Figure 2 illustrates the key functional components of the mobile application and the relationships between them.
Developing Applications for the Cloud on the Microsoft Windows Azure Platform describes the Tailspin back end and Subscriber website architecture, design, and implementation in detail. These components, which run on Windows Azure, enable subscribers to design new surveys and to analyze the responses that the application collects. The book also describes a public website that people can use to complete surveys by using a web browser. The scenario described in this guidance focuses on an application running on the Windows Phone 7 device that provides an additional way for Tailspin to capture survey results.
The Surveys application on the Windows Phone 7 device comprises three components. A user interface (UI) enables the user to complete surveys and perform other tasks. A storage repository holds survey definitions and survey responses. A synchronization compo nent is responsible for downloading survey definitions from the Tailspin back end and for uploading completed survey data.
To enable the Windows Phone 7 application to communicate with the back end, the cloud components now include an API that exposes the functionality that the mobile application requires. Tailspin decided to use Windows Communication Foundation (WCF) REST to transport the data over the network. The Windows Phone 7 application must also authenticate with the back end so that the back end can determine which surveys it should make available to the mobile
client and can track which responses come from which user. In the scenario described in this guidance, the mobile client authenticates with the back end using basic authentication, but it is designed in such a way that it could be extended to accept more sophisticated mechanisms, such as a claims-based approach.
The application uses push notifications to inform the mobile client that there are new surveys available to download. These push notifications will reach the Windows Phone 7 device even when the mobile Surveys application is not running.
The Surveys application also includes a website for mobile clients that it uses to enable the Windows Phone 7 device to download and install the client application from Windows Marketplace. Tailspin plans to use this website to host additional resources, such as help and guidance notes for users of the mobile application.
Later chapters in this guide describe these three components in more detail.
All links in this book are accessible from the book’s online bibliography. The URL to the bibliography can be found in the preface, in the final section, entitled, “Where to Go for More Information.”