3.2.5.Caching

• Negative impact of statelessness

  • Negative impact on performance

  • Chattiness

  • Higher data traffic (impact's scalability)

• Caching

  • Counterbalances the statelessness

  • May occur on server, client or mid tier (intermediaries)

  • Response messages from the service to its consumers must be explicitly labeled as cacheable or non-cacheable

    • Caching is controlled by the server using the HTTP headers

      • Cache-Control

        • Cache policy directive - Who, How long, Under what conditions. e.g., private;max-age = 60

      • Expires

        • Tells when the resource will get expired

      • Last-Modified

        • Tells when the resource was last changed

      • ETag

        • Unique identified associated with a response