Research for a big picture for DataFacade

[wangyoucao577]

No description provided.

[CodeBear801]

Questions:

• Why need Facade layer in OSRM and what its used for
• When/how to Init Facade, Research for Low-Level Storage Layout for DataFacade Implementation #55
• What Facade could do, which means, the interfaces: Research for DataFacade Interfaces #54

Target:

• Understand OSRM Facade, which is DataAccessAPI in current product and GraphAPI for what we want to do
• Understand why customize didn't use mmap to open files like routed

[CodeBear801]

https://github.com/Telenav/open-source-spec/blob/master/osrm/doc/osrm_facade_simple_case.md

[CodeBear801]

https://github.com/Telenav/open-source-spec/blob/master/osrm/doc/osrm_facade.md

[CodeBear801]

For why current facade didn't be used in preprocessing steps like customizer, please go to here:
#55 (comment)