Added some code for call tree generation

src/main/java/kieker/diagnosis/domain/AbstractOperationCall.java

@@ -17,6 +17,8 @@
 package kieker.diagnosis.domain;
 
 import java.util.ArrayList;
+import java.util.Deque;
+import java.util.LinkedList;
 import java.util.List;
 
 /**
@@ -176,4 +178,28 @@ public abstract class AbstractOperationCall<T extends AbstractOperationCall<T>>
 		return true;
 	}
 
+	public final String toDotForCallTree() {
+		final Deque<AbstractOperationCall<T>> stack = new LinkedList<>();
+		final StringBuilder sb = new StringBuilder();
+
+		sb.append("digraph G {");
+		sb.append("rankdir = TB;");
+		sb.append("node [shape = none];");
+
+		stack.push(this);
+		while (!stack.isEmpty()) {
+			final AbstractOperationCall<T> call = stack.pop();
+			sb.append(call.operation).append(';');
+
+			for (final AbstractOperationCall<T> child : call.children) {
+				sb.append(call.operation).append(" -> ").append(child.operation).append(';');
+				stack.push(child);
+			}
+		}
+
+		sb.append("}");
+
+		return sb.toString();
+	}
+
 }

src/test/java/kieker/diagnosis/domain/AbstractOperationCallTest.java

@@ -20,7 +20,6 @@ import static org.hamcrest.core.Is.is;
 import static org.hamcrest.core.IsEqual.equalTo;
 import static org.hamcrest.core.IsNot.not;
 import static org.junit.Assert.assertThat;
-import kieker.diagnosis.domain.AbstractOperationCall;
 
 import org.junit.Test;
 
@@ -98,4 +97,14 @@ public abstract class AbstractOperationCallTest<T extends AbstractOperationCall<
 		assertThat(fstCall, is(not(equalTo(sndCall))));
 	}
 
+	@Test
+	public void toDotForCallTreeShouldWorkForSimpleCase() {
+		final T call = this.createOperationCall("container", "component", "operation");
+
+		call.addChild(this.createOperationCall("container1", "component1", "operation1"));
+		call.addChild(this.createOperationCall("container2", "component2", "operation2"));
+
+		assertThat(call.toDotForCallTree(), is("digraph G {rankdir = TB;node [shape = none];operation;operation -> operation1;operation -> operation2;operation2;operation1;}"));
+	}
+
 }