Graph System

/**
 * Basic directed graph implementation
 */
public class Graph {
    /** Creates a new empty graph */
    public Graph();
    
    /** Adds a node to the graph */
    public void addNode(Node node);
    
    /** Removes a node from the graph */
    public void removeNode(Node node);
    
    /** Returns all nodes in the graph */
    public Set<Node> getNodes();
    
    /** Sets the nodes in the graph */
    public void setNodes(Set<Node> nodes);
    
    /** Gets a node by its name */
    public Node getNodeByName(String name);
    
    /** Adds an edge to the graph */
    public void addEdge(Edge edge);
    
    /** Adds an edge between named nodes */
    public void addEdge(String from, String to);
    
    /** Removes an edge from the graph */
    public void removeEdge(Edge edge);
    
    /** Removes edge between named nodes */
    public void removeEdge(String fromNodeName, String toNodeName);
    
    /** Returns all edges in the graph */
    public Set<Edge> getEdges();
    
    /** Sets the edges in the graph */
    public void setEdges(Set<Edge> edges);
    
    /** Finds all edges connected to the specified node */
    public Set<Edge> findEdges(Node node);
    
    /** Finds all edges originating from the specified node */
    public Set<Edge> findEdgesFrom(Node from);
    
    /** Gets path between named nodes using BFS algorithm */
    public Route getPath(String nodeNameOrigin, String nodeNameDest);
    
    /** Gets path between nodes using BFS algorithm */
    public Route getPath(Node from, Node to);
    
    /** Inserts a new node on an existing edge */
    public void insertNode(Edge edge, String nodeName);
    
    /** Inserts a new node on an existing edge */
    public void insertNode(Edge edge, Node node);
}

import org.eclipse.jetty.deploy.graph.*;

// Create a custom deployment graph
Graph deploymentGraph = new Graph();

// Add nodes for deployment states
Node undeployed = new Node("undeployed");
Node deploying = new Node("deploying");
Node deployed = new Node("deployed");
Node starting = new Node("starting");
Node started = new Node("started");

deploymentGraph.addNode(undeployed);
deploymentGraph.addNode(deploying);
deploymentGraph.addNode(deployed);
deploymentGraph.addNode(starting);
deploymentGraph.addNode(started);

// Connect nodes with edges
deploymentGraph.addEdge(undeployed, deploying);
deploymentGraph.addEdge(deploying, deployed);
deploymentGraph.addEdge(deployed, starting);
deploymentGraph.addEdge(starting, started);

// Find path between states
Route deploymentPath = deploymentGraph.getPath("undeployed", "started");
System.out.println("Deployment path: " + deploymentPath);

// Insert intermediate state
Node configuring = new Node("configuring");
Edge deployingToDeployed = new Edge(deploying, deployed);
deploymentGraph.insertNode(deployingToDeployed, configuring);

// Query graph structure
Set<Node> allNodes = deploymentGraph.getNodes();
Set<Edge> allEdges = deploymentGraph.getEdges();
Set<Edge> edgesFromDeployed = deploymentGraph.findEdgesFrom(deployed);

/**
 * Represents a basic graph node
 */
public final class Node {
    /** Creates a node with the specified name */
    public Node(String name);
    
    /** Returns the node name */
    public String getName();
    
    /** Returns string representation of the node */
    public String toString();
    
    /** Returns hash code for the node */
    public int hashCode();
    
    /** Checks equality with another object */
    public boolean equals(Object obj);
}

/**
 * Represents a basic graph edge connecting two nodes
 */
public final class Edge {
    /** Creates an edge from one node to another */
    public Edge(Node from, Node to);
    
    /** Returns the source node */
    public Node getFrom();
    
    /** Returns the destination node */
    public Node getTo();
    
    /** Returns string representation of the edge */
    public String toString();
    
    /** Returns hash code for the edge */
    public int hashCode();
    
    /** Checks equality with another object */
    public boolean equals(Object obj);
}

/**
 * Represents a route through the graph as a sequence of edges and nodes
 */
public class Route {
    /** Creates a new empty route */
    public Route();
    
    /** Adds an edge to the route */
    public void add(Edge edge);
    
    /** Creates a copy of this route */
    public Route forkRoute();
    
    /** Returns the nodes in the route */
    public List<Node> getNodes();
    
    /** Returns the edges in the route */
    public List<Edge> getEdges();
    
    /** Gets node at the specified index */
    public Node getNode(int index);
    
    /** Returns first node in the route */
    public Node firstNode();
    
    /** Returns last node in the route */
    public Node lastNode();
    
    /** Returns number of nodes in the route */
    public int nodes();
    
    /** Returns number of edges in the route */
    public int edges();
    
