=head1 NAME
Embperl - Building dynamic Websites with Perl
=head1 SYNOPSIS
=head1 DESCRIPTION
Embperl is a framework for building websites with Perl.
For the beginner it's any easy to setup and use way of embeddingPerl code in HTML pages.
It delivers several features that ease the task of creating a websites,
including dynamic tables, formfield-processing, escaping/unescaping,
session handling, caching and more.
If your demands grows it gives you the power
to make your Web site object-oriented and build it out of small reusable
components. If you don't like the idea of mixing up all your layout and code
Embperl supports separating it in different objects (e.g. createing an
MVC application). Of course Embperl doesn't ties you to HTML, it allows
components to be from different source formats (e.g. HTML, WML, XML, POD, ...)
and if necessary transforms it (for example via XSLT) to other output formats.
This is achieved by diving the output generation in small steps, where each
is processed by a plugable provider.
Advanced user can create their own syntax definitions (for example tag libraries)
and extent Embperl by writing their own providers and much more
=head1 SYNTAX
Embperl understands two categories of commands. The first one are
special Embperl commands, and the second category consists of some HTML tags
which can trigger special processing. Embperl commands can span
multiple lines and need not start or end at a line boundary.
Before the special Embperl commands are processed, and for the VALUE
attribute of the INPUT tag (see below), all HTML tags are removed and
special HTML characters are translated to their ASCII values (e.g.,
`<' is translated to `<'). You can avoid this behavior by
preceding the special character or HTML tag with a backslash. This is
done in case your favorite (WYSIWYG) HTML editor inserts tags like
line breaks or formatting into your Embperl commands where you don't
want them.
B<VERY IMPORTANT NOTE:> If you do use an ASCII editor to write your HTML documents,you should set the option B<optRawInput> so that Embperl does not
preprocess your source. You can also HTML-escape your code
(i.e. write `<' instead of `<'), to avoid ambiguity. In most cases
it will also work without the optRawInput and HTML-escaping, but in
some cases Embperl will detect an HTML tag were there isn't one.
B<If you have any trouble with your code, especially with HTML tags or filehandles
in your Perl code, be sure to understand input- and output- escaping and
unescaping. Read the section
L<"Inside Embperl"|"Inside Embperl - How the embedded Perl code is actually processed">
to see what's going on!!>
All Embperl commands start with a `[' and end with a `]'. To get a
real `[' you must enter `[['.
Embperl does not use SGML comments (i.e., <! ... !> or similar things)because some HTML editors can't create them, or it's much more
complicated. Since every HTML editor takes (or B<should> take) `['
and `]' as normal text, there should be no problem.
=head2 [+ Perl code +]
Replace the command with the result you get from evaluating the Perl code.
The Perl code can be anything which can be used as an argument to a Perl
eval statement. (See L<"(Safe-)Namespaces and opcode restrictions"> below
for restrictions.) Examples:
[+ $a +] Replaces the [+ $a +] with the content of
the variable $a
[+ $a+1 +] (Any expression can be used)
[+ $x[$i] +] (Arrays, hashes, and more complex
expressions work)
C<NOTE:> Whitespace is ignored. The output will be automatically
HTML-escaped (e.g., `<' is translated to `<') depending on the
value of the variables C<$escmode>. You do not have to worry about
it.
=head2 [- Perl code -]
Executes the Perl code, but deletes the whole command from the HTML
output.
Examples:
[- $a=1 -] Set the variable $a to one.
No output will be generated.
[- $i=0; while ($i<5) {$i++} -] Even more complex
statements or multiple
statements are possible.
C<NOTE:> Statements like if, while, for, etc., must be contained in a
single Embperl command. You cannot have the if in one command block
and the terminating `}' or else in another.
C<NOTE:> To define subroutines, use L<"[! Perl Code !]"> (see below) instead of[- ... -] to avoid recompilation of the subroutine on every request.
=head2 [! Perl Code !]
Same as [- Perl Code -] with the exception that the code is only
executed at the first request. This could be used to define
subroutines, or do one-time initialization.
=head2 [* Perl code *]
(only version 1.2b2 or higher) B<EXPERIMENTAL!>
This is similar to [- Perl Code -].
The main difference is, while [- Perl Code -]
always has its own scope, all [* Perl code *] blocks runs in the same scope.
This allows you to define "local" variables with a scope of the
whole page. Normally, you don't need to use local, because Embperl takes care of separate namespaces
of different documents and cleanup after the request is finished, but in special cases it's
necessary. For example, if you want to recursively call an Embperl document via Execute.
There is a second reason to use the [* Perl code *] instead of the [- Perl Code -]. If you liketo use perl's control structures. Perl's if, while, for etc. can B<not> span mulitple [- Perl Code -]blocks, but it can span multiple [* Perl Code *].
Example:
[* foreach $i (1..10) { *]
[- $a = $i + 5 -]
loop count + 5 = [+ $a +] <br>
[* } *]
The following B<won't> work:
[- foreach $i (1..10) { -]
some text here <br>
[- } -]
The same can be done with Embperl L<meta commands|"[$ Cmd Arg $] (Meta-Commands)"> (see below)
[$ foreach $i (1..10) $]
[- $a = $i + 5 -]
loop count + 5 = [+ $a +] <br>
[$ endforeach $]
B<NOTE 1:> [* ... *] blocks _must_ always end with a B<;>,B<{> or B<}>
B<NOTE 2:> [* ... *] cannot apear inside a html tag that is interpreted by Embperl
(unless you disable the interpretation of such tags like table, input etc.)
