Developing for Windows Phone

For Windows Phone 7 and Windows Phone 8 (WP) developers, BrightstarDB provides a fast, schema-less persistent data store, that is easily managed as part of the isolated storage for an app. When running on a phone, all the key features of BrighstarDB are available, including the Data Object Layer and the Entity Framework as well as the RDF Client API. This section covers the main differences with the .NET 4.0 version of BrightstarDB and some important considerations when writing your WP7 app to use BrightstarDB. The SDK provides libraries that are compatible with Windows Phone 7.1 and Windows Phone 8, so all apps you develop with BrightstarDB will need to target that version of the Windows Phone OS.

Data Storage And Connection Strings

When running on WP, BrightstarDB writes its data using the IsolatedStorage APIs. This means that a BrightstarDB store opened within an application will be written into the IsolatedStorage for that application. This keeps the stores used by different applications separate from each other. An application can also use multiple stores, as long as each store has a unique store name. As the BrightstarDB server is not running on the phone, the only access to the store is by using the embedded connection type. A typical connection string used in a WP application is shown in the code snippet below::

var connectionString = "type=embedded;storesdirectory=brightstar;storename=MyAppStore";

SDK Libraries

The BrightstarDB libraries for WP are all contained in [INSTALLDIR]\SDK\WP71. You need to add references to these libraries to your WP application project.

Development Considerations

For the most part, working with BrightstarDB on Windows Phone is the same as working with it on the full .NET Framework. However due to the platform and some .NET restrictions there are a few things that you need to keep in mind when building your application.

Store Shutdown

Because BrightstarDB uses separate threads to process updates to its stores, it is necessary for any WP app that uses BrightstarDB to cleanly shutdown the database when the application is not in use. The easiest way to achieve this is to add code to the Application_Deactivated and Application_Closing methods in the main application class as shown below. There is no corresponding global startup required as BrightstarDB will automatically start the required threads the first time you access a store.

// Code to execute when the application is deactivated (sent to background)
// This code will not execute when the application is closing
private void Application_Deactivated(object sender, DeactivatedEventArgs e)
{
    BrightstarService.Shutdown(true);
}


// Code to execute when the application is closing (eg, user hit Back)
// This code will not execute when the application is deactivated
private void Application_Closing(object sender, ClosingEventArgs e)
{
    BrightstarService.Shutdown(true);
}

EntityFramework Interfaces Must Be Public

Due to differences between the .NET Framework and Silverlight, there are is one known limitation on the Entity Framework. All interfaces that are marked with the [Entity] attribute must be public interfaces when building a Windows Phone application. This is because Silverlight prevents reflection on internal classes / interfaces for reasons of code security.

Deploying a Reference Store

As well as using BrightstarDB to store user-modifiable data, you can also ship reference data with your application. A BrightstarDB reference store can be embedded as part of your application content and deployed to the Isolated Storage on the mobile device. Once deployed, the store can be queried and/or updated through your code as normal. The basic steps to deploying a store in a mobile application are as follows:

1. Create the reference store
2. Add the reference store files to your application and compile it
3. Deploy the application to the device
4. At runtime, copy the reference store files from the application directory to Isolated Storage
5. Access the copied store from your code

Create The Reference Store

BrightstarDB stores are fully portable between the desktop and a mobile device through simple file copy. You can create and update a BrightstarDB database using a .NET application on a desktop workstation or a server and use the database files on a mobile device without the need for any conversion.

Note

If the database you are deploying has been through a number of update transactions you may want to consider creating a coalesced copy of the database for deployment purposes. Coalescing the database will reduce the database size by copying only the current state of the database and removing all the historical states of the data.

Add Database File To Your Application

Every BrightstarDB store exists in its own folder and contains at least the following files:

• master.bs
• data.bs
• resources.bs
• transactionheaders.bs
• transactions.bs

For normal operation you only need to add the master.bs, resources.bs and data.bs files to your solution. The transactionheaders.bs and transactions.bs files are required only if your application will need to replay the transactions that built the database.

To add the reference database to your application

1. With Visual Studio, create a project for the Windows Phone application that consumes the reference store.
2. From the Project menu of the application, select Add Existing Item.
3. From the Add Existing Item menu, select the master.bs file for the BrightstarDB store that you want to add, then click Add. This will add the local file to the project.
4. In Solution Explorer, right-click the local file and set the file properties so that the file is built as Content and always copied to the output directory (Copy always).
5. Repeat steps 3 and 4 for the data.bs file and resources.bs file
6. Optionally repeat steps 3 and 4 for transactionheaders.bs and transactions.bs

Note

It is good practice to put the BrightstarDB data files you are copying into a folder under your project. If you want to deploy multiple reference databases, you will have to put the files for each store in a separate folder to avoid name clashes. The folders you define in your project will be mirrored in the installation directory when the application is deployed.

