if m.handlers.hasAny(id) && !id.isTestHandler() {
			return ErrHandlerAlreadyExists
		}
		m.handlers.streams[id] = &h
		return nil
	}
	subID := makeSubHandlerID(id, h.Subroute)
	if m.handlers.hasSubhandler(subID) && !id.isTestHandler() {
		return ErrHandlerAlreadyExists
	}
	m.handlers.subStreams[subID] = &h
	// Copy so clients can also pick it up for other subpaths.
	m.handlers.subStreams[makeZeroSubHandlerID(id)] = &h

## Handlers & Routes

Handlers have a predefined Handler ID. 
In addition, there can be several *static* subroutes used to differentiate between different handlers of the same ID.
A subroute on a client must match a subroute on the server. So routes cannot be used for dynamic routing, unlike HTTP.

## Override the default exception handlers

**FastAPI** has some default exception handlers.

These handlers are in charge of returning the default JSON responses when you `raise` an `HTTPException` and when the request has invalid data.

You can override these exception handlers with your own.

### Override request validation exceptions

	s := &CniPluginServer{
		handlers:  handlers,
		dataplane: dataplane,
		cniListenServer: &http.Server{
			Handler: mux,
		},
		cniListenServerCancel: cancel,
		sockAddress:           pluginSocket,
		ctx:                   ctx,
	}

	mux.HandleFunc(pconstants.CNIAddEventPath, s.handleAddEvent)
	return s
}

func (s *CniPluginServer) Stop() {
	s.cniListenServerCancel()
}

			return newMuxStateless(ctx, m, c, *handler)
		})
	} else {
		// Stream:
		var handler *StreamHandler
		if subID == nil {
			if !m.Handler.valid() {
				gridLogIf(ctx, c.queueMsg(m, muxConnectError{Error: "Invalid Handler"}))
				return
			}
			handler = c.handlers.streams[m.Handler]
		} else {
			handler = c.handlers.subStreams[*subID]
		}
		if handler == nil {

		ctx,
		pod,
		util.GetPodIPsIfPresent(pod),
		"",
	).Return(nil)

	server := &meshDataplane{
		kubeClient: client.Kube(),
		netServer:  fs,
	}

	handlers := setupHandlers(ctx, client, server, "istio-system")
	client.RunAndWait(ctx.Done())
	go handlers.Start()

	// label the namespace
	labelsPatch := []byte(fmt.Sprintf(`{"metadata":{"labels":{"%s":"%s"}}}`,
		constants.DataplaneMode, constants.DataplaneModeAmbient))

	).Return(nil)

	dpServer := &meshDataplane{
		kubeClient: client.Kube(),
		netServer:  fs,
	}

	handlers := setupHandlers(ctx, client, dpServer, "istio-system")

	// We are not going to start the server, so the sockpath is irrelevant
	pluginServer := startCniPluginServer(ctx, "/tmp/test.sock", handlers, dpServer)

	// label the namespace
	labelsPatch := []byte(fmt.Sprintf(`{"metadata":{"labels":{"%s":"%s"}}}`,

	if err != nil {
		return "", "", err
	}
	return handlers.InferPodInfoFromTypedResource(name, i.NamespaceOrDefault(namespace), MakeKubeFactory(client))
}

func (i *instance) InferPodsFromTypedResource(name, namespace string) ([]string, string, error) {
	client, err := i.CLIClient()
	if err != nil {
		return nil, "", err
	}

    }

    @Override
    public void addHandlers(Map<String, ArtifactHandler> handlers) {
        throw new UnsupportedOperationException("Adding handlers programmatically is not supported anymore");
    }

    @Deprecated
    public Set<String> getHandlerTypes() {
        throw new UnsupportedOperationException("Querying handlers programmatically is not supported anymore");
    }

{!../../../docs_src/events/tutorial001.py!}
```

In this case, the `startup` event handler function will initialize the items "database" (just a `dict`) with some values.

You can add more than one event handler function.

And your application won't start receiving requests until all the `startup` event handlers have completed.

### `shutdown` event