Provided by: aolserver4-dev_4.5.1-16_amd64 
NAME
ns_register_filter, ns_register_proc, ns_register_trace - Register a filter, proc or trace
callback
SYNOPSIS
ns_register_filter option ?arg arg ...?
ns_register_proc option ?arg arg ...?
ns_register_trace option ?arg arg ...?
_________________________________________________________________
DESCRIPTION
ns_register_filter:
Registers a Tcl filter script for the specified method/URL combination on a virtual
server. The script can be called at one or more of three given times: pre-authorization,
post-authorization before page data has been returned to the user, and after the
connection has been processed and closed.
This function will be called at the specified stage of a connection, if the method/URL
combination for the filter matches the method/URL combination for the connection using
glob style matching.
The URLpattern can contain standard string-matching characters. For example, these are
valid URL patterns:
/employees/*.tcl /accounts/*/out
Valid values for the "when" argument are: preauth, postauth, and trace. Using pre-
authorization, the procedure will be called (assuming that the method/URL combination
matches) just before authorization. If the procedure returns with a code of:
TCL_OK (using: return "filter_ok"): The server will continue to the next pre-
authorization filter for this connection, or, if there are no more pre-
authorization filters, it will continue on with authorization.
TCL_BREAK (using: return "filter_break"): The server will not process any more pre-
authorization filters for this connection, and it will continue on with
authorization.
TCL_RETURN (using: return "filter_return"): The server will close the connection and will
not run any more pre-authorization filters. It will not authorize the request,
and it will not run the function registered for this METHOD/URL. It WILL run
any trace functions registered for this METHOD/URL, usually including logging.
It is assumed that the filter has sent a proper response (e.g., using
ns_return) to the client before returning TCL_RETURN.
Using post-authorization, the procedure will be called (assuming that the method/URL
combination matches) just after successful authorization. If the procedure returns:
TCL_OK (using: return "filter_ok"): The server will continue to the next post-
authorization filter for this connection, or, if there are no more post-
authorization filters, it will run the function registered to handle this
request.
TCL_BREAK (using: return "filter_break"): The server will not process any more post-
authorization filters for this connection, and it will run the function
registered to handle this request.
TCL_RETURN (using: return "filter_return"): The server will close the connection and will
not run any more post-authorization filters and it will not run the function
registered for this METHOD/URL. It WILL run any trace functions registered for
this METHOD/URL, usually including logging. It is assumed that the filter has
returned a proper response (e.g., using ns_return) to the client before
returning TCL_RETURN.
Using trace, the procedure will be called (assuming that the method/URL combination match)
after the connection has been totally processed and closed. If the procedure returns:
TCL_OK (using: return "filter_ok"): The server will continue to the next trace
filter.
TCL_BREAK (using: return "filter_break"): The rest of the trace filters are ignored.
TCL_RETURN (using: return "filter_break"): The rest of the trace filters are ignored.
Syntax for the registered procedure:
The conn (connection) argument is optional for procedures registered by ns_register_filter
if the procedure has 1 or 2 arguments (including why but not including conn). The
following examples show the variations that can be used in this case:
ns_register_filter trace GET /noargs filter_noargs
ns_register_filter trace GET /context filter_context fnord
ns_register_filter trace GET /conncontext filter_conncontext
proc filter_noargs { why } {
ns_log Notice "filter noargs"
return filter_ok
} ;# filter_noargs
proc filter_context { arg why } {
ns_log Notice "filter context. Arg: $arg"
return filter_ok
} ;# filter_noargs
proc filter_conncontext { conn arg why } {
ns_log Notice "filter conn context"
return filter_ok
} ;# filter_noargs
The conn (connection) argument is required for procedures registered by ns_register_filter
if the procedure has 3 or more arguments (including why but not including conn). The conn
argument is automatically filled with the connection information. The first argument
following conn will always take the value supplied by ns_register_filter, if there is one,
or an empty value. The why argument at the end is automatically filled with the type of
filter requested. All other arguments must supply a default value. The following examples
show the variations that can be used in this case:
ns_register_filter postauth GET /threeargs threeargs aaa
ns_register_filter postauth GET /fourargs fourargs aaa bbb ccc
proc threeargs { conn context { greeble bork } why } {
...
} ;
proc fourargs { conn context { greeble bork } {hoover quark} why } {
...
} ;
When a GET of /threeargs is requested, the conn and why arguments will be filled
automatically, the context argument will be assigned "aaa" and the greeble argument will
be assigned the default value "bork". When a GET of /fourargs is requested, the conn and
why arguments will be filled automatically, the context argument will be assigned "aaa",
the greeble argument will be assigned "bbb", and the hoover argument will be assigned the
default value "quark".
ns_register_trace:
Register a Tcl trace script to a method and matching URL. (Note: This function is
obsolete. Use ns_register_filter instead.)
ns_register_trace registers a Tcl script as a trace for the specified method/URL
combination. After the server handles the request for the specified method on an URL that
matches the URLpattern, it calls the trace script with the connection id and any arguments
(args) specified. The URLpattern can contain standard string-matching characters. For
example, these are valid URLpatterns:
/employees/*.tcl /accounts/*/out
Note ns_register_trace is similar to ns_register_proc except that the pattern-matching for
the URL is performed differently. With ns_register_proc, the specified URL is used to
match that URL and any URL below it in the hierarchy. Wildcards such as "*" are meaningful
only for the final part of the URL, such as /scripts/*.tcl. With ns_register_trace, the
URLpattern is used to match URLs as a string with standard string-matching characters.
ns_register_proc results in a single match, whereas multiple ns_register_trace's can be
matched and will be called.
SEE ALSO
ns_register_proc(n), ns_register_tag(n), ns_register_adptag(n)