1. Create a port when a debugger object is created for an isolate, use this

include/dart_debugger_api.h

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef INCLUDE_DART_DEBUGGER_API_H_
 #define INCLUDE_DART_DEBUGGER_API_H_
 
 #include "include/dart_api.h"
 
 typedef struct _Dart_Breakpoint* Dart_Breakpoint;
 
 typedef struct _Dart_StackTrace* Dart_StackTrace;
 
 typedef struct _Dart_ActivationFrame* Dart_ActivationFrame;
 
+/**
+ * An id used to uniquely represent an Isolate in the debugger wire protocol
+ * messages.
+ */
+typedef Dart_Port Dart_IsolateId;
+
+/**
+ * ILLEGAL_ISOLATE_ID is a number guaranteed never to be associated with a
+ * valid isolate.
+ */
+#define ILLEGAL_ISOLATE_ID ILLEGAL_PORT
+
 typedef void Dart_BreakpointHandler(
                  Dart_Breakpoint breakpoint,
                  Dart_StackTrace stack_trace);
 
 typedef void Dart_BreakpointResolvedHandler(
                  intptr_t bp_id,
                  Dart_Handle url,
                  intptr_t line_number);
 
 typedef void Dart_ExceptionThrownHandler(
                  Dart_Handle exception_object,
                  Dart_StackTrace stack_trace);
 
 typedef enum {
   kCreated = 0,
   kInterrupted,
   kShutdown,
 } Dart_IsolateEvent;
 
-typedef void Dart_IsolateEventHandler(Dart_Isolate isolate,
+typedef void Dart_IsolateEventHandler(Dart_IsolateId isolate_id,
                                       Dart_IsolateEvent kind);
 
 /**
  * Caches a given \object and returns an object id. The object id is only
  * valid while the VM is paused. The cache is invalidated when the VM
  * resumes.
  *
  * Requires there to be a current isolate.
  *
  * Returns an id >= 0 on success, or -1 if there is an error.
@@ skipping 490 matching lines @@
 /**
 * Returns the url of the library \library_id.
 *
 * Requires there to be a current isolate.
 *
 * \return A string handle containing the URL of the library.
 */
 DART_EXPORT Dart_Handle Dart_GetLibraryURL(intptr_t library_id);
 
 
+/**
+* Returns the isolate object corresponding to the isolate id.
+*
+* \return The Dart_Isolate object corresponding to the isolate id.
+* If the specified id is invalid NULL is returned.
+*/
+DART_EXPORT Dart_Isolate Dart_GetIsolate(Dart_IsolateId isolate_id);
+
 #endif  // INCLUDE_DART_DEBUGGER_API_H_