# Source: https://raw.githubusercontent.com/ServiceStack/docs.servicestack.net/refs/heads/main/MyApp/_pages/caching.md

---
slug: caching
title: Caching Providers
---

As caching is an essential technology in the development of high-performance web services, ServiceStack has a number of different caching options available that each share the same
[common client interface (ICacheClient)](https://github.com/ServiceStack/ServiceStack/blob/master/src/ServiceStack.Interfaces/Caching/ICacheClient.cs)
for the following cache providers:

* [Memory Cache](https://github.com/ServiceStack/ServiceStack/blob/master/src/ServiceStack/Caching/MemoryCacheClient.cs) - Useful for single host web services without needing any infrastructure dependencies.
* [Redis](https://github.com/ServiceStack/ServiceStack.Redis) - A fast key-value store with non-volatile persistent storage and support for rich comp-sci data structures.
* [OrmLiteCacheClient](https://www.nuget.org/packages/ServiceStack.Server) - Supports all [OrmLite's RDBMS providers](/ormlite/) for using an existing RDBMS as a distributed cache.
* [Memcached](https://nuget.org/packages/ServiceStack.Caching.Memcached) - The original, tried and tested distributed memory caching provider.
* [Aws DynamoDB](https://www.nuget.org/packages/ServiceStack.Aws/) - Uses Amazon's Dynamo DB backend hosted on Amazon Web Services
* [Azure Table Storage](/azure#virtual-filesystem-backed-by-azure-blob-storage) - Uses Azure Table Storage for when your application is hosted on Azure.

### Async Cache Clients

All remote Caching Providers also implement the [ICacheClientAsync](https://github.com/ServiceStack/ServiceStack/blob/master/src/ServiceStack.Interfaces/Caching/ICacheClientAsync.cs) async APIs whilst any other `ICacheClient` only providers like the local in-memory `MemoryCacheClient` are still able to use the `ICacheClientAsync` interface as they'll return an [Async Wrapper](https://github.com/ServiceStack/ServiceStack/blob/master/src/ServiceStack/Caching/CacheClientAsyncWrapper.cs) over the underlying sync APIs. 

So even if you're currently only using `MemoryCacheClient` or your own `ICacheClient` sync implementation, you can still use the async Caching Provider API now and easily switch to an async caching provider in future without code changes.

The Async Caching Provider APIs are accessible via the `CacheAsync` property in ServiceStack `Service` or `ServiceStackController` classes, e.g:

```csharp
public async Task<object> Any(MyRequest request)
{
    var item = await CacheAsync.GetAsync<Item>("key");
    //....
}

public class HomeController : ServiceStackController
{
    public async Task<ActionResult> Index()
    {
        var item = await CacheAsync.GetAsync<Item>("key");
    }
}
```

Whilst outside of ServiceStack you can `AppHost.GetCacheClientAsync()`, e.g:

```csharp
var cache = HostContext.AppHost.GetCacheClientAsync();
var item = await cache.GetAsync<Item>("key");
```

### Configure Caching Providers

To configure which cache should be used, the particular client has to be registered in the IoC container against the `ICacheClient` interface:

### Memory cache:

By default ServiceStack registers an MemoryCacheClient by default when no `ICacheClient` is registered so no registration is necessary.

```csharp
//services.AddSingleton<ICacheClient>(new MemoryCacheClient());
```

Even if you have an alternative `ICacheClient` registered you can still access the in memory cache via the `LocalCache` property in your Services
and ServiceStack MVC Controllers or anywhere else via the `HostContext.AppHost.GetMemoryCacheClient()` singleton as well as
`[CacheResponse(UseLocalCache=true)]` when using the [Cache Response Attribute](/cacheresponse-attribute).

