roscpp/2008-09-04 Design Review

Package Developer:

• Morgan
• Brian pushing through review proces

Reviewers:

• Stu
• Tully
• Ioan
• Ken
• Eric
• Josh
• Rob

Package Summary

Minutes

Init (and command-line remapping)

• Concerns with it being required, specifically in GUI programs where [argc, argv] access is difficult
• Want it to be safe to call multiple times

Fini

• Want to be able to call multiple times (as many times as init called?)
• Or want to associate with proxy object

Subscribe

• Want to allow multiple subscriptions
• Requires change to subscription bookkeeping, and change to prevent unsubscribe from being ambiguous
• Question of using handles vs. functors for unsubscribe?
• Use boost::function equality operator for unsubscribe lookup
• Question of function within object vs. just callback function handle
  • Josh recommends boost::function and boost::bind to resolve this
  • Other option is different types of functors (method functor and function functor)
• Question of replacing functor (replace with boost)

New threading model

• Run with only one server thread, or with startup option run with only one thread
• In single-threaded mode, you must call tcpros_server_update() call [needs renaming for transport indepedence]
  • Also needs minimum time to wait (can be used as a sleep call)
  • Either with default or 0 waittime argument it should never block

Unadvertise (topic and service)

• After unadvertise service, callback will never be called

Unsubscribe

• Modified to guarantee no more callbacks once it's been called

Conclusions

Command-line remapping needs to be resolved

Explore proxy object or remove singleton constraint

We will start depending on boost::function for all callbacks, and for unsubscribe lookups

Need to do another review to make it through full API and review changes

---