Configurable Output Caching via VariableService

[danlorb]

Configurable Output Caching via VariableService

🎯 Summary

• Goal: Integrate ASP.NET Core Output Caching into the xSDK framework, leveraging the internal VariableService for dynamic, configuration-driven policy management.
• Stack: Microsoft.AspNetCore.OutputCaching, xSdk.Extensions.Variable, .NET 10.0, IConfiguration

🛠 Roadmap (Pomodoro Tasks)

• Task 1: Define the OutputCacheSettings POCO class within the xSDK namespace to map VariableService configuration keys (e.g., xsdk:cache:output).
• Task 2: Implement a VariableService binder to hydrate OutputCacheOptions from the centralized configuration store during the AddXSdk() startup sequence.
• Task 3: Create a ServiceCollection extension that registers AddOutputCache() only if VariableService.Get<bool>("Cache:Output:Enabled") returns true.
• Task 4: Develop a PolicyFactory that iterates through VariableService lists to dynamically register named policies (e.g., Default, ShortLived, NoAuth).
• Task 5: Implement a custom IOutputCachePolicy that respects xSDK-specific headers or tenant IDs retrieved via the VariableService environment context.
• Task 6: Hook into the IApplicationBuilder pipeline to inject UseOutputCache() at the technically correct position (after Routing, before Auth/Endpoints).
• Task 7: Add a VariableService watcher or reload token integration to allow updating cache durations without restarting the application.
• Task 8: Create an internal xSDK attribute [XSdkOutputCache(PolicyName)] that acts as a wrapper to provide better IntelliSense and framework-specific defaults.

🔍 Acceptance Criteria

• Output Caching is togglable via VariableService at runtime or startup.
• Named policies defined in the VariableService JSON/Environment are correctly registered in the DI container.
• The middleware order ensures that xSDK's internal VariableService updates are processed before cache lookup if necessary.
• Technical validation: Responses are cached according to the expiration values defined in the Variable store.

⚠️ Constraints & Out-of-Scope

• Dependency: Must rely strictly on the xSdk.Extensions.Variable pattern for configuration, avoiding direct IConfiguration access where possible.
• Scope: Initial implementation focuses on the In-Memory provider. Distributed stores (Redis) are deferred to a separate Epic.

💡 AI-Suggestions

• Dynamic Tags: Use VariableService to define "Invalidation Groups" so that changing a single variable value can trigger a BasePolicy cache eviction.
• Telemetry: Integrate ILogger within the policy execution to track Cache Hits/Misses specifically for xSDK-managed endpoints.

📚 Resources

• Microsoft: Output Caching Documentation
• xSDK: VariableService Source