Robotics Service Bus

h1. Coding Guidelines

h2. Error Handling / Exceptions

* Use a common rsb::Exception for all exceptions

* Rationale: Provides in the client application a way to handle all error from the communication layer uniquely

** In languages where multiple inheritance is a pain, this class inherits from a runtime-like error and a custom exception tree with e.g. InvalidArgument is created underneath this root exception type.

** If multiple inheritance is feasible, use it to reuse the existing language exception types.

* in C++, don't use exceptions in constructors if you have objects that need a manual deallocation (to be verified that the destructor is not called for half-constructed instances)

h3. Barricade Strategy

* Generally user-induced data should be validated on the client level.

* Exception to this rule is the converter mechanism -> user data member of the event class

** Generally performing a validation already in client-level code is too expensive

** OutRoute:

*** Always using exceptions in the sending stack is not possible for asynchronous sending strategies.

*** An invalid combination of data and converter is a (user-induced) fatal error

*** exit the program (using a macro/function that creates a segfault in any case to get a backtrace, assert could be switched off and the error would be unnoticed or untraceable)

** InRoute:

*** two cases:

***# no converter available:

***#* Could happen because the receiver is not the cause of the message

***#* for Reader (pull-based model) an exception is possible without any problems

***#* Asynchronous case requires user checking for exceptions:

***#** Special event or tag in event for error condition

***#** A method for the user to check whether the event is an error condition or not

***# Error while converting