    /** Returns true if route is empty */
    public boolean isEmpty();
    
    /** Returns first edge in the route */
    public Edge firstEdge();
    
    /** Returns last edge in the route */
    public Edge lastEdge();
    
    /** Gets edge at the specified index */
    public Edge getEdge(int index);
    
    /** Returns string representation of the route */
    public String toString();
}

// Working with routes from path finding
Route route = graph.getPath("undeployed", "started");

if (!route.isEmpty()) {
    System.out.println("Route from undeployed to started:");
    
    // Iterate through nodes in the route
    List<Node> nodes = route.getNodes();
    for (int i = 0; i < nodes.size(); i++) {
        Node node = route.getNode(i);
        System.out.println("Step " + i + ": " + node.getName());
    }
    
    // Access route endpoints
    Node start = route.firstNode();
    Node end = route.lastNode();
    System.out.println("Route: " + start.getName() + " -> " + end.getName());
    
    // Work with edges in the route
    for (int i = 0; i < route.edges(); i++) {
        Edge edge = route.getEdge(i);
        System.out.println("Transition: " + edge.getFrom().getName() + 
                         " -> " + edge.getTo().getName());
    }
}

// Create and manipulate routes manually
Route customRoute = new Route();
customRoute.add(new Edge(new Node("start"), new Node("middle")));
customRoute.add(new Edge(new Node("middle"), new Node("end")));

// Fork routes for parallel processing
Route originalRoute = graph.getPath("deployed", "started");
Route alternativeRoute = originalRoute.forkRoute();
// Modify alternativeRoute independently

/**
 * Utility for outputting graphs in GraphViz Dot format
 */
public class GraphOutputDot {
    /** Writes graph to DOT file for GraphViz visualization */
    public static void write(Graph graph, File outputFile) throws IOException;
}

import org.eclipse.jetty.deploy.graph.GraphOutputDot;
import java.io.File;
import java.io.IOException;

// Export graph to DOT format for visualization
Graph graph = deploymentManager.getLifeCycle();
File dotFile = new File("deployment-lifecycle.dot");

try {
    GraphOutputDot.write(graph, dotFile);
    System.out.println("Graph exported to: " + dotFile.getAbsolutePath());
    
    // The generated DOT file can be used with GraphViz tools:
    // dot -Tpng deployment-lifecycle.dot -o deployment-lifecycle.png
    // dot -Tsvg deployment-lifecycle.dot -o deployment-lifecycle.svg
} catch (IOException e) {
    System.err.println("Failed to export graph: " + e.getMessage());
}

// Visualize custom graphs
Graph customGraph = new Graph();
// ... build custom graph structure ...
GraphOutputDot.write(customGraph, new File("custom-states.dot"));

// Create a state machine for application deployment
Graph stateMachine = new Graph();

// Define states
Node[] states = {
    new Node("undeployed"),
    new Node("deploying"), 
    new Node("deployed"),
    new Node("starting"),
    new Node("started"),
    new Node("stopping"),
    new Node("failed")
};

// Add all states to graph
for (Node state : states) {
    stateMachine.addNode(state);
}

// Define state transitions
stateMachine.addEdge("undeployed", "deploying");
stateMachine.addEdge("deploying", "deployed");
stateMachine.addEdge("deploying", "failed");
stateMachine.addEdge("deployed", "starting");
stateMachine.addEdge("starting", "started");
stateMachine.addEdge("starting", "failed");
stateMachine.addEdge("started", "stopping");
stateMachine.addEdge("stopping", "deployed");
stateMachine.addEdge("stopping", "failed");

// Any state can transition to failed
for (Node state : states) {
    if (!"failed".equals(state.getName())) {
        stateMachine.addEdge(state, stateMachine.getNodeByName("failed"));
    }
}

// Validate that a transition is possible
public boolean canTransition(Graph graph, String fromState, String toState) {
    Route route = graph.getPath(fromState, toState);
    return route != null && !route.isEmpty();
}

// Get all possible next states
public Set<String> getNextStates(Graph graph, String currentState) {
    Node currentNode = graph.getNodeByName(currentState);
    Set<Edge> outgoingEdges = graph.findEdgesFrom(currentNode);
    
    return outgoingEdges.stream()
        .map(edge -> edge.getTo().getName())
        .collect(Collectors.toSet());
}

// Find shortest path between states
public List<String> getTransitionPath(Graph graph, String from, String to) {
    Route route = graph.getPath(from, to);
    if (route == null || route.isEmpty()) {
        return Collections.emptyList();
    }
    
    return route.getNodes().stream()
        .map(Node::getName)
        .collect(Collectors.toList());
}