Information Technology Reference
In-Depth Information
Web Server/Hosted Service : This is a logical container that pres-
ents all machines (web/worker/virtual machine roles) running an
application in Azure. The application can be elastically scaled up
or down and accessed as a service hosted in Azure. In Azure, a
hosted service has been taken as a web server that differs from a
normal web server to constitute a PaaS infrastructure. In Amazon
EC2, this is a machine instance with Apache or, potentially, IIS
under an IaaS deployment.
Storage Account : The application uses the blob storage in Azure and
the Elastic Block Storage in EC2.
Entity Framework Model and Web Services : WCF-RIA domain ser-
vices provide data access to the Silverlight client according to the
application logic running on the web server.
Database Server : SQL Azure has been used to support geospatial data-
bases in Azure.
As described in Section 7.3, the client sends an HTTP request to the server.
The server then processes it and sends a web page to the client, which then
displays a Silverlight map on the screen as shown in Figure 7.4.
Specifically, the user selects a region type—which in turn requires region
spatial data to be requested from the database and displayed on the map.
To accomplish this, the client-side application generates a LINQ (Language
FIGURE 7.4
Main screen of our cloud-based GIS application in Azure.
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