Extracted constants to constants.json for better parameterisation

dispatch_system/constants.json

@@ -8,6 +8,14 @@
     "couchdb_host": "10.129.6.5:5984",
     "couchdb_db_name": "serverless",
     "topics": {
-        
+        "request_dm_2_rm": "request",
+        "heartbeat": "heartbeat",
+        "deployed": "deployed",
+        "remove_worker": "removeWorker",
+        "response_rm_2_dm": "RESPONSE_RM_2_DM_DUMMY",
+        "hscale": "hscale"
+    },
+    "autoscalar_metrics": {
+        "open_request_threshold": 100
     }
 }
\ No newline at end of file

dispatch_system/dispatch_manager/index.js

@@ -40,11 +40,11 @@ let kafka = require('kafka-node'),
     Consumer = kafka.Consumer,
     consumer = new Consumer(client,
         [
-            { topic: 'heartbeat' }, // receives heartbeat messages from workers, also acts as worker join message
-            { topic: "deployed" }, // receives deployment confirmation from workers
-            { topic: "removeWorker" }, // received when a executor environment is blown at the worker
-            { topic: "RESPONSE_RM_2_DM" }, // receives deployment details from RM
-            { topic: "hscale" } // receives signals for horizontal scaling
+            { topic: constants.topics.heartbeat }, // receives heartbeat messages from workers, also acts as worker join message
+            { topic: constants.topics.deployed }, // receives deployment confirmation from workers
+            { topic: constants.topics.remove_worker }, // received when a executor environment is blown at the worker
+            { topic: constants.topics.response_rm_2_dm }, // receives deployment details from RM
+            { topic: constants.topics.hscale } // receives signals for horizontal scaling
         ],
         [
             { autoCommit: true }
@@ -66,7 +66,6 @@ let requestQueue = []
 const WINDOW_SIZE = 10
 const port = constants.master_port
 const registry_url = constants.registry_url
-const AUTOSCALAR_THRESHOLD = 100;
 
 /**
  * REST API to receive deployment requests
@@ -260,7 +259,7 @@ function dispatch() {
 
 
             let payloadToRM = [{
-                topic: "REQUEST_DM_2_RM", // changing from REQUEST_DM_2_RM
+                topic: constants.topics.request_dm_2_rm, // changing from REQUEST_DM_2_RM
                 messages: JSON.stringify({
                     resource_id,
                     "memory": 332,
@@ -370,7 +369,7 @@ consumer.on('message', function (message) {
         logger.info("response " + message);
         
         
-    } else if (topic === "heartbeat") {
+    } else if (topic === constants.topics.heartbeat) {
         message = JSON.parse(message)
         if (Date.now() - message.timestamp < 1000)
             if (!workerNodes.has(message.address))  {
@@ -378,7 +377,7 @@ consumer.on('message', function (message) {
                 logger.warn("New worker discovered. Worker List: ")
                 logger.warn(workerNodes)
             }
-    } else if (topic == "deployed") {
+    } else if (topic == constants.topics.deployed) {
         try {
             message = JSON.parse(message)
         } catch (e) {
@@ -386,7 +385,7 @@ consumer.on('message', function (message) {
         }
         postDeploy(message)
         
-    } else if (topic == "removeWorker") {
+    } else if (topic == constants.topics.remove_worker) {
         logger.warn("Worker blown: Removing Metadata " + message);
         try {
             message = JSON.parse(message)
@@ -411,7 +410,7 @@ consumer.on('message', function (message) {
         }
         
 
-    } else if (topic == "hscale") {
+    } else if (topic == constants.topics.hscale) {
         message = JSON.parse(message)
         let resource_id = libSupport.makeid(20), // each function resource request is associated with an unique ID
             runtime = message.runtime,
@@ -431,7 +430,7 @@ consumer.on('message', function (message) {
 
 
         let payloadToRM = [{
-            topic: "request", // changing from REQUEST_DM_2_RM
+            topic: constants.topics.request_dm_2_rm, // changing from REQUEST_DM_2_RM
             messages: JSON.stringify({
                 resource_id,
                 "memory": 332,
@@ -443,7 +442,7 @@ consumer.on('message', function (message) {
             console.log("sent rm");
 
         })
-    } else if (topic == "RESPONSE_RM_2_DM") {
+    } else if (topic == constants.topics.response_rm_2_dm) {
         
         logger.info("Response from RM: " + message);
         message = JSON.parse(message)
@@ -482,7 +481,8 @@ consumer.on('message', function (message) {
 function autoscalar() {
     functionToResource.forEach((resourceList, functionKey, map) => {
         
-        if (resourceList.length > 0 && resourceList[resourceList.length - 1].open_request_count > AUTOSCALAR_THRESHOLD) {
+        if (resourceList.length > 0 && 
+            resourceList[resourceList.length - 1].open_request_count > constants.autoscalar_metrics.open_request_threshold) {
             let resource = resourceMap.get(resourceList[resourceList.length - 1].resource_id)
             logger.warn(`resource ${resourceList[resourceList.length - 1]} exceeded autoscalar threshold. Scaling up!`)
             let payload = [{