B<NOTE 3:> There are still benefits of using [- ... -] and metacommands:
- much better debugging in the log file.
- no restriction on where they can be used. You can use themanywhere; even inside html tags that are interpreted by Embperl.
=head2 [
(only version 1.2b2 or higher)
This is a comment block. Everything between the [
the output.
B<NOTE 1:> The [* ... *] blocks are interpreted before the comment block, so they are
executed also inside a comment.
B<NOTE 2:> Everything (except [* ... *]) is really removed from the source, so you
=head2 [$ Cmd Arg $] (Meta-Commands)
Execute an Embperl metacommand. B<Cmd> can be one of the following.
(B<Arg> varies depending on <Cmd>).
=over 4
=item B<if>, B<elsif>, B<else>, B<endif>
Everything following the B<if> metacommand until the B<else>,
B<elsif>, or B<endif> is only output if the Perl expression given in
B<Arg> is true. B<else> and B<elsif> work similarly.
Example:
[$ if $ENV{REQUEST_METHOD} eq 'GET' $]
Method was GET<BR>
[$ else $]
Method other than GET used<BR>
[$ endif $]
This will send one of the two sentences to the client, depending on the
request method used to retrieve the document.
=item B<while>, B<endwhile>
Executes a loop until the B<Arg> given to B<while> is false.
Example: (see eg/x/loop.htm)
[- $i = 0; @k = keys %ENV -]
[$ while ($i < $#k) $]
[+ $k[$i] +] = [+ $ENV{$k[$i]} +]<BR>
[- $i++ -]
[$ endwhile $]
This will send a list of all environment variables to the client.
NOTE: The `<' is translated to `<' before calling Perl eval,
unless optRawInput is set.
=item B<do>, B<until>
Executes a loop until the B<Arg> given to B<until> is true.
Example:
[- $i = 0 -]
[$ do $]
[+ $i++ +] <BR>
[$ until $i > 10 $]
=item B<foreach>, B<endforeach>
Executes a loop for each element of the second B<Arg>, setting the
first B<Arg> accordingly.
Example:
[- @arr = (1, 3, 5) -]
[$ foreach $v @arr $]
[+ $v +] <BR>
[$ endforeach $]
=item B<next>
Inside of looks same as Perl next statement. You could also use the followingsyntax, which allows to add an addtional condition (or any other Perl code):
[* next if ($foo) *]
=item B<last>
Inside of looks same as Perl last statement. You could also use the followingsyntax, which allows to add an addtional condition (or any other Perl code):
[* last if ($foo) *]
=item B<redo>
Inside of looks same as Perl redo statement. You could also use the followingsyntax, which allows to add an addtional condition (or any other Perl code):
[* redo if ($foo) *]
=item B<hidden>
B<Arg> consists of zero, one or two names of hashes (with or without
the leading %) and an optional array as third parameter. The
B<hidden> metacommand will generate hidden fields for all data
contained in the first hash but not in the second hash. The default used for
the first hash is C<%fdat>, C<%idat> is used for the second.
If the third parameter is specified, the fields are written in the
order they appear in this array. That is, all keys of the first hash
must be properly sorted in this array. This is intended for
situations where you want to pass data from one form to the next, for
example, two forms which should be filled in one after the other.
(Examples might be an input form and a second form to review and
accept the input, or a Windows-style "wizard"). Here you can pass
along data from previous forms in hidden fields. (See eg/x/neu.htm
for an example.) If you use just the 'hidden' command withoutparameters, it simply generates hidden fields for all form fields
submitted to this document which aren't already contained in another
input field.
Example:
<FORM ACTION="inhalt.htm" METHOD="GET">
<INPUT TYPE="TEXT" NAME="field1">
[$ hidden $]
</FORM>
If you request this with
the output will be
<FORM ACTION="inhalt.htm" METHOD="GET">
<INPUT TYPE="TEXT" NAME="feld1" VALUE="A">
<INPUT TYPE="HIDDEN" NAME="field2" VALUE="B">
<INPUT TYPE="HIDDEN" NAME="field3" VALUE="C">
</FORM>
C<NOTE:> This should only be used for a small amount of data, since the
hidden fields are sent to the browser, which sends it back with the
next request. If you have a large amount of data, store it in a file
with a unique name and send only the filename in a hidden field. Be
aware of the fact that the data can be changed by the browser if the
user doesn't behave exactly as you expect. Users have a nasty habit of
doing this all of the time. Your program should be able to handle
such situations properly.
=item B<var>
The var command declares one or more variables for use within thisEmbperl document and sets the B<strict> pragma. The variable names
must be supplied as a space-separated list.
Example:
[$var $a %b @c $]
This is the same as writing the following in normal Perl code:
NOTE 1: `use strict' within an Embperl document will only apply to theblock in which it occurs.
=item B<sub>
(Only Embperl 1.2b5 and above)
Defines a Embperl subroutine. Example:
[$ sub foo $]
<p> Here we do something </p>
[$ endsub $]
You can call this subroutine either as a normal Perl subroutine
[- foo -]
or via the Embperl::Execute function.
