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----------------
Wapp is designed to be easy to use. A hello-world program is as follows:
>
package require wapp ;# OR source wapp.tcl
proc wapp-default {req} {
wapp "<h1>Hello, World!</h1>\n"
}
wapp-start $::argv
The application defines one or more procedures that accept HTTP requests
and generate appropriate replies.
For an HTTP request where the initial portion of the URI is "abcde", the
procedure named "wapp-page-abcde" will be invoked to construct the reply.
If no such procedure exists, "wapp-default" is invoked instead. The latter
technique is used for the hello-world example above.
The procedure generates a reply using one or more calls to the "wapp"
command. Each "wapp" command appends new text to the reply.
The "wapp-start" command starts up the application.
To run this application, copy the code above into a file named "main.tcl"
and then enter the following command:
>
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----------------
Wapp is designed to be easy to use. A hello-world program is as follows:
>
package require wapp ;# OR source wapp.tcl
proc wapp-default {req} {
wapp-subst {<h1>Hello, World!</h1>\n}
}
wapp-start $::argv
The application defines one or more procedures that accept HTTP requests
and generate appropriate replies.
For an HTTP request where the initial portion of the URI is "abcde", the
procedure named "wapp-page-abcde" will be invoked to construct the reply.
If no such procedure exists, "wapp-default" is invoked instead. The latter
technique is used for the hello-world example above.
The procedure generates a reply using one or more calls to the "wapp-subst"
command. Each "wapp-subst" command appends new text to the reply, applying
various substitutions as it goes. The only substitution in this example is
the \n at the end of the line.
The "wapp-start" command starts up the application.
To run this application, copy the code above into a file named "main.tcl"
and then enter the following command:
>
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dict variable. The following sample program shows the information
available in ::wapp.
>
package require wapp
proc wapp-default {} {
global wapp
wapp "<h1>Hello, World!</h1>\n"
set B [dict get $wapp BASE_URL]
wapp-subst {<p>See the <a href='%html($B)/env'>Wapp }
wapp "Environment</a></p>"
}
proc wapp-page-env {} {
global wapp
wapp "<h1>Wapp Environment</h1>\n"
wapp "<pre>\n"
foreach var [lsort [dict keys $wapp]] {
if {[string index $var 0]=="."} continue
wapp-subst {%html($var) = %html([list [dict get $wapp $var]])\n}
}
wapp "</pre>"
}
wapp-start $::argv
In this application, the default "Hello, World!" page has been extended
with a hyperlink to the /env page. The "wapp-subst" command works like "wapp"
in that it appends its argument text to the web page under construction.
But "wapp-subst" also does safe substitutions of text. Within the "wapp-subst"
argument, "%html(...)" is replaced by the expansion of "..." which has been
escaped for safe inclusion in HTML text. Similarly, "%url(...)" is replaced
by "..." after it has been expanded and escaped for use as a URL query
parameter. The argument to "wapp-subst" should always be enclosed in
{...}. Backslash substitutions are performed automatically.
The /env page is implemented by the "wapp-page-env" proc. This proc
generates HTML that describes the content of the ::wapp dict.
Keys that begin with "." are for internal use by Wapp and are skipped
for this display. Notice the use of "wapp-subst" to safely escape text
for inclusion in an HTML document.
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dict variable. The following sample program shows the information
available in ::wapp.
>
package require wapp
proc wapp-default {} {
global wapp
wapp-subst {<h1>Hello, World!</h1>\n}
set B [dict get $wapp BASE_URL]
wapp-subst {<p>See the <a href='%html($B)/env'>Wapp }
wapp-subst {Environment</a></p>\n}
}
proc wapp-page-env {} {
global wapp
wapp-subst {<h1>Wapp Environment</h1>\n<pre>\n}
foreach var [lsort [dict keys $wapp]] {
if {[string index $var 0]=="."} continue
wapp-subst {%html($var) = %html([list [dict get $wapp $var]])\n}
}
wapp-subst {</pre>\n}
}
wapp-start $::argv
In this application, the default "Hello, World!" page has been extended
with a hyperlink to the /env page. The "wapp-subst" command now contains
a "%html(...)" substitution. The "..." argument is expanded using the
usual TCL rules, but then the result is escaped so that it is safe to include
in an HTML document. Other supported substitutions are "%url(...)" for
URLs on the href= and src= attributes of HTML entities, and "%unsafe(...)"
for direct literal substitution. As its name implies, the %unsafe()
substitution should be avoid whenever possible.
The /env page is implemented by the "wapp-page-env" proc. This proc
generates HTML that describes the content of the ::wapp dict.
Keys that begin with "." are for internal use by Wapp and are skipped
for this display. Notice the use of "wapp-subst" to safely escape text
for inclusion in an HTML document.
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