Caching

Caravel apps can use .NET's caching services directly. Start with IDistributedCache when you want the same application code to work with an in-memory or shared database cache. There is no separate Caravel cache package or facade yet.

Start in memory

builder.Services.AddDistributedMemoryCache();

This stores values in the current process. It doesn't share them between app instances, and restarting loses them.

Inject IDistributedCache from Microsoft.Extensions.Caching.Distributed:

await cache.SetStringAsync("public:catalog:v1", serializedCatalog,
    new DistributedCacheEntryOptions
    {
        AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(5)
    }, cancellationToken);

var cached = await cache.GetStringAsync("public:catalog:v1", cancellationToken);
await cache.RemoveAsync("public:catalog:v1", cancellationToken);

For a plain Generic Host, add Microsoft.Extensions.Caching.Memory; ASP.NET Core already supplies it through the shared framework.

Share values through SQL Server

Add Microsoft.Extensions.Caching.SqlServer to the application, aligned with the framework's .NET LTS version, then replace the memory registration:

builder.Services.AddDistributedSqlServerCache(options =>
{
    options.ConnectionString = builder.Configuration.GetConnectionString("Cache")
        ?? throw new InvalidOperationException("Set the Cache connection string.");
    options.SchemaName = "dbo";
    options.TableName = "CacheEntries";
});

Create the backing table with Microsoft's sql-cache tool as part of your deployment. Caravel doesn't create it or reuse Clarion tables. Follow the distributed caching guide for provider setup and tooling.

Keep the cache replaceable

Treat a miss as normal and rebuild the value from its authoritative source. A cache write isn't durable acceptance of an event or job. Decide how a cache outage affects each endpoint rather than hiding every infrastructure error.

For per-user data, include the tenant or account and a data version in the cache key, and use an unambiguous separator. Never cache one user's filtered results under a key another user could hit. Don't cache passwords or credentials just because entries expire eventually.

Set an expiration, keep values small, and remove affected entries after you save changes. IDistributedCache doesn't make read-compute-write atomic, so two requests can fill the same entry at once. A Caravel RememberAsync helper, tags and locking are ideas for the roadmap.