YSlow

• Download Component Size – YSlow provides the size of the downloaded component and provides suggestion in keeping the optimum amount of data size that the component should be. This include images, Javascripts, CSS and cookie size are just few of the examples.
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  YSlow Screenshot

  Bad Requests – It detects missing components that churns 404 errors.  Addressing 404 errors can help improve performance at the client and server end by removing requests made on missing objects as well as removing time needed to handle this requests on missing objects on the server.

• Detect duplicate requests/components – It detects duplicate HTTP requests made which degrades both the client and the server performance.  It also detects duplicate Javascripts which can result in duplicate request to the server or further slowing down the client browser.
• Placement of files – Another good feature made by YSlow is the detection of the placement of the Javascripts and CSS files.  The placement of the Javascripts and CSS files will help improve the performance at the client side.
• Detect expiry of components – YSlow can help determine if a component should be retrieved on every web page loading.  If a component such as an image (company banner) does not changed frequently, it is suggested to it expire at a far later date.  Else, for every time the page loads, a request will be made to the image.

What is great about YSlow is it provides you with the best practises for creating high performance web sites.  It helps you detect which components are too big and provide suggestions for you to improve the performance.  The best practises for high performance web sites can be found at Yahoo! YSlow Developer Network.

The disadvantage of YSlow is it is not installable on Internet Explorer, unlike HTTPWatch.  If you are a fan of the real-time analysing the response (wait) time on HTTPWatch, then you will be disappointed with YSlow on this.  YSlow does not provide any visual indicator on the time taken during loading (or requesting to the server) in real time.  It will only display the time only after the entire web page is downloaded.

The above are just some of the features that are available in YSlow.  You can download YSlow and start profiling your website. We hope to hear your review soon!

HTTPWatch is like a traffic sniffer (they termed it traffic viewer).  Once you start a recording a session, you can view almost anything that is sent via the browser, such as the HTTP headers, the response code, cookies, any caching used, methods, redirections, compression, encoding, and authentication.

What I like most out of the available information is the header, status codes, errors, cookies, redirections and compression.   HTTPWatch can view the following:

• Header – Is a valid header being sent from the client and if the server is returning a valid header as well?
• Status Codes – What is the status code returning?  Is it giving me a correct HTTP 200 or something else (e.g. 302, 404) that may cause degradation of the client side performance?  Note: HTTP codes other than 200 may degrade the web server as well.
• Cookies – Are cookies under-performing?  Are the cookies being retrieved correctly?  Having cookies expired or should they be made to expired?
• Redirections – Are unnecessary redirections made due to invalid requests to invalid objects or missing objects that were removed (e.g. 404 errors)?
• Compression – Have all HTTP requests made from the client returned in compression thus decreasing the throughput?

The plugin can be installed for both Internet Explorer and Firefox users.  There is a free version readily available to download which is sufficient for you to conduct most performance troubleshooting and fix problems on the web server.   The problem with HTTP Watch is that it needs to install in to the system, and this can be considered intrusive if your organisation or your client has a policy against installation of non-compliance software.  It has a Firefox version which means you can use a portable version of Firefox with HTTPWatch installed with it.  This is a workaround against the policy.  Personally, I have a preference over YSlow (another HTTP sniffer/viewer in Firefox portable) than HTTPWatch as it has a cleaner interface (in my opinion).

You can use HTTPWatch if you need to profile one single user for your web application and considering not using a stop watch (at least it’s more professional than a stopwatch technique in your client’s opinion).

Click here to download HTTPWatch!

What iMacro can do is similar to most automated testing tool and macros.  It uses a record and playback engine, and generates a script for you.  The script is in .imm format but it is very intuitive and easy to understand (like plain English).   The script can be open by any text editor and amended to your needs.  You can pass in different parameter values to test your web application.  You can loop the script to test the different values.

The below sample script:

VERSION BUILD=6240709 RECORDER=FX
SET !ERRORIGNORE YES
SET !DATASOURCE C:\ DataSource\ ParameterList.txt
SET !LOOP 1
SET !DATASOURCE_LINE {{!LOOP}}
TAB T=1
TAB CLOSEALLOTHERS
URL GOTO=http://www.communitysamplesite. com/ members/{{!COL1}}/

1. The version of the build (no effect)
2. Set ignoring of error to yes – the effect is that the script will not stop if there is an error (similar to LoadRunner continue-on-error feature)
3. Set the data source to obtain the parameter value list – The parameter list can be manipulate by any text editor or excel-applications
4. Set the starting value (row ) from the parameter  to 1 – Meaning pulling the 1^st record
5. Set the starting row in the parameter list (data source)
6. Set the target tab on Firefox browser
7. Close all other tabs in Firefox  browser
8. Go to URL of the member of Community Sample Site

One thing that I’m unsure of is if iMacro has the ability to log errors during looping.  If you set iMacro to loop through the parameter values without SET !ERRORIGNORE YES, the script will abort when an error is encountered.  On the other hand, if SET !ERRORIGNORE YES is defined, the script will continue to run and not able to log any errors encountered.  I’m not too sure about this as I’ve not explored the log files yet or encountered any errors during my script execution.  Anyone who have done so, please fill us in with the details!  Greatly appreciated!

You can download iMacro from Mozilla Add-ons