Make QmlDebug protocol more robust

The protocol so far was client->server only. That is, there was no
sane way for a client to check whether a plugin on the server (service)
was available or not. E.g. calling Client::setEnabled(true) 'succeeded',
without a check whether there is actually a service to talk to.

The new protocol replaces this shortcoming by a service discovery
mechanism: Both client & service announce their available plugins at
handshake time, and later on if there are changes. The status is
reflected in Client::status() and Service::Status() , which are either

  NotConnected - no network connection, or not registered properly
  Unavailable - TCP/IP connection works, but no plugin with the same
name on the other side
  Enabled - You can connect to plugin on other side

The status changes happen automatically (no setEnabled() anymore).

Furthermore a version ID was added to the handshake, so that we can
extend the protocol further in the future :)

1 files changed, 6 insertions, 1 deletions

diff --git a/src/declarative/debugger/qdeclarativedebug_p.h b/src/declarative/debugger/qdeclarativedebug_p.h
index 2b1a115..3d83e8a 100644
--- a/src/declarative/debugger/qdeclarativedebug_p.h
+++ b/src/declarative/debugger/qdeclarativedebug_p.h
@@ -69,7 +69,11 @@ class Q_DECLARATIVE_EXPORT QDeclarativeEngineDebug : public QObject
 {
 Q_OBJECT
 public:
-    QDeclarativeEngineDebug(QDeclarativeDebugConnection *, QObject * = 0);
+    enum Status { NotConnected, Unavailable, Enabled };
+
+    explicit QDeclarativeEngineDebug(QDeclarativeDebugConnection *, QObject * = 0);
+
+    Status status() const;
 
     QDeclarativeDebugPropertyWatch *addWatch(const QDeclarativeDebugPropertyReference &,
                             QObject *parent = 0);
@@ -101,6 +105,7 @@ public:
 
 Q_SIGNALS:
     void newObjects();
+    void statusChanged(Status status);
 
 private:
     Q_DECLARE_PRIVATE(QDeclarativeEngineDebug)