Event Broken Concept

pkg/eventbroker/example_usage.go

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+// nolint
+package eventbroker
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/bitechdev/ResolveSpec/pkg/logger"
+)
+
+// Example demonstrates basic usage of the event broker
+func Example() {
+	// 1. Create a memory provider
+	provider := NewMemoryProvider(MemoryProviderOptions{
+		InstanceID:      "example-instance",
+		MaxEvents:       1000,
+		CleanupInterval: 5 * time.Minute,
+		MaxAge:          1 * time.Hour,
+	})
+
+	// 2. Create a broker
+	broker, err := NewBroker(Options{
+		Provider:    provider,
+		Mode:        ProcessingModeAsync,
+		WorkerCount: 5,
+		BufferSize:  100,
+		RetryPolicy: DefaultRetryPolicy(),
+		InstanceID:  "example-instance",
+	})
+	if err != nil {
+		logger.Error("Failed to create broker: %v", err)
+		return
+	}
+
+	// 3. Start the broker
+	if err := broker.Start(context.Background()); err != nil {
+		logger.Error("Failed to start broker: %v", err)
+		return
+	}
+	defer func() {
+		err := broker.Stop(context.Background())
+		if err != nil {
+			logger.Error("Failed to stop broker: %v", err)
+		}
+	}()
+
+	// 4. Subscribe to events
+	broker.Subscribe("public.users.*", EventHandlerFunc(
+		func(ctx context.Context, event *Event) error {
+			logger.Info("User event: %s (operation: %s)", event.Type, event.Operation)
+			return nil
+		},
+	))
+
+	broker.Subscribe("*.*.create", EventHandlerFunc(
+		func(ctx context.Context, event *Event) error {
+			logger.Info("Create event: %s.%s", event.Schema, event.Entity)
+			return nil
+		},
+	))
+
+	// 5. Publish events
+	ctx := context.Background()
+
+	// Database event
+	dbEvent := NewEvent(EventSourceDatabase, EventType("public", "users", "create"))
+	dbEvent.InstanceID = "example-instance"
+	dbEvent.UserID = 123
+	dbEvent.SessionID = "session-456"
+	dbEvent.Schema = "public"
+	dbEvent.Entity = "users"
+	dbEvent.Operation = "create"
+	dbEvent.SetPayload(map[string]interface{}{
+		"id":    123,
+		"name":  "John Doe",
+		"email": "john@example.com",
+	})
+
+	if err := broker.PublishAsync(ctx, dbEvent); err != nil {
+		logger.Error("Failed to publish event: %v", err)
+	}
+
+	// WebSocket event
+	wsEvent := NewEvent(EventSourceWebSocket, "chat.message")
+	wsEvent.InstanceID = "example-instance"
+	wsEvent.UserID = 123
+	wsEvent.SessionID = "session-456"
+	wsEvent.SetPayload(map[string]interface{}{
+		"room":    "general",
+		"message": "Hello, World!",
+	})
+
+	if err := broker.PublishAsync(ctx, wsEvent); err != nil {
+		logger.Error("Failed to publish event: %v", err)
+	}
+
+	// 6. Get statistics
+	time.Sleep(1 * time.Second) // Wait for processing
+	stats, _ := broker.Stats(ctx)
+	logger.Info("Broker stats: %d published, %d processed", stats.TotalPublished, stats.TotalProcessed)
+}
+
+// ExampleWithHooks demonstrates integration with the hook system
+func ExampleWithHooks() {
+	// This would typically be called in your main.go or initialization code
+	// after setting up your restheadspec.Handler
+
+	// Pseudo-code (actual implementation would use real handler):
+	/*
+		broker := eventbroker.GetDefaultBroker()
+		hookRegistry := handler.Hooks()
+
+		// Register CRUD hooks
+		config := eventbroker.DefaultCRUDHookConfig()
+		config.EnableRead = false // Disable read events for performance
+
+		if err := eventbroker.RegisterCRUDHooks(broker, hookRegistry, config); err != nil {
+			logger.Error("Failed to register CRUD hooks: %v", err)
+		}
+
+		// Now all CRUD operations will automatically publish events
+	*/
+}
+
+// ExampleSubscriptionPatterns demonstrates different subscription patterns
