Functional Scope (In-Scope)
- WebSocket Streaming Pushes: Connects live dashboard sessions, pushing incremental updates to clients instead of relying on polling.
- Materialized Snapshot View: Caches frequently queried metrics in a materialized view store, serving instant dashboard state immediately on connect.
- Adaptive Throttle & Snapshots: Caps push rates per-metric (e.g. max N/sec) to avoid web UI freezes, batching transient peaks into the latest updates.
- Lifecycle Connection Management: Monitors active clients, cleanly freeing subscription bindings and resources upon connection teardowns.
Explicit Boundaries (Out-of-Scope)
- Custom Alert Policies: Relies on external notification engines to evaluate boundary checks and routing.
- True Socket Frameworks: Excludes deep physical network configuration and socket-io protocol keepalives, modeling channels as mock connections.
Production reference implementations demonstrating real-time WebSocket pushes, materialized cache views, and adaptive throttle loops in Java and Python:
// ─── JAVA BLUEPRINT ──────────────────────────────────────────────────────────
import java.util.*;
import java.util.concurrent.*;
class MetricValue {
private final String metricName;
private final double value;
private final long timestampMs;
public MetricValue(String metricName, double value, long timestampMs) {
this.metricName = metricName;
this.value = value;
this.timestampMs = timestampMs;
}
public String getMetricName() { return metricName; }
public double getValue() { return value; }
public long getTimestampMs() { return timestampMs; }
}
interface ClientConnection {
void sendUpdate(MetricValue val);
}
class MockClientConnection implements ClientConnection {
private final String clientId;
public MockClientConnection(String clientId) {
this.clientId = clientId;
}
@Override
public void sendUpdate(MetricValue val) {
System.out.println("PUSH -> Client: " + clientId + " | Metric: " + val.getMetricName() + " = " + val.getValue());
}
}
class DashboardSession {
private final String sessionId;
private final ClientConnection connection;
private final Set<String> subscribedMetrics = ConcurrentHashMap.newKeySet();
private final ConcurrentHashMap<String, Long> lastPushTimeMap = new ConcurrentHashMap<>();
private final ConcurrentHashMap<String, MetricValue> pendingUpdates = new ConcurrentHashMap<>();
public DashboardSession(String sessionId, ClientConnection connection) {
this.sessionId = sessionId;
this.connection = connection;
}
public String getSessionId() { return sessionId; }
public ClientConnection getConnection() { return connection; }
public Set<String> getSubscribedMetrics() { return subscribedMetrics; }
public ConcurrentHashMap<String, Long> getLastPushTimeMap() { return lastPushTimeMap; }
public ConcurrentHashMap<String, MetricValue> getPendingUpdates() { return pendingUpdates; }
public void subscribe(String metricName) {
subscribedMetrics.add(metricName);
}
public void unsubscribe(String metricName) {
subscribedMetrics.remove(metricName);
lastPushTimeMap.remove(metricName);
pendingUpdates.remove(metricName);
}
}
class MaterializedViewCache {
private final ConcurrentHashMap<String, MetricValue> cache = new ConcurrentHashMap<>();
public void update(String metricName, double value) {
cache.put(metricName, new MetricValue(metricName, value, System.currentTimeMillis()));
}
public MetricValue get(String metricName) {
return cache.get(metricName);
}
}
class RealtimeDashboardService {
private final ConcurrentHashMap<String, DashboardSession> activeSessions = new ConcurrentHashMap<>();
private final ConcurrentHashMap<String, Set<DashboardSession>> metricSubscriptions = new ConcurrentHashMap<>();
private final MaterializedViewCache viewCache = new MaterializedViewCache();
private final ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor();
private final long throttleIntervalMs;
public RealtimeDashboardService(long throttleIntervalMs) {
this.throttleIntervalMs = throttleIntervalMs;
this.scheduler.scheduleAtFixedRate(this::flushThrottledUpdates, 100, 100, TimeUnit.MILLISECONDS);
}
public void registerSession(DashboardSession session) {
activeSessions.put(session.getSessionId(), session);
System.out.println("Session connected: " + session.getSessionId());
}
public void disconnectSession(String sessionId) {
DashboardSession session = activeSessions.remove(sessionId);
if (session != null) {
for (String metric : session.getSubscribedMetrics()) {
Set<DashboardSession> subs = metricSubscriptions.get(metric);
if (subs != null) {
subs.remove(session);
}
}
System.out.println("Session disconnected: " + sessionId);
}
}
public void subscribeClient(String sessionId, String metricName) {
DashboardSession session = activeSessions.get(sessionId);
if (session == null) return;
session.subscribe(metricName);
metricSubscriptions.computeIfAbsent(metricName, k -> ConcurrentHashMap.newKeySet()).add(session);
MetricValue cachedVal = viewCache.get(metricName);
if (cachedVal != null) {
session.getConnection().sendUpdate(cachedVal);
}
}
public void ingestMetric(String metricName, double value) {
viewCache.update(metricName, value);
MetricValue metricValue = viewCache.get(metricName);
Set<DashboardSession> subscribers = metricSubscriptions.get(metricName);
if (subscribers == null || subscribers.isEmpty()) return;
long now = System.currentTimeMillis();
for (DashboardSession session : subscribers) {
synchronized (session) {
long lastPush = session.getLastPushTimeMap().getOrDefault(metricName, 0L);
if (now - lastPush >= throttleIntervalMs) {
session.getConnection().sendUpdate(metricValue);
session.getLastPushTimeMap().put(metricName, now);
session.getPendingUpdates().remove(metricName);
} else {
session.getPendingUpdates().put(metricName, metricValue);
}
}
}
}
private void flushThrottledUpdates() {
long now = System.currentTimeMillis();
for (DashboardSession session : activeSessions.values()) {
synchronized (session) {
List<String> toRemove = new ArrayList<>();
session.getPendingUpdates().forEach((metricName, value) -> {
long lastPush = session.getLastPushTimeMap().getOrDefault(metricName, 0L);
if (now - lastPush >= throttleIntervalMs) {
session.getConnection().sendUpdate(value);
session.getLastPushTimeMap().put(metricName, now);
toRemove.add(metricName);
}
});
for (String key : toRemove) {
session.getPendingUpdates().remove(key);
}
}
}
}
public void shutdown() {
scheduler.shutdown();
}
}
public class Main {
public static void main(String[] args) throws InterruptedException {
System.out.println("=== JAVA REALTIME DASHBOARD SIMULATION ===");
RealtimeDashboardService service = new RealtimeDashboardService(500);
MockClientConnection conn = new MockClientConnection("client-1");
DashboardSession session = new DashboardSession("session-1", conn);
service.registerSession(session);
service.subscribeClient("session-1", "cpu.usage");
System.out.println("Ingesting first metric update...");
service.ingestMetric("cpu.usage", 45.2);
System.out.println("Ingesting second update immediately (should be throttled)...");
service.ingestMetric("cpu.usage", 48.7);
System.out.println("Ingesting third update immediately (should overwrite second in queue)...");
service.ingestMetric("cpu.usage", 52.1);
Thread.sleep(600);
service.disconnectSession("session-1");
service.shutdown();
System.out.println("=== END OF JAVA SIMULATION ===");
}
}