= 18 September 2014 meeting =

== Attendees ==

Greg, Eric, Conrad, TomG

== Agenda ==

Presentation of Hydra architecture and migration path

== Action Items ==

Conrad: Propose Toolshed and Tools APIs

Greg: Propose Session and Application APIs

Eric: Continue wx ui implementation.

TomG: Continue ambient occlusion implementation

== Results ==

[http://www.cgl.ucsf.edu/chimera/data/hydra-sep2014/hydraarch.html Hydra architecture and migration path slides]

**Session object**. TomG explained Hydra Session object that holds all application global state.

**Circular references**. Discussed the advantages of avoiding circular dependencies between Chimera 2 modules.
Previously Scooter advocated this saying Cytoscape modules have a dependency graph that is a tree
and communicating to a module that is not a dependent is only done by quequeing events.
Eric and TomG did not understand the value of this.  Requires further discussion, maybe with Scooter.

**Application class**. Conrad suggested current Hydra Session be divided into an Application class and a Session class where
the latter stores global state and the former initializes that state at start-up.  This will allow code for
different application start-up modes (e.g. nogui vs gui) to be cleanly separated.

**Migration path**. Discussed migration path from Hydra to a Chimera 2 release.  Conrad suggests that APIs for Session,
Application, ToolShed and Tools to establish the framework is an immediate need, even if such APIs
are only for in-lab developers after an initial release.