Match the request and populate the Valum.Context.
This is expected to be *very* fast and thus, no blocking operation must be performed. If necessary, it is preferable to use a Valum.HandlerCallback and invoke the 'next' continuation when ready.
| req |
request being matched |
| context |
context which may be initial or derive from a parent |
|
'true' if the request is matched, otherwise 'false' |