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)
KEYWORDS¶