Mutli node interrup example in langGraph4j
Your agents flow might require interruption or human-in-loop at multiple node executions. Here is the code sample to do so
package ai;
import org.bsc.langgraph4j.*;
import org.bsc.langgraph4j.checkpoint.MemorySaver;
import org.bsc.langgraph4j.state.AgentState;
import org.bsc.langgraph4j.state.StateSnapshot;
import java.util.*;
import java.util.concurrent.CompletableFuture;
import static org.bsc.langgraph4j.StateGraph.END;
import static org.bsc.langgraph4j.StateGraph.START;
/**
* Multi-Stage Approval Workflow with 3 Interrupt Points
*
* Shows how to:
* - Handle multiple checkpoints
* - Identify which checkpoint you're at
* - Handle different logic for each stage
*/
public class MultiStageApprovalExample {
// Nodes
private static Map<String, Object> submitRequest(AgentState state) {
System.out.println("\n[SUBMIT] Request submitted");
int amount = (int) state.data().get("amount");
Map<String, Object> updates = new HashMap<>();
updates.put("status", "submitted");
updates.put("current_stage", "manager_review");
updates.put("amount", amount);
return updates;
}
private static Map<String, Object> managerReview(AgentState state) {
int amount = (int) state.data().get("amount");
System.out.println("\n[MANAGER] Reviewing $" + amount);
Map<String, Object> updates = new HashMap<>();
updates.put("status", "pending_manager_approval");
updates.put("current_stage", "manager_review");
updates.put("message", "Awaiting manager approval");
return updates;
}
private static Map<String, Object> financeReview(AgentState state) {
int amount = (int) state.data().get("amount");
System.out.println("\n[FINANCE] Reviewing $" + amount);
Map<String, Object> updates = new HashMap<>();
updates.put("status", "pending_finance_approval");
updates.put("current_stage", "finance_review");
updates.put("message", "Awaiting finance approval");
return updates;
}
private static Map<String, Object> ceoReview(AgentState state) {
int amount = (int) state.data().get("amount");
System.out.println("\n[CEO] Reviewing $" + amount);
Map<String, Object> updates = new HashMap<>();
updates.put("status", "pending_ceo_approval");
updates.put("current_stage", "ceo_review");
updates.put("message", "Awaiting CEO approval");
return updates;
}
private static Map<String, Object> executeRequest(AgentState state) {
System.out.println("\n[EXECUTE] Processing approved request");
Map<String, Object> updates = new HashMap<>();
updates.put("status", "completed");
updates.put("current_stage", "completed");
return updates;
}
// Build workflow with 3 interrupts
public static CompiledGraph<AgentState> buildWorkflow() throws Exception {
StateGraph<AgentState> workflow = new StateGraph<>(AgentState::new);
workflow.addNode("submit", state -> CompletableFuture.completedFuture(submitRequest(state)));
workflow.addNode("manager_review", state -> CompletableFuture.completedFuture(managerReview(state)));
workflow.addNode("finance_review", state -> CompletableFuture.completedFuture(financeReview(state)));
workflow.addNode("ceo_review", state -> CompletableFuture.completedFuture(ceoReview(state)));
workflow.addNode("execute", state -> CompletableFuture.completedFuture(executeRequest(state)));
workflow.addEdge(START, "submit");
workflow.addEdge("submit", "manager_review");
workflow.addEdge("manager_review", "finance_review");
workflow.addEdge("finance_review", "ceo_review");
workflow.addEdge("ceo_review", "execute");
workflow.addEdge("execute", END);
// THREE INTERRUPT POINTS!
