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cache-dotnet-how-to-use-azure-redis-cache.md

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Quickstart: Use Azure Cache for Redis in .NET Framework
In this quickstart, learn how to access Azure Cache for Redis from your .NET apps
flang-msft
franlanglois
cache
csharp
quickstart
devx-track-csharp, mvc, mode-other
03/25/2022

Quickstart: Use Azure Cache for Redis in .NET Framework

In this quickstart, you incorporate Azure Cache for Redis into a .NET Framework app to have access to a secure, dedicated cache that is accessible from any application within Azure. You specifically use the StackExchange.Redis client with C# code in a .NET console app.

Skip to the code on GitHub

Clone the repo from (https://github.com/Azure-Samples/azure-cache-redis-samples/tree/main/quickstart/dotnet on GitHub.

Prerequisites

Create a cache

[!INCLUDE redis-cache-create]

[!INCLUDE redis-cache-access-keys]

  1. Create a file on your computer named CacheSecrets.config and place it C:\AppSecrets\CacheSecrets.config.

  2. Edit the CacheSecrets.config file and add the following contents:

    <appSettings>
    <add key="CacheConnection" value="<host-name>,abortConnect=false,ssl=true,allowAdmin=true,password=<access-key>"/>
</appSettings>

  3. Replace <host-name> with your cache host name.

  4. Replace <access-key> with the primary key for your cache.

  5. Save the file.

Configure the cache client

In this section, you prepare the console application to use the StackExchange.Redis client for .NET.

  1. In Visual Studio, select Tools > NuGet Package Manager > Package Manager Console, and run the following command from the Package Manager Console window.

    Install-Package StackExchange.Redis

  2. Once the installation is completed, the StackExchange.Redis cache client is available to use with your project.

Connect to the Secrets cache

In Visual Studio, open your App.config file to verify it contains an appSettings file attribute that references the CacheSecrets.config file.

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.7.2" />
    </startup>

    <appSettings file="C:\AppSecrets\CacheSecrets.config"></appSettings>
</configuration>

Never store credentials in source code. To keep this sample simple, we use an external secrets config file. A better approach would be to use Azure Key Vault with certificates.

Connect to the cache with RedisConnection

The connection to your cache is managed by the RedisConnection class. The connection is first made in this statement from Program.cs:

     _redisConnection = await RedisConnection.InitializeAsync(connectionString: ConfigurationManager.AppSettings["CacheConnection"].ToString());

The value of the CacheConnection appSetting is used to reference the cache connection string from the Azure portal as the password parameter.

In RedisConnection.cs, you see the StackExchange.Redis namespace with the using keyword. This is needed for the RedisConnection class.

using StackExchange.Redis;

The RedisConnection code ensures that there is always a healthy connection to the cache by managing the ConnectionMultiplexer instance from StackExchange.Redis. The RedisConnection class recreates the connection when a connection is lost and unable to reconnect automatically.

For more information, see StackExchange.Redis and the code in a GitHub repo.

Executing cache commands

In program.cs, you can see the following code for the RunRedisCommandsAsync method in the Program class for the console application:

private static async Task RunRedisCommandsAsync(string prefix)
    {
        // Simple PING command
        Console.WriteLine($"{Environment.NewLine}{prefix}: Cache command: PING");
        RedisResult pingResult = await _redisConnection.BasicRetryAsync(async (db) => await db.ExecuteAsync("PING"));
        Console.WriteLine($"{prefix}: Cache response: {pingResult}");

        // Simple get and put of integral data types into the cache
        string key = "Message";
        string value = "Hello! The cache is working from a .NET console app!";

        Console.WriteLine($"{Environment.NewLine}{prefix}: Cache command: GET {key} via StringGetAsync()");
        RedisValue getMessageResult = await _redisConnection.BasicRetryAsync(async (db) => await db.StringGetAsync(key));
        Console.WriteLine($"{prefix}: Cache response: {getMessageResult}");

