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ns_filter(3aolserver) AOLserver Built-In Commands ns_filter(3aolserver)
 


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





  

    4.0
    AOLserver