Prototype Implementation of a Presence-based Multimedia Session Sharing System

Transcription

1 Prototype Implementation of a Presence-based Multimedia Session Sharing System Khong Neng Choong Wireless Communications Cluster MIMOS Berhad Malaysia kn.choong@mimos.my Abstract ing has been and it is still continue to be the most common way for many people to share information using texts and/or with attachments. More popular alternatives nowadays are using the Instant Messengers (IM) and online community networks which convey presence information and provide higher degree of interactions with richer multimedia experience. However, these existing systems involve human intervention onto updating the status information, e.g. the presence status message is manually entered and remains unchanged until the next manual update. A more sophisticated presence system would be those which can determine a user s status automatically, with the objective to enable more interactions including indirect contents sharing. In this paper, we present the prototype implementation of a presence-based multimedia session sharing system. This proposed system helps users to publish their session dynamically, and enable their buddies/contacts to join the same session as to consume the contents. We envisaged that the proposed system would help service providers to advertise and promote their contents at lower cost with a viral effect. Presence; Session Sharing;IP Multimedia Subsystem I. INTRODUCTION Presence [1] is the basic technology that provides an application, such as IM or conferencing system, with indicators of the status and availability of contacts. The basic presence information shows whether the users devices are online, and further offer some descriptions of their status such as busy, away, or with a manually-entered message. The ability of users to be able to convey and share their presence status among friends within an online community network is already a common feature with today s ubiquitous access to telecommunication or Internet means. However, these existing systems still require certain degree of human intervention onto updating the status information. The presence status message of each user is still manually entered and remains unchanged until the next manual update. A more sophisticated presence system would be those which can determine a user s status automatically without any manual inventions. By doing this, a user s status could be intelligently updated according to the current activity of the user. For example, the user s status is turned to busy if the PowerPoint is in presentation mode. Whenever a user is watching a movie, the movie title embedded with the associated URL will be automatically reflected as part of the presence status. With such a system, user could easily publish and share their presence actively and seamlessly, with only the minor efforts to configure the permission on their presence accessibility as to Cheng Suan Lee Wireless Communications Cluster MIMOS Berhad Malaysia csuan@mimos.my curb any privacy issues. Our work is partially aligned to a study in [2] where it was revealed that the feeling of social presence of people of interest when watching content was found to add value to the viewing experience. We focus on dynamically updating the active media as part of the presence status information in this paper, other dynamic presence information include users geographic location, types of devices being used, the name (or perhaps the path/link) of the currently active applications or documents on the device etc. Such extension to the basic presence information encompassing data from a variety of sources, from devices, sensors, networks and applications is generally described by the term rich presence [3]. It was commented that rich presence may be viewed as the first practical, large-scale enablement of the vision of context-aware computing [4]. However, efforts were still being made on selecting and delivering succinct and summarized context to avoid clogging the system and users with unnecessary context data [5, 6]. This paper studies the design and implementation of a presence-based multimedia session sharing system, which is built on top of a 3GPP standardized platform called the IP Multimedia Subsystem (IMS) [7]. Unlike the similar feature provided by other IM such as MSN and Yahoo, which has access limitation to only within their own community networks (in silos) [8], our approach adopted the 3GPP standardized approach for subscribing and publishing the presence information. We did not adopt Extensible Messaging and Presence Protocol (XMPP) [9] because there exists a working Presence application server on top of IMS. Besides publishing the basic presence information such as busy, available, away, we have also incorporated the ability to detect the live video being consumed and later publish it as part of the presence status. Other users who have the permission to access such active presence information could just click on such presence status, and will then be redirected to the server for a copy of the same content. This paper is organized as follows. Section 2 presents the design considerations of the proposed system. Section 3 describes the architecture and usage scenario of the proposed system, followed by the descriptions on the prototype implementation with sample screenshots in Section 4. Section 5 discusses about the tests and verifications we have conducted, and the summary is found in Section /11/$ IEEE 373 ICOIN 2011

