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Using Arc2Earth for Tile Caching across Air Gapped Networks
Zekiah supports many organizations, especially in the federal government, that have a need to run ArcGIS Server on networks that are not connected to the internet. Oftentimes, these organizations use tiled basemaps that are built from data or services that are available (whether free or by subscription) from the internet. While ArcGIS Server can produce these tile caches, organizations with production servers on disconnected networks can find it impractical to do so. Although the cost of running two ArcGIS Servers is sometimes a factor, we find more often that IT and information security policies make it difficult for these organizations to stand up servers on internet-connected networks. In such situations, a desktop solution is preferable.
In August of 2010, Arc2Earth expanded the ability of their ArcGIS Desktop extension to generate tile caches that are compatible with ArcGIS Server. This development presented an efficient solution to this problem of jumping an air gap to maintain tile caches on disconnected networks. Using Arc2Earth, an organization can generate a tile cache using their internet connected desktop and then move it to their disconnected network to be hosted on their ArcGIS Server. This approach allows the use of the familiar tools and powerful cartographic capabilities of ArcMap for designing the basemap as well as the generation of the final cache.
The following steps show how use Arc2Earth to generate a tile cache for ArcGIS Server and host the cache on your disconnected network:
- To try out Arc2Earth to see if it might be right for you go to: http://www.arc2earth.com/communityedition/ and register for the community edition. Then download the software from: http://www.arc2earth.com/products/download/. Once downloaded, run the executable, and the next time you launch ArcMap the toolbar will be visible.
Arc2Earth cuts tiles in a WGS84 Web Mercator Auxiliary Sphere projection. I find it good practice to start out by setting your map projection with the same projection. Using ArcMap open a map that you would like to cache, then set your data frame properties accordingly.
On the Arc2Earth Toolbar, click the “Export” tab and set up the process using the parameters that are suitable for your mapping environment. You’ll see that the tool has the capability to cut tiles in many formats other than ArcGIS Server. If you are using ArcGIS Server, it’s important to set the “Map Name” to be “Layers” if it’s not already. ArcGIS Server requires the folder structure to be a certain way, and “Layers” will define it properly.
Once the process completes, click “close”
Now that Arc2Earth has successfully cut the tiles, the files need to be moved to your production network. I’ve tested several methods for copying a cache, and have found that an app called FastCopy (http://ipmsg.org/tools/fastcopy.html.en) works the best (I’ll provide more information on this in a future post). Copy the files to an external hard drive (or similar media) in order to bridge the gap between the isolated networks. Once loaded to the drive, offload to the appropriate location that is preconfigured for ArcGIS server caches to reside (i.e. share created, permissions set, virtual directories created in IIS, etc.). Pay close attention to folder structure when loading.
- Now publish a service that’ll pick up the cache that has been loaded. Using ArcGIS Server Manager or ArcCatalog make an administrative connection to ArcGIS Server.
Once published, the service should recognize the cache that you copied. If you click on the “cache” tab in the service properties, it should look like this:
Now the cache is ready to be deployed in a thick or thin client application.
That’s the full process. In my experience, any time you are developing your cache on a system that’s not physically connected to the production environment, Arc2Earth can really help. Examples of such situations are:
- Secure networks that are physically disconnected from the internet.
- Stand-alone development environments within your office or elsewhere, such as test-beds or virtualized environments.
- Delivery of tile caches by data providers that may not have a need for ArcGIS Server to off-site customers who are running ArcGIS Server.
The approach described above has been useful in supporting our customers who, for various reasons, need to generate tile caches in one location and then move them to another. This post did not address some of the more advanced features of Arc2Earth Desktop, such as change detection and multiple tile cutters, which can really optimize the generation and maintenance of large tile caches.
We have found Arc2Earth to be a powerful and economical way to extend the value of our customers’ investments in ArcGIS Desktop and to support their unique data production and maintenance workflows.
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