WCF Performance Tuning

To enhance the performance of WCF, several strategies can be employed, including optimizing service configuration, improving message size and format, utilizing efficient transport protocols, and managing resource usage effectively.

1. Select the proper WCF Binding

The performance of a WCF service is influenced by the selection of the binding type. WCF offers various bindings, each with a specific purpose and security model. For instance, using WSHttpBinding may incur additional overhead due to security features, reliable sessions, and transaction flow.

By choosing a simpler binding like BasicHttpBinding, which lacks these features, performance can be significantly improved. The key is to select the appropriate binding based on the service's requirements.

2. Throttling

Throttling is an important factor in optimizing WCF performance. WCF provides properties such as maxConcurrentCalls, maxConcurrentInstances, and maxConcurrentSessions to control the number of instances or sessions created at the application level.

• maxConcurrentCalls: Limits the maximum number of messages the service host processes simultaneously. The default value is 16 (WCF 4.0 increases this to 16 times the processor count).
• maxConcurrentInstances: Specifies the maximum number of context object instances executing at one time. The default is Int32.MaxValue.
• maxConcurrentSessions: Limits the number of sessions at any given time. The default is 10 (WCF 4.0 increases this to 100 times the processor count).

<configuration>
  <system.serviceModel>
    <services>
      <service
        <!-- Service configuration -->
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior name="ServiceBehavior">
          <serviceThrottling
            maxConcurrentCalls="16" maxConcurrentSessions="100" maxConcurrentInstances="10" />
          <serviceMetadata httpGetEnabled="true" />
        </behavior>
      </serviceBehaviors>
    </behaviors>
  </system.serviceModel>
</configuration>

3. Use data contract serialization

Serialization is the process of converting an object into a format that can be easily transferred, such as XML or binary. XML serialization is widely used for its interoperability, while binary serialization is preferred for transferring objects between .NET applications.

Data contract serialization is approximately 10% faster than XML serialization, which can be important when handling large datasets. Additionally, the Data Contract Serializer can serialize not only public members but also private and protected members, providing more flexibility.

4. Caching

External dependencies can negatively impact WCF service performance, but caching can help mitigate this issue by storing data in memory or elsewhere for quick retrieval. There are two types of caching:

In-memory Caching: By default, WCF services do not have access to the ASP.NET cache. However, this can be enabled through ASP.NET compatibility by adding the AspNetCompatibilityRequirements attribute and configuring the serviceHostingEnvironment setting.

[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
<system.serviceModel>
    <!-- Other service model configuration -->
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
    <!-- Other service model configuration -->
</system.serviceModel>

External Caching: In-memory caching can be problematic for managing cache expiration, especially when data changes. Sticky sessions, which route all requests from the same source IP to the same server, can address this issue. Additionally, Windows Server AppFabric can be used as an external cache server for improved performance.

5. Close Proxy Connections

It is important to always close the proxy connection when the client is finished using it. Closing the proxy connection expires the service's session and terminates the connection between the server and client, ensuring proper resource management and preventing potential memory leaks or performance issues.

using (var proxy = new MyWcfServiceClient())
{
    // Call service operations
    proxy.SomeOperation();

    // The proxy will be closed automatically at the end of the using block
}

The using statement ensures that the proxy is disposed of properly, which in turn calls the Close method on the proxy.

6. Compress data

To improve performance, only serialize and send the data that is required by the end user. Avoid transmitting unnecessary data across the network to reduce bandwidth usage and enhance efficiency.

7. Configure Transport Properties

WCF transport properties, such as timeout, memory allocation limits, and collection size limits, play a key role in improving service performance.

• Timeout: Helps mitigate Denial of Service (DOS) attacks by limiting the duration of service operations.
• Memory Allocation Limits: Prevents a single connection from consuming all system resources, ensuring that other connections remain unaffected.
• Collection Size Limits: Restricts resource consumption by limiting the size of data collections that can be processed.

8. ReaderQuotas Property

The ReaderQuotas property in WCF, which includes settings like MaxDepth, MaxStringContentLength, MaxArrayLength, MaxBytesPerRead, and MaxNameTableCharCount, helps restrict message complexity. By limiting these values, it protects the service from Denial of Service (DOS) attacks, ensuring that excessively large or complex messages do not overload the system.