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This article is based on a presentation that I made at the Adobe Flex seminar in August 2006 (www.flexseminar.com/), after which the master of ceremonies Jeremy Geelan asked me to explain how to make great mapping mashups using Adobe Flex.

My name is Mansour Raad. I'm the senior software architect of ESRI's ArcWeb Services. ESRI (www.esri.com) is a provider of Geographic Information Systems (GIS). On any given day, more than one million people around the world use ESRI's GIS to improve the way their organizations conduct business.

A geographic information system is a system for management, analysis, and display of geographic knowledge, which is represented using a series of information sets such as maps and globes, geographic data sets, processing and work flow models, data models, and metadata. A GIS can produce information that answers specific questions and allows you to share that information with others. By visualizing relationships, con-nections, and patterns in data, you can make informed decisions and increase efficiency throughout your organization.

ArcWeb Services are GIS Web services that are hosted by ESRI and uses ESRI's software and best-of-breed geographic data. Basically, we have created Web services out of our geographic processing engines and made these available for commercial consumption.

In other words, there is no software to install and no data to maintain. We take care of that for you by providing a 7 by 24, 99.9% uptime in two geographically separate data centers. The system currently produces over six million maps per day. And, ArcWeb Services offers much more than just street maps. We can give you aerial photos, satellite pictures, shaded reliefs, topographic, demographic, thematic, business listings. Some of the data such as satellite pictures are static, others are dynamic such as traffic, weather and current earthquake locations and magnitudes. Using our portal application at www.arcwebservices.com, you can create custom map styles by layering data using your own cartographic criteria. That is part of the beauty of our system: we not only host our data, but we can host your data too. You can upload your own address points, lines and areas of interest.

When it comes to geo-processing mashups, ArcWeb Services also provides capa-bilities to locate places such as "London", points of interest such a "Disneyland", dot domain names such as www.esri.com, or Internet Protocol (IP) addresses such as 63.241.153.171. The latter is perfect for creating mashups of locations derived from firewall attack logs, or finding the locations of prospective buyers that are surfing the net to purchase a home.

In addition, if you're a Sprint or a Canada Bell Mobility user and have granted access to the location of your cell phone, we have Web services that enable applications to locate you via GPS or tower triangulation. As you can see, these services are international in their scope. We also provide more than "A-to-B" routing. Our enhanced Web services give you directions and path geometries for a multi-stop route, and they can solve routes for the least distance or time while avoiding specific barriers and traffic locations.

With ArcWeb Services, you can mash up live data (such as traffic) and static data (points) and inject time constraints. For example, if you need to be at this location between 10 and 11 a.m. and at this other location between 1 and 2 p,m., you will get the best route that considers all stops based on current traffic conditions and where you are right now!

The services that we provide are more than just a simple "where is the nearest pizza shop"; for example. ArcWeb Services provides drive time and drive distance solutions. Here is a perfect, if dramatic, example. An Amber Alert is reported at a specific location and you need to rapidly find the half-hour, one-hour and a two-hour drive-time destinations from that location that will intersect major and minor highways so officers can be dispatched for road blocks (see Figure 1). I hope that none of us have to do this search, but you can see that there is a lot of expressiveness in our services and data and it has to come out somehow, and thus enters Adobe Flex. "Finally" you say after this soapbox speech.

To best experience what I have just described, just open a browser and go to www.arcwebservices.com/awx/index.jsp. There, you will see a Flex-based application that is hosted by ESRI. We have been using Flex since the first beta. One of the things that attracted us to Flex is the fact that it's a Java-based Web application. You can run it in Apache Tomcat; just take the .war file and drop it in the webapps directory and voila.

The second impressive point about Flex is the abundance and range of built-in, rich client-side widgets such as trees and tables. As a developer, I don't have to build these items from scratch, and instead put my energy into creating Rich Internet Applications like the ArcWeb Explorer application that you opened.

Another of Flex's strong points is the integrated support of Web services. Since ArcWeb Services is a Web-based service, this feature is imperative for our development initiatives. Let me walk you through an example. If you still have the ArcWeb Explorer open, you have a map of the world in front of you. Let's switch to a satellite view. Click on the "Map Types" top menu element and a widget will show up. Click on the satellite icon, and the map should switch to a tiled satellite view. Dispose of the widget by click-ing on the top left X. I love the dispose effect, which is one of the many cool effects of Flex. Now, you can hold down the left-mouse button and pan the map around. You can quickly zoom to an area of interest by holding down the shift key and dragging the mouse while holding down the left button. Hold down the right-mouse button, and select "World Map" to see the full world again. Select the "Find" menu item. A single line input widget should show up. Click on the computer icon to invoke the IP search Web service to locate yourself (most likely, your ISP provider) on the map. Mouse over the map marker and click on the globe icon to get more information about your location. Cool, or what?

