Sh Cache Service

There are three main components of the Sh Cache Service.

Sh Cache Service
Figure 1. Sh Cache Service

  1. Decode HTTP Request — decode and validate Sh/HTTP requests.

  2. Cache Facade — provide an interface to the Cassandra database so the service can query and update the cache.

  3. HSS Facade — provide an interface for the service to query and update the external HSS.

The following sections outline the behaviour of the Sh Cache Service for two simple scenarios.

Cache Miss Scenario

Sh Cache Service cache miss
Figure 2. Cache miss scenario

  1. Decode and validate a Sh/HTTP request. The request is valid so …​

  2. Query the cache to see if a result can be returned immediately.

  3. In this case there is nothing in the cache so …​

  4. Send an Sh query to the external HSS

  5. The HSS processes the query and sends a response

  6. Receive the Sh response and …​

  7. Update the cache …​

  8. By updating the Cassandra database

  9. Send an HTTP response to the the original Sh/HTTP request

Cache Hit Scenario

Sh Cache Service cache hit
Figure 3. Cache hit scenario

  1. Decode and validate a Sh/HTTP request. The request is valid so …​

  2. Query the cache to see if a result can be returned immediately.

  3. In this case there is something in the cache so …​

  4. Send an HTTP response to the the original Sh/HTTP request

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