How to Configure Entity Framework Caching?

Caching with Entity Framework

The Entity Framework is a set of technologies in ADO.NET that support the development of data-oriented software applications. With the Entity Framework, developers can work at a higher level of abstraction when they deal with data, and can create and maintain data-oriented applications with less code than in traditional applications.

NCache introduces the caching provider which acts between Entity Framework and the Data source. The major reason behind the EF Caching provider is to reduce database trips (which slow down application performance) and serve the query result from the cache. The provider acts in between the ADO.NET entity framework and the original data source. Therefore caching provider can be plugged without changing/compiling the current code.

Integration Modes

NCache Entity Framework Caching provider works under two modes. It can either be in "Caching" or in "Analysis" mode. In caching mode you can cache result-set of selected queries. Analysis mode works in pass-through mode and helps you find the queries that you should cache by generating a report showing which queries are being called with what frequency. For more help on Integration Modes

Database Synchronization

NCache Entity Framework provider also ensures that data in cache is always synchronized with the database. Therefore NCache uses .NET SqlCacheDependeny which registers a SQL query with SQL Server so if any row in the dataset represented by this query is changed in the database, SQL Server throws an event notification to NCache. NCache then removes the corresponding result-set from the cache.

How to Integrate NCache with Entity Framework?

Prerequisites:

1. You should have an Entity Framework application. (you can also use sample application for EFCaching from NCache sample applications from the following path:
"Installeddirectory:/ProgramFiles/NCache/samples/clr20/EntityDataModelIntegrationDemo"

In every Entity Framework application, ADO.NET Entity Data Model is already added which automatically generates two files:

• SSDL
• Application (or web) configuration file

2. Microsoft Visual Studio 2010 for Entity Framework 3.5 and 4.0 and Microsoft Visual Studio 2012/2013 for Entity Framework 6.0 and 6.1

3. Database Tool (e.g. MS SQL SERVER 2008, ORACLE)

Steps to Enable NCache Caching

Step 1: Add Reference

Add Alachisoft.Integrations.EntityFramework.CachingProvider reference to your Entity Framework application. This .dll file is placed on the following path:
"Installeddirectory:/ProgramFiles/NCache/integration/MSEntityFramework"
After adding the reference, changes are required in 3 different files:

Step 2: SSDL Configurations (for Entity Framework 3.5 and 4.0)

In SSDL file which is generated on adding ADO.NET Entity Data Model in Entity Framework application, required following changes:

Below are the sample changes for an SQL 2008 database;

In SSDL, the provider name is specified in the Provider attribute of the <Schema/> element as shown below:

[Existing Code]

<Schema Namespace = "NorthwindModel.Store" Alias = "Self" Provider = "System.Data.SqlClient" ProviderManifestToken = "2005" 
xmlns:store ="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" 
xmlns ="http://schemas.microsoft.com/ado/2006/04/edm/ssdl">

In order to inject our NCache Entity Framework Provider, we need to override the above highlighted attributes to plugin our provider. In SSDL, we put the name of the new provider in the Provider attribute and concatenate the previous provider with our provider manifest token in the ProviderManifestToken field, as shown below:

[Changed Code]

<Schema Namespace = "NorthwindModel.Store" Alias = "Self" 
Provider = "Alachisoft.Integrations.EntityFramework.CachingProvider"
ProviderManifestToken = "System.Data.SqlClient;2005" 
xmlns:store = "http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" 
xmlns = "http://schemas.microsoft.com/ado/2006/04/edm/ssdl">

Step 3: Application (or Web) Configurations

Application (or web) configuration file which is generated on adding ADO.NET Entity Data Model in Entity Framework application, requires following changes:

Entity Framework 3.5 and 4.0

• Provider invariant name is specified in the connection string of application or web configuration file:

  <connectionStrings>
      <add name="NorthwindEntities" 
      connectionString="metadata=res://*/NorthwindCustomerModel.csdl
      |res://*/NorthwindCustomerModel.ssdl
      |res://*/NorthwindCustomerModel.msl;
      provider=System.Data.EntityClient;
      provider connection string="
      Data Source=localhost;Initial Catalog=Northwind;user id= userid;
      password=password;MultipleActiveResultSets=True"" 
      providerName="System.Data.EntityClient"/>
  </connectionStrings>