[- Execute ('#foo') # short form -]
[- Execute ({ sub => 'foo'})
The difference is that the Execute function will reset the internal
states of Embperl like they were before the subrountine call, when
the subroutine returns. Also Execute could handle recursive call, which
currently not work when calling it as a Perl subroutine.
You may also pass Parameters to the subroutine:
[$ sub foo $]
[- $p = shift -]
<p> Here we show the first parameter [+ $p +]</p>
[$ endsub $]
[- foo ('value') -]
If you have a couple of commonly used subroutines you can define then in one
file and import them into the modules where they are neccesary:
[- Execute ({ inputfile => 'mylib.htm', import => 1 }) -]
This will import all subroutines from the file I<mylib.htm> into the current page
where they could call just as a normal Perl subroutine.
=back
=head2 HTML Tags
Embperl recognizes the following HTML tags in a special way. All others are
simply passed through, as long as they are not part of a Embperl
command.
=over 4
=item B<TABLE>, B</TABLE>, B<TR>, B</TR>
Embperl can generate dynamic tables (one- or two-dimensional). You
only need to specify one row or column.
Embperl generates as many rows or columns as necessary. This is done
by using the magic variables $row, $col, and $cnt. If you don't use
$row/$col/$cnt within a table, Embperl does nothing and simply passes
the table through.
Embperl checks if any of $row, $col, or $cnt is used. Embperl repeats
all text between <table> and </table>, as long as the expressions in
which $row or $cnt occurs are defined.
Embperl repeats all text between <tr> and </tr>, as long as the
expressions in which $col or $cnt occurs are defined.
See also L<"$tabmode"> (below) for end-of-table criteria.
Examples: (see eg/x/table.htm for more examples)
[- @k = keys %ENV -]
<TABLE>
<TR>
<TD>[+ $i=$row +]</TD>
<TD>[+ $k[$row] +]</TD>
<TD>[+ $ENV{$k[$i]} +]</TD>
</TR>
</TABLE>
This will show all entries in array @k (which contains the keys from
%ENV), so the whole environment is displayed (as in the B<while>
example), with the first column containing the zero-based index, the
second containing the content of the variable name, and the third the
environment variable's value.
This could be used to display the result of a database query if you have
the result in an array. You may provide as many columns as you need.
It is also possible to call a 'fetch' subroutine in each table row.
=item B<TH>, B</TH>
The <TH> tag is interpreted as a table heading. If the whole row is made
up of <TH> </TH> instead of <TD> </TD>, it is treated as a column heading.
Everything else will be treated as row headings in the future, but are not
now: everything else is ignored in the current version.
=item B<DIR>, B<MENU>, B<OL>, B<UL>, B<DL>, B<SELECT>, B</DIR>, B</MENU>,
B</OL>, B</UL>, B</DL>, B</SELECT>
Lists and dropdowns or list boxes are treated exactly as one-
dimensional tables. Only L<"$row">, L<"$maxrow">, L<"$col">, L<"$maxcol"> and L<"$tabmode">
are honored. $col and $maxcol are ignored. See eg/x/lists.htm for an
example.
=item B<OPTION>
Embperl checks if there is a value from the form data for a specific
option in a menu. If so, this option will be pre-selected.
Example:
<FORM METHOD="POST">
<P>Select Tag</P>
If you request this document with list.htm?SEL1=x
you can specify that the element which has a value
of x is initially selected
<P><SELECT NAME="SEL1">
<OPTION VALUE="[+ $v[$row] +]">
[+ $k[$row] +]
</OPTION>
</SELECT></P>
</FORM>
=item B<INPUT>
The INPUT tag interacts with the hashes C<%idat> and C<%fdat>. If the
input tag has no value and a key exists with the same text as the
NAME attribute of the input tag, Embperl will generate a VALUE
attribute with the corresponding value of the hash key.
All values of <INPUT> tags are stored in the hash C<%idat>, with NAME
as the hash key and VALUE as the hash value. Special processing is
done for TYPE=RADIO and TYPE=CHECKBOX. If the VALUE attribute
contains the same text as the value of the hash the CHECKED attribute
is inserted, else it is removed.
So, if you specify, as the ACTION URL,
the file which contains the form itself, the form will be redisplayed
with same values as entered the first time. (See eg/x/neu.htm for an
example.)
=item B<TEXTAREA>, B</TEXTAREA>
The C<TEXTAREA> tag is treated exactly like other input fields.
=item B<META HTTP-EQUIV=>
<meta http-equiv= ... > will over-ride the corresponding http header.
This keeps Netscape from asking the user to reload the document
when the content-type differs between the http header and the
meta http-equiv.
This can also be used to set http headers. When running under mod_perl
http-headers can also be set by the function B<header_out>
Example of how to set a http header:
<META HTTP-EQUIV="Language" CONTENT="DE">
This is the same as using the Apache function
[- $req_rec -> header_out("Language" => "DE"); -]
=item B<A>, B<EMBED>, B<IMG>, B<IFRAME>, B<FRAME>, B<LAYER>
The output of perl blocks inside the C<HREF> attribute of the C<A> Tags and the
C<SRC> attribute of the other Tags are URL escaped instead of HTML escaped.
