Web Services (ASMX 1.1) Performance Checklist

J.D. Meier, Srinath Vasireddy, Ashish Babbar, Rico Mariani, and Alex Mackman

Design Considerations

• Design chunky interfaces to reduce round trips.
• Prefer message-based programming over remote procedure call (RPC) style.
• Use literal message encoding for parameter formatting.
• Prefer primitive types for Web service parameters.
• Avoid maintaining server state between calls.
• Consider input validation for costly Web methods.
• Consider your approach to caching.
• Consider approaches for bulk data transfer and attachments.
• Avoid calling local Web Services.

Connections

• Configure the maxconnection attribute.
• Prioritize and allocate connections across discrete Web services.
• Use a single identity for outbound calls.
• Consider UnsafeAuthenticatedConnectionSharing with Windows Integrated Authentication.
• Use PreAuthenticate with Basic authentication.

Threading

• Tune the thread pool using the formula for reducing contention.
• Consider minIoThreads and minWorkerThreads for intermittent burst load.

One Way (Fire and Forget) Communication

• Consider using the OneWay attribute if you do not require a response.

Asynchronous Web Methods

• Use asynchronous Web methods for I/O operations.
• Do not use asynchronous Web methods when you depend on worker threads.

Asynchronous Invocation

• Consider calling Web services asynchronously when you have additional parallel work.
• Use asynchronous invocation to call multiple unrelated Web services.
• Call Web services asynchronously for UI responsiveness.

Timeouts

• Set your proxy timeout appropriately.
• Set your ASP.NET timeout greater than your Web service timeout.
• Abort connections for ASP.NET pages that timeout before a Web services call completes.
• Consider the responseDeadlockInterval attribute.

WebMethods

• Prefer primitive parameter types.
• Consider buffering.
• Consider caching responses.
• Enable session state only for Web methods that need it.

Serialization

• Reduce serialization with XmlIgnore.
• Reduce round trips.
• Consider XML compression.

Caching

• Consider output caching for less volatile data.
• Consider providing cache-related information to clients.
• Consider perimeter caching.

State Management

• Use session state only where it is needed.
• Avoid server affinity.

Attachments

• Prefer Base64 encoding. Direct Internet Message Encapsulation (DIME) is a supported part of Web Services Enhancements (WSE), but Microsoft® is not investing in this approach long-term. DIME is limited because the attachments are outside the SOAP envelope.

COM Interop

• Avoid single-threaded apartment (STA) COM objects.

Resources

• See online at http://msdn.microsoft.com/library/en-us/dnpag/html/ScaleNetCheck09.asp