MQTT progress

Author: Robert Winkler

kotlin-wot-binding-mqtt/src/main/kotlin/mqtt/MqttProtocolClient.kt

@@ -147,7 +147,7 @@ class MqttProtocolClient(
 
         try {
             log.debug(
-                "Publishing to topic '{}' on broker '{}' with response expected on '{}'",
+                "Publishing message to topic '{}' on broker '{}' with response expected on '{}'",
                 topic,
                 "${client.config.serverHost}:${client.config.serverPort}",
                 responseTopic

kotlin-wot-binding-mqtt/src/main/kotlin/mqtt/MqttProtocolServer.kt

@@ -172,7 +172,7 @@ class MqttProtocolServer(
 
     private suspend fun exposeTD(thing: ExposedThing) {
         val topic = thing.id
-        log.debug("Publishing Thing Description '{}' to topic '{}'", thing.id, topic)
+        //log.debug("Publishing Thing Description '{}' to topic '{}'", thing.id, topic)
 
         try {
             val content = ContentManager.valueToContent(thing.toJson(), "application/json")
@@ -181,8 +181,10 @@ class MqttProtocolServer(
                 .topicFilter(tdTopic)
                 .qos(MqttQos.AT_LEAST_ONCE) // Use AT_LEAST_ONCE QoS level
                 .callback { message ->
+                    val responseTopic = message.responseTopic.get()
+                    log.debug("Sending Thing Description of thing '{}' to topic '{}'", thing.id, responseTopic)
                     CoroutineScope(Dispatchers.IO + exceptionHandler).launch {
-                        respondToTopic(content, message.responseTopic.get())
+                        respondToTopic(content, responseTopic)
                     }
                 }
                 .send().await()  // Sending the subscription request

kotlin-wot/src/main/kotlin/Servient.kt

@@ -8,7 +8,7 @@ import ai.ancf.lmos.wot.thing.filter.DiscoveryMethod.*
 import ai.ancf.lmos.wot.thing.filter.ThingFilter
 import ai.ancf.lmos.wot.thing.form.Form
 import ai.ancf.lmos.wot.thing.schema.DataSchemaValue
-import ai.ancf.lmos.wot.thing.schema.ObjectSchema
+import ai.ancf.lmos.wot.thing.schema.StringSchema
 import ai.ancf.lmos.wot.thing.schema.WoTExposedThing
 import ai.anfc.lmos.wot.binding.*
 import kotlinx.coroutines.async
@@ -166,18 +166,17 @@ class Servient(
      * @return
      */
      suspend fun fetch(url: URI): ThingDescription {
-        log.debug("Fetch thing from url '{}'", url)
+        log.debug("Fetching thing description from '{}'", url)
         val scheme = url.scheme
         try {
             val client = getClientFor(scheme)
             if (client != null) {
-                val form = Form(href = url.toString())
+                val form = Form(href = url.toString(), contentType = "application/json")
                 val content = client.readResource(form)
                 try {
-                    val dataSchemaValue = ContentManager.contentToValue(content, ObjectSchema())
-                    dataSchemaValue as DataSchemaValue.ObjectValue
-
-                    return ThingDescription.fromMap(dataSchemaValue.value)
+                    val dataSchemaValue = ContentManager.contentToValue(content, StringSchema())
+                    dataSchemaValue as DataSchemaValue.StringValue
+                    return ThingDescription.fromJson(dataSchemaValue.value)
                 } catch (e: ContentCodecException) {
                     throw ServientException("Error while fetching TD: ${e.message}", e)
                 }

kotlin-wot/src/main/kotlin/thing/ExposedThing.kt

@@ -655,12 +655,12 @@ data class ThingDescription (
          * @param json JSON string to parse.
          * @return A Thing instance if parsing is successful, otherwise null.
          */
-        fun fromJson(json: String?): ThingDescription? {
+        fun fromJson(json: String): ThingDescription {
             return try {
                 JsonMapper.instance.readValue(json, ThingDescription::class.java)
             } catch (e: IOException) {
                 log.warn("Unable to read json", e)
-                null
+                throw e
             }
         }
 

kotlin-wot/src/main/kotlin/thing/form/Form.kt

@@ -29,7 +29,7 @@ data class Form(
     val href: String, // Target IRI of a link or submission target of a form. Mandatory
 
     @JsonInclude(NON_EMPTY)
-    val contentType: String = "text/plain", // Assign a content type. Default is "text/plain"
+    val contentType: String = "application/json", // Assign a content type. Default is "application/json"
 
     @JsonInclude(NON_EMPTY)
     val contentCoding: String? = null, // Optional content coding values