digraph ThreeTierArchitecture {
    // Presentation Tier
    web_browser [label="Web Browser", type="technology", shape="box"];
    mobile_client [label="Mobile Client", type="technology", shape="box"];
    
    web_server [label="Web Server (Nginx)", type="technology", shape="box"];
    cdn [label="CDN", type="technology", shape="diamond"];
    
    // Application Tier
    app_server_1 [label="Application Server 1", type="technology", shape="box"];
    app_server_2 [label="Application Server 2", type="technology", shape="box"];
    
    presentation_layer [label="Presentation Layer", type="application", shape="box"];
    business_logic [label="Business Logic Layer", type="application", shape="box"];
    data_access_layer [label="Data Access Layer", type="application", shape="box"];
    
    // Data Tier
    primary_db [label="Primary Database", type="technology", shape="box"];
    replica_db [label="Replica Database", type="technology", shape="box"];
    cache_layer [label="Cache Layer (Redis)", type="technology", shape="box"];
    file_storage [label="File Storage", type="technology", shape="box"];
    
    // Infrastructure
    load_balancer [label="Load Balancer", type="technology", shape="diamond"];
    firewall [label="Firewall", type="technology", shape="box"];
    
    // User to Presentation
    web_browser -> cdn [label="requests from"];
    mobile_client -> cdn [label="requests from"];
    cdn -> web_server [label="serves or proxies to"];
    
    // Presentation Tier
    web_server -> firewall [label="protected by"];
    firewall -> load_balancer [label="routes to"];
    load_balancer -> app_server_1 [label="distributes to"];
    load_balancer -> app_server_2 [label="distributes to"];
    
    // Application Tier Layers
    app_server_1 -> presentation_layer [label="hosts"];
    app_server_2 -> presentation_layer [label="hosts"];
    presentation_layer -> business_logic [label="calls"];
    business_logic -> data_access_layer [label="uses"];
    
    // Data Access
    data_access_layer -> cache_layer [label="checks"];
    data_access_layer -> primary_db [label="writes to"];
    data_access_layer -> replica_db [label="reads from"];
    
    // Database Replication
    primary_db -> replica_db [label="replicates to"];
    
    // File Storage
    presentation_layer -> file_storage [label="stores files in"];
    business_logic -> file_storage [label="stores files in"];
    
    // Caching Strategy
    business_logic -> cache_layer [label="caches in"];
    presentation_layer -> cache_layer [label="caches in"];
}