Next, click the "Clear" button on the Find widget and type 909 793 2853 (ESRI phone number) and click Go. A phone marker should appear on the map. Next, erase the 909 number and type "Disneyland" (no quotes) and hit enter. The map should center onto Disneyland. Now, let's say that you want to get the directions from 909 793 2853 to Disneyland. Click the "Directions" menu item to get the directions widget. From the Find widget, select the row with the telephone icon by clicking on it; while holding down the left-mouse button, drag it on top of the Directions widget and let go (Drag and Drop is just one of the many built-in behaviors in Flex). Do the same for the Disneyland row and click Go in Directions. Isn't this how it is supposed to be? The directions should appear and the map is updated with the route. Since this is a Rich Internet Application, the data is transferred and resides on the client side. This can be seen by moving the mouse over any section of the route where a tooltip will appear and give information about that section without a round-trip to the server.

Clear the directions and dispose of the Directions widget and let's get some census information about the area around ESRI. Drag-and-drop that 909 telephone number from the Find widget onto the map. This will automatically center the map. Click the Reports menu element and the Reports widget will show up. Click "Use Map Center" as the location and a two-mile radius for a report area definition. Click on "Get Report". This will invoke the report Web service, which will send back a PDF document summarizing the 2000 census information. Again, this is cool.

Now that you have learned how to manually do all these cool things in Flex, I will show you how to do them programmatically. In addition to the SOAP interface, we provided a REST and a JavaScript-based API for mashup purposes and for people who think that SOAP is too "heavy." The documentation of the REST API can be found at www.arcwebservices.com/v2006/help/index.htm#rest/samples.htm. URLs are cre-ated with parameters to create maps in Flash format. You can create apps with very little coding that pan as well as zoom in and out. You can acetate lines, points, and polygons. In addition, legends and north arrows can be specified for authentic cartographic representation. And, because the geographic data is vector based and generated on the fly, a user can specify a map projection for distance or area fidelity based on the center of the view in latitude and longitude. An example of what I have just described can be found at: Click Here!.

If you are interested in experimenting with different parameters, I included a refer-ence to the source code of a Flex 2-based application that you can download in the re-sources section. Compile the application using the Flex2 SDK (www.adobe.com/products/flex). This will produce a swf file that you can load in a browser with the ubiquitous Flash player.

Now for great mapping mashups. From Wikipedia: "A mashup is a Website or a Web 2.0 application that uses content from more than one source to create a completely new service." What does that mean in terms of Flex, ArcWeb Services and you? Your data (residing on your server) published in XML format from an HTTP/GET request can be placed, or mashed up on top of map generated from ArcWeb Services in an expressive Flash/Flex-based client application. Your data can be persistent in a flat file or an RDBMS, and it can be extracted using a .NET ASP, ColdFusion, or JSP application that is called from the browser client application and converts it to markers on the map.

Let me illustrate the power of mashup in a somewhat dramatic personal account. Back in July and August 2006, the news from the Middle East was dominated by the war in Lebanon between Israel and Hezbollah. I followed the war from a text-only blog that detailed the events minute-by-minute and where they occurred (see Figure 2). I thought it would be more expressive if I could screen-scrape this text information and send it to ArcWeb Services for geo-tagging and totally mutate the page to display a new page with a spatial widget and temporal widget. The spatial widget (the map) can show me where events are happening, and the temporal widget will give me their sequence. Then I wondered: What if I could click on one widget and get info from the other. Would I see patterns? Now this type of application is really expressive and much more informative! Mashup really change your perspective.

Using the Aardvak Firefox extension (http://karmatics.com/aardvark/), I drilled down to the HTML section on the page that contained the to-be screen-scraped info. It con-sisted of an unorder list element (ul) with list item (li) children tags. The text in the li tag consisted of a timestamp followed by a description of the event and sometimes where the event occurred (for example, 6:01 Exchanges of fire between Israel Defense Force (IDF) and Hezbollah continue in Bint Jabail).

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