2 II. DESIGN REQUIREMENTS AND CONSIDERATIONS There are some requirements and considerations that shape the design of our proposed system. Basically the system is based on a client/server model where the client will register to and establish sessions via a central server. The session management protocol is the Session Initiation Protocol (SIP) [10]. Other detailed requirements are described in the following 2 subsections. A. Server Components and Access For standardized access, we have decided to provision the presence server as the application server on top of the IMS core. IMS core is basically a session management server that consists of two components, namely the Call Session Control Function (CSCF) and Home Subscriber Server (HSS). The CSCF can be further divided into 3 subcomponents [11], but in general they all play a role during registration, session establishment and form the SIP routing machinery. B. IMS-based Client with Multimedia Capabilities In generally, there are two main features we are seeking after on a suitable IMS client application. First is the audio/video communication capability and second is the support of video playback. For the communication feature, the client must work with SIP, and for the video playback, the client must work with video streaming/multicasting. The last requirement is that the client application must be an open source software so as to allow feature customization. C. User Friendly Interface Users must be able to easily see what his/her authorised buddies current activities are, and be able to gain access to the same session. For example, by knowing that Bob is currently watching the BBC channel, Alice could also click on Bob s BBC channel presence status to watch the same content directly fed from the BBC server. III. SYSTEM ARCHITECTURE AND USAGE SCENARIO Figure 1 shows the overall network architecture where our proposed system shall work on. The IMS server consists of 4 fundamental components as follows: Open IMS Core (the 4 components forming a diamond shape) as the core session management and message routing platform, Figure 1. Overall network architecture. There are two client applications residing on the client device, namely Linphone [14] and VLC. Both were chosen for their unique features as follows. Linphone is supports both audio/video communications and works with SIP. Hence only slight efforts are needed to adapt the existing Linphone to work with the IMS core. VLC is a media player that can perform video playback on either streaming or multicasting packets. More importantly, both are open source and could be customized. For a quick implementation to serve as a proof-of-concept, we have loosely integrated both Linphone and VLC to function as a single client, through the use of an intermediate files to update and retrieve media/session information between both client applications as shown in Figure 2. Both the client applications communicate through writing and reading on/from two files, namely CallSession.info and SAP.info. Whenever a new call on Linphone is established, the CallSession.info will be updated. This is to allow the VLC (in case where there is an active video playback) to lower down its volume as to not disturb the VoIP conversation. Whenever the call is terminated, the volume setting shall be restored back to the previous configuration. SAP.info is used by VLC to update the current video property such as the source URL, channel name etc., as to allow Linphone to read and later publish as part of the presence status information. Open SIPS [12] as the Presence Server that keeps, publishes and manages subscribers status information DHCP Server as the dynamic IP address manager for clients VLC [13] as the media content server that provides media streaming to clients over the network Figure 2. Architectural overview of client application. 374

3 Figure 3 shows the one of the potential usage scenarios of the proposed system. It started off with both IMS clients register to the IMS server. After sometime, Alice starts watching a video on BBC channel from the content server. This is followed by an update on Alice s latest presence, i.e. watching a video from BBC server. The updated status information is automatically reflected on her buddy Bob s IMS client, who is now informed that Alice is currently watching a BBC channel. Bob can now see what Alice is watching by requesting contents from the same server. Both Alice and Bob could later establish a voice conversation to chat about the BBC news/contents. central content server. By doing this, the presence status of these users would also be automatically updated. Figure 4 shows the screenshots of the modified Linphone. There are two contacts listed on the screen where each is currently consuming different content. To follow or see what they are watching is only 2 steps away. First is to select the particular user, and then click on the Follow-Me-Now. Next, VLC will pop up and playback the video as requested. Figure 3. Usage scenario of the proposed system. IV. PROTOTYPE IMPLEMENTATION The proposed system works in a client/server model. However, since there is no change needed on the server components, efforts were only made on configuring the CSCF and provisioning of both presence server and content server. Development works were mainly taking place on the client applications. The implementation on client application is done and tested on Linux Ubuntu (8.04) Hardy Heron, and the software tools include GCC compiler, Gtk+ interface designer, Linphone interface designer and Geany as the editor. 1. Linphone performs registration to the IMS server. VLC media player will be invoked from Linphone and hence no registration is needed 2. User can now use the VLC media player to watch any video content from the remote content server and this will trigger VLC daemon to update the intermediate file (i.e. SIP.info) with information of the video being watched. This includes the video source URL, group name and channel name 3. The daemon on Linphone will periodically check on any change of the intermediate file, and if there was a change, it would read the updated information from the file and update the presence status Any user who is a trusted buddy of this user will be able to see his/her active presence information. This means they could click on the active presence information and join into the same session so as to consume to the same contents directly from the Figure 4. Screenshot of modified Linphone. To view the profile of the contact, we could just select the particular user, followed by a right-click to select the Profile item from the pop-up menu. The profile interface is shown in Figure 5a, while Figure 5b shows the detailed information of the media currently being consumed by the selected contact. Figure 5a Figure 5b Figure 5. User profile information and media information. We have also incorporated an additional feature into Linphone, which is called callback alert. This feature is made available at the time of making new call. The steps involved are as follows: 1. Linphone will first check whether the callee is available (i.e. the presence status shows online) before making any call. If not available, a pop-up window is shown asking caller to leave a message as shown in Figure 6a, and also offering caller to set an alert (i.e. to check on the Alert for callback feature) against the next availability of the callee, as shown in Figure 6b 2. Whenever the callee s status is changed back to online, the caller will be offered to immediately re-establish another call to the callee as shown in Figure 6c 375