+func ExampleSubscriptionPatterns() {
+	broker := GetDefaultBroker()
+	if broker == nil {
+		return
+	}
+
+	// Pattern 1: Subscribe to all events from a specific entity
+	broker.Subscribe("public.users.*", EventHandlerFunc(
+		func(ctx context.Context, event *Event) error {
+			fmt.Printf("User event: %s\n", event.Operation)
+			return nil
+		},
+	))
+
+	// Pattern 2: Subscribe to a specific operation across all entities
+	broker.Subscribe("*.*.create", EventHandlerFunc(
+		func(ctx context.Context, event *Event) error {
+			fmt.Printf("Create event: %s.%s\n", event.Schema, event.Entity)
+			return nil
+		},
+	))
+
+	// Pattern 3: Subscribe to all events in a schema
+	broker.Subscribe("public.*.*", EventHandlerFunc(
+		func(ctx context.Context, event *Event) error {
+			fmt.Printf("Public schema event: %s.%s\n", event.Entity, event.Operation)
+			return nil
+		},
+	))
+
+	// Pattern 4: Subscribe to everything (use with caution)
+	broker.Subscribe("*", EventHandlerFunc(
+		func(ctx context.Context, event *Event) error {
+			fmt.Printf("Any event: %s\n", event.Type)
+			return nil
+		},
+	))
+}
+
+// ExampleErrorHandling demonstrates error handling in event handlers
+func ExampleErrorHandling() {
+	broker := GetDefaultBroker()
+	if broker == nil {
+		return
+	}
+
+	// Handler that may fail
+	broker.Subscribe("public.users.create", EventHandlerFunc(
+		func(ctx context.Context, event *Event) error {
+			// Simulate processing
+			var user struct {
+				ID    int    `json:"id"`
+				Email string `json:"email"`
+			}
+
+			if err := event.GetPayload(&user); err != nil {
+				return fmt.Errorf("invalid payload: %w", err)
+			}
+
+			// Validate
+			if user.Email == "" {
+				return fmt.Errorf("email is required")
+			}
+
+			// Process (e.g., send email)
+			logger.Info("Sending welcome email to %s", user.Email)
+
+			return nil
+		},
+	))
+}
+
+// ExampleConfiguration demonstrates initializing from configuration
+func ExampleConfiguration() {
+	// This would typically be in your main.go
+
+	// Pseudo-code:
+	/*
+		// Load configuration
+		cfgMgr := config.NewManager()
+		if err := cfgMgr.Load(); err != nil {
+			logger.Fatal("Failed to load config: %v", err)
+		}
+
+		cfg, err := cfgMgr.GetConfig()
+		if err != nil {
+			logger.Fatal("Failed to get config: %v", err)
+		}
+
+		// Initialize event broker
+		if err := eventbroker.Initialize(cfg.EventBroker); err != nil {
+			logger.Fatal("Failed to initialize event broker: %v", err)
+		}
+
+		// Use the default broker
+		eventbroker.Subscribe("*.*.create", eventbroker.EventHandlerFunc(
+			func(ctx context.Context, event *eventbroker.Event) error {
+				logger.Info("Created: %s.%s", event.Schema, event.Entity)
+				return nil
+			},
+		))
+	*/
+}
+
+// ExampleYAMLConfiguration shows example YAML configuration
+const ExampleYAMLConfiguration = `
+event_broker:
+  enabled: true
+  provider: memory  # memory, redis, nats, database
+  mode: async       # sync, async
+  worker_count: 10
+  buffer_size: 1000
+  instance_id: "${HOSTNAME}"
+
+  # Memory provider is default, no additional config needed
+
+  # Redis provider (when provider: redis)
+  redis:
+    stream_name: "resolvespec:events"
+    consumer_group: "resolvespec-workers"
+    host: "localhost"
+    port: 6379
+
+  # NATS provider (when provider: nats)
+  nats:
+    url: "nats://localhost:4222"
+    stream_name: "RESOLVESPEC_EVENTS"
+
+  # Database provider (when provider: database)
+  database:
+    table_name: "events"
+    channel: "resolvespec_events"
+
+  # Retry policy
+  retry_policy:
+    max_retries: 3
+    initial_delay: 1s
+    max_delay: 30s
+    backoff_factor: 2.0
+`