Scopes designate channel instances on the unified bus. Channel instances are themselves hierarchical, hence scopes also reflect this structure.

Scope Strings

There is a string-based notation for scopes based on UNIX/URL paths. For example:


This scope designates the channel /a/b/c/ which is a sub-channel of the channels designated by:


/ is sometimes called “root-scope”.

Generally, a scope string is valid if it matches the regular expression /([-_a-zA-Z0-9]+/)*, i.e. scopes are case-sensitive.


For convenience, the final / in scope strings may be omitted when specifying scopes in user interfaces. However, when scope strings are used as keys in associative arrays or in network protocols, scope strings have to be normalized such that they contain the terminating /.

Reserved Scopes

The scope /__rsb/ and its subscopes are reserved for implementation purposes and should not be used for user-level communication.

Deriving Scopes from Strings

When designing communication patterns based on RSB, it is sometimes necessary to derive components of scopes from arbitrary strings. This section defines a procedure that should be used when such a derivation is needed:

  1. Replace any character of the input string that is not one of the allowed scope component characters (i.e. [-_a-zA-Z0-9]) with the _ character.
  2. The resulting string can be used as a component in a scope.


Of course, this procedure does not necessarily produce distinct scope components from distinct strings. This possibility of clashes has to be taken into account.


Language File(s)
C++ “0.14” branch of at src/rsb/Scope.{h,cpp}
Java /../rsb-java/rsb-java/src/main/java/rsb/
Python /../rsb-python/rsb/
Common Lisp /../rsb-cl/src/scope.lisp