Add JetStream request-reply and provisioner examples

docker/docker-compose.yaml

@@ -1,7 +1,7 @@
 version: '3.9'
 services:
   nats:
-    image: docker.io/nats:2.9.0
+    image: docker.io/nats:2.9.3
     command:
       - "--debug"
       - "--http_port=8222"

examples/jetstream/request-reply/go/go.mod

@@ -0,0 +1,14 @@
+module github.com/bruth/nats-by-example/examples/jetstream/request-reply/go
+
+go 1.19
+
+require github.com/nats-io/nats.go v1.18.1-0.20221015130652-e09f13da2bd8
+
+require (
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/nats-io/nats-server/v2 v2.9.3 // indirect
+	github.com/nats-io/nkeys v0.3.0 // indirect
+	github.com/nats-io/nuid v1.0.1 // indirect
+	golang.org/x/crypto v0.0.0-20220926161630-eccd6366d1be // indirect
+	google.golang.org/protobuf v1.28.1 // indirect
+)

examples/jetstream/request-reply/go/go.sum

@@ -0,0 +1,30 @@
+github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
+github.com/golang/protobuf v1.5.2 h1:ROPKBNFfQgOUMifHyP+KYbvpjbdoFNs+aK7DXlji0Tw=
+github.com/golang/protobuf v1.5.2/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
+github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/klauspost/compress v1.15.11 h1:Lcadnb3RKGin4FYM/orgq0qde+nc15E5Cbqg4B9Sx9c=
+github.com/minio/highwayhash v1.0.2 h1:Aak5U0nElisjDCfPSG79Tgzkn2gl66NxOMspRrKnA/g=
+github.com/nats-io/jwt/v2 v2.3.0 h1:z2mA1a7tIf5ShggOFlR1oBPgd6hGqcDYsISxZByUzdI=
+github.com/nats-io/nats-server/v2 v2.9.3 h1:HrfzA7G9LNetKkm1z+jU/e9kuAe+E6uaBuuq9EB5sQQ=
+github.com/nats-io/nats-server/v2 v2.9.3/go.mod h1:4sq8wvrpbvSzL1n3ZfEYnH4qeUuIl5W990j3kw13rRk=
+github.com/nats-io/nats.go v1.18.1-0.20221015130652-e09f13da2bd8 h1:2qzLrWyP1GFlcIegd5RJlGV0NQyB/yZDhrRL3M+GNG8=
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+github.com/nats-io/nkeys v0.3.0 h1:cgM5tL53EvYRU+2YLXIK0G2mJtK12Ft9oeooSZMA2G8=
+github.com/nats-io/nkeys v0.3.0/go.mod h1:gvUNGjVcM2IPr5rCsRsC6Wb3Hr2CQAm08dsxtV6A5y4=
+github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
+github.com/nats-io/nuid v1.0.1/go.mod h1:19wcPz3Ph3q0Jbyiqsd0kePYG7A95tJPxeL+1OSON2c=
+golang.org/x/crypto v0.0.0-20210314154223-e6e6c4f2bb5b/go.mod h1:T9bdIzuCu7OtxOm1hfPfRQxPLYneinmdGuTeoZ9dtd4=
+golang.org/x/crypto v0.0.0-20220926161630-eccd6366d1be h1:fmw3UbQh+nxngCAHrDCCztao/kbYFnWjoqop8dHx05A=
+golang.org/x/crypto v0.0.0-20220926161630-eccd6366d1be/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20220928140112-f11e5e49a4ec h1:BkDtF2Ih9xZ7le9ndzTA7KJow28VbQW3odyk/8drmuI=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/time v0.0.0-20220922220347-f3bd1da661af h1:Yx9k8YCG3dvF87UAn2tu2HQLf2dt/eR1bXxpLMWeH+Y=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
+google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
+google.golang.org/protobuf v1.28.1 h1:d0NfwRgPtno5B1Wa6L2DAG+KivqkdutMf1UhdNx175w=
+google.golang.org/protobuf v1.28.1/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=

examples/jetstream/request-reply/go/main.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/nats-io/nats.go"
+)
+
+func main() {
+	natsURL := os.Getenv("NATS_URL")
+
+	nc, _ := nats.Connect(natsURL)
+	defer nc.Drain()
+
+	js, _ := nc.JetStream()
+
+	// Create a [work-queue][wq] stream that will act as a buffer for requests.
+	js.AddStream(&nats.StreamConfig{
+		Name:      "REQUESTS",
+		Subjects:  []string{"requests.*"},
+		Retention: nats.WorkQueuePolicy,
+	})
+
+	// Create an ephemeral consumer + subscription responsible for replying.
+	sub, _ := js.Subscribe("requests.*", func(msg *nats.Msg) {
+		var r string
+		switch msg.Subject {
+		case "requests.order-sandwich":
+			r = "🥪"
+		case "requests.order-bagel":
+			r = "🥯"
+		case "requests.order-flatbread":
+			r = "🥙"
+		default:
+			return
+		}
+		msg.Respond([]byte(r))
+	})
+	defer sub.Drain()
+
+	// Send some requests.
+	rep, _ := js.Request("requests.order-sandwich", nil, time.Second)
+	fmt.Println(string(rep.Data))
+
+	rep, _ = js.Request("requests.order-flatbread", nil, time.Second)
+	fmt.Println(string(rep.Data))
+
+	// If a request cannot be fulfilled, the message is terminated.
+	_, err := js.Request("requests.order-drink", nil, time.Second)
+	fmt.Printf("timeout? %v\n", err == nats.ErrTimeout)
+
+	info, _ := js.StreamInfo("REQUESTS")
+	fmt.Printf("%d remaining in the stream\n", info.State.Msgs)
+}

examples/jetstream/request-reply/meta.yaml

@@ -0,0 +1,18 @@
+title: Request-Reply
+description: |
+  This is an experimental preview of a possible request-reply API
+  for JetStream. With core NATS, if a given client is not showing
+  interest in a subject at the time a message is published on that
+  subject, the message will not be received.
+
+  In general, this behavior is expected of request-reply since these
+  are expected to behave like a *phone call* where someone needs to
+  *pick up* in order to talk. The alternative is relying on a mailbox
+  which is essentially what a peristent stream enables.
+
+  The question is what happens with the reply if a message can be
+  sent, queued, and the responder comes online later when the original
+  requester is now offline?
+
+  These are some active questions the NATS team are evaluating if you
+  want to show your interest and use cases!

examples/use-cases/auto-scaler/go/go.mod

@@ -0,0 +1,14 @@
+module github.com/bruth/nats-by-example/examples/jetstream/request-reply/go
+
+go 1.19
+
+require github.com/nats-io/nats.go v1.18.1-0.20221015130652-e09f13da2bd8
+
+require (
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/nats-io/nats-server/v2 v2.9.3 // indirect
+	github.com/nats-io/nkeys v0.3.0 // indirect
+	github.com/nats-io/nuid v1.0.1 // indirect
+	golang.org/x/crypto v0.0.0-20220926161630-eccd6366d1be // indirect
+	google.golang.org/protobuf v1.28.1 // indirect
+)

examples/use-cases/auto-scaler/go/go.sum

@@ -0,0 +1,32 @@
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