BTEC NCF Dip in Comp - Unit 15 Website Development Lesson 05 – Website Performance Mr C Johnston

Learning Outcome Know different factors which can affect the performance of a website Understand how each factor can affect the performance of a website and steps which can be taken to limit the affect

Starter What factors can make browsing the internet an unpleasant experience?

Factors Affecting Website Performance Where scripts run on the web server – server-side scripts on the local client machine – client-side scripts Browser compliance which elements are supported by different browsers Sever-side factors bandwidth availability, number of hits, file types to send Client-side factors upload and download speeds, browser, cache memory, processor speed, interactivity.

Client vs Server Side Scripting Client side scripting are scripts which are run on the computer which is displaying the website These add some sort of interactivity to the website Calculating prices when ordering multiple goods Handling image galleries Messages that popup and indicate forms are not filled out correctly Server side scripting are commands run by the computer hosting the website More complex algorithms and often server side scripting is based around databases querying them to generate dynamic webpage's processing login requests processing data collected from a form

Client Side Scripts vs Server Side Scripts ASP, CGI, PHP Script

Review Questions What are the pros and cons of using scripting? Is client side scripting or server side scripting better? If you have to use scripting what is best practice?

Browser Compliance Different browsers handle HTML, client side scripting and embedded elements differently Its important to check compliance before rolling out your website Can provide alternative code for different browser so the same outcome is achieved

Supported Media

Supported Plugins Browser ActiveX NPAPI Java Gears RSS Atom Other Google Chrome No Dropped Yes ? Internet Explorer Microsoft Edge Mozilla Firefox Opera Safari Partial

Review Questions How can you ensure that your website will work on different browsers? Plugins don’t seem to be supported anymore by the major browsers Why has this happened? What impact does this have on web developers? What impact does this have on web users?

Discuss… Client Side Factors

Discuss… Server Side Factors

User / Client Side Factors Your Internet Connection Type, speed, ISP, Local popularity, Distance from exchange, Hardware Using To Browse Type, Specification, Size of monitor (resolution), How interact, Age, Connection method (wired/wireless), Type of router, Browser Software Choice, Age, Speed of Page Delivery, Support features, plugins, security policy, Security Software Features, firewall settings, Other Home Factors Other users, position of router, house construction, other signals

Server Side Factors Server Internet Connection Server Hardware Upload speed vital, DSL so is at least same as download speed Server Hardware Type, Specification, Age, Number of sites running on server Few paid for hosts are dedicated probably several sites running on same – is the servers load balanced properly?? Number of hits – especially simultaneously Files which make up the site: Lots of small files better than few big ones Optimise images so are correct size – web browser shouldn’t download image with large dimensions and shrink, Correct file type with compression – graphics, audio, video Selective use of media (flash, video, sound) – correct format, compress, steam video if possible (progressive download rather than waiting for full file)

Activity BTEC (2010) Book – p8-11 Link #1, Link #2, Link #3 Factors Set your page to landscape and create a table similar to the one below which can be used to summarise the different factors which affect website performance For each factor suggest how they can impact browsing and steps which can be taken to minimise the impact Factor Description Impact on Browsing Steps to Minimise Impact