Configure Redis cache

24 Jun 20262 minutes to read

Redis is an in-memory key-value store commonly used as a distributed cache. Caching frequently requested PDF bytes in Redis reduces repeated conversion or I/O, lowers server load, and improves response times for the PDF Viewer web service. Keep in mind Redis is volatile storage: entries may be evicted or lost on restart, so the cache should be considered an optimization, not the primary data source.

Configure Redis for the PDF Viewer web service

1. Provision a Redis instance (for example, Azure Cache for Redis or a self-hosted cluster). See Azure documentation for deployment guidance: https://learn.microsoft.com/en-us/azure/azure-cache-for-redis/cache-dotnet-how-to-use-azure-redis-cache

2. Create or adapt a PDF Viewer web service. See the Syncfusion web-service guide for a reference implementation: https://www.syncfusion.com/kb/11063/how-to-create-pdf-viewer-web-service-in-net-core-3-0-and-above or use the sample web service: https://github.com/SyncfusionExamples/EJ2-PDFViewer-WebServices

3. Install Redis client and cache packages. Preferred packages for modern .NET applications are StackExchange.Redis and Microsoft.Extensions.Caching.StackExchangeRedis. As an alternative to AddDistributedRedisCache(), consider AddStackExchangeRedisCache() where available.

4. Register the distributed cache in Startup.ConfigureServices (or the equivalent in .NET 6+ minimal hosting). Supply the Redis connection string and optional instance name.

public void ConfigureServices(IServiceCollection services)
{
    // Add Redis Cache
    services.AddDistributedRedisCache(options =>
    {
        options.Configuration = redisCacheConnectionString;
    });
}

Step 5: Use the Redis cache in the PDF Viewer controller action:

To use Redis Cache in PDF Viewer, you can implement the IDistributedCache interface and use the Redis Cache service to store and
retrieve

the PDF document bytes.

    private readonly IHostingEnvironment _hostingEnvironment;
    public IMemoryCache _cache;
    private IDistributedCache _dCache;
    private IConfiguration _configuration;
    private int _slidingTime = 0;
    string path;
    public PdfViewerController(IMemoryCache memoryCache, IHostingEnvironment hostingEnvironment, IDistributedCache cache, IConfiguration configuration)
    {
        _cache = memoryCache;
        _dCache = cache;
        _hostingEnvironment = hostingEnvironment;
        _configuration = configuration;
        path = _configuration["DOCUMENT_PATH"];
        //check the document path environment variable value and assign default data folder
        //if it is null.
        path = string.IsNullOrEmpty(path) ? Path.Combine(_hostingEnvironment.ContentRootPath, "Data") : Path.Combine(_hostingEnvironment.ContentRootPath, path);
    }

Once Redis is configured, the PDF Viewer application will automatically use Redis cache for improved performance and scalability.