1. Transforming VLC into an SA-Aware Application
Telecommunications Software Engineering Lab
Concordia University
Presenters: Anik Mishra and Ali Kanso

2. Overview Objective of the Work VLC Design of a SAF Compliant VLC
Introduction
Workflow
Design of a SAF Compliant VLC
Choosing components
Levels of Integration
Sample system configuration
Evaluation of the Work

3. Objective of the Work
Go through the steps of modifying a regular application for High Availability and Service Continuity using SAF standards
Have a running application for testing and analyzing configuration and upgrade campaign generation
Document methodology/lessons learned
Contrast results achieved with effort required

4. Introduction to VLC
Started as an academic project in 1996 at the École Centrale Paris
Intended to consist of a client and server to stream videos across a campus network
Server portion later integrated with client
Now managed by the VideoLAN non-profit organization

5. VLC Workflow RTSP server Control module «create» Internet «create» VLM
(as needed)
File IO, demux,
RTP send

6. Choosing Components Multiple criteria for choosing components:
Unit of failure detection and/or recovery
One aspect of components is failure detection and recovery
Components must be able to be started separately
Unit of service
At what granularity is the service request?
VLC: highly threaded design
Each RTP stream in its own thread
However, threads are not separable
Therefore
Two possible configurations

7. Choosing Components VLC as a Container component:
Broadcast: streams as a contained component
Each CSI represents one stream
VoD: RTSP servers as contained components (?)
Each RTSP server is its own CSI?
Each different media stream is its own CSI?
Container components not supported by OpenSAF at design time
VLC as single component
Unit of failure: only one process

8. VLC Component: Arguments
VLC needs to be configured
Objective: simplest configuration possible
One argument: VLC Configuration File
Non-proxied non-SA aware
SA-aware
specified as a command line argument
specified as CSI Attribute

9. Levels of Integration Higher availability & complexity VLC
Non-SA Aware Non-proxied VLC
SA Aware VLC
(no service continuity)
VLC with checkpointed positions
VLC

10. Target Configuration Two components IP address VLC Comp category:
Non-proxied non-sa-aware: no state
SA Aware
Dependency:
none
Depends on IP address component

11. Configuration Application SG Node 1 SU 1 Node 2 SU 2 IP-Comp IP-Comp
VLC-Comp
VLC-Comp SI
IP-CSI
Video-CSI

12. Redundancy Model
Redundancy model should be based on component capabilities and desired availability
In our case:
Non-proxied Non-SaAware: non-preinstantiable
SaAware: 1_active_or_1_standby
Chosen redundancy models:
Non-proxied Non-SaAware : NoRed
SaAware: 2N

13. Evaluation: Non-Preinstantiable SAF Managed Component
Client experience after administrative action
Broadcast: video restarts after client resynchronisation timeout (~10 seconds for VLC GUI)
VoD: Client required to re-request video stream
Benefits:
Managed by SAF
Administrative functions (like locking)
Benefits w/IP component
Broadcast: None
VoD: Server immediately available at same IP after management operation

14. Non-Preinstantiable SAF Managed Component: Implementation
Problems:
VLC failures not detected by OpenSAF (no monitoring)
Passive monitoring needed
Difficulty: Low
Effort:
“3” lifecycle commands
IMM XML:
VLC component: ~295 “lines”
IP components: +110 “lines”
No changes to VLC needed

15. Non-Preinstantiable SAF Managed Component: VLC CLC CLI
Instantiate:
cvlc --daemon --pidfile /var/run/vlc/vlc.pid
Terminate
kill "$(< /var/run/vlc/vlc.pid)“
Cleanup
kill -9 "$(< /var/run/vlc/vlc.pid)“
rm /var/run/vlc/vlc.pid

16. Non-Preinstantiable SAF Managed Component: IP CLC CLI
Instantiate:
ip addr add $ip dev $dev
arping -U -c 1 –I $dev $ip
Terminate/Cleanup
ip addr del $ip dev $dev

17. Evaluation: SA Aware Client Experience: Added Benefits:
Same as Non-Preinstantiable
However, VLC crashes are noticed (and corrected) without passive monitoring
Added Benefits:
Program crashes detected by SAF; extra healthchecks possible
Configuration through CSI Arguments
Faster recovery after failure (executable already pre-instantiated)

18. SA Aware: Implementation
Difficulty:
Medium (VLC architecture knowledge needed)
Changes to VLC needed:
Additional control module
Effort:
Control module: ~400 lines + 30 lines build system
Only “2” lifecycle commands
IMM XML: Roughly the same

19. SA Aware: Control Module
Implements VLC’s control module interface
Also implements AMF’s callback interface
saAmfCSISetCallback
saAmfCSIRemoveCallback
saAmfComponentTerminateCallback
CSI Set can receive 4 states
STANDBY
ACTIVE
QUIESCED
QUIESCING

20. Evaluation: Checkpointing Broadcast Streams
Client Experience After Failure:
Video resumes at roughly the same position after a brief pause
Added Benefits:
Better user experience
Difficulty:
High, edits to main VLC code needed

21. Checkpointing: Implementation
Changes to VLC needed:
Edits to VL Manager:
Move over current configuration
Restart streams at a specific offset
Edits to RTP stream_out to bind specific source IP/port
Effort:
Control module: +~390 LoC
VLM and RTP changes: ~150 LoC

22. VLC modified workflow Control module (OpenSAF) Internet Playlist VLM
Video status
Video status
File IO, demux,
RTP send

23. Non-proxied Non-SaAware VLC
Summary
Integration level
Effort
Added benefit
Shortcoming
Non-proxied Non-SaAware VLC
Lowest
No changes to VLC
SAF managed
Redundant server is available after failure
(After a failure)
User experiences service outage
User has to request the video again (VoD)
SaAware VLC
Higher
New VLC control module
Crashes automatically detected by AMF
Faster recovery
No service continuity (the video starts over after failure)
With Checkpointing
Highest
Additional changes to control module
Synchronization through checkpoint service
Better user experience (after a failure the video resumes at roughly the same position after a brief pause) −

24. Work done in context of MAGIC
MAGIC: Modeling and Automatic Generation of Information and upgrade Campaigns for Service Availability
A collaboration between Ericsson and Concordia
Funded by NSERC and Ericsson

25. Discussion?