CompileConfig config = CompileConfig.builder()
.checkpointSaver(new MemorySaver())
.interruptAfter("manager_review") // Checkpoint 1
.interruptAfter("finance_review") // Checkpoint 2
.interruptAfter("ceo_review") // Checkpoint 3
.build();
return workflow.compile(config);
}
/**
* Helper: Identify which stage we're at
*/
public static String identifyCurrentStage(StateSnapshot<AgentState> snapshot) {
AgentState state = snapshot.state();
// Option 1: Check the "current_stage" field we set in nodes
String currentStage = (String) state.data().get("current_stage");
if (currentStage != null) {
return currentStage;
}
// Option 2: Check the status field
String status = (String) state.data().get("status");
if (status != null) {
if (status.contains("manager")) return "manager_review";
if (status.contains("finance")) return "finance_review";
if (status.contains("ceo")) return "ceo_review";
}
// Option 3: Check what's next
List<String> nextNodes = snapshot.next();
if (!nextNodes.isEmpty()) {
String next = nextNodes.get(0);
// We're paused just before this next node
return "before_" + next;
}
return "unknown";
}
/**
* Handle approval for specific stage
*/
public static void handleApprovalAtStage(
CompiledGraph<AgentState> app,
RunnableConfig config,
String stage,
String approverName,
boolean approved
) throws Exception {
System.out.println("\n" + "=".repeat(70));
System.out.println("HANDLING APPROVAL AT STAGE: " + stage);
System.out.println("=".repeat(70));
Map<String, Object> updates = new HashMap<>();
switch (stage) {
case "manager_review":
updates.put("manager_approved", approved);
updates.put("manager_name", approverName);
updates.put("manager_timestamp", System.currentTimeMillis());
app.updateState(config, updates, "manager_review");
break;
case "finance_review":
updates.put("finance_approved", approved);
updates.put("finance_name", approverName);
updates.put("finance_timestamp", System.currentTimeMillis());
app.updateState(config, updates, "finance_review");
break;
case "ceo_review":
updates.put("ceo_approved", approved);
updates.put("ceo_name", approverName);
updates.put("ceo_timestamp", System.currentTimeMillis());
app.updateState(config, updates, "ceo_review");
break;
default:
throw new IllegalStateException("Unknown stage: " + stage);
}
System.out.println("✓ Updated checkpoint at stage: " + stage);
}
/**
* Main workflow orchestration
*/
public static void main(String[] args) {
try {
System.out.println("╔════════════════════════════════════════════════════════════╗");
System.out.println("║ Multi-Stage Approval Workflow (3 Checkpoints) ║");
System.out.println("╚════════════════════════════════════════════════════════════╝");
CompiledGraph<AgentState> app = buildWorkflow();
// Initial request
String requestId = "REQ-MULTI-001";
RunnableConfig config = RunnableConfig.builder()
.threadId(requestId)
.build();
Map<String, Object> initialData = new HashMap<>();
initialData.put("amount", 50000);
initialData.put("requester", "Alice");
// ================================================================
// EXECUTION 1: Start workflow, pause at manager_review
// ================================================================
System.out.println("\n" + "=".repeat(70));
System.out.println("EXECUTION #1: Initial Request");
System.out.println("=".repeat(70));
app.stream(initialData, config).forEach(output -> {
System.out.println(" → " + output.node());
});
// Check where we are
StateSnapshot<AgentState> snapshot1 = app.getState(config);
String stage1 = identifyCurrentStage(snapshot1);
System.out.println("\n✋ PAUSED at stage: " + stage1);
System.out.println(" Status: " + snapshot1.state().data().get("status"));
System.out.println(" Message: " + snapshot1.state().data().get("message"));
System.out.println(" Next nodes: " + snapshot1.next());
// ================================================================
// EXECUTION 2: Manager approves, pause at finance_review
// ================================================================
System.out.println("\n\n" + "=".repeat(70));
System.out.println("EXECUTION #2: Manager Approval");
System.out.println("=".repeat(70));
Thread.sleep(500);
System.out.println("\n👤 Manager Bob Smith reviews and approves");
// Handle manager approval
handleApprovalAtStage(app, config, stage1, "Bob Smith", true);