(see also L<$escmode>). Also, when inside such a URL, I<Embperl> expands array and hash references
to URL parameter syntax. Example:
[-
$A = { A => 1, B => 2 } ;
@A = (X, 9, Y, 8, Z, 7)
-]
is expanded by I<Embperl> to
=back
=head1 Variable scope and cleanup
The scope of a variable declared with B<my> or B<local> ends at the
end of the enclosing [+/- ... -/+] block; the [+/- ... -/+] blocks act
much like Perl's { ... } in that regard.
Global variables (everything not declared with B<my> or B<local>) will
be undef'ed at the end of each request, so you don't need to worry
about any old variables laying around and causing suspicious results.
This is only done for variables in the package the code is eval'ed in --every variable that does not have an explicit package name. Allvariables with an explicit package name (i.e., in modules you use)will stay valid until the httpd child process dies. Embperl will
change the current package to a unique name for every document, so theinfluence between different documents is kept to a minimum. You can
set the name of the package with B<EMBPERL_PACKAGE>. (See also
L<"(Safe-)Namespaces and opcode restrictions">.)
Since a CGI script is always a process of its own, you don't need to
worry about that when you use Embperl as a CGI script.If you need to declare variables which need to live longer than just one
HTTP request (for example, a database handle), you must either put it's
name in the hash C<%CLEANUP> or declare them in
another package (i.e., $Persistent::handle instead of $handle).
If you want to use the strict pragma, you can do this by using the B<var> metacommand todeclare your variables.
C<NOTE:> Bacause Apache::DBI has its own namespace, this module will
work together with Embperl to maintain your persistent database
connection.
You can disable the automatic cleanup of global variables with
B<EMBPERL_OPTIONS> or the B<cleanup> parameter of the B<Execute>
function.
You can define exceptions to the cleanup rule with the hash B<%CLEANUP>.
If you like to do your own cleanup you can define a subroutine B<CLEANUP>
in your document. This will be called right before the variables are
cleaned up, but after the connection to the client is closed.
EXAMPLE:
[! sub CLEANUP { close FH ; } !]
=head1 Predefined variables
Embperl has some special variables which have a predefined meaning.
=head2 %ENV
Contains the environment as seen from a CGI script.
=head2 $epreq
Contains a reference to the Embperl request object. This is the same
as adding C<$epreq = shift> at the top of each page.
=head2 $epapp
Contains a reference to the Embperl application object. This is the same
as C<$epreq -> app> would return.
=head2 %fdat
Contains all the form data sent to the script by the calling form.
The NAME attribute builds the key and the VALUE attribute is used as
the hash value. Embperl doesn't care if it is called with the GET or
POST method, but there may be restrictions on the length of parameters
using GET -- not from Embperl, but perhaps from the web server,
especially if you're using Embperl's CGI mode -- it is safer to use
POST.
If multiple fields with the same name are sent to a Embperl page, they will
put in the same hash element and separated be tabs. You can split it up in
an array, by writting:
@array = split (/\t/, $fdat{'fieldname'}) ;
Embperl also supports ENCTYPE multipart/form-data, which is used for
file uploads. The entry in %fdat corresponding to the file field will
be a filehandle, as with CGI.pm. (Embperl uses CGI.pm internally to
process forms encoded with multipart/form-data.)
File upload example:
HTML page:
<FORM METHOD="POST" ENCTYPE="multipart/form-data">
<INPUT TYPE="FILE" NAME="ImageName">
</FORM>
Embperl ACTION:
[- if (defined $fdat{ImageName}) {
open FILE, "> /tmp/file.$$";
print FILE $buffer
while read($fdat{ImageName}, $buffer, 32768);
close FILE;
}
-]
When you have installed CGI.pm 2.46 or above, you may also retrieve the
filename (local filename, as it was on the browser side) and the information
provided by the CGI.pm uploadInfo function. To get the filename, simply print out
the value of the corresponding %fdat entry, instead of using it as a filehandle.
To get the B<uploadInfo> use the fieldname with a dash in front of it: Example:
Filename: [+ $fdat{ImageName} +] <br>
Content-Type: [+ $fdat{-ImageName} -> {'Content-Type'} +] <br>
B<NOTE:> The way B<uploadInfos> are accessed before 1.2b11 is not supported
anymore.
B<NOTE:> This works the other
way as well: any input fields with names that are
%fdat keys, and without values, will have their values automatically set to
the appropriate %fdat value. See L<"HTML Tags"> C<INPUT/OPTION/TEXTAREA>.
=head2 @ffld
Contains all the field names in the order in which they were sent by
the browser. This is normally -- but not necessarily -- the order in
which they appear in your form.
=head2 %idat
Contains all the values from all input tags processed so far.
=head2 %udat (only 1.2b1 or higher)
You can use B<%udat> to store per user data. As long as you don't use %udat, nothinghappens, but as soon as you write anything to %udat, Embperl creates a session id and
sends it via a cookie to the browser. The data you have written to %udat is stored by
Apache::Session. The next time the same user request an Embperl page, the browser sends
the cookie with the session id back and Embperl fills the %udat hash from Apache::Session
with the same values as you have stored for that user. (See also L<"Session handling">)
=head2 %mdat (only 1.2b2 or higher)
You can use B<%mdat> to store per module/page data. As long as you don't use %mdat, nothinghappens, but as soon as you write anything to %mdat, Embperl creates a session id and
stores the data via Apache::Session. The next time any user hits the same Embperl page,
Embperl fill the %mdat hash from Apache::Session with the same values as you have
stored within the last request to that page. (See also L<"Session handling">)
=head2 $row, $col
Row and column counts for use in dynamic tables. (See L<"HTML tag table"|"HTML Tags">.)