        Console.WriteLine($"{Environment.NewLine}{prefix}: Cache command: SET {key} \"{value}\" via StringSetAsync()");
        bool stringSetResult = await _redisConnection.BasicRetryAsync(async (db) => await db.StringSetAsync(key, value));
        Console.WriteLine($"{prefix}: Cache response: {stringSetResult}");

        Console.WriteLine($"{Environment.NewLine}{prefix}: Cache command: GET {key} via StringGetAsync()");
        getMessageResult = await _redisConnection.BasicRetryAsync(async (db) => await db.StringGetAsync(key));
        Console.WriteLine($"{prefix}: Cache response: {getMessageResult}");

        // Store serialized object to cache
        Employee e007 = new Employee("007", "Davide Columbo", 100);
        stringSetResult = await _redisConnection.BasicRetryAsync(async (db) => await db.StringSetAsync("e007", JsonSerializer.Serialize(e007)));
        Console.WriteLine($"{Environment.NewLine}{prefix}: Cache response from storing serialized Employee object: {stringSetResult}");

        // Retrieve serialized object from cache
        getMessageResult = await _redisConnection.BasicRetryAsync(async (db) => await db.StringGetAsync("e007"));
        Employee e007FromCache = JsonSerializer.Deserialize<Employee>(getMessageResult);
        Console.WriteLine($"{prefix}: Deserialized Employee .NET object:{Environment.NewLine}");
        Console.WriteLine($"{prefix}: Employee.Name : {e007FromCache.Name}");
        Console.WriteLine($"{prefix}: Employee.Id   : {e007FromCache.Id}");
        Console.WriteLine($"{prefix}: Employee.Age  : {e007FromCache.Age}{Environment.NewLine}");
    }

Cache items can be stored and retrieved by using the StringSetAsync and StringGetAsync methods.

In the example, you can see the Message key is set to value. The app updated that cached value. The app also executed the PING and command.

Work with .NET objects in the cache

The Redis server stores most data as strings, but these strings can contain many types of data, including serialized binary data, which can be used when storing .NET objects in the cache.

Azure Cache for Redis can cache both .NET objects and primitive data types, but before a .NET object can be cached it must be serialized.

This .NET object serialization is the responsibility of the application developer, and gives the developer flexibility in the choice of the serializer.

One simple way to serialize objects is to use the JsonConvert serialization methods in System.text.Json.

Add the System.text.Json namespace to Visual Studio:

  1. Select Tools > NuGet Package Manager > Package Manager Console*.

  2. Then, run the following command from the Package Manager Console window.

    Install-Package system.text.json

The following Employee class was defined in Program.cs so that the sample could also show how to get and set a serialized object :

class Employee
{
    public string Id { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }

    public Employee(string employeeId, string name, int age)
    {
        Id = employeeId;
        Name = name;
        Age = age;
    }
}

Run the sample

Press Ctrl+F5 to build and run the console app to test serialization of .NET objects.

:::image type="content" source="media/cache-dotnet-core-quickstart/cache-console-app-complete.png" alt-text="Console app completed":::

Clean up resources

If you continuing to the use this quickstart, you can keep the resources created and reuse them.

Otherwise, if you are finished with the quickstart sample application, you can delete the Azure resources created in this quickstart to avoid charges.

Important

Deleting a resource group is irreversible and that the resource group and all the resources in it are permanently deleted. Make sure that you do not accidentally delete the wrong resource group or resources. If you created the resources for hosting this sample inside an existing resource group that contains resources you want to keep, you can delete each resource individually on the left instead of deleting the resource group.

Sign in to the Azure portal and select Resource groups.

In the Filter by name... textbox, type the name of your resource group. The instructions for this article used a resource group named TestResources. On your resource group in the result list, select ... then Delete resource group.

:::image type="content" source="media/cache-dotnet-core-quickstart/cache-delete-resource-group.png" alt-text="Delete":::

You are asked to confirm the deletion of the resource group. Type the name of your resource group to confirm, and select Delete.

After a few moments, the resource group and all of its contained resources are deleted.

Next steps