### Redis

```csharp
services.AddSingleton<IRedisClientsManager>(c => 
    new RedisManagerPool("localhost:6379"));

services.AddSingleton(c => c.GetRequiredService<IRedisClientsManager>().GetCacheClient());
```

##### NuGet Package: [ServiceStack.Redis](http://www.nuget.org/packages/ServiceStack.Redis)

### OrmLite

```csharp
//Register OrmLite Db Factory if not already
services.AddSingleton<IDbConnectionFactory>(c => 
    new OrmLiteConnectionFactory(connString, SqlServerDialect.Provider));

services.AddSingleton<ICacheClient, OrmLiteCacheClient>();

//Create 'CacheEntry' RDBMS table if it doesn't exist already
appHost.Resolve<ICacheClient>().InitSchema(); 
```

#### SQL Server Memory Optimized Cache

SQL Server's Memory Optimized support can be used to improve the performance of `OrmLiteCacheClient` 
by configuring it to use the above In Memory Table Schema instead, e.g:

```csharp
services.AddSingleton<ICacheClient>(c => 
    new OrmLiteCacheClient<SqlServerMemoryOptimizedCacheEntry>());
```

##### NuGet Package: [ServiceStack.Server](http://www.nuget.org/packages/ServiceStack.Server)

### Memcached

```csharp
services.AddSingleton<ICacheClient>(
    new MemcachedClientCache(new[] { "127.0.0.0" }); //Add Memcached hosts
```

##### NuGet Package: [ServiceStack.Caching.Memcached](http://www.nuget.org/packages/ServiceStack.Caching.Memcached)

### AWS DynamoDB

```csharp
var awsDb = new AmazonDynamoDBClient(
    AWS_ACCESS_KEY, AWS_SECRET_KEY, RegionEndpoint.USEast1);

services.AddSingleton<IPocoDynamo>(new PocoDynamo(awsDb));
services.AddSingleton<ICacheClient>(c => 
    new DynamoDbCacheClient(c.GetRequiredService<IPocoDynamo>()));

var cache = appHost.Resolve<ICacheClient>();
cache.InitSchema();
```

##### NuGet Package: [ServiceStack.Aws](http://www.nuget.org/packages/ServiceStack.Aws)

### Azure:

```csharp
services.AddSingleton<ICacheClient>(new AzureTableCacheClient(cacheConnStr));
```

##### NuGet Package: [ServiceStack.Azure](http://www.nuget.org/packages/ServiceStack.Azure)

### Multi CacheClient

The `MultiCacheClient` can be used to utilize a write-through multi-tiered cache client where all "writes" are made to all
registered cache providers whilst "reads" are only accessed until a value exists. E.g. you can register a local memory
and redis server backed Cache Client with:

```csharp
services.AddSingleton<ICacheClient>(c => new MultiCacheClient(
    new MemoryCacheClient(),
    c.GetRequiredService<IRedisClientsManager>().GetCacheClient()));
```

## Cache a response of a service

To cache a response you simply have to call `ToOptimizedResultUsingCache` which is an extension method existing in `ServiceStack.ServiceHost`.

In your service:

```csharp
public class OrdersService : Service
{
    public object Get(CachedOrders request)
    {
        var cacheKey = "unique_key_for_this_request";
        return base.Request.ToOptimizedResultUsingCache(base.Cache,cacheKey,()=> 
            {
                //Delegate is executed if item doesn't exist in cache 
                //Any response DTO returned here will be cached automatically
            });
    }
}
```

::: info Tip
There exists a class named [UrnId](https://github.com/ServiceStack/ServiceStack/blob/master/src/ServiceStack.Common/UrnId.cs) which provides helper methods to create unique keys for an object
:::

`ToOptimizedResultUsingCache` also has an overload which provides a parameter to set the timespan when the cache should be deleted (marked as expired). If now a client calls the same service method a second time and the cache expired, the provided delegate, which returns the response DTO, will be executed a second time.

```csharp
var cacheKey = "some_unique_key";
//Cache should be deleted in 1h
var expireInTimeSpan = new TimeSpan(1, 0, 0);
return base.Request.ToOptimizedResultUsingCache(
    base.Cache, cacheKey, expireInTimeSpan, ...)
```

## Delete cached responses

If now for example an order gets updated and the order was cached before the update, the webservice will still return the same result, because the cache doesn't know that the order has been updated.

