Advantages And Disadvantages Of Optimisation Techniques
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Specific Optimisation Techniques to be used for the Website
The different optimisation techniques are:
Minimise HTTP requests
Add an expiry or a cache control header
Put scripts at the bottom
Remove duplicate scripts
Make Ajax cacheable
Post load components
Pre load components
Reduce DNS Lookups
Minimise HTTP requests
The majority of the time taken when a page is loading is a result of HTTP requests. Reducing the number of components will thus reduce the number of HTTP requests required to render the page. This is the key to faster loading pages.
Combined files are a way to reduce the number of HTTP requests by combining all scripts into a single script, and similarly combining all CSS into a single stylesheet.
Discussing the decisions for each page
The Home page is the one which should be fast, attractive and interactive. The Home page will make up the rapport of your website. In order to make it attractive we need to use different images, CSS, graphical interfaces and flash content. Images and graphical interfaces are bigger in size so we will scale them and try to convert them into a more suitable format such as Portable Network Graphics (.png).
The user's login page, discussion page, upload page and modify page will be much simpler than home page but they will contain lots of videos and images with the description. Thus, we can just remove the white space characters from their code reducing the size of the webpage and optimising the images. Videos are too big in size so we will not upload it on our server. We will use YouTube or other free video upload sites and embed the link on our webpage.
Product Catalogue will contain all the images of the product that can be searched and sorted by category and brands. The loops will be optimised for faster search and sorting.
Business information, current employees and product information will contain the detailed textual description with images of what we do, what we sell and who works in our company. All this information is static, so we will cache the information and optimise the images.
Q2. Client side security issues are an extremely important component of any web-based application.
Client side security is one of the most important topics in internet security. All the information which has been downloaded from servers is stored on the client's machine. All the site preferences as well as your login details are stored as cookies on the local machine and we need to keep those files safe from hackers. We use different antiviruses and firewalls on the local machine, however they are not as efficient as they should be.
(Uta Priss, 2012, Advanced Client-Side Security:What many users do not know, From http://www.upriss.org.uk/awt/lec4a.pdf)
In this document we will look at the major threats, type of client side attacks and some strategies for minimising those risks.
Nowadays internet is a basic necessity of day to day life. We are so dependent on internet these days. Everything from paying our electricity bills to international business meetings we do online. All our bank details are on our local machine which is vulnerable to hackers. For this reason do we need a secure system to work safely online. Whenever we use internet our local system stores the information from the server which contains your preferences, form data and the history of the webpages you viewed.
How do hackers operate..?
Hackers try to bypass the firewall and gain inappropriate access to local host resources. There are more chances to breach the security of the firewall when the hacker and the host are on the same network because request for resources originating within the network can be trusted more than request originating from outside the network. (Bidgoli Hossein , Wiley John & Sons, (2006) Hanew Jersey, John Wiley & Sons)
Cross-Site Scripting attacks are a type of injection problem, in which malicious scripts are injected into the otherwise benign and trusted websites. Cross-site scripting (XSS) attacks occur when an attacker uses a web application to send a malicious code, generally in the form of a browser side script, to a different end user. Flaws that allow these attacks to succeed are quite widespread and occur anywhere a web application uses input from a user in the output it generates without validating or encoding it.
An attacker can use XSS to send a malicious script to an unsuspecting user. The end user's browser has no way to know that the script should not be trusted, and will execute the script. Because it thinks the script came from a trusted source, the malicious script can access any cookies, session tokens, or other sensitive information retained by your browser and used within that site. These scripts can even rewrite the content of the HTML page.
Validate, filter, and sanitise all input
Process output response stream data through encoding
Many modern browsers will attempt to detect an XSS attack and notify the user
CSRF (Cross-Site Request Forgery) is an attack which forces an end user to execute unwanted actions on a web application in which he/she is currently authenticated. With a little help of social engineering (like sending a link via email/chat), an attacker may force the users of a web application to execute actions of the attacker's choosing. A successful CSRF exploit can compromise end user data and operation in the case of a normal user. If the targeted end user is the administrator account, this can compromise the entire web application.
Implement strong XSS mitigations
Use Tokens to verify expected user actions
Hidden form value fields
E.g., RoR & ASP.Net MVC provide framework support
Use POST for any actions that alter data on server side
Is the idempotent web paradigm for HTTP GET compromised?
Check HTTP Referrer
Most modern browsers include features to palliate the following attacks:
Destruction or corruption of data or configuration
Theft of configuration information
Installation of malware
Theft of information and identification
(Oriyano Sean-Philip and Shimonsk Robert,(2012)Client Side Attacks and Defense, USA, Elsevier, Pg 130)