Web GIS Lab 3

Goal and Background

The goal of this lab was to introduce us to building Web GIS applications with the Web AppBuilder for ArcGIS. We created and application, authored it and added our own services, configured and brought in customized widgets and then deployed the web app for use by an end user. Thinking about the amount of coding that is going on in the background of the app is another goal of this lab. In the app builder we don't have to do any coding but in upcoming labs we will be doing some of the coding that is needed to make a web app function properly.

Methods

Part 1 Building web GIS apps through Web AppBuilder Integrated Edition

You have been employed by Virtual Geospatial Analytics and you are tasked with creating a web GIS applicatruion that displays historic earthwuakes ad hurricanes to the public, Your supervisor wants the web GIS app to be able to perform the following:

• Provide pop-up windows to show the earthquakes and hurricanes.
• Zoom to the entire United States in its initial view
• Provide bookmarks so that users can easily zoom to predefined areas
• Allow users to chart and compare the selected attributes of selected earthquakes
• Allow  users to query for features based on their attributes
• Display appropriate logo, title, subtitle, add links in the banner
• Allow users to update recent earthquake information through batch editing

This was the scenario we were given for the first part of the lab by Dr. Wilson. The first step to completing this task was downloading data provided by Dr. Wilson. We then logged into ArcGIS Online and began creating a web app using Web AppBuilder. Create a new app and then bring in the web map created last week containing the hurricane and earthquakes features. This will serve as the map for the web app. Then we started to add widgets to the app. Widgets are tabs that allow the end user to complete additional tasks in the app. In our app we added the base map widget which allows the end user to switch between base maps like the imagery or topographic base map. The measurement widget allows the end user to measure the distance from one point to the another on the map. The bookmark widget allows the end user to set a certain zoom over a place on the map for easy access to that area in the future. All these widgets are very easy to add and use while at the same time dramatically increasing the interaction capabilities of the map. After the widgets are added.you can select a format that you want your map to display in. You can chose from PC, to iPhone, tablets or many other formats. Some additional widgets were added later on in the process. The chart widget allows a user to select some of the earthquakes and it displays attributes such as magnitude and depth in a bar chart for easy comparison. The query widget allows the user to select earthquakes based on attributes such as magnitudes, year it occurred, and other attributes. It makes finding a specific size or date of a earthquake easy to find. You also have widgets showing the layers of the map that you can turn on and off as well as a draw widget where the user can draw on the map if they chose to do so. That was the first part of the lab just creating a pretty simple easy to use web app with widgets. Figure 1 is that web app.

Figure 1 This is the first web map with the majority of the widgets in it.
Click the image to view the app.

Part 2 Customizing Web AppBuilder for ArcGIS (Developer Edition)

For the first part of the lab we were able to work on ArcGIS Online to create our web app but for this portion of the lab we worked on a local computer. In order to do this we used a program called node.js. Web AppBuilder is a program installed on the computers as part of the ESRI software package. The first step is too give AppBuilder a URL from which it can access your ArcGIS Online material. Then you go onto ArcGIS Online and create a new app and match the URL to the one you gave AppBuilder so that Appbuilder can access the app. This will give you an app ID which gives you access to the app. The app will be launched in a new browser window and it will ask for access to my ArcGIS Online enterprise account. I approve that and it launches AppBuilder. When it opens I then imported the web app I created in the first part of the lab. Once it is imported we can go ahead and begin making edits to it. Again we added widgets to the map. This time however this is a fully custom widget that is not in the program. It is called the Batch Attribute Editor widget. This widget allows the end user to make edits to some of the data on the map. In this case they are able to edit the location information of all of the earthquakes on the map.Right now the locations are pretty vague but if an end user wants to spend some time and make them more specific they have the ability to do so. This makes crowd sourcing available in the app. After this widget was added the next step is to save the app data on the local computer. To do this you download a zip with all the app info in it and map a network drive where you then connect to a server and paste the app info there. When the app is launched in a browser window this is where the URL path leads for the app information. This web app is hosted on a local computer which means it can not be opened on the internet unless you are on that computer. For that reason I can not put a link to it here.

Sources

Fu, Pinde (2015). HERE, Census at:   

 \\EsriPress\GTKWebGIS\Chapter3\Data.gdb\Earthquakes, courtesy of USGS National Atlas. \\EsriPress\GTKWebGIS\Chapter3\Data.gdb\Hurricanes, courtesy of NOAA National Climatic Data Center.