Sep 22, 2011

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.

Sep 20, 2011

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  section in chrome developer tools. This looked very odd, but on referring to the w3c specification I found this: "When the setItem(), removeItem(), and clear() methods are called on a Storage object x that is associated with a local storage area, if the methods did something, then in every Document object whose Window object's localStorage attribute's Storage object is associated with the same storage area, other than x, a storage event must be fired". This meant that, the storage event would be fired in any other window\tab which used the same storage area.

Now on opening another tab and on clicking the Add\Clear button the localStorage area was affected and a storage event was fired in the other tab; not on the one that invoked the setItem or clear method. In a way this makes sense because the invoking window would already know of event and would perform the necessary action. Windows that share the same storage area would then be notified of the event and can update the DOM or perform the required action.


Sep 15, 2011

A Cloud of Productivity features in ColdFusion Builder

Yesterday at the ColdFusion Developer Week, I had demonstrated the Productivity features in ColdFusion Builder. Here is a cloud of these features: 

Aug 24, 2011

Speaking at Adobe ColdFusion Developer Week

The Adobe ColdFusion Developer Week is here and is scheduled from 12th of September to 16th of September 2011. I'm pleased to announce that I'll be speaking on Wednesday, 14th of September and my session title is 'ColdFusion Builder: The Professional IDE to Boost Your Productivity'.

This session would focus on how you can get started with using ColdFusion Builder and productivity features that would enable you to develop ColdFusion applications in no time. I'll also be demonstrating the new features that have been introduced in ColdFusion Builder 2.0.

You can register for the session here - http://www.adobe.com/cfusion/event/index.cfm?event=detail&id=1489920&loc=en_us


Aug 9, 2011

Kiss My App: Collaborating using HTML5 Canvas and WebSockets

The Canvas element introduced in HTML5 is the most talked about feature in HTML5. It allows a developer to draw on a rectangular area and the ability to control each pixel in it. I'm not a very big fan of powerful graphics and animation on the web, however I wanted to try Canvas in conjunction with another popular feature - Web Sockets. The idea is to use the mouse events to draw on the Canvas and then send the coordinates to remote clients using Web Sockets. I have used the pusherapp Web Socket library in my example and this video shows how two clients can play a Tic-Tac-Toe game:

Unable to display content. Adobe Flash is required.


As you can see in this video, the mouse movements made on the canvas will draw lines on it and also cause lines to be drawn on another browser window.

Jul 19, 2011

Using Google Maps Places API and ColdFusion's CFMAP to render places of interests

Google announced the Places API recently at Google I/O (2011) and I was looking into this, to see how this API can be used in conjunction with ColdFusion maps created with CFMAP. The Places API can be used to retrieve place information which includes:
  • Places of interests such as parks, restaurants, hospitals which are nearby to the users location.
  • More detailed information on the place, such as the address, phone number etc,.
The API can also be used to perform check-in at a particular place and to add\delete a place. These check-ins can then be used to evaluate the popularity of the place. In this post I'll explain how to retrieve the places of interests and displaying the same on a ColdFusion map using CFMAP.

Jul 8, 2011

Custom validation messages for HTML5 Input elements using the constraint validation API

HTML5 has introduced several input types such as EMAIL, URL, RANGE, SEARCH, DATE, TIME, etc,. Most of the modern browsers have implemented them and are ready to be used in a HTML document. Another exciting feature introduced in HTML5 is the form validation. Instead of writing JavaScript to validate users input, browsers can now validate it and show an appropriate message if the validation fails. The validation message is shown in line with the field for which the validation has failed. The default error message is shown when the validation fails. In this post I'll explain how these error messages can be changed.

Jul 7, 2011

Submitting Form using FormData object in HTML5 using XmlHttpRequest Level 2

The other day I had posted on uploading a file using XmlHttpRequest 2 and tracking the progress of the file upload process using the progress event on XHR2 object and the progress tag. Another enhancement added to the XHR2 specification is the introduction of FormData object. Using the FormData object, one can create a set of key-value pairs and send them as form data in a XHR request. The FormData object is passed in the send() method of the XHR object: