Web Application Performance Design Inspection Checklist

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


Contents

Deployment and Infrastructure

  • Use distributed architectures appropriately. Do not introduce distribution unnecessarily.
  • Carefully select appropriate distributed communication mechanisms.
  • Locate components that interact frequently within the same boundary or as close to each other as possible.
  • Take infrastructure restrictions into account in your design.
  • Consider network bandwidth restrictions.
  • Identify resource restrictions.
  • Ensure your design does not prevent you from scaling up.
  • Ensure your design does not prevent you from scaling out and it uses logical layers, does not unwittingly introduce affinity, and supports load balancing.


Coupling and Cohesion

  • Ensure your design is loosely coupled.
  • Exhibit appropriate degrees of cohesion in your design and group together logically related entities, such as classes and methods.
  • Restrict use of late binding and only use late binding where it is necessary and appropriate.


Communication

  • Interfaces do not enforce chatty communication.
  • Ensure your application only makes remote calls where necessary. Impact is minimized by client-side validation, client-side caching, and batching of work.
  • Optimize remote data exchange.
  • Choose appropriate secure communication mechanisms.
  • Use message queues to decouple component parts of your system.
  • Mitigate the impact of long-running calls by using message queues, "fire-and forget" approaches, and asynchronous method calls.
  • Do not use processes where application domains are more appropriate.


Concurrency

  • In your application do not create threads on a per-request basis, and use the common language runtime (CLR) thread pool instead.
  • Only types that need to be thread-safe are made thread-safe.
  • Carefully consider lock granularity..
  • Ensure your application acquires shared resources and locks late and releases them early to reduce contention.
  • Choose appropriate synchronization primitives.
  • Choose an appropriate transaction isolation level.
  • Ensure your application uses asynchronous execution for I/O bound tasks and not for CPU bound tasks.


Resource Management

  • Ensure your design supports and makes effective use of pooling.
  • Ensure your application acquires resources late and releases them early.


Caching

  • Use caching for data that is expensive to retrieve, compute, and render.
  • Cache appropriate data such as relatively static Web pages, specific items of output data, stored procedure parameters, and query results.
  • Do not use caching for data that is too volatile.
  • Select an appropriate cache location.
  • Select an appropriate cache expiration policy.


State Management

  • Your design favors stateless components. Or, you considered the negative impact on scalability if you decided to use stateful components.
  • If you use Microsoft® .NET Framework remoting and need to support load balancing, you use single call server-activated objects (SAO).
  • If you use Web services, you also use a message-based stateless programming model.
  • If you use Enterprise Services, also use stateless components to facilitate object pooling.
  • Objects that you want to store in state stores support serialization.
  • Consider the performance impact of view state.
  • Use statistics relating to the number of concurrent sessions and average session data per user to help choose an appropriate session state store.


Data Structures and Algorithms

  • Ensure your design uses appropriate data structures.
  • Use custom collections only where absolutely necessary.
  • Extend the IEnumerable interface for your custom collections.


Data Access

  • Pass data across the layers by using the most appropriate data format. Carefully consider the performance implications.
  • Use stored procedures with the Parameters collection for data access.
  • Only process the data that is required.
  • Where appropriate, provide data paging solutions for large result sets.
  • Use Enterprise Services declarative transactions for transactions that span multiple resource managers or where you need to flow transaction context across components.
  • If you manipulate binary large objects (BLOBs), use appropriate chunking techniques, and do not repeatedly move the same BLOB.
  • Consolidate repeated data access code into helper classes.


Exception Handling

  • Do not use exceptions to control regular application flow.
  • Use well-defined exception handling boundaries.
  • Structured exception handling is the preferred error handling mechanism. Do not rely on error codes.
  • Only catch exceptions for a specific reason and when it is required.


Class Design Considerations

  • Classes own the data that they act upon.
  • Do not use explicit interfaces unnecessarily. Use explicit interfaces for versioning and for polymorphism where you have common functionality across multiple classes.
  • Classes do not contain virtual methods when they are not needed.
  • Prefer overloaded methods to methods that take variable parameters.
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