Nitro 0.10.0

Nitro is an efficient, yet simple engine for developing professional Web Applications using the Ruby language. Nitro aims to provide a robust infrastructure for scalable web applications that can be distributed over a server cluster. However, Nitro can also power simple web applications for deployment on intranets or even personal computers. Nitro integrates the powerful Og Object-Relational mapping library.

Nitro is a multiparadigm application framework and will incorporate ideas from Rails, Wee, PHP, JSP and Microsoft.NET.

Features

A short summary of the major features:

Multiparadigm web applications.

You can write applications in the ASP/JSP/PHP style, ie by writting server pages that are automatically transalted to Ruby code by Nitro.

Alternatively, you can write Rails style application by utilizing the powerfull Controller mechanism.

Advanced Code generation.

Nitro in essence writes your Web application for you. The system provides a number of domain spefic language extensions (meta-languages) to automate generate of common code (OR mapping, validation, forms generation, syndication, markup and more).

Object-Relational Mapping

Nitro integrates the Og (ObjectGraph) object-relational mapping library. Og provides transparent serialization of object graphs to a RDBMS backend. Unlike other similar libraries Og maps standard Ruby objects to SQL tables and not vice versa. Og provides a meta language to describe the relations between objects, a flexible and intuitive api for querieng the database, raw access to the SQL language if needed (for example to fine tune the automatically generated SQL tables, or for custom queries), provides automatic validation, suports deserialization to Ruby objects or tuples, automatically generates join tables for many_to_many relations and provides a collection of usefull Mixins to synthesize common Entities. Og is a combination of the best features of Active Record and the former O-R mapping library included in Nitro (NDB). Adapters for PostgreSQL, MySQL and SQLite are included.

XML server pages (.xhtml)

Nitro uses standard, fully xml compliant xhtml pages with logic code, thus combining the power of embededed Ruby (like erb, eruby) with the xml compliance of Amrita. Even though it is a ‘Callback’ style templating system it is flexible enough to run as ‘Pipeline’ style system if the developer prefers this mode of operation. <?xml version=“1.0”?> <!– example page –> <html>

<?r title = ‘Example’ version = params ?> <h1>#title</h1> <?r if version > 1 ?> Version: #version <?r end ?> </html>

Action / Fragment Synthesis

Nitro actions and templates can include other actions or templates to allow for component-