feat: create signalR client

Author: andrea-acampora

src/main/kotlin/infrastructure/signalr/SignalRClient.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2023. Smart Operating Block
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
+ */
+
+package infrastructure.signalr
+
+import application.presenter.EventConsumer
+import application.presenter.EventParser
+import com.microsoft.signalr.HubConnectionBuilder
+import entities.events.Event
+import infrastructure.digitaltwins.DTEventParser
+import io.reactivex.rxjava3.core.FlowableEmitter
+
+/**
+ * The consumer of events from a SignalR topic.
+ */
+class SignalRClient : EventConsumer<String> {
+
+    init {
+        requireNotNull(System.getenv("SIGNALR_CONNECTION_STRING")) {
+            println("Invalid connection String: please provide a valid connection String!")
+        }
+    }
+
+    private val connection = HubConnectionBuilder.create(System.getenv("SIGNALR_CONNECTION_STRING")).build()
+    private val eventParser: EventParser<String> = DTEventParser()
+
+    override fun start(emitter: FlowableEmitter<Event<Any>>) {
+        connection.on("newMessage", { event ->
+                emitter.onNext(consumeEvent(event))
+            }, String::class.java)
+        connection.start()
+    }
+
+    override fun consumeEvent(inputEvent: String): Event<Any> = eventParser.parseEvent(inputEvent)
+
+}