Thunderhead Explorer

We have been plotting x,y,z and time for a while now. But this is all syntax; Tim Berners-Lee believes that the future of the web is semantics , and I could not agree more. You have a glimpse of it today when you use for example Apple’s Siri . In our GIS space, MetaCarta at one time had a great appliance/service that inferred location from the semantics of a sentence. For example, “Joe ate a Chicago style pizza in downtown Boston”, would return the latitude and longitude of Downtown Boston and would ignore “Chicago” as a location, Impressive! With the explosion of social media and the infusion of geo-locations as ‘fields’ in our records, we are reduced to plotting locations with cute popups. Boring! We humans are quite the emotional animals (some more that others, specially if these humans come from the Middle East :-) and these emotions are quite visible now within our tweets and facebook posts. So, what if I can plot these sentiments, there could be something to “see” in these map...

So….I always wanted to Drag and Drop an external file into a Flex application running in the browser. Well.. you can use the FileReference API to browse and load a file, but I really wanted to DnD. Unfortunately, this is not allowed due to security constraints of the Flash Player. However, using the latest proposed W3C DnD API and the File API , I should be able to use the last two and the AS3 ExternalInterface API to accomplish what I want. So, here is the content of a simple xml file that I would like to DnD and render on a map: <markers> <marker x="45" y="45" label="M 1" info="This is M1"/> <marker x="-45" y="-45" label="M 2" info="This is M2"/> </markers> I modified the HTML wrapper to use the JavaScript DnD and File API (if available) to listening for “dragenter”, “dragover” and “drop” events on the FlashPlayer container. var DnD = { loadHandler:function () { var...

In this post I will demonstrate how to write a Flex mobile application that displays a map with a tiled layer, where the tile source is the unpacked content of a tpk file. A tile package or tpk is generated using ArcMap and is a zip file that contains a couple of configuration files holding tile metadata and a set of ISAM files where the variable length files contain the tile images. The mobile application enables a user to download one or more tpk files from a web server to the local storage and disconnect from the “network” for offline viewing. When the user selects a local tpk, it will be unpacked and a map will render a tiled layer whose tile source is the local file unpacked images, enabling the user to zoom in and out and pan over the available levels as defined in the metadata file. This is possible due to the availability of the ByteArray class in AS3 and the capability to read and write binary files. The application is based on the Holistic Framework and is linked with the ...

The Holistic micro-architecture framework for building RIAs and RMAs (Rich Mobile Applications) "borrows" from Robotlegs , PureMVC , Cairngorm , SWIZ ,  AS3Signals and the SpringFramework . Each has one or two things that I really like about it, but what I wanted is to bring all these things into one simple, very lightweight framework that enables me to quickly and more importantly methodically build mobile, web and desktop applications. This Holistic API is designed to work on top of either the Flex web or mobile framework and takes advantage of the Flex compiler, environment and lifecycle. Several "design patterns" are utilized in the API, such as Model-View-Controller , Loose Coupling, Locator , Usage of Interface, Delegation , Dependency Injection , Separation of Concerns and Inversion Of Control , not sure if some of latter are pure design patterns per GoF , but bear with me :-) One thing that is heavily relied on, is programming to convention versus progr...

So… Google introduced an offline feature to their mobile mapping application, enabling you to view map tiles when you are disconnected from the network. This is pretty neat and very useful now that local storage is so “abundant” on mobile devices. In this post, I would like to show you how to use the mobile device local storage for offline tile retrieval using the ArcGIS API for Flex . When we built the API, we always had the vision of extensibility to enable people to do things that we did not think about. One of then was to enable the control of the URL from where the tiles will be retrieved. A while back, I did such an implementation using Amazon S3 . So, I rehashed that code using Adobe AIR File capabilities. The demo application that I am featuring here operates in two modes; an online mode and an offline mode. In the online mode, I keep a set all downloaded tiles for a particular viewing session. Before I go offline, I download the map server metadata and all the visited tile...

So the Flex Spark architecture promotes the separation of a component model/controller from its view, or in Flex lingo, its skin. Here is the PITA process that I go throughout when creating a skinnable component manually: I create an ActionScript class (the host component) that subclasses SkinnableComponent. I define and annotate the skin parts. I try to define the skin part types to be as high as possible in the class hierarchy. What I mean by that is instead of defining a part to be of type Button, I make it of type ButtonBase. I override the partAdded function and add all the event listeners for each part, as event handling should be done in the host component not in the skin. I override the partRemoved function and remove all the added event listeners, as I want to be a “good citizen”. I create a subclass of Skin and associate it with the host component. I add the skin parts and any graphic elements to make it “pretty”. I “ClassReference” the skin to its host component as ...

The ArcGIS API for Flex is pretty amazing and very powerful, but it is very GIS centric. Flex Programmers have to know for example the difference between mercator and geographical coordinates systems and have to understand the concepts of map layers, etc…. Programmers just want to put dots on maps at a specific latitude and longitude. This is very easy to do say for example using the google map API and folks have been asking for something like that for a while. So, I am please to tell you about an open source project that we have launched on github that is exactly that. A simple mapping API that is based on the core API to enable Flex developers to build mapping applications. The idea to open source the project is to let you see how some high level functions are implemented using the low level API. Here is a quick sample: <?xml version="1.0" encoding="utf-8"?> <s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s=...