Rob Gravelle

Calculate the Distance between Two Points in your Web Apps As more and more Web apps are run on mobile devices, the more demand for geolocation capabilities increase. As the name suggests, Geolocation is about the reporting of your location to other users, as well as associating real-world locations (such as landmarks) to your location. […]

Respond to DOM Changes with Mutation Observers Earlier this year, the World Wide Web Consortium (W3C) introduced the DOM4 specification, which includes DOM Mutation Observers. These replace the long-standing DOM Mutation Events, which never really caught on due to their slowness, verbosity, and propensity to crash the browser! Unlike Mutation Events, which fired an event […]

Automate Form Submissions using Bookmarklets I recently learned of a technically inclined user who wrote “macros” to streamline data entry into a complex enterprise Web application. My initial reaction was: “There are no macros in Internet Explorer so how did he hook into the page?” It turned out that he was using something called a […]

In the Build a User Interface using the Vaadin Mobile App Framework tutorial, we generated a variety of built-in controls for the Exercises Catalog application that we later updated in the Extending the Vaadin Mobile Application Framework’s Built-in Themes tutorial. The updated controls replaced the default textboxes generated by the FieldGroup class’s buildAndBind() method. As […]

Create a Java Enterprise Application Controller in Eclipse Enterprise JavaBeans were created as server-side components that were supposed to facilitate rapid and simplified development of distributed, transactional, secure and portable applications. Unfortunately, their designers were not wildly successful on either the rapid or simplified development fronts. Today, with the EJB 3.1 spec in production, things […]

Form Element Conversion Made easy with jQuery This tutorial is the follow up to last month’s Convert a List into a Select Dropdown using jQuery article. In it, we learned how to create an in-place editor for an ordered or unordered list by converting it into a dropdown. Today we’ll be modifying our conversion […]

Defining JPA Persistence Units in your Java Enterprise Applications In the Java Persistence API (JPA), Persistence Units are declared in the persistence.xml file. JPA defines a Persistence Unit as a logical grouping of persistable classes along with their related settings. The Persistence Unit settings are then referenced by the EntityManagerFactory in JPA in order to […]

Extending the Vaadin Mobile Application Framework’s Built-in Themes In last month’s Using Built-in Vaadin Themes in your HTML5 Applications tutorial, we learned how Vaadin uses Sass’s (“Syntactically Awesome Style Sheets”) CSS3 extension format to apply styling themes to its applications. You may choose between several pre-defined themes or extend one of them to make it […]

Convert a List into a Select Dropdown using jQuery Look around the Internet and you’ll find lots of JavaScript in-place editor libraries that allow you to convert display text into an editable field. Just as interesting, but less common, is the select-in-place list. That works much the same way as in-place text editing, but allows […]

Parsing Atom Feeds using XPath Atom has become a very popular way to share information over the World Wide Web. The Atom Syndication format is built on the XML standard so that it may be displayed directly in modern browsers or parsed by scripts and software to fetch pertinent information in real time. Once converted […]

Using Built-in Vaadin Themes in your HTML5 Applications Making an HTML5 application that looks like an application takes more than sticking some form controls on a page. It requires some slick CSS and client-side scripting to differentiate an application from a static web page. The Vaadin Mobile Application Framework has you covered in both cases. […]

Getting Fancy with the JavaScript For Loop Of all the loop types in JavaScript, the for loop is arguably the most versatile. It’s concise, easy to use, and can handle just about any looping tasks that you might be faced with. In fact, you can do a lot more with for loops that you probably […]