• Change provider name to NCache Entity Framework Provider and also add the provider wrapper information in connection string as shown below:

  <connectionStrings>
      <add name="NorthwindEntities" 
      connectionString="metadata=res://*/NorthwindCustomerModel.csdl
      |res://*/NorthwindCustomerModel.ssdl
      |res://*/NorthwindCustomerModel.msl;
      provider=Alachisoft.Integrations.EntityFramework.CachingProvider;
      provider connection string="
      wrappedProvider=System.Data.SqlClient;        
      Data Source=localhost;Initial Catalog=Northwind;user id= userid;
      password=password;MultipleActiveResultSets=True"" 
      providerName="System.Data.EntityClient"/>
  </connectionStrings>
  

• Also add the provider factory for initialization of NCache Entity Framework Provider. The invariant attribute should be the same as the provider name in connection string.

<DbProviderFactories>
    <add name="EF Caching Data Provider" 
    invariant="Alachisoft.Integrations.EntityFramework.
    CachingProvider" 
    description="Caching Provider Wrapper" 
    type="Alachisoft.NCache.Integrations.
    EntityFramework.EFCachingProviderFactory, 
    Alachisoft.Integrations.EntityFramework.
    CachingProvider, 
    Version=1.0.0.0,
    Culture=neutral,
    PublicKeyToken=cff5926ed6a53769"/>
</DbProviderFactories>

Entity Framework 6.0

• Provider invariant name is also specified in the application (or web) configuration file:

  <entityFramework>
      <providers>
  		<provider invariantName="System.Data.SqlClient"
        type="System.Data.Entity.SqlServer.SqlProviderServices,
         EntityFramework.SqlServer" />
      </providers>
  </entityFramework>

• Change invariant name to EFCachingProviderServices and type to Alachisoft.NCache.Integrations.EntityFramework.EFCachingProviderServices, Alachisoft.Integrations.EntityFramework.CachingProvider as shown below:

<entityFramework>
    <providers>
        <provider invariantName="EFCachingProviderServices" 
        type="Alachisoft.NCache.Integrations.EntityFramework.EFCachingProviderServices,
         Alachisoft.Integrations.EntityFramework.CachingProvider" />
    </providers>
</entityFramework>

Entity Framework 6.1

• Add an interceptor in provider section in the application (or web) configuration file:

  <entityFramework>
      <providers>
          <provider invariantName="System.Data.SqlClient"
           type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
      </providers>
     
      <interceptors>
  		<interceptor type="Alachisoft.NCache.Integrations.EntityFramework.Caching.EFCommandInterceptor,
           Alachisoft.Integrations.EntityFramework.CachingProvider" />
      </interceptors>
  </entityFramework>
  

• Following information should be added in appSettings of app.config/web.config:

  <appSettings> <add key = "app-id" value = "PersonNameApp2"/> <add key = "logging-level" value = "Debug"/> </appSettings>
  

  1. App-id : This will be the identifier for current application. This ID will be used to read configuration from efcaching.ncconf
  2. Logging-level : Determine the logging level for application. Our provider will log exceptions and errors only when level is set to Error. When the level is set to Debug, both exceptions/errors and other detailed information will be logged. Nothing will be logged if level is set to Off (default). Path at which log files will be generated: Default =<install-dir> <install-dir>/log-files/efcaching-logs/
  3. For applying the above changes, application should be restarted after these changes are made

NOTE: App-id for efcaching.ncconf should be same as in application (app.config) otherwise it will prompt an error)

Alternative Method

Entity Framework 3.5 or 4.0

Apart from specifying connection string in app.config/web.config, the connection can also be specified while creating ObjectContext or EntityConnection. While creating a connection string programmatically, the wrapper information must be included in a connection string. Here is how the connection string can be created and ObjectContext or EntityConnection can be initialized.