So there are two options:

* Use **time based** caching (and expire cache earlier)
* Cache on **validity**

::: info
When the cache is based on **validity** the caches are invalidated manually (e.g. when a user modified his profile, > clear his cache) which means you always get the latest version and you never need to hit the database again to rehydrate the cache if it hasn't changed, which will save resources
:::

So if the order gets updated, you should delete the cache manually:

```csharp
public class CachedOrdersService : Service
{
    public async Task Put(CachedOrders request)
    {
        //The order gets updated...
        var cacheKey = "some_unique_key_for_order";
        await CacheAsync.ClearCachesAsync(cacheKey);
    }
}
```

If now the client calls the web service to request the order, he'll get the latest version.

### LocalCache

As it sometimes beneficial to have access to a local in-memory Cache in addition to your registered `ICacheClient`
[Caching Provider](/caching) we also pre-register a `MemoryCacheClient` that all your Services now have access to from the `LocalCache`
property, i.e:

```csharp
MemoryCacheClient LocalCache { get; }
```

This doesn't affect any existing functionality that utilizes a cache like Sessions which continue to use
your registered `ICacheClient`, but it does let you change which cache you want different responses to use, e.g: 

```csharp
var cacheKey = "unique_key_for_this_request";
return base.Request.ToOptimizedResultUsingCache(LocalCache, cacheKey, () => {
    //Delegate is executed if item doesn't exist in cache 
});
```

Or if you're using the [CacheResponse](/cacheresponse-attribute) attribute you can specify to cache responses in the local cache with:

```csharp
[CacheResponse(LocalCache = true)]
public object Any(MyRequest request) { ... }
```

::: info
If you don't register a `ICacheClient` ServiceStack automatically registers a `MemoryCacheClient` for you 
which will also refer to the same instance registered for `LocalCache`
:::

## [ICacheClientExtended](https://github.com/ServiceStack/ServiceStack/blob/master/src/ServiceStack.Interfaces/Caching/ICacheClientExtended.cs)

The [ICacheClientExtended](https://github.com/ServiceStack/ServiceStack/blob/master/src/ServiceStack.Interfaces/Caching/ICacheClientExtended.cs)
API is used to to provide additional non-core functionality to our most popular 
[Caching providers](/caching):

* Redis
* OrmLite RDBMS
* In Memory
* AWS
* Azure

The new API's are added as Extension methods on `ICacheClient` so they're easily accessible without casting, the new API's available include:
  
* GetKeysByPattern(pattern) - return keys matching a wildcard pattern
* GetAllKeys() - return all keys in the caching provider
* GetKeysStartingWith() - Streaming API to return all keys Starting with a prefix

With these new API's you can now easily get all active User Sessions using any of the supported Caching providers above with:

```csharp
var sessionPattern = IdUtils.CreateUrn<IAuthSession>(""); //= urn:iauthsession:
var sessionKeys = Cache.GetKeysStartingWith(sessionPattern).ToList();

var allSessions = Cache.GetAll<IAuthSession>(sessionKeys);
```

### CacheClient with Prefix

The `CacheClientWithPrefix` class lets you decorate any `ICacheClient` to prefix all cache keys using the `.WithPrefix()` extension method. This could be used to easily enable multi-tenant usage of a single redis instance, e.g:

```csharp
services.AddSingleton(c => 
    c.GetRequiredService<IRedisClientsManager>().GetCacheClient().WithPrefix("site1"));
```

## Live Example and code

A live demo of the ICacheClient is available in [The ServiceStack.Northwind's example project](https://northwind.netcore.io/). Here are some requests to cached services:

* [/customers](https://northwind.netcore.io/cached/customers)
* [/customers/ALFKI](https://northwind.netcore.io/cached/customers/ALFKI)
* [/customers/ALFKI/orders](https://northwind.netcore.io/cached/customers/ALFKI/orders)

Which are simply existing web services wrapped using **ICacheClient** that are contained in [CachedServices.cs](https://github.com/ServiceStack/ServiceStack.Examples/blob/master/src/ServiceStack.Northwind/ServiceStack.Northwind.ServiceInterface/CachedServices.cs)