Deploy Application

Compile and deploy your application as normal. The store files you have copied will be available in the installation directory of the application (under the folders that you created in the project if applicable).

Copy Database Files To Isolated Storage

BrightstarDB on a mobile device will only access stores from a named directory in the application’s Isolated Storage. It is therefore necessary when your application starts up to ensure that the data is copied or moved to Isolated Storage. Each BrightstarDB store you deploy must be in its own named directory, and those directories must in turn be in a named directory under the Isolated Storage root folder. These directory names are important as they form the values in the connection string you provide to BrightstarDB. The directory structure used by the sample application is shown below:

IsolatedStorageFile Root
|
+-brightstar    <-- the storesDirectory value in the connection string, create a sub
  |                 create one sub-directory for each store you want to access
  |
  +-dining      <-- the storeName value in the connection string,
                    only the files for a single store should go in here

The precise way you choose to deploy or update the BrightstarDB store files is up to you, but the simplest method (as shown in the sample code) is to check for the presence of the store and if it is not there, copy the files from the application installation directory to Isolated Storage. The code to do this in the sample can be found in the App() constructor in the App.xaml.cs file:

if (!BrightstarDbDeploymentHelper.StoreExists("brightstar", "dining"))
{
    BrightstarDbDeploymentHelper.CopyStore("data", "brightstar", "dining");
}

The helper class can also be found in the sample project and has the following methods:

public static class BrightstarDbDeploymentHelper
{
    public static bool StoreExists(string storeDirectoryName, string storeName)
    {
        IsolatedStorageFile iso = IsolatedStorageFile.GetUserStoreForApplication();
        return iso.DirectoryExists(storeDirectoryName + "\\\\" + storeName) &&
               iso.FileExists(storeDirectoryName + "\\\\" + storeName + "\\\\master.bs") &&
               iso.FileExists(storeDirectoryName + "\\\\" + storeName + "\\\\resources.bs") &&
               iso.FileExists(storeDirectoryName + "\\\\" + storeName + "\\\\data.bs");
    }


    public static void CopyStore(string resourceFolderPath,
                                 string storeDirectoryName,
                                 string storeName)
    {
        IsolatedStorageFile iso = IsolatedStorageFile.GetUserStoreForApplication();
        CopyStoreFile(iso, "data.bs", resourceFolderPath, storeDirectoryName, storeName);
        CopyStoreFile(iso, "master.bs", resourceFolderPath, storeDirectoryName, storeName);
        CopyStoreFile(iso, "resources.bs", resourceFolderPath, storeDirectoryName, storeName);
    }


    private static void CopyStoreFile(IsolatedStorageFile iso, string fileName,
                                      string resourceFolderPath,
                                      string storeDirectoryName, string storeName)
    {
        if (!iso.DirectoryExists(storeDirectoryName))
        {
            iso.CreateDirectory(storeDirectoryName);
        }
        if (!iso.DirectoryExists(storeDirectoryName + "\\\\" + storeName))
        {
            iso.CreateDirectory(storeDirectoryName + "\\\\" + storeName);
        }


        // Create a stream for the file in the installation folder.
        var appResource =
            Application.GetResourceStream(
              new Uri(resourceFolderPath + "\\\\" + fileName, UriKind.Relative));
        if (appResource != null)
        {
            using (Stream input = appResource.Stream)
            {
                // Create a stream for the new file in isolated storage.
                using (
                    IsolatedStorageFileStream output =
                        iso.CreateFile(storeDirectoryName + "\\\\" + storeName + "\\\\" + fileName))
                {
                    // Initialize the buffer.
                    var readBuffer = new byte[4096];
                    int bytesRead = -1;
                    // Copy the file from the installation folder to isolated storage.
                    while ((bytesRead = input.Read(readBuffer, 0, readBuffer.Length)) > 0)
                    {
                        output.Write(readBuffer, 0, bytesRead);
                    }
                }
            }
        }
        else
        {
            // There is no application resource for this file, so create it as an empty file

            iso.CreateFile(storeDirectoryName + "\\\\" + storeName + "\\\\" + fileName).Close();
        }
    }
}

Access Reference Database Files

Once deployed to Isolated Storage, the BrightstarDB store can be accessed as normal. You can use the RDF API, DataObjects API or EntityFramework to access the data depending on your application requirements. The connection string used to access the store is as follows:

type=embedded;storesDirectory={path to directory containing store directories};storeName={name of store directory}

With our sample application, the store is contained in a directory named “dining”, which is itself contained in a directory named “brightstar”, so the full connection string is:

type=embedded;storesDirectory=brightstar;storeName=dining

When the sample application runs, you should see a listing of top restaurants generated from a LINQ query against the EntityFramework.