try
  {
      SqlConnectionStringBuilder sqlConnBuilder =     new SqlConnectionStringBuilder();
      sqlConnBuilder.DataSource = "localhost";
      sqlConnBuilder.InitialCatalog = "EFTestDB";
      sqlConnBuilder.IntegratedSecurity = true;
      string conString = sqlConnBuilder.ToString();
      EntityConnectionStringBuilder efConnBuilder = new EntityConnectionStringBuilder();
      efConnBuilder.Provider = "EFCachingProvider";
      efConnBuilder.ProviderConnectionString = @"wrappedProvider=System.Data.SqlClient;" + conString;
      efConnBuilder.Metadata = "res:// /NorthwindCustomerModel.csdl|res:" + "// /NorthwindCustomerModel.ssdl|res:" +"// /NorthwindCustomerModel.msl;";
      EntityConnection connection = new EntityConnection(efConnBuilder.ToString());
  }
  catch (Exception ex)
  { 
      // handle exception
  }

Entity Framework 6.0

Apart from specifying provider invariant in app.config/web.config, the provider invariant can be specified while initializing the configuration (class inheriting DbConfiguration). Here is how the provider invariant can be specified:

try
{
    this.SetProviderServices("EFCachingProviderServices", EFCachingProviderServices.Instance);
}
catch (Exception ex)
{ 
    // handle exception
}

Entity Framework 6.1

Apart from specifying database interceptor in app.config/web.config, the database interceptor can be specified while initializing the configuration (class inheriting DbConfiguration). Here is how the interceptor can be specified:

try
{
    this.AddInterceptor(new EFCommandInterceptor());
}
catch (Exception ex)
{ 
    // handle exception
}

Through API (6.0 and 6.1)

User can now also cache results using extension provided for IQueryable.

• Specify the namespace

  using Alachisoft.NCache.Integrations.EntityFramework.Caching;

• Call cache method overloads now from IQueryable instance

  var students = from s in db.Students
                 select s;
  students.Cache(); 
  // results are not cached yet
  foreach (Student student in students) 
  //results are cached when enumerator from query is iterated completely
  	{
  	  //using student
  	}

Step 4: efcaching.ncconf Configurations:

Changes required in "efcaching.ncconf".

1. Efcaching.ncconf is placed on the following path: "Installeddirectory:/Program Files/NCache/config".

2. Provider Configuration contains cache and caching policy related information. Below are the changes required in efcaching.ncconf.

   <configuration>
         <app-config app-id = "PersonNameApp" mode = "analysis|caching">

3. "Analysis" mode is used for monitoring the number of times each query executes and then it generates a report. Report contains the Query text and the call count for each query. This report can be used in Custom policy. No caching is done at this mode.

   <analysis-policy log-path = "" analysis-time = "1min" cache-enable-threshold = "1" default-expiration-type = "Sliding" default-expiration-time = "180sec" dbsyncdependency= "false"/>

4. Log-path: Path at which analysis log files will be generated.
   Default = < install-dir > /log-files/efcaching-analysis-logs/

5. For "Caching" mode, wrapping provider will cache the results of all the specified queries. Both policies have their own specifications. Whenever update is detected (either UPDATE, INSERT or DELETE) in a respective database, the provider invalidates affected cache entries by evicting all cached queries which were dependent on any of the updated tables.

   <cache-policy-configuration database = "none|sqlserver|oracle" cache-id = "mycache">  

6. For custom policy, it includes user-configurable list of queries that should be cached with their results. Only those query results will be cached for which the caching is enabled. You can specify custom caching policy for all queries.

   <!--sql-query = "SELECT [Extent1].[CustomerID] AS [CustomerID],= @param_0"-->
   	<query>
           <cache-query query text="SELECT [Extent1].[OrderID] AS [OrderID], < @param_0"/>
               <cache-policy vary-by-cache-param="param_0" expiration-type="Sliding"
                enabled="True" expiration-time="180sec" dbsyncdependency="False"/>
   	</query>

7. In case of stored procedures, query text will be the name of a stored procedure, and there will be no default policy or database sync dependency. User can cache stored procedures result with expiration only, no database dependency is required here.

8. In case of API Level Caching (supported in Entity Framework 6.0 and 6.1), you can cache query using extension method provided in the namespace
   using Alachisoft.NCache.Integrations.EntityFramework.Caching;
   and you can provide caching policy for API level caching in configuration file in the following tag:

   <api-level-caching expiration-type="sliding|absolute" enable="True|False"
    expiration-time="120sec" dbsyncdependency="True|False">