chore(queue): support NSQ as backend. (#600)

core/queue.go

@@ -0,0 +1,18 @@
+package core
+
+// Queue as backend
+type Queue string
+
+var (
+	// LocalQueue for channel in Go
+	LocalQueue Queue = "local"
+	// NSQ a realtime distributed messaging platform
+	NSQ Queue = "nsq"
+	// NATS Connective Technology for Adaptive Edge & Distributed Systems
+	NATS Queue = "nats"
+)
+
+// IsLocalQueue check is Local Queue
+func IsLocalQueue(q Queue) bool {
+	return q == LocalQueue
+}