Development of a Remote Object Webcam Controller (ROWC) using CORBA and JMF

Development of a Remote Object Webcam Controller (ROWC) using CORBA and JMF Thesis Project University of Arkansas at Little Rock Frank McCown http://www.harding.edu/fmccown/rowc/

Technologies Used • CORBA • Middleware for remote method invocations in a heterogeneous environment • Java Virtual Machine • Platform independent run-time environment • Java Media Framework (JMF) • API for development and incorporation of time-based media (like audio and video) into Java applications • Real-time Transfer Protocol (RTP) • Quick delivery protocol layered on top of UDP for providing streaming video

System Architecture Streaming video Streaming archived video QuickTime video files Media Server WebCam Processors WebCam Controllers

WebCam Processor • Running on machine with JMF-compatible webcam

WebCam Controller • Can view video from any webcam and any archived video

Media Server • Stores QuickTime video to file • Metadata stored in MS SQLServer

Architectural View

Event Notification • CORBA’s Event Service and Notification Service • Useful in large distributed systems where management and proliferation of events are difficult to control • Distributed Callback Model1 • Client calls method on Server and supplies a callback • Server responds using client’s callback 1D. Schmidt and S. Vinoski, “Distributed Callbacks and Decoupled Communication in CORBA,” C++ Report, vol. 8, October 1996.

Registration Object IDL interface Registration { // Notify MediaServer that a new CamController has started oneway void addCamController(in string hostName, in CamControllerCallback callback); // Notify MediaServer that CamController is going down oneway void removeCamController(in string hostName); // Notify MediaServer that a new CamProcessor is available oneway void addWebCam(in string location); // Notify MediaServer that a CamProcessor is no longer available oneway void removeWebCam(in string location); // Used by CamProcessor to get MediaServer's host name string getServerHostName(); // Return array containing locations of all active CamProcessors StringArray getLocations(); };

CamControllerCallback IDL interface CamControllerCallback { // Notifies all CamControllers that a new CamProcessor is // available oneway void addWebCam(in string location); // Notifies all CamControllers that a CamProcessor is no longer // available oneway void removeWebCam(in string location); };

RegistrationImpl.java public class RegistrationImpl extends rowc.RegistrationPOA { protected Hashtable camControllers; public synchronized void addCamController(String hostName, CamControllerCallback callback) { camControllers.put(hostName, callback); … } public synchronized void addWebCam(String location) { // Notify all webcam controllers of new webcam at given location Enumeration enum = camControllers.elements(); while(enum.hasMoreElements()) { CamControllerCallback callback = (CamControllerCallback)enum.nextElement(); callback.addWebCam(location); } … }

VideoViewer.java This class controls the GUI for the Webcam Controller. public class CamControllerCallbackImpl extends rowc.CamControllerCallbackPOA { // Server notifying us that new webcam is available. Add it to our list of locations. public synchronized void addWebCam(String location) { locationsComboBox.addItem(location); locationsComboBox.repaint(); } … }

For More Information • Thesis, source code, and presentation is available at http://www.harding.edu/fmccown/rowc/

Development of a Remote Object Webcam Controller (ROWC) using CORBA and JMF