This document proposes using HTTP Live Streaming to enable streaming web processing services. This allows for asynchronous and progressive transfer of geodata between a client and server. It improves performance, scalability, and the user experience over traditional synchronous WPS. The approach was implemented using 52North WPS and evaluated using a use case of generalizing OpenStreetMap data streams. Results demonstrated this streaming approach reduces memory footprint and improves processing time compared to a reference implementation.

1. Live Geoinformation with
Standardized Geoprocessing Services
Theodor Foerster, Bastian Baranski &
Harald Borsutzky
AGILE 2012

2. What is your initial thought on Geo
Web Services?
http://purl.net/ifgi/isw2011

3. Performance

4. Scalability

5. Usability

6. Research @
Integration of Geodata
and Processes
Live
Geoinformation
Origin of Communication
Geodata of Geodata

7. Web Service interaction
Current
Desired
Improved user experience
Improved performance & scalability

8. Web Processing Service (WPS)
Data Information
WPS
Process 1
GetCapabilities Process 2
DescribeProcess Process n
Execute

9. Requirements
• Progressive transfer
• Handling, processing, creating of geodata
streams
• Loss-less encoding and transfer of geodata
• Interoperability & portability

10. Approach
• Asynchronous communication
• Input/output as reference
• Start processing immediately after receiving
the first piece of data
• HTTP Live Streaming

11. HTTP Live Streaming
• HTTP-based Media Streaming Protocol
• Sequence of small HTTP-based file downloads
• M3U playlist containing media chunk or sub-
streams

12. Playlist examples
#EXTM3U
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=1280000
http://example.com/low.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=2560000
http://example.com/mid.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=7680000
http://example.com/hi.m3u8
#EXTM3U
#EXTINF:8,
http://priv.example.com/fileSequence2680.ts
#EXTINF:8,
http://priv.example.com/fileSequence2681.ts
#EXTINF:8,
http://priv.example.com/fileSequence2682.ts

13. Streaming WPS

14. Tweaks
• Example playlist endpoint
– http://host:port/wps/playlist?id=123&pol
lingRate=10
• Polling rate
• Update of playlist
– New items
– Remove retrieved items

15. Use case
• Generalization
– Simplifying street geometries
• Data
– OpenStreetMap
– Available in playlist format
• Implementation
– 52°North WPS – pluggable & extensible
– GWT Client

16. Processing of OSM data

17. Processing of OSM data

18. Processing of OSM data

19. Processing of OSM data

20. Demo

21. Evaluation - memory footprint
Streaming approach
Reference

22. Evaluation - performance
Time elapsed (ms)
Number of features

23. Implementation available
www.52north.org/wps

24. Outlook
• Enhance other services with HTTP Live
Streaming
– Data and sensor services
– Workflows & scheduling
• Extend to other use cases
– Live analysis of plane tracks (ADS-B) & ship tracks
(AIS)

25. Conclusions
• Live Geoinformation
– Data  information
– Streaming
– HTTP Live Streaming
• Improved performance & scalability
• Improved user experience
• Processing of potentially unlimited streams of
sensor data
• Relevant for other service types

26. Thanks for your attention!
swsl.uni-muenster.de
@tf_tweetz