SSE htmx example (#435)

* SSE htmx example

_examples/real-world-examples/server-sent-events-htmx/Dockerfile

@@ -0,0 +1,11 @@
+FROM golang:1.22 AS builder
+
+COPY . /src
+WORKDIR /src/
+
+RUN CGO_ENABLED=0 go build -ldflags="-s -w" -trimpath -o /main .
+
+FROM alpine
+RUN apk add --no-cache ca-certificates
+COPY --from=builder /main /main
+CMD ["/main"]

_examples/real-world-examples/server-sent-events-htmx/docker-compose.yml

@@ -0,0 +1,45 @@
+version: '3.7'
+services:
+  server:
+    build:
+      context: docker
+    volumes:
+      - ./:/src
+      - go_pkg:/go/pkg
+      - go_cache:/go-cache
+    working_dir: /src
+    ports:
+      - '8080:8080'
+    environment:
+      - PORT=8080
+      - DATABASE_URL=postgres://postgres:postgres@postgres:5432/postgres?sslmode=disable
+      - PUBSUB_PROJECT_ID=local
+      - PUBSUB_EMULATOR_HOST=pubsub:8681
+    restart: unless-stopped
+    networks:
+      - sse
+
+  postgres:
+    image: postgres:15
+    restart: unless-stopped
+    environment:
+      - POSTGRES_PASSWORD=postgres
+    ports:
+      - 5432:5432
+    networks:
+      - sse
+
+  pubsub:
+    image: messagebird/gcloud-pubsub-emulator:latest
+    restart: unless-stopped
+    ports:
+      - '8681:8681'
+    networks:
+      - sse
+
+networks:
+  sse:
+
+volumes:
+  go_pkg:
+  go_cache:

_examples/real-world-examples/server-sent-events-htmx/docker/Dockerfile

@@ -0,0 +1,8 @@
+FROM golang:1.22
+
+RUN go install github.com/cespare/reflex@latest
+RUN go install github.com/a-h/templ/cmd/templ@latest
+
+COPY reflex.conf /
+
+ENTRYPOINT ["/go/bin/reflex", "-c", "/reflex.conf"]

_examples/real-world-examples/server-sent-events-htmx/docker/reflex.conf

@@ -0,0 +1,2 @@
+-r '(\.go$|go\.mod$)' -s go run .
+-r '\.templ$' templ generate

_examples/real-world-examples/server-sent-events-htmx/events.go

@@ -0,0 +1,171 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"cloud.google.com/go/pubsub"
+	"github.com/ThreeDotsLabs/watermill"
+	"github.com/ThreeDotsLabs/watermill-googlecloud/pkg/googlecloud"
+	"github.com/ThreeDotsLabs/watermill-http/v2/pkg/http"
+	"github.com/ThreeDotsLabs/watermill/components/cqrs"
+	"github.com/ThreeDotsLabs/watermill/message"
+	"github.com/ThreeDotsLabs/watermill/message/router/middleware"
+)
+
+type PostViewed struct {
+	PostID int `json:"post_id"`
+}
+
+type PostReactionAdded struct {
+	PostID     int    `json:"post_id"`
+	ReactionID string `json:"reaction_id"`
+}
+
+type PostStatsUpdated struct {
+	PostID          int     `json:"post_id"`
+	ViewsUpdated    bool    `json:"views_updated"`
+	ReactionUpdated *string `json:"reaction_updated"`
+}
+
+type Routers struct {
+	EventsRouter *message.Router
+	SSERouter    http.SSERouter
+	EventBus     *cqrs.EventBus
+}
+
+func NewRouters(cfg config, repo *Repository) (Routers, error) {
+	logger := watermill.NewStdLogger(false, false)
+
+	publisher, err := googlecloud.NewPublisher(
+		googlecloud.PublisherConfig{
+			ProjectID: cfg.PubSubProjectID,
+		},
+		logger,
+	)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	eventBus, err := cqrs.NewEventBusWithConfig(
+		publisher,
+		cqrs.EventBusConfig{
+			GeneratePublishTopic: func(params cqrs.GenerateEventPublishTopicParams) (string, error) {
+				return params.EventName, nil
+			},
+			Marshaler: cqrs.JSONMarshaler{},
+			Logger:    logger,
+		},
+	)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	eventsRouter, err := message.NewRouter(message.RouterConfig{}, logger)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	eventsRouter.AddMiddleware(middleware.Recoverer)
+
+	eventProcessor, err := cqrs.NewEventProcessorWithConfig(
+		eventsRouter,
+		cqrs.EventProcessorConfig{
+			GenerateSubscribeTopic: func(params cqrs.EventProcessorGenerateSubscribeTopicParams) (string, error) {
+				return params.EventName, nil
+			},
+			SubscriberConstructor: func(params cqrs.EventProcessorSubscriberConstructorParams) (message.Subscriber, error) {
+				return googlecloud.NewSubscriber(
+					googlecloud.SubscriberConfig{
+						ProjectID: cfg.PubSubProjectID,
+						GenerateSubscriptionName: func(topic string) string {
+							return fmt.Sprintf("%v_%v", topic, params.HandlerName)
+						},
+					},
+					logger,
+				)
+			},
+			Marshaler: cqrs.JSONMarshaler{},
+			Logger:    logger,
+		},
+	)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	err = eventProcessor.AddHandlers(
+		cqrs.NewEventHandler(
+			"UpdateViews",
+			func(ctx context.Context, event *PostViewed) error {
+				err = repo.UpdatePost(ctx, event.PostID, func(post *Post) {
+					post.Views++
+				})
+				if err != nil {
+					return err
+				}
+
+				statsUpdated := PostStatsUpdated{
+					PostID:       event.PostID,
+					ViewsUpdated: true,
+				}
+
+				return eventBus.Publish(ctx, statsUpdated)
+			},
+		),
+		cqrs.NewEventHandler(
+			"UpdateReactions",
+			func(ctx context.Context, event *PostReactionAdded) error {
+				err := repo.UpdatePost(ctx, event.PostID, func(post *Post) {
+					post.Reactions[event.ReactionID]++
+				})
+				if err != nil {
+					return err
+				}
+
+				statsUpdated := PostStatsUpdated{
+					PostID:          event.PostID,
+					ReactionUpdated: &event.ReactionID,
+				}
+
+				return eventBus.Publish(ctx, statsUpdated)
+			},
+		),
+	)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	sseSubscriber, err := googlecloud.NewSubscriber(
+		googlecloud.SubscriberConfig{
+			ProjectID: cfg.PubSubProjectID,
+			GenerateSubscriptionName: func(topic string) string {
+				return fmt.Sprintf("%v_%v", topic, watermill.NewShortUUID())
+			},
+			SubscriptionConfig: pubsub.SubscriptionConfig{
+				ExpirationPolicy: time.Hour * 24,
+			},
+		},
+		logger,
+	)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	sseRouter, err := http.NewSSERouter(
+		http.SSERouterConfig{
+			UpstreamSubscriber: sseSubscriber,
+			Marshaler:          http.StringSSEMarshaler{},
+		},
+		logger,
+	)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	return Routers{
+		EventsRouter: eventsRouter,
+		SSERouter:    sseRouter,
+		EventBus:     eventBus,
+	}, nil
+}

