Web Services (ASMX 1.1) Performance Checklist

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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.


  • 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.


  • 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.


  • 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.


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


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


  • 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.


  • 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.