=head2 $maxrow, $maxcol
Maximum number of rows or columns to display in a table. To prevent
endless loops, $maxrow defaults to 100 and $maxcol to 10.
(See L<"HTML tag table"|"HTML Tags">.)
=head2 $cnt
Contains the number of table cells displayed so far.
(See L<"HTML tag table"|"HTML Tags">.)
=head2 $tabmode
Determines how the end of a dynamic table is detected. Tables are always
limited to the size specified in $maxrow and $maxcol, but can be ended early
when the row ($row) and column ($col) variables become undefined. $tabmode operates as
follows:
=over 4
=item B<$tabmode = 1>
End table looping when any one of the expressions in the table row
using $row returns undefined. The row
containing the undefined expression is B<not> displayed. Only those
expressions are observed which contain an access to the variable $row.
=item B<$tabmode = 2>
End when an expression with $row becomes undefined. The row
containing the undefined expression B<is> displayed.
=item B<$tabmode = 4>
End when $maxrow rows have been displayed.
=back
B<end of row>
=over 4
=item B<$tabmode = 16>
End table column looping when any one of the expressions in the table column
using $col returns undefined.
The column
containing the undefined expression is B<not> displayed. Only those
expressions are observed which contain an access to the variable $col.
=item B<$tabmode = 32>
End when an expression with $col becomes undefined. The column
containing the undefined expression B<is> displayed.
=item B<$tabmode = 64>
End when $maxcol columns have been displayed.
=back
The default is B<17>, which is correct for all sort of arrays. You
should rarely need to change it. The two values can be added
together.
=head2 $escmode
Turn HTML and URL escaping on and off. The default is on ($escmode =
3).
B<NOTE:> Normaly you can disable escaping by preceeding the item that
normaly is escaped with a backslash. While this is a handy thing, it could
be very dangerous in situations, where content that is inserted by some
user is redisplayed, because they can enter arbitary HTML and preceed them
with a backslash to avoid correct escaping when their input is redisplayed
again. To avoid this problem, add 4 to the values below. This will cause
Embperl to ignore the backslash when it does output escaping at all.
(only 1.3b4 and above)
B<NOTE 2:> If you want to output binary data, you must set the escmode
to zero. (only 1.3b6 and above)
=over 4
=item B<$escmode = 8 (or 15)> (2.0b4 and above)
The result of a Perl expression is always XML-escaped (e.g., `>'
becomes `>' and ' become ').
=item B<$escmode = 3 (or 7)>
The result of a Perl expression is HTML-escaped (e.g., `>' becomes
`>') in normal text and URL-escaped (e.g., `&' becomes `%26')
within of C<A>, C<EMBED>, C<IMG>, C<IFRAME>, C<FRAME> and C<LAYER> tags.
=item B<$escmode = 2 (or 6)>
The result of a Perl expression is always URL-escaped (e.g., `&'
becomes `%26').
=item B<$escmode = 1 (or 5)>
The result of a Perl expression is always HTML-escaped (e.g., `>'
becomes `>').
=item B<$escmode = 0>
No escaping takes place.
=back
=head2 $req_rec
This variable is only available when running under control of
mod_perl. It contains the request record needed to access the Apache
server API. See B<perldoc Apache> for more information.
=head2 LOG
This is the filehandle of the Embperl logfile. By writing `print LOG
"something"' you can add lines to the logfile. NOTE: The logfile line
should always start with the pid of the current process and continue
with a four-character signature delimited by a ':', which specifies
the log reason.
Example: print LOG "[$$]ABCD: your text\n" ;
If you are writing a module for use under Embperl you can say tie *LOG, 'Embperl::Log';
to get a handle by which you can write to the Embperl logfile.
=head2 OUT
This filehandle is tied to Embperl's output stream. Printing to it has the same effect
as using the [+ ... +] block. (See also L<optRedirectStdout|"EMBPERL_OPTIONS">)
=head2 @param
Will be setup by the B<'param'> parameter of the B<Execute> function. Could be used
to pass parameters to an Embperl document and back. (see
L<Execute|"By calling Embperl::Execute">
for further docs)
=head2 %http_headers_out (only 1.2b10 and above)
You can put any http headers you want to send into this hash.
If you set a location header,
Embperl will automaticly set the status to 301 (Redirect). Example:
however, it is possible to specify a two element array for Location, the second
element of which gives the desired HTTP status:
Starting with version 1.3.2 all headers with the exception of
"Content-Type" can take multiple values.
For instance, if you wanted to set two cookies, you can proceed as follows:
[- $http_headers_out{'Set-Cookie'} =
['name=cook1;value=2;','name=cook2;value=b'] ; -]
If you supply multiple values for "Location" or "Content-Type" via an array
reference, then Embperl will simply use the first in the list. Empty arrayswill be ignored. For instance, the following will neither change the status
to 301 nor create a Location: line in the HTTP headers:
[- $http_headers_out{'Location'} = [] ; -]
see also META HTTP-EQUIV=
=head2 $optXXX $dbgXXX
All options (see L<"EMBPERL_OPTIONS">) and all debugging flags (see L<"EMBPERL_DEBUG">) can
be read and set by the corresponding variables.
