts can interact with "the outside world". In fact, it relies on the environment to provide the ability to include/import scripts.
variadic functions
An indefinite number of parameters can be passed to a function. The function can access them through formal parameters and also through the local arguments object.
array and object literals
Like many scripting languages, arrays and objects (associative arrays in other languages) can each be created with a succinct shortcut syntax.
regular expressions
JavaScript also supports regular expressions in a manner similar to Perl, which provide a concise and powerful syntax for text manipulation that is more sophisticated than the built-in string functions.
f)Vendor-specific extensions
ReplyDeleteJavaScript is officially managed by Mozilla Foundation, and new language features are added periodically. However, only some non-Mozilla JavaScript engines support these new features:
• property getter and setter functions (also supported by WebKit, Opera,[29] ActionScript, and Rhino)[30]
• conditional catch clauses
• iterator protocol adopted from Python
• shallow generators/coroutines also adopted from Python
• array comprehensions and generator expressions also adopted from Python
• proper block scope via new let keyword
• array and object destructuring (limited form of pattern matching)
• concise function expressions (function(args) expr)
• ECMAScript for XML (E4X), an extension that adds native XML support to ECMAScript