4 Figure 6a. Figure 6b. Figure. 6c Figure 6. To leave message, Callback alert, Auto callback. V. TEST AND VERIFICATION Table 1 shows the test plan with 4 test cases that we have identified to properly verify the functionalities of the proposed system. It has been executed for more than 20 times at different date and time, and the results were consistently positive. VI. SUMMARY AND FUTURE WORKS We have presented the design and implementation of a presence-based multimedia session sharing system that is built on top the IMS system. This proposed system leverages on the standard 3GPP presence status information to convey current activities of a user including the media currently being consumed, so as to allow his/her authorized buddies to also join the same session by connecting to the same remote server. Since this is only a quick prototype, there exist a few limitations that need to be further enhanced. First, running multiple instances of VLC could generate inconsistent media information, because all of them share the same intermediate file for storing media information. Second, VLC that was started or invoked by Linphone shares the same process space with Linphone. Hence for proper shutdown, VLC must first be terminated before Linphone, otherwise Linphone s state will be unstable. A proper implementation would be to get Linphone to make use of VLC API and Libvlc header, so as to properly manage VLC execution as a thread object instead of an external process. ACKNOWLEDGMENT We would like to express our gratitude to our student intern Alfin Syafalni for assisting us onto completing this prototype implementation. REFERENCES [1] 3GPP specification: Presence service architecture [Online]. [2] S. Mate and I. Curcio, Mobile and interactive social television, IEEE Communications Magazine, vol. 47, Issue 12, pp , Dec [3] H. Schulzrinne et al. RPID : Rich Extensions to the Presence Information Data Format (PIDF), In RFC 4880, IETF, July 2006 [4] Jerome, A. Misra, D. Sow, D. and S. Jakobsson, PASTA: Deriving rich presence for converged telecommunications network applications, in Proc. Communication Systems Software and Middleware, 2007, p [5] A.J.H. Peddemors, M.M. Lankhorst, and J. Heer, Presence, location and instant messaging in a context-aware application framework, in Proc. Of the 4 th International Conference on Mobile Data Management (MDM), [6] G.H. Ter Hofte, I. Mulder and C. Verwijs, Close encounters of the virtual kind: A study on place-based presence, Journal of Al & Society, Springer London, vol. 20, Number 2, pp , March [7] (2006) IP Multimedia Subsystem. [Online]. Available: Marquis%20C/rafferty03.ppt [8] (2010) Beyond Social Media [Online]. Available : TABLE I TEST PLAN No. Test Case Test Description Test Procedure 1 Register and To proof Linphone Deregister Linphone works as an IMS Client to/from the IMS Server successfully 2 Publish Presence To publish and share Status, Media Status presence status between and Profile Info users 3 See the same video as being watched by other user with Linphone To stream the same media from the server using VLC 4 Make Call To make call in any condition 1. Run Linphone and registration will be performed after the correct user ID and password were entered 2. Close Linphone, and deregistration will be performed 1. Change the basic presence status into any status 2. Play a video from VLC to get the media status updated 3. Open the User Profile Information window to check on the user profile 4. Set the presence status into offline to see that the media status will also be marked as unavailable 1. Ensure there is an active media status from the list of contacts 2. Select a contact and click on the Follow-Me-Now 3. The VLC media player will pop-up and playback the content 4. Do not close the VLC, because it will be used for Test Try to call an offline contact 2. Enable callback alert on the pop-up window 3. Change the presence status of the offline contact back to online 4. The auto callback window will pop-up offering to re-establish the call 5. Once the call is answered, the sound volume of VLC will be muted automatically 6. One the call is terminated, the sound volume of VLC is restored automatically 376

5 [9] (2010) XMPP Standards Foundation [Online]. Available : [10] (2010) SIP : Session Initiation Protocol [Online]. Available : [11] P. Miikka, N. Aki, K. Hisham and M. Georg, The IMS: IP Multimedia Concepts and Services, 2nd ed., Wiley, [12] (2010) OpenSIPS Project. [Online]. Available: [13] (2010) VideoLAN VLC media player [Online]. Available : [14] (2010) Linphone open-source voip software [Online]. Available : 377