Example:
[- $optRawInput = 1 -]
Now write something here
[- $optRawInput = 0 -]
[+ $dbgCmd +]
There are a few exceptions, where the variables can only be read. Setting of such options
must be done via the config-files. Read-only variables are:
=over 4
=item $optDisableVarCleanup
=item $optSafeNamespace
=item $optOpcodeMask
=item $optDisableChdir
=item $optEarlyHttpHeader
=item $optDisableFormData
=item $optAllFormData
=item $optRedirectStdout
=item $optAllowZeroFilesize
=item $optKeepSrcInMemory
=back
=head2 %CLEANUP
Embperl cleanups up only variables with are defined within the Embperl page. If you want Embperl
to cleanup additional variables you can add them to the hash %CLEANUP, with the key set to the
variable name and the value set to one. The other way you could prevent Embperl from cleaning
up some variables, is by adding them to this hash, with values of zero.
=head2 %CLEANUPFILE (1.2b6+)
Same purpose as C<%CLEANUP>, but you may add filenames. All variables defined inside that file
will be cleaned up.
=head1 Session handling
From 1.2b1 and higher Embperl is able to handle per user sessions for you. You
can store any data in the L<%udat> hash and if the same user requests an
Embperl document again, you will see the same values in that hash again.
From 1.2b2 and higher Embperl is able to handle per module/page persistent data
for you. You can store any data in the L<%mdat> hash and if any request comes
to the same Embperl document, you will see the same values in that hash again.
Session handling has changed from 1.3.3 to 1.3.4 and 2.0b3 to 2.0b4. You must either
install Apache::SessionX or set
PerlSetEnv EMBPERL_SESSION_HANDLER_CLASS "Embperl::Session"
to get the old behaviour. If you have Apache::SessionX installed, you
don't have to make addtional configuration, otherwise you must do the following
things. You are also able to override the Apache::SessionX defaults, by
using the following parameters:
To configure I<Embperl> to do session management for you, you must
have installed I<Apache::Session> (B<1.53 or higher>) and tell Embperl which
storage and locker classes you would like to use for
I<Apache::Session>. This is done by setting the environment variable
C<EMBPERL_SESSION_CLASSES>.
If you want to use a MySQL database for storing your sessions, you may have aB<startup.pl> for your httpd which looks like this:
BEGIN
{
$ENV{EMBPERL_SESSION_CLASSES} = "MySQL Semaphore" ;
$ENV{EMBPERL_SESSION_ARGS} = "DataSource=dbi:mysql:session UserName=test" ;
} ;
or you may put this in the httpd/srm.conf:
PerlSetEnv EMBPERL_SESSION_CLASSES "MySQL Semaphore"
PerlSetEnv EMBPERL_SESSION_ARGS "DataSource=dbi:mysql:session UserName=test"
PerlModule Embperl ;
Refer to the I<Apache::Session> docs (e.g. I<Apache::Session::Store::MySQL>) on how
to setup your database tables.
C<EMBPERL_SESSION_ARGS> is a space separated list of name/value pairs, which gives
additional arguments for Apache::Session classes.
Here is an example for using a filesystem based storage:
PerlSetEnv EMBPERL_SESSION_CLASSES "File Semaphore"
PerlSetEnv EMBPERL_SESSION_ARGS "Directory=/path/to/your/sessions"
Refer to the I<Apache::Session> docs to find out which other storage/locker methods are available.
C<EMBPERL_SESSION_CLASSES> can (optionally) take two more classnames, which specify
the class for serialization (Default: C<Storable>) and for generating the id
(Default: C<MD5>).
B<NOTE:> The above configuration works only with I<Apache::Session> 1.52 and I<Embperl> 1.3b5
or above. Older versions of Embperl only support I<Apache::Session> 1.0x, which has
different parameters for C<EMBPERL_SESSION_CLASSES>
(e.g. C<$ENV{EMBPERL_SESSION_CLASSES} = "DBIStore SysVSemaphoreLocker" ; >)
I<Apache::Session> 1.0x still works with this Embperl version.
Now you are able to use the %udat and %mdat hashes for your user/module sessions. As long as youdon't touch %udat or %mdat,
Embperl will not create any session, and Apache::Session is not loaded. As soon as you store any
value to %udat, Embperl will create a new session and send a cookie to the browser to maintain
its id, while the data is stored by Apache::Session. (Further version may also be able to use
URL rewriting for storing the id).
When you modify %mdat, Embperl will store the data via Apache::Session and retrieve it
when the next request comes to the same page.
=head2 Functions/Methods for session handling
=head2 Embperl::Req::SetupSession ($req_rec, $Inputfile) [1.3b6+]
This can be used from a script that will later call L<Embperl::Execute|Execute> to
preset the session so it's available to the calling script.
=over 4
=item $req_rec
Apache request record when running under mod_perl, C<undef> otherwise.
=item $Inputfile
Name of file that will be later processed by Embperl. It is used to setup L<%mdat>. If you
don't pass the C<$Inputfile>, C<%mdat> is not setup.
=back
Returns a reference to L<%udat> or, if call in an array context, a reference to L<%udat>
and L<%mdat>. See also C<CleanupSession>.
=head2 Embperl::Req::GetSession / $r -> GetSession [1.3b6+]
Returns a reference to L<%udat> or, if called in an array context, a reference to L<%udat>
and L<%mdat>. This could be used by modules that are called from inside an Embperl page,
where the session management is already setup. If called as a method C<$r> must be
a Embperl::Req object, which is passed as first parameter to every Embperl page in @_ .
