Web Browsers, Applications and Cloud Computing

Hosted on a local network

- A local area network (LAN) - A wide area network (WAN) - Access applications on the server's local storage; - Internet access not required; - Network (LAN or WAN) required;

Cloud Computing User Benefits

- No need to purchase applications and install them on local computer; - Use online versions of applications and pay a monhtly subscription; - More cost effective; - Access most current software versions; - Save local storage space; - Work collaboratively in real time;

Cookies

- Small text-based data stores information about your computer when browsing; - Save session information; - More customized browsing experience; - Example: Online shopping basket; - Cookies can be useful but could be malicious; - Tracking browsing activity; - Falsifying your identity

V-shaped model

- Verification and Validation model; - Coding and Testing are concurrent, implemented at development stage;

N-tier model

- A number of tiers; - Multitier model: workspace-based client, web-server or database server, security, additional servers; - Advantages: + Changes can be made to specific tiers; + Each tier can have its own security settings; + Different tiers can be load balanced; + Tiers can be individually backed up by IT administrators; - Disadvantages: Changes to all tiers may take longer;

Proxy Server

- Acts as go-between when browsing the web; - Website thinks the proxy is the site visitor; - Protects privacy ot bypasses content retrictions; - Allows organisations to maintain web security, web monitoring, and content filtering; - Controls what, when, who; - Reduces bandwidth consumption and improves speed;

One-tier model

- Also called monolithic model; - Applications run on a local computer;

Lean model

- Application of Lean principles; - Focuses on delivery speed; - Continuous improvement; - Reducing waste each phase;

Cloud hosted

- Available over the Internet; - Internet Access reuqired; - Service Access required; - Files saved in the cloud

Agile model

- Joint development process over several short cycles; - Teams work in cycles, typically two to four weeks; - Testing happens in each sprint, minimizes risk; - Iterative approach to development; - At the end of sprint, basic product developed for user feedbacks; - Process is repeated every sprint cycle;

Waterfall model

- Linear sequential model; - Output of one phase is input for the next phase; - Next phase does not start until work is complete on previous phase;

Local Installation

- Locally installed; - Application exisits locally; - Network not required; - Files saved locally;

Web Browser

- Software interface to access resources on the Internet (Text, images, music, video, online games); - Browsers request and retrieve web-based content stored on web servers; - Web content is displayed on web pages in the browser window on your device;

Malicious plug-ins and extensions

- Typically not displayed in list of installed apps and features; - Use an anti-malware program to remove them; - Use trusted sources for plug-ins and extensions to avoid malware;

Spiral Model (SDLC)

- Use waterfall and prototype models; - Good for large projects; - Largely reduce risk; - Planning, risk analysis, engineering, and evaluation;

Web Browser Components

- User Interface: Search bar, Address bar, Buttons; - Browser Engine: Code that queries and controls rendering engine based on user interactions in UI layer above; + Data Persistence: Data Storage component, small database on local device, Stores user data (cache, session storage, cookies, bookmarks, user profile preferences; - Rendering Engine: Presents requested web pages on screen. interprets HTML code, XML, images, display other content using plugins and extensions; + Networking: Retrieves URLs using HTTP/S and FTP protocols; Handles and reissues content from cache: reduce network trafffic, speed up web requests, eliminates need to go back to source content; + JavaScript Interpreter: Interprets and executes JavaScript code embedded in websites; Results are directed to rendering engine for rendering in browser; + UI Backend: Responsible for drawing basic widgets (Windows, Combo Boxes); Uses UI methods from underlying OS to expose generic interface; UI is not platform specific or dependent;

Client-side scripting

- Web pages were static in early day of WWW; - Dynamic web pages adapt to situation/user; - Server-side scripting performed by server hosting dynamic pages; - Client-side scripting performed by client's web browser; - Code is embedded in web page (JavaScript) - Pros: Client side scripts are visible to user; No reliance on web server resources; - Cons: Client-side scripts have security implications; Malware developers constantly trying to find security flaws; You may need to disable client-side scripts;

Cloud Service Models

1. IaaS (Infrastructure as a service): access the infrastructure and physical computing resources such as servers, networking, storage, and data center space without the need to manage or operate them. 2. PaaS (Platform as a Service): Access the platform that comprises hardware and software tools that are ussually needed to develop and deploy applications to users over the Internet. 3. SaaS (Software as a Service): software licensing and delivery model in which software and applications are centrally hosted and licensed on a subscription basis.

Agile model - 04 core values

1. Individuals and interations over processes and tools; 2. Working software over comprehensive documentation; 3. Customer collaboration over contract negotiation; 4. Responding to change over following plan;

Cloud Computing characteristics

1. On-demand self-service; 2. Broad network access; 3. Resource Pooling; 4. Rapid elasticity; 5. Measured service; Cloud computing is about using technology as a service by leveraging remote system on-demand over the Internet; It has changed the way the world consumes compute services, making them more cost-efficient while making organisations more agile in response to change.

Cloud Deployment Models

1. Public cloud; 2. Private cloud; 3. Hybrid cloud;

06 major steps in SDLC

1. Requirement Analysis and Planning; 2. Design; 3. Coding; 4. Testing; 5. Deployment; 6. Maintenance

three-tier model

A system that effectively isolates an end user from a database by introducing a middle-tier server. Each tier can be: - Individually developed and updated by a seperate team; - Modified and upgraded without affecting other tiers;

Browser extensions

Application that provides extended functionality for a web browser; Enables users to customise a web browser; Extensions and plug-ins may seem very similar but they work quite differently; Plug-ins are executable software code that provided added functionality on a specific web page or website; Extensions consist of non-executable source code that extend core functionality and features of a web browser; Extensions can customise a web browser's context menus, add buttons, toolbars, manage cookies, block pop-ups - which plug-ins cannot; Extensions are widely used by all web browser - while plug-ins are being replaced and not supported.

Main difference between Cache and Cookie

Cache is used to store online page resources during a browser for the long run purpose or to decrease the loading time. On the other hand, cookies are employed to store user choices such as browsing session to trace the user preferences.

What is cloud computing?

Delivery of on-demand computing resources: Networks, Servers, Storage, Applications, Services, Data Centers over the Internet on a pay-for-use basis. User access Applications and Data over the Internet rather than locally. Ex: Online web apps, secure online business applications, storing personal files (Google Drive, One Drive, Dropbox)

Private browsing

Mode that doesn't save history, passwords, form data, cookies, cache. Only hidden locally. ISPs, websites, workplace can view data.

How does a proxy server work?

Proxy servers perform networl address translation to request and retrieve web content on behalf of requesting computers on the network;

Browser plugins

Software that adds functionality to a web browser. It extends the capability of the web browser. Example: Adobe Reader, Adobe Flash, Java

Software Development Life Cycle

Structured methodology that defines creating and developing software; Detailed plan to develop, maintain, or enhance software; Methodology for consistent development that ensures quality production;

Cache

Temporary storage area; Store web data so it can be quickly retrieved and reused without going to original source; Stored on local disk; Improves speed, performance, and bandwidth usage; Cache can be cleared when no longer required;

Iterative model

The 'iterative" or "incremental" model, which starts with initial planning and research. Then begins a cycle -- consisting of planning, requirements, analysis and design, implementation, testing, and evaluation -- which repeats as needed until the decision is made to do deployment. These models were developed in response to identified weaknesses of the waterfall model and often considered cyclical in nature.

Key reasons to update your web browsers

Website compatibility; Security; New Features;

two-tier model

the client workstation or system runs an application that communicates with the database that is running on a different server