POCO C++ Server Page Compiler User Guide
PageCompiler

!!!Introduction
PageCompiler is a command line tool that translates HTML files (and other kinds of files, such as
cascading style sheet files), into
C++ code, more precisely, subclasses of Poco::Net::HTTPRequestHandler.
The source files can contain special directives that allow it to include C++ code into
the source file. The syntax of this directives is based on the syntax used for 
Java Server Pages (JSP) and PHP.

The following introductory sample shows the code for a simple page that displays the
current date and time.

    <%@ page class="TimeHandler" %>
    <%!
        #include "Poco/DateTime.h"
        #include "Poco/DateTimeFormatter.h"
        #include "Poco/DateTimeFormat.h"
        
        
        using Poco::DateTime;
        using Poco::DateTimeFormatter;
        using Poco::DateTimeFormat;
    %>
    
    <%
        DateTime now;
        std::string dt(DateTimeFormatter::format(now, DateTimeFormat::SORTABLE_FORMAT));
    %>
    <html>
    <head>
    <title>Time Sample</title>
    </head>
    <body>
    <h1>Time Sample</h1>
    <p><%= dt %></p>
    </body>
    </html>
----    

Sending the above code to the page compiler will generate two files, a header file
(<[TimeHandler.h]>) and an implementation file (<[TimeHandler.cpp]>).
The files define a subclass of Poco::Net::HTTPRequestHandler named <[TimeHandler]>.
The generated <[handleRequest]> member function contains code to send the HTML
code contained in the source file to the client, as well as the C++ code fragments found 
in between the Scriptlet tags. 


!!!C++ Server Page Syntax

The following special tags are supported in a C++ server page (CPSP) file.

!!Hidden Comment

A hidden comment documents the CPSP file, but is not sent to the client.

    <%-- <comment> --%>
----

!!Implementation Declaration

An implementation declaration is copied to the implementation file immediately after
the block containing the standard <[#include]> directives.
It is used to include additional header files and <[using]> declarations,
as well as to define classes needed later on.

    <%!
        <declaration>
        ...
    %>
----

!!Header Declaration

A header declaration is copied to the header file immediately after the
block containing the standard <[#include]> directives.
It is usually used to include the header file containing the definition
of the base class for the request handler, if a custom base class
is required.

    <%!!
        <declaration>
        ...
    %>
----

!!Expression

The result of any valid C++ expression can be directly inserted into the page,
provided the result can be written to an output stream. Note that the expression
must not end with a semicolon.

    <%= <expression> %>
----

!!Scriptlet

Arbitrary C++ code fragments can be included using the Scriptlet directive.

    <%
        <statement>
        ...
    %>
----

!!Include Directive

Another CPSP file can be included into the current file using the Include
Directive.

    <%@ include page="<path>" %>
----

If the given path is relative, it is considered relative to the path of
the currently processed CPSP file.

!!Page Directive

The Page Directive allows the definition of attributes that control
various aspects of C++ code generation.

    <%@ page <attr>="<value>" ... %>
----

The following page attributes are supported:

!class

Specifies the name of the generated class.
Defaults to the base name of the source file with the word "Handler" appended.

!namespace

If specified, sets the namespace where the generated classes will be in.
No namespace will be used if omitted.

!baseClass

Specifies the name of the class used as the base class for the generated 
request handler class.
Defaults to Poco::Net::HTTPRequestHandler. Do not forget to add a Header Declaration
containing an <[#include]> directive for the header file containing the definition
of that class, otherwise the generated code won't compile.

!ctorArg

Allows to specify the type of a single argument being passed to the constructor
of the generated request handler class. Can only be used together with <[baseClass]>.
The argument is passed on to the constructor of the base class, therefore, one of the 
constructors of the base class must also accept a single argument of the specified type.

!export

Allows to specify a DLL import/export directive that is being added to the request
handler class definition. Useful for exporting a request handler class from a
Windows DLL.

!form

Enable or disable automatic form handling. If enabled, which is the default,
a Poco::Net::HTMLForm object is automatically created in the request handler
and accessible through a variable named <[form]>.
Set the value to <[false]> to disable form handling.