_examples/real-world-examples/server-sent-events-htmx/go.mod

@@ -0,0 +1,66 @@
+module main
+
+go 1.22.0
+
+require (
+	cloud.google.com/go/pubsub v1.36.1
+	github.com/ThreeDotsLabs/watermill v1.3.5
+	github.com/ThreeDotsLabs/watermill-googlecloud v1.2.0
+	github.com/ThreeDotsLabs/watermill-http/v2 v2.2.0
+	github.com/a-h/templ v0.2.663
+	github.com/kelseyhightower/envconfig v1.4.0
+	github.com/labstack/echo/v4 v4.11.4
+	github.com/lib/pq v1.10.9
+)
+
+require (
+	cloud.google.com/go v0.112.1 // indirect
+	cloud.google.com/go/compute v1.24.0 // indirect
+	cloud.google.com/go/compute/metadata v0.2.3 // indirect
+	cloud.google.com/go/iam v1.1.7 // indirect
+	github.com/cenkalti/backoff/v3 v3.2.2 // indirect
+	github.com/felixge/httpsnoop v1.0.4 // indirect
+	github.com/go-chi/chi v4.0.2+incompatible // indirect
+	github.com/go-chi/render v1.0.1 // indirect
+	github.com/go-logr/logr v1.4.1 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang-jwt/jwt v3.2.2+incompatible // indirect
+	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
+	github.com/golang/protobuf v1.5.4 // indirect
+	github.com/google/s2a-go v0.1.7 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/googleapis/enterprise-certificate-proxy v0.3.2 // indirect
+	github.com/googleapis/gax-go/v2 v2.12.3 // indirect
+	github.com/hashicorp/errwrap v1.1.0 // indirect
+	github.com/hashicorp/go-multierror v1.1.1 // indirect
+	github.com/labstack/gommon v0.4.2 // indirect
+	github.com/lithammer/shortuuid/v3 v3.0.7 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/oklog/ulid v1.3.1 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/sony/gobreaker v0.5.0 // indirect
+	github.com/valyala/bytebufferpool v1.0.0 // indirect
+	github.com/valyala/fasttemplate v1.2.2 // indirect
+	go.opencensus.io v0.24.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.49.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.49.0 // indirect
+	go.opentelemetry.io/otel v1.24.0 // indirect
+	go.opentelemetry.io/otel/metric v1.24.0 // indirect
+	go.opentelemetry.io/otel/trace v1.24.0 // indirect
+	golang.org/x/crypto v0.21.0 // indirect
+	golang.org/x/net v0.22.0 // indirect
+	golang.org/x/oauth2 v0.18.0 // indirect
+	golang.org/x/sync v0.6.0 // indirect
+	golang.org/x/sys v0.18.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
+	golang.org/x/time v0.5.0 // indirect
+	google.golang.org/api v0.170.0 // indirect
+	google.golang.org/appengine v1.6.8 // indirect
+	google.golang.org/genproto v0.0.0-20240213162025-012b6fc9bca9 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20240314234333-6e1732d8331c // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20240311132316-a219d84964c2 // indirect
+	google.golang.org/grpc v1.62.1 // indirect
+	google.golang.org/protobuf v1.33.0 // indirect
+)