I am old and slow, but suppose I am in OpeNDAP, are you proposing
to separate say constraint expressions and server-side function
requests basically the same (ie I just scan what is after each
comma) or do you propose some method that signifies in the URL
that what follows is an expression? In F-TDS and GDS the form of
the URL is:
First, I am proposing to subsume DAP constraints.
Second, I am proposing, like DAP, to put the expressions
in the query part of the URL (i.e. after the '?').
So, I would rewrite this as something more-or-less like this:
Where the expressions would include the references to dataset2, dataset3,
and the constraint.
BTW, the reason I have asked about the experience of people who
are using F-TDS and GDS on whether synchronous requests can cover
the large majority of cases, is because I am very partial to
systems where the URL completely defines the request, and hence
essentially use GET as the verb.
The synchronous/asynchronous issue is, for me, a separable issue.
I should note that GET has a limit on the size of URLS, so
there needs to be ways to deal with that. Two possibilities are
1) use POST or PUT, or 2) provide a way to upload a long expression
in parts USING multiple GETs.
The reason for this is long
experience. where client code has broken with changes in
operating system and/or application, fixes were slow in coming,
so many users were left with nothing working. In a system where
the URL completely defined the request, say ERDDAP, in Matlab:
Will get the related file, and the entire command is in Matlab,
no extra code required. The same in R is:
again, "download.file" is an R command.
I think that we do not want to be R/MATLAB specific
in a proposal to put stuff in URLs. I would rather
propose to allow uploading of R/MATLAB scripts to serve
as additional, user-defined functions.
I would prefer to
maintain this simplicity and cover 80% of the cases if possible,
than cover the rest but where more complex, application specific
code would have to be developed and maintained.
Agreed. However my assumption is the the output of any function that
is not assigned to a single-assignment variable will be returned as part
of the response; but other ways of specifying this are possible within
the functional framework I am proposing.