Implemented the following points:

- Roster/Auctionhouse send initial getExecutors request
- Remove executor (made DELETE endpoint in executor pool)

roster/src/main/java/ch/unisg/roster/RosterApplication.java

@@ -8,6 +8,7 @@ import javax.annotation.PostConstruct;
 
 import ch.unisg.roster.roster.adapter.out.persistence.mongodb.RosterRepository;
 import ch.unisg.roster.roster.application.port.in.LoadRosterItemPort;
+import ch.unisg.roster.roster.application.service.GetExecutorsService;
 import ch.unisg.roster.roster.domain.Roster;
 import ch.unisg.roster.roster.domain.RosterItem;
 import org.eclipse.paho.client.mqttv3.MqttException;
@@ -36,6 +37,8 @@ public class RosterApplication {
 		SpringApplication rosterApp = new SpringApplication(RosterApplication.class);
         ENVIRONMENT = rosterApp.run(args).getEnvironment();
         bootstrapMarketplaceWithMqtt();
+        var getExecutorsService = new GetExecutorsService();
+        getExecutorsService.getExecutorsFromExecutorPool();
 	}
 
     /**

roster/src/main/java/ch/unisg/roster/roster/adapter/out/web/GetExecutorsInExecutorPoolWebAdapter.java

@@ -0,0 +1,61 @@
+package ch.unisg.roster.roster.adapter.out.web;
+
+import ch.unisg.roster.roster.domain.ExecutorInfo;
+import org.apache.logging.log4j.Level;
+import org.json.JSONArray;
+import org.json.JSONObject;
+import org.springframework.http.HttpStatus;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.util.LinkedList;
+import java.util.List;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+public class GetExecutorsInExecutorPoolWebAdapter {
+    private static final Logger LOGGER = LogManager.getLogger(GetExecutorsInExecutorPoolWebAdapter.class);
+
+    // TODO get from config
+    String server = "http://localhost:8083";
+
+    public List<ExecutorInfo>  getExecutorsInExecutorPool(){
+        var client = HttpClient.newHttpClient();
+        var request = HttpRequest.newBuilder()
+            .uri(URI.create(server + "/executor-pool/GetAllExecutorsInExecutorPool"))
+            .GET()
+            .build();
+
+        try {
+            var response = client.send(request, HttpResponse.BodyHandlers.ofString());
+
+            if(response.statusCode() != HttpStatus.OK.value()){
+                LOGGER.log(Level.INFO, "Could not get executors from Executor Pool");
+                return null;
+            }
+
+            LOGGER.log(Level.INFO, "Executors received from ExecutorPool: " + response.body());
+
+            var jsonExecutorArray = new JSONArray(response.body());
+            var executorList = new LinkedList<ExecutorInfo>();
+
+            for(int i = 0; i < jsonExecutorArray.length(); i++){
+                var jsonExecutorObject = jsonExecutorArray.getJSONObject(i);
+                var executorURI = jsonExecutorObject.getString("executorUri");
+                var executorType = jsonExecutorObject.getString("executorTaskType");
+                executorList.add(new ExecutorInfo(executorURI, executorType));
+            }
+
+            return executorList;
+        } catch (IOException e) {
+            e.printStackTrace();
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+
+        return null;
+    }
+}

roster/src/main/java/ch/unisg/roster/roster/application/service/GetExecutorsService.java

@@ -0,0 +1,18 @@
+package ch.unisg.roster.roster.application.service;
+
+import ch.unisg.roster.roster.adapter.out.web.GetExecutorsInExecutorPoolWebAdapter;
+import ch.unisg.roster.roster.domain.ExecutorRegistry;
+
+// TODO should this implement a port in the Hexagonal architecture?
+public class GetExecutorsService {
+
+    public boolean getExecutorsFromExecutorPool(){
+        var getExecutorsAdapter = new GetExecutorsInExecutorPoolWebAdapter();
+        var executors = getExecutorsAdapter.getExecutorsInExecutorPool();
+        if(executors == null){
+            return false;
+        }
+        var executorRegistry = ExecutorRegistry.getInstance();
+        return executorRegistry.addExecutors(executors);
+    }
+}

roster/src/main/java/ch/unisg/roster/roster/domain/ExecutorInfo.java

@@ -5,6 +5,8 @@ import ch.unisg.common.valueobject.ExecutorURI;
 import lombok.Getter;
 import lombok.Setter;
 
+import java.net.URI;
+
 public class ExecutorInfo {
     @Getter
     @Setter
@@ -13,4 +15,9 @@ public class ExecutorInfo {
     @Getter
     @Setter
     private ExecutorType executorType;
+
+    public ExecutorInfo(String executorURI, String executorType){
+        this.executorURI = new ExecutorURI(executorURI);
+        this.executorType = new ExecutorType(executorType);
+    }
 }

roster/src/main/java/ch/unisg/roster/roster/domain/ExecutorRegistry.java

@@ -30,8 +30,8 @@ public class ExecutorRegistry {
     /**
      * Adds an executor to the registry for a given task type.
      *
-     * @param taskType the type of the task
-     * @param executorIdentifier the identifier of the executor (can be any string)
+     * @param executorType the type of the task
+     * @param executorURI the identifier of the executor (can be any string)
      * @return true unless a runtime exception occurs
      */
     public boolean addExecutor(ExecutorType executorType, ExecutorURI executorURI) {
@@ -44,6 +44,15 @@ public class ExecutorRegistry {
         return true;
     }
 
+    public boolean addExecutors(List<ExecutorInfo> executors){
+        for (var executor : executors) {
+            if(!addExecutor(executor.getExecutorType(), executor.getExecutorURI())){
+                return false;
+            }
+        }
+        return true;
+    }
+
     /**
      * Removes an executor from the registry. The executor is disassociated from all known task types.
      *