// Resume
System.out.println("\n▶️ Resuming workflow...");
app.stream(null, config).forEach(output -> {
System.out.println(" → " + output.node());
});
// Check where we are now
StateSnapshot<AgentState> snapshot2 = app.getState(config);
String stage2 = identifyCurrentStage(snapshot2);
System.out.println("\n✋ PAUSED at stage: " + stage2);
System.out.println(" Status: " + snapshot2.state().data().get("status"));
System.out.println(" Message: " + snapshot2.state().data().get("message"));
System.out.println(" Manager: " + snapshot2.state().data().get("manager_name") + " ✓");
// ================================================================
// EXECUTION 3: Finance approves, pause at ceo_review
// ================================================================
System.out.println("\n\n" + "=".repeat(70));
System.out.println("EXECUTION #3: Finance Approval");
System.out.println("=".repeat(70));
Thread.sleep(500);
System.out.println("\n👤 Finance Director Carol approves");
// Handle finance approval
handleApprovalAtStage(app, config, stage2, "Carol Johnson", true);
// Resume
System.out.println("\n▶️ Resuming workflow...");
app.stream(null, config).forEach(output -> {
System.out.println(" → " + output.node());
});
// Check where we are now
StateSnapshot<AgentState> snapshot3 = app.getState(config);
String stage3 = identifyCurrentStage(snapshot3);
System.out.println("\n✋ PAUSED at stage: " + stage3);
System.out.println(" Status: " + snapshot3.state().data().get("status"));
System.out.println(" Message: " + snapshot3.state().data().get("message"));
System.out.println(" Manager: " + snapshot3.state().data().get("manager_name") + " ✓");
System.out.println(" Finance: " + snapshot3.state().data().get("finance_name") + " ✓");
// ================================================================
// EXECUTION 4: CEO approves, completes workflow
// ================================================================
System.out.println("\n\n" + "=".repeat(70));
System.out.println("EXECUTION #4: CEO Approval (Final)");
System.out.println("=".repeat(70));
Thread.sleep(500);
System.out.println("\n👤 CEO David approves");
// Handle CEO approval
handleApprovalAtStage(app, config, stage3, "David CEO", true);
// Resume - should complete now
System.out.println("\n▶️ Resuming workflow...");
app.stream(null, config).forEach(output -> {
System.out.println(" → " + output.node());
});
// Final state
StateSnapshot<AgentState> finalSnapshot = app.getState(config);
System.out.println("\n" + "=".repeat(70));
System.out.println("✓ WORKFLOW COMPLETED!");
System.out.println("=".repeat(70));
System.out.println("\n📊 Final State:");
System.out.println(" Status: " + finalSnapshot.state().data().get("status"));
System.out.println(" Amount: $" + finalSnapshot.state().data().get("amount"));
System.out.println(" Approved by:");
System.out.println(" • Manager: " + finalSnapshot.state().data().get("manager_name"));
System.out.println(" • Finance: " + finalSnapshot.state().data().get("finance_name"));
System.out.println(" • CEO: " + finalSnapshot.state().data().get("ceo_name"));
// ================================================================
// SUMMARY
// ================================================================
System.out.println("\n" + "=".repeat(70));
System.out.println("KEY TECHNIQUES FOR MULTIPLE INTERRUPTS");
System.out.println("=".repeat(70));
System.out.println("\n1️⃣ Store current_stage in state:");
System.out.println(" updates.put(\"current_stage\", \"manager_review\");");
System.out.println("\n2️⃣ Check where you are:");
System.out.println(" String stage = (String) state.data().get(\"current_stage\");");
System.out.println("\n3️⃣ Handle each stage differently:");
System.out.println(" switch(stage) {");
System.out.println(" case \"manager_review\": ...");
System.out.println(" case \"finance_review\": ...");
System.out.println(" case \"ceo_review\": ...");
System.out.println(" }");
System.out.println("\n4️⃣ Update at correct node:");
System.out.println(" app.updateState(config, updates, stage);");
System.out.println("\n5️⃣ Resume from checkpoint:");
System.out.println(" app.stream(null, config);");
} catch (Exception e) {
System.err.println("Error: " + e.getMessage());
e.printStackTrace();
}
}
}
