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Using HTML5's Navigation Timing API to measure Page Load speed

To measure the time taken for a page to load one can use the Date object in the head section and calculate the time taken for the page to load in window.onload function. However, it calculates the time taken for the page to load after the first bit of JavaScript in the head is executed. This doesn't indicate the time taken by the web server to serve the requested page. The Navigation Timing API introduced in HTML5 provides data that can be used to measure the performance of a website. The API provides a PerformanceTiming interface which contains several attributes that can be used to get end-to-end latency data.

Using HTML5's PageVisibility API

Today I stumbled upon the PageVisibility API introduced in HTML5, which gives developers an opportunity to improve the performance of a web page and to better the user experience. Whenever a user opens a new tab or navigates to another tab, the behavior of the current page from which user navigated can be controlled using this API. Consider a webmail client that is trying to look for new mails every two seconds, if a user opens a new tab or minimizes the browser window then retrieving mails every two seconds would expend resources, whilst the user is not actively viewing the page. Here the PageVisibilty API would come handy and would allow developers to alter the behavior of the web page.

PubSubHubBub and ColdFusion

I came across a publisher\subscriber protocol called PubSubHubBub. It is a server-to-server web-hook-based pubsub (publish/subscribe) protocol - an extension to Atom and RSS. Here the parties (servers) get an instant notification when a feed URL, that  they are interested in is updated.

Traditionally a subscriber would subscribe to a feed and poll for it at regular intervals, to see if there is an updated feed available. In this protocol rather than polling for a feed, the content is pushed out from the publisher. The theory here is that the subscriber can subscribe to a feed via a 'Hub', which then would inform the subscribers when the feed is updated.

How PubSubHubBub works?
A Publisher instead of sending an update to every subscriber, it includes a in its feed URL and sends an update to the Hub.A Subscriber sends a subscription request to the Hub with the feed URL that it is interested in. The request also contains a callback URL to which the Hub should send an update.To ver…

Steve Jobs - An insanely brilliant man passes away

Today when I woke up and switched on the Television to see what's making the news; I heard about Steve Jobs death. For the first time in my life, I'm feeling very sorry for a tech giant who passed away. Steve was an extraordinary human being. He kissed success not just once but many times. He changed the way we experience technology. His charisma, passion and more importantly desperation to do something great is matchless.

Building resposive Web applications with HTML5 Web Workers

One of the key aspects of building web applications that deliver great user experience is to build applications that are highly responsive. Browser vendors are trying to improve the speed of their JavaScript engines and are enabling the web applications to perform well. Since JavaScript was introduced, there has been no way to execute the code outside of the browser UI thread i.e. it has remained single threaded. The Web Workers API introduced in HTML5 enables web applications to run scripts in the background, independent of the UI thread.

The performance of a web application can be greatly improved by using Web Workers since each worker would spawn its own thread. These threads can be used to perform computationally intensive tasks in the background without affecting the performance of the entire application.

Merging password protected PDF files in ColdFusion

In ColdFusion, CFPDF tag can be used to perform several PDF related operations such as adding a watermark, generating thumbnails, deleting pages, merging documents and securing a PDF with password. Today I wanted to merge all my bank statements into a single PDF document, such that only the first page from each document containing the summary of the statement is present in the merged document.

An odd behavior with localStorage events in HTML5

Today I was looking into web storage (localStorage) feature introduced in HTML5. Most of the modern browsers provide means through which key/value pairs can be securely stored and retrieved for later use. Browser cookies can indeed be used for the storage of persistent data but are limited in capacity. Also with cookies, the data is transmitted in every HTTP request thereby making the web applications run slow. Unlike cookies, in local storage there is no limit on the size of the data and it is never transmitted to the web server unless an attempt is made to send it manually. Whenever the data in the storage area changes a 'storage' event is fired. This event is fired whenever the methods setItem(), removeItem(), or clear() are called on the localStorage object.


However, when I tried to use these methods to update the localStorage area, the storage event never fired:

The methods setItem and clear did change the storage area and I confirmed this by referring to the resources  s…