=head2 Embperl::Req::CleanupSession / $r -> CleanupSession [1.3b6+]
Must be called at the end of a script by scripts that use C<SetupSession>,but do not call L<Embperl::Execute|Execute>.
If called as a method C<$r> must be
a Embperl::Req object, which is passed as first parameter to every Embperl page in @_ .
=head2 Embperl::Req::DeleteSession / $r -> DeleteSession [1.3b6+]
Deletes the session data and removes the cookie from the browser.
If called as a method C<$r> must be
a Embperl::Req object, which is passed as first parameter to every Embperl page in @_ .
=head2 Embperl::Req::RefreshSession / $r -> RefreshSession [1.3b6+]
Triggers a resend of the cookie. Normaly the cookie is only send the first time.
If called as a method C<$r> must be
a Embperl::Req object, which is passed as first parameter to every Embperl page in @_ .
=head2 Embperl::Req::SetSessionCookie / $r -> SetSessionCookie [1.3b7+]
Must be called by scripts that use C<SetupSession>,but do not call L<Embperl::Execute|Execute>. This is neccessary to set the cookie
for the session id, in case a new session is created, which is normaly done by
L<Embperl::Execute|Execute>. If called as a method C<$r> must be
a Embperl::Req object, which is passed as first parameter to every Embperl page in @_ .
=head1 (Safe-)Namespaces and opcode restrictions
Since most web servers will contain more than one document, it is
necessary to protect the documents against each other. Embperl does
this by using Perl namespaces. By default, Embperl executes every
document in its own namespace (package). This will prevent documents
from accidentally overriding the other's data. You can change this
behavior (or simply the package name) with the configuration directiveB<EMBPERL_PACKAGE>. NOTE: By explicitly specifying a package name, youcan access data that is used by another document.
If Embperl is used by more than one person, it may be neccessary to
protect documents from each other. To do this, Embperl
gives you the option of using safe namespaces. Each document runs in
its own package and can't access anything outside of this package.(See the documentation of Safe.pm for a more detailed discussion of
safe namespaces.)
To make a document run in a safe namespace, simply add
B<optSafeNamespace> to B<EMBPERL_OPTIONS>. The default package nameused is the same as in normal operation and can be changed with
B<EMBPERL_PACKAGE>. NOTE: From the perspective of the document being
executed, the code is running in the package B<main>!A second option to make Embperl more secure is the use of the opcoderestriction mask. Before you can use the opcode mask, you must set upa safe compartment.
B<$cp = Embperl::AddCompartment($name);>
This will create a new compartment with a default opcode mask and the
name $name. (The name is used later to tell Embperl which compartment
to use.) Now you can change the operator mask. For example:
B<$cp->deny(':base_loop');>
In your configuration you must set the option B<optOpcodeMask> in
B<EMBPERL_OPTIONS> and specify from which compartment the opcode mask
should be taken by setting B<EMBPERL_COMPARTMENT>.
Example (for use with mod_perl):
B<srm.conf:>
PerlScript startup.pl
SetEnv EMBPERL_DEBUG 2285
Alias /embperl /path/to/embperl/eg
<Location /embperl/x>
SetHandler perl-script
PerlHandler Embperl
Options ExecCGI
PerlSetEnv EMBPERL_OPTIONS 12
PerlSetEnv EMBPERL_COMPARTMENT test
</Location>
B<startup.pl:>
$cp = Embperl::AddCompartment('test');
$cp->deny(':base_loop');
This will execute the file startup.pl on server startup. startup.pl
sets up a compartment named `test', which will have a default opcode
mask and additionaly, will have loops disabled. Code will be executed
in a safe namespace.
NOTE: The package name from the compartment is B<NOT> used!Look at the documentation of Safe.pm and Opcode.pm for more detailed
information on how to set opcode masks.
=head1 Utility Functions
=head2 AddCompartment($Name)
Adds a compartment for use with Embperl. Embperl only uses the opcode
mask from it, not the package name. AddCompartment returns the newly-created compartment so you can allow or deny certain opcodes. See the
Safe.pm documentation for details of setting up a compartment. See the
chapter about L<"(Safe-)Namespaces and opcode restrictions"> for details on how Embperl uses compartments.
Example:
$cp = Embperl::AddCompartment('TEST');
$cp->deny(':base_loop');
=head2 MailFormTo($MailTo, $Subject, $ReturnField)
Sends the content of the hash %fdat in the order specified by @Z<>ffld to
the given B<$MailTo> addressee, with a subject of B<$Subject>.
If you specify $ReturnField the value of that formfield will be used
as B<Return-Path>. Usually, this will be the field where the user enters his
e-mail address in the form.
If you specifiy the following example code as the action in your form
<FORM ACTION="x/feedback.htm" METHOD="POST"
ENCTYPE="application/x-www-form-urlencoded">
The content of the form will be mailed to the given e-mail address.
MailFormTo uses L<"EMBPERL_MAILHOST"> as SMTP server or B<localhost>
if non given.
Example:
<HTML>
<HEAD>
<TITLE>Feedback</TITLE>
</HEAD>
<BODY>
[- MailFormTo('webmaster@domain.xy',
'Mail from WWW Form', 'email') -]
Your data has been successfully sent!