!formPartHandler

Allows you to pass a Poco::Net::PartHandler object to the form object for 
processing file uploads. A subclass of Poco::Net::PartHandler must be
defined (using an Implementation Declaration), and the constructor of the part 
handler must take a (const) reference to the request handler instance as argument.

!contentType

Allows you to specify the MIME content type for the page. Defaults to text/html.

!chunked

Allows you to specify whether the response is sent using chunked transfer encoding.
Defaults to <[true]>.
Set the value to <[false]> to disable chunked transfer encoding.

!precondition

Allows the specification of a precondition, which must be a C++ expression
valid in the context of the request handler. This can be used to implement
authentication.

Example:

    <%@ page
        class="AuthSamplePage"
        precondition="checkCredentials(request, response)"
    %>

    <%!
	bool checkCredentials(Poco::Net::HTTPServerRequest& request, Poco::Net::HTTPServerResponse& response)
	{
		bool isAuthenticated = false;
		if (request.hasCredentials())
		{
			std::string scheme;
			std::string authInfo;
			request.getCredentials(scheme, authInfo);
			if (scheme == Poco::Net::HTTPBasicCredentials::SCHEME)
			{
				Poco::Net::HTTPBasicCredentials cred(request);
				isAuthenticated = (cred.getUsername() == "joeuser" && cred.getPassword() == "s3cr3t");
			}
		}
		if (!isAuthenticated)
		{
			response.requireAuthentication("Restricted Area");
			response.send();
		}
		return isAuthenticated;
	}
    %>
    <html>
    <head>
    <title>Restricted Area</title>
    </head>
    <body>
    <h1>Restricted Area</h1>
    </body>
    </html>
----    
   
    
!session (OSP only)

For use with the POCO Open Service Platform only.

Specifies the identifier of the session obtained from the OSP Web Session Manager.
If specified, a Poco::OSP::Web::WebSession object will be available in the
request handler through a variable named <[session]>. The variable is of type
Poco::OSP::Web::WebSession::Ptr.

!sessionTimeout (OSP only)

For use with the POCO Open Service Platform only.

Specifies the session timeout in minutes.


!!Implicit Objects

The following objects are available in the handler code.

!request

The HTTP request object - an instance of Poco::Net::HTTPServerRequest.

!response

The HTTP response object - an instance of Poco::Net::HTTPServerRequest.

!form

An instance of Poco::Net::HTMLForm for processing form arguments.
Only available if form processing has not been disabled by
setting the <[form]> page attribute to <[false]>.

!session (OSP only)

An instance of Poco::OSP::Web::WebSession::Ptr for accessing the
Poco::OSP::Web::WebSession object for the current session.
Only available with the POCO Open Service Platform, and if the
<[session]> page attribute has been specified.


!!!Invoking the Page Compiler

The Page Compiler is invoked from the command line. The file names of the
CPSP files to be compiled are specified as arguments.

A number of options control the code generation. Options are specified
using the usual command-line option syntax for the current operating
system (e.g., <[/help]> on Windows, <[--help]> or <[-h]> on Unix).

  * help (h): display usage information
  * define (D): define a configuration property
  * config-file (f): load configuration properties from a file
  * osp (O): add factory class definition/implementation for use with OSP
  * apache (A): add factory class definition/implementation and shared library manifest for use with ApacheConnector

!!Configuration Properties

The Page Compiler supports one configuration property, named
<[PageCompiler.fileHeader]>, to optionally specify a header that is 
included in every generated file.

The file header can contain references to other configuration properties,
using the usual property syntax: <[${property}]>.

For example, invoking the Page Compiler with the following configuration
file:

    PageCompiler.fileHeader = //\n// ${outputFileName}\n//\n
----

places the following header at the beginning of each generated file
(<[<filename>]> is replaced with the actual name of the file):

    //
    // <filename>
    //
----

The following pre-defined properties can be used in the file header:

  * <[${inputFileName}]>: the name of the input file (with directories removed)
  * <[${inputFilePath}]>: the complete path of the input file
  * <[${dateTime}]>: the current date and time (YYYY-MM-DD HH:MM:SS)
  * <[${outputFileName}]>: the name of the current output file (header or implementation file), with
    directories removed
  * <[${outputFilePath}]>: the complete path of the current output file

