Jason Simmons
217bfed9bd
Handler functions may return a Future<Response> that completes with an error. If that happens, then the top level error handling in the Shelf server will try to log the error to stderr. But this will fail because DDS closes its stderr at startup. So Shelf will not write any response to the client, and the client will time out. This PR adds a middleware to the DDS pipeline that receives errors thrown by the pipeline's handlers and returns a failure response. Change-Id: I31beaf6abb0cbb42137c6b03f6081809de5d7119 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/405681 Commit-Queue: Ben Konyi <bkonyi@google.com> Reviewed-by: Ben Konyi <bkonyi@google.com>
A package used to spawn the Dart Developer Service (DDS), which is used to communicate with a Dart VM Service instance and provide extended functionality to the core VM Service Protocol.
Functionality
Existing VM Service clients can issue both HTTP, websocket, and SSE requests to a running DDS instance as if it were an instance of the VM Service itself. If a request corresponds to an RPC defined in the VM Service Protocol, DDS will forward the request and return the response from the VM Service. Requests corresponding to an RPC defined in the DDS Protocol will be handled directly by the DDS instance.
SSE Support
For certain web clients it may be preferable or required to communicate with DDS using server-sent events (SSE). DDS has an SSE handler listening for requests on /$debugHandler.
SSE and package:vm_service example
import 'package:sse/sse.dart';
import 'package:vm_service/vm_service.dart';
void main() {
// Establish connection with DDS using SSE.
final ddsChannel = SseClient('${ddsUri}\$debugHandler');
// Wait for ddsChannel to be established
await ddsChannel.onOpen.first;
// Initialize VmService using the sink and stream from ddsChannel.
final vmService = VmService(
ddsChannel.stream,
(e) => ddsChannel.sink.add(e),
);
// You're ready to query DDS and the VM service!
print(await vmService.getVersion());
}