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Sample brazil Handler Configurations
How to combine
handlers
Introduction
Typical applications of the Brazil system combine one or more existing
components together with custom additions, consisting of one or more
implementations of:
handlers
- The primary extension interface, which allows for the custom handling
of URL's.
filters
- A special type of handler, used in conjunction with the
FilterHandler
that permits content obtained from other handlers to be rewritten.
templates
- Are classes that work in conjunction with the
TemplateFilter or TemplateHandler
that allow html/XML content to be processed on an entity by
entity basis.
When the server is created, it is provided with a Java
Properties object, which both defines the interrelationships
among the components (handlers, filters, and templates),
as well as providing the
means for information to be shared among them. This document presents
several configurations -- java properties objects -- that
are represented as java properties files, which may be
used directly by the sample Main program.
Traditional Web Server Configurations
The trivial example
provides the server with no properties.
In this case, the server, listening on port 8080, uses the
FileHandler
to deliver ordinary files, using the current directory as the document root.
This allows the system to be tested out of the box, with no
configuration provided.
The following configuration could be used as a simple, traditional
web-server. It delivers normal files, runs CGI scripts, provides
directory listings, and a "custom" page for not-found documents.
On Unix systems, it permits individual users to have "personal pages".
Simple traditional web server configuration
handler=simple
simple.class=sunlabs.brazil.server.ChainHandler
simple.handlers=home file cgi directory missing
home.class=sunlabs.brazil.handler.HomeDirHandler
file.class=sunlabs.brazil.server.FileHandler
cgi.class=sunlabs.brazil.handler.CgiHandler
cgi.suffix=.cgi
directory.class=sunlabs.brazil.handler.DirectoryHandler
missing.class=sunlabs.brazil.handler.NotFoundHandler
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Since the server dispatches all requests to a single handler,
The ChainHandler allows for multiple handlers to
have a chance at servicing the request.
The HomeDirHandler demonstrates the use of
side effects, or the ability of one handler to communicate with
another by changing the server configuration "on the fly", by modifying
the server properties. In this case, the document root the
fileHandler uses to find files.
A slightly more complex example
In this example, we've added a password protected section, the
ability to "publish" pages, and the redirection to another site of
all content in /moved.
Changes from the previous configuration are in
bold face.
Expanded traditional web server configuration
handler=simple
simple.class=sunlabs.brazil.server.ChainHandler
simple.handlers=home moved protected publish file cgi directory missing
home.class=sunlabs.brazil.handler.HomeDirHandler
file.class=sunlabs.brazil.server.FileHandler
cgi.class=sunlabs.brazil.handler.CgiHandler
cgi.suffix=.cgi
directory.class=sunlabs.brazil.handler.DirectoryHandler
missing.class=sunlabs.brazil.handler.NotFoundHandler
#
# Redirect all request in /moved/... to a new site
#
moved.class=sunlabs.brazil.handler.UrlMapperHandler
moved.match=/moved/(.*)
moved.replace=http://www.moved.here/new/\\1
moved.ignoreCase=true
moved.redirect=true
#
# require basic authentication for all files under /protected/...
#
protected.class=sunlabs.brazil.handler.BasicAuthHandler
protected.realm=a-secret
protected.prefix=/protected/
protected.mapFile=data.credentials
#
# Allow netscape style publishing of pages
#
publish.class=sunlabs.brazil.handler.PublishHandler
publish.realm=Sample server web site administration
publish.mapFile=publish.credentials
publish.prefix=/
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Brazil style server configuration
Although Brazil can be used to mimic traditional web server functionality,
as shown above, it was intended to be used for more dynamic content
generation. In the simple example below, we implement a "company phone
book" application, using a single "html" file. Here is the server
configuration:
Brazil style configuration file for "phone book" application
# Company telephone directory application, demonstrating a sample
# use of the TemplateHandler, incorporating:
# - PropsTemplate for substituting data into html "Template" pages
# - SqlTemplate for doing data base queries
# - BSLTemplate for allowing conditional html code, and dynamic
# table generation
#
handler=org
org.class=sunlabs.brazil.template.TemplateHandler
org.templates= \
sunlabs.brazil.template.PropsTemplate \
sunlabs.brazil.template.SqlTemplate \
sunlabs.brazil.template.BSLTemplate
#
# Place all query data into the request.props
# object, so we can manipulate it from our template. This provides
# a simple mechanism for replacing the functionality of most CGI
# scripts.
#
org.query=Query.
#
# Use the "mm" jdbc drivers to talk to the MySql database.
# Make sure the jar file containing the driver is in the classpath.
#
org.driver=org.gjt.mm.mysql.Driver
#
# Provide the server and database names to the SQL template
#
org.url=jdbc:mysql://mack.eng/test?user=brazil&password=xxxx
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The server configuration operates with the following HTML file. Notice
that additional HTML entities are incorporated along with the ordinary
HTML, and used by the templates to generate dynamic
content. Each template defines one or more new "html entities", that
it processes, replacing them with standard HTML, In this example,
the SqlTemplate processes the text between
<sql>...</sql> and provides data to the
other two templates. The PropsTemplate replaces
entities of the form
<property name=xxx>
with the value of xxx.
The BSLTemplate implements a simple HTML based
scripting language (the Brazil Sripting Language)
that processes entities of the form:
- <if>...<elseif>...<else>...</if>
- <foreach>...</foreach>
to allow for dynamic and conditional HTML generation.
Note that the form embedded in the page submits the form data back to
itself, which is used to create the next version of the page.
HTML template for "phone book" application
<title>Sample company phone book using the SQLtemplate</title>
<h1>Welcome to the company telephone book</h1>
<p>
This page uses SQL to retrieve phonebook information
from an SQL database.
<hr>
<form>
Last name:<input name=name>
</form>
<p>
<if org.error>
<center><font color=red>Error: <b>
<property org.error>
</b></font></center>
</if>
<if Query.name>
<sql debug eval prefix=names>
select id, last, first, mi , phone, location
from namelist
where last='${Query.name}'
</sql>
<table border=2>
<foreach name=index property=names.rows>
<tr>
<foreach name=field list="first mi last phone location">
<td><property name=names.namelist.${field}.${index}></td>
</foreach>
</tr>
</foreach>
</table>
</if>
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Additional Examples
As the previous example illustrates, real Brazil applications
involve server configurations operating in conjunction with a set of
HTML files to provide the desired functionality, and often use the
session management capability to provide individualized content to
to various users.
Consequently, it is too cumbersome to describe the example in the context
of a single HTML page.
Instead, two complete sample Brazil applications are included in this
distribution to help you get started.
The
portal example demonstrates the use of Brazil to
provide a personal portal, permitting users to customize the look and feel
of other web sites on the Internet.
The
proxy example demonstrates the use of Brazil
as a customizable web proxy, which keeps track of individual
user's browser cookies and URL history.
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