</BODY>
</HTML>
This will send an email with all the form fields to webmaster@domain.xy, with the
Subject 'Mail from WWW Form' and will set the Return-Path of the mail to the
address which was entered in the field with the name 'email'.
B<NOTE:> You must have Net::SMTP (from the libnet package) installed
=head2 exit
B<exit> will override the normal Perl exit in every Embperl document. Calling
exit will immediately stop any further processing of that file and send the
already-done work to the output/browser.
B<NOTE 1:> If you are inside of an Execute, Embperl will only exit this Execute, but
the file which called the file containing the exit with Execute will continue.
B<NOTE 2:> If you called exit with an argument it exits the whole request.
B<NOTE 3:> If you write a module which should work with Embperl under mod_perl,
you must use Apache::exit instead of the normal Perl exit (as always when running under mod_perl).
=head1 Performance
To get the best performace from Embperl, it is necessary to restrict
logging to a minimum. You can drastically slow down Embperl if you
enable all logging options. (This is why `make test' takes a while to
run.) You should B<never> enable B<dbgFlushOutput> or B<dbgFlushLog>
in a production environment. More debugging
options are useful for development where it doesn't matter if the
request takes a little bit longer, but on a heavily-loaded server they
should be disabled.
Additionally the options L<optDisableChdir>, L<optDisableHtmlScan>,
L<optDisableCleanup> have consequences for the performance.
Also take a look at B<mod_perl_tuning.pod> for general ideas about
performance.
=head1 Bugs
None known.
Under perl5.004 there are memory leaks. This is not an Embperl bug,
but can cause your httpd to grow endlessly when running under
mod_perl. Please upgrade to perl5.004_04 to fix this. You should
also upgrade to a mod_perl version higher than 1.07_01 as soon as
possible, because until 1.07_01 there is a memory leak in
Apache->push_handler.
=head1 Compatibility
I have tested Embperl successfully
=head2 on Linux 2.x with
=over 4
=item perl5.004_04
=item perl5.005_03
=item perl5.6.0
=item perl5.6.1
=item perl5.8.5
=item apache_1.3.0 - apache_1.3.31, apache 2.0.50
=item apache_ssl (Ben SSL)
=item Stronghold 2.2
=item Stronghold 2.4.1
=item Apache_1.3.x with mod_ssl 2.x.x
=back
I know from other people that it works on many other UNIX systems
=head2 on Windows NT 4.0 with
=over 4
=item perl5.004_04
=item perl5.005
=item perl5.6.1
=item perl5.8.x
=item apache_1.3.0 - apache_1.3.31
=back
=head2 on Windows 95/98 with
=over 4
=item perl5.004_02 (binary distribution, only Offline Mode)
=item perl5.005_02 + apache_1.3.6
=back
=head1 Support
=head2 Feedback and Bug Reports
Please let me know if you use or test this module. Bugs, questions,suggestions for things you would find useful, etc., are discussed on
the Embperl mailing list. If you have a site that is using Embperl,
I would love to mention it in list of sites using Embperl. Please drop
me a mail with a short description, if your site uses Embperl.
The Embperl mailing list (embperl@perl.apache.org) is available for Embperl users
and developers to share ideas, solve problems and discuss things related to Embperl
To subscribe to this list, send mail to embperl-subscribe@perl.apache.org.
To unsubscribe send email to embperl-unsubscribe@perl.apache.org .
For mod_perl related questions you may search the mod_perl mailing list
=head2 Commerical Support
You can get free support on the mod_perl mailing list (see above). If
you need commercial support, ecos can provide it for you. We offer:
=over 4
=item * Consulting and assitance for you and your programmers
=item * Planning of your dynamic website
=item * Creating of parts or a whole website
=item * Fixing bugs in Embperl (also available for mod_perl)
=item * Adding new features
=back
For more information about our support see
=head2 How to Support the Developement of Embperl
If you use and like Embperl and want to support it's ongoing developementyou have two possibilities:
=over 4
=item 1
Send me patches for things you like to see in Embperl
=item 2
Buy commercial support (see above). Also you B<may> get the same answers
to your questions on the mailing list, by buying the commercial support
you not only buy support for yourself and can be sure you get an answer,
you also give us the possibility to put more power in the further
developement of Embperl.
=back
=head1 Links and Download
=head2 Information
=head2 Download
B<Informations on how to install Embperl can be found in> L<INSTALL.pod>
=head2 CVS
The latest developments are available via CVS.
Look at L<"perldoc CVS.pod"|CVS.pod> for a detailed description.
=head1 Syntaxmodes for various editors
=head2 Emacs
From: Erik Arneson [erik@mind.net]
Here's the amount of documentation I've got right now.
They need to get mmm.el from this URL:
Then download my mmm-embperl.el from this one:
The documentation for using these is included in those two elisp files.
=head2 VIM
Vim Syntaxfile for Vim 5.x & 6.x from Lukas Zapletal with syntax highliting for JavaScript, VBScript,
Perl+Embperl, CSS and HTML, yellow background for Perl`s code (like M$ Interdev) and
working Perl folding can be found at
=head2 Dreamweaver
Dreamweaver extension which tells Dreamweaver not to touch Embperl code can
=head1 Author
G. Richter (richter@dev.ecos.de)
=head1 See Also
perl(1), mod_perl, Apache httpd