Distributed Session Announcement Agents for Real-time Streaming Applications

1. Distributed Session Announcement Agents for Real-time Streaming Applications Keio University, Graduate School of Media and Governance Kazuhiro Mishima <three@sfc.wide.ad.jp> This work is partly supported byNational Institute of Information and Communications Technology (NICT), Japan.

2. Background • Development of Multimedia contents • Demand of increasing multimedia contents • High-quality streaming architecture • Session Information • Contains… • Media Locater (Streaming Source Information) • Meta-level Information (Title, Description etc…) • Receiver MUST obtain the information about the specified multimedia content (Require some announcement method)

3. Requirements of Session Announcement • Scalability • System MUST manage a large number of session information • Dynamicity • Streaming sessions change frequently • System MUST announce information fast • Policy Definition • Session Information MUST be limited to specified receivers by sender (Secret or Private contents)

4. Purpose of our work • Building a new Session Announcement or Distribution Architecture as an alternative to present announcement system for the future media streaming services

5. Related Works • SAP (Announcement with ASM) Pros: Broadly used on multicast environment Pros: Low latency (UDP multicast) Cons: No reliability Cons: Scalability issue (SAP DoS/SAP Storm) Cons: No access control • Search Engine Pros: Scalability using server distribution Pros: Contents information aggregation Cons: Latency issue (occurred by robot crawling) Cons: Central management (no scope or user control)

6. System Operation Overview

7. Architecture • Tree-based System • Multiple Agent • Agent Tree • Transfer the info. through the tree structure • DHT-based System • Multiple Agent • Each agents create the DHT global storage • DHT Global Cloud • All information are stored into this cloud

8. Tree-based system: Registration Store Registration Store Hop-by-Hop Transfer Store Store Agent Store Store WebUI LocalDB Agent stores information and transfer to the neighbor agents All information are stored into LocalDB by agent

9. Tree-based system: Retrieve Retrieve Request Use only LocalDB to retrieve the information Search Agent WebUI LocalDB

10. DHT-based system: Registration selected by DHT algorithm Registration Replicate Store selected by DHT algorithm DHT Engine LocalDB WebUI for global session information (if specify “Global”) for local session information (if specify “Local”)

11. DHT-based system: Retrieve Retrieve from selected node Request Retrieve Search DHT Engine LocalDB WebUI Search results are combined LocalDB’s and DHT’s data

12. Policy-aware Information Distribution • To fulfill the “Policy Definition” requirement, we propose a new Information Distribution technique • Tree-based system • At the Hop-by-Hop transfer time, each agent confirm the agent has “Group Label”. If the agent has no specified “Group Label”, transferred information will discard. • DHT-based system • Next slide… • Using this method, secret or private information are distributed only specified agent

13. Policy-aware Information Distribution • DHT-based system • Information Filtering method using the DHT’s characteristic (Exact Match) • DHT key: Secret! ff02:9a8c:aacd::3 <secret value><DHT key> • DHT value: session_title ff02:9a8c:aacd::3 2001:200::13ca 2008-10-03 ... <DHT value> By putting the secret value on top of the DHT key, users who know the secret value, only can retrieve the information

14. Policy-aware Information Distribution

15. Implementation • gSOAP • XMLRPC-C • MySQL • for storing session and management data • DHT • OpenDHT • Algorithm: Pastry

16. Evaluation • Perform on PlanetLab • Tree-based system • 51 nodes on US site • 6 root • 45 neighbor • All sites are statically connected • DHT-based system • Using OpenDHT • About 200 nodes Tree-based evaluation connection

17. Performance of Tree-based system • Registration time • Message size: 800B • Min.: 2.39s • Avg.: 5.18s • Std.: 3.9 • Retrieval time • Message size: 800B • Min: 0.045s • Avg.: 0.047s • Std.: 0.001 Registration Retrieve

18. Performance of DHT-based system • Registration time • Message size: 400B • Min.: 0.55s • Avg.: 0.59s • Std.: 0.079 • Retrieval time • Message size: 800B • Min: 0.23s • Avg.: 0.33s • Std.: 0.088 Registration Retrieve

19. Tree-based v.s. DHT-based • On the “Latency” view • Tree-based: Longer registration time since hop-by-hop transfer, but very short time to retrieve • DHT-based: Less registration and retrieval time • On the “Scalability” view • DHT-based system’s transmitted message size is half of the Tree-based system • On the “Management” view • Tree-based system must maintain the tree statically by site administrator (Very High Cost!!)

20. Conclusion • New Session Announcement Architecture • Cooperation with multiple agents • Actual implementation of our agent system with two methods of operation • Tree-based system • DHT-based system • Performance evaluation using real network environment (on the PlanetLab)

21. Future works • Promote our agent system • Agent and DHT bootstrap node address acquisition method • Adaptive to end-user’s communication environment • Computing Resource of end-user’s machine • Authentication of end-user