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, 3 deletions

diff --git a/src/declarative/debugger/qdeclarativedebugservice_p.h b/src/declarative/debugger/qdeclarativedebugservice_p.h
index c461ddf..0cadbe5 100644
--- a/src/declarative/debugger/qdeclarativedebugservice_p.h
+++ b/src/declarative/debugger/qdeclarativedebugservice_p.h
@@ -56,12 +56,15 @@ class Q_DECLARATIVE_EXPORT QDeclarativeDebugService : public QObject
     Q_OBJECT
     Q_DECLARE_PRIVATE(QDeclarativeDebugService)
     Q_DISABLE_COPY(QDeclarativeDebugService)
+
 public:
-    QDeclarativeDebugService(const QString &, QObject *parent = 0);
+    explicit QDeclarativeDebugService(const QString &, QObject *parent = 0);
+    ~QDeclarativeDebugService();
 
     QString name() const;
 
-    bool isEnabled() const;
+    enum Status { NotConnected, Unavailable, Enabled };
+    Status status() const;
 
     void sendMessage(const QByteArray &);
 
@@ -74,7 +77,7 @@ public:
     static bool hasDebuggingClient();
 
 protected:
-    virtual void enabledChanged(bool);
+    virtual void statusChanged(Status);
     virtual void messageReceived(const QByteArray &);
 
 private: