Is it possible to access user session using ProxyContext, the same was as we can using RoutingContext?

General
1

In Eclipse Vert.x , while using Vert.x Web, applying session handler to the router, allows us to access the session using RoutingContext , in the handler. Is there any way we can access the session using ProxyContext , which is used in ProxyInterceptor implementation?

2

In Eclipse Vert.x, when using Vert.x Web and applying a SessionHandler to your router, session information becomes accessible through the RoutingContext (via routingContext.session()).

However, when you’re working with service proxies (like ProxyInterceptor), the context you’re dealing with is a ProxyContext, not a RoutingContext.

Problem

You’re asking if it’s possible to access the HTTP session from ProxyContext — and the short answer is:

No, not directly.

ProxyContext is not tied to the HTTP layer — it’s designed for event bus communication, and does not expose the underlying HTTP request or session data from RoutingContext.

Why This Happens

The session is part of the HTTP layer managed by RoutingContext. Once a request is proxied over the event bus (as it is with Vert.x service proxies), the context becomes abstracted away from the HTTP request/session.

The event bus handler (e.g., the service proxy implementation or ProxyInterceptor) receives only:

  • Serialized method arguments
  • Delivery options (metadata, headers, etc.)
  • ProxyContext, which may contain some metadata but not the session

Workarounds / Alternatives

If you need to pass session-related data to your service proxy, consider these approaches:

1. Pass Required Session Attributes Explicitly

Before calling the service proxy, extract values from the session and pass them as parameters:

String userId = routingContext.session().get("userId");
myServiceProxy.doSomething(userId, otherParams, handler);

Then in your proxy or interceptor, handle it accordingly.

2. Pass Session Info in Event Bus Metadata

You can add session-derived metadata (e.g., user roles, tokens, etc.) to DeliveryOptions.headers():

DeliveryOptions opts = new DeliveryOptions();
opts.addHeader("userId", routingContext.session().get("userId"));
proxyClient.send(someAddress, payload, opts);

Then access it in the proxy interceptor via context.headers().

3. Use Vert.x Context Local Storage

If you’re in the same Vert.x context (same event loop), you can use LocalMap:

routingContext.vertx().getOrCreateContext().put("userId", userId);

Then access it from any handler running in the same context (note: not across event bus boundaries).

Why Not Just Inject the RoutingContext?

Because ProxyContext is part of the Vert.x Service Proxy system, it doesn’t have access to HTTP-layer constructs. There’s no built-in way to map a ProxyContext back to the original HTTP RoutingContext.

Conclusion

You cannot access the HTTP session directly from ProxyContext. Instead:

  • Extract needed values from the session in RoutingContext
  • Pass them explicitly (as parameters or headers) when calling the proxy

Let me know if you want a sample implementation of passing session values via event bus headers.