Summa

This is the third in the Mvp4g Multiple Presenters series (part 1 and part 2). In this post I will demonstrate how to use the GWT generator to differentiate events that are to be filtered by an event group. This gives you more freedom when defining your events and gets rid of the “$” that we used to define the event name. Plus in this post I will also remove the presenter registry and enhance the event filtering by overriding the isActivated() method.

Continue Reading 1 comment

Continuing from part 1, now let’s look at a way of using Mvp4g activation/deactivation of handlers with the setActivated method. Here we want to get rid of the IF condition on each and every event between our presenter groups.

Continue Reading 2 comments

When building large applications with GWT, code splitting is a must - otherwise, the entire application (i.e. Javascript bundle) is downloaded in one chunk on the initial load of the application, which is a good recipe for frustrated users! Fortunately, the folks at Google have made the code splitting mechanism extremely simple, and have provided a really handy tool for analyzing and debugging to boot.

Even still, implementing code splitting can be a bit tricky, especially deciding where in your framework to build it in. There are some helpful constructs and patterns out there (e.g. AsyncProxy, Async Provider, etc.), but it’s still not really clear if there is a definitive best practice for code splitting in large applications using GWT MVP. So…for the purpose of (hopefully!) sparking some conversation on this topic, here’s a solution we came up with on a recent project. Please feel free to share your solutions…or any thoughts/criticism you have. Here goes…

Continue Reading 5 comments

Mvp4g is a great library to manage your large GWT application structure. Especially when using MVP where your Presenters talk to each other using events. Without Mvp4g you can follow plain vanilla GWT but you will need to create and manage a set of Handlers and Events to communicate those presenters. And on top of that, you’ll need to manage the registry and instantiation of those presenter instances.

In an application we recently built we used Mvp4g. We had this special requirement that the screen layout was to be built dynamically. That meant we would need to create presenters on the fly, but not only that, there might be multiple instances of a presenter at any given time - e.g. one screen would have two chart components with different supporting data. The presenter responsibility was the same for both, display a bar chart from the under laying data (a simple multi-column query).

Continue Reading 2 comments

As Javascript has become more powerful over the years, user input fields have evolved to be more innovative and intuitive. One particular example is a time-picker, which has been around in JQuery for a while now. Imagine you are working in a room reservation system and you want your user to pick hours and minutes to reserve a room. JQuery has jQuery.timepickr.js.

Continue Reading 12 comments

When creating large web applications with GWT, it’s not always clear how to get started. The most important (but most difficult!) question, I’ve found, is exactly how to structure the project - i.e. what justifies creating multiple web applications, multiple GWT modules, multiple EntryPoints, or everything all in one. Although there is plenty of discussion out there (here, here, here, and here), the general consensus is still a little muddy. Like anything in our business, it seems the “right” answer is “it depends”, and so in this post I hope to highlight a few of the factors in this decision.

Continue Reading 21 comments

The asynchronous nature of GWT makes for more powerful and usable web applications, but as a developer, it can take a little while to get used to. Here’s one example: imagine a scenario where some client-side class needs to call two service operations before it can do something. Simple, right? In a synchronous world, it would be…

Continue Reading 14 comments

In a recent project the interface designer in my team asked whether we could disable the anchor tag (for expand/collapse) on the disclosure panel header and have a single button do the job, helping the user with a hint that this panel is actually expandable. I said OK, let’s see the DisclosurePanel javadoc. Suprise! All you can do is have a header and that itself is surrounded by the clickable anchor… time to extend Composite!

Continue Reading 4 comments

It’s very tempting, given the power and ease of GWT, to jump in head-first and start building flashy new RIA applications for your customers right away. Slow down! Although I’m not generally an advocate of big design up front (BDUF), there are a few usability requirements that I think you’ll want to understand before you start coding – requirements that will fundamentally shape how you design your client-side GWT architecture, and therefore minimize re-work later.

So, toward the goal of evoking usability requirements, here are 6 important questions to ask your users or business owners:

Continue Reading 8 comments

AJAX development requires deeper knowledge in JavaScript and there is a slightly different set of features in different browsers. There are also technologies created out there called JavaScript libraries – such as Ext JS and Yahoo User Interface – and JavaScript toolkits – such as Google Web Toolkit (GWT) and DOJO – that can help you ease the burden. Basically, the libraries’ role is to speed up development for the client side and take care of the browser compatibility holdups. Further, the toolkits offer even more infrastructure providing support for the development and deployment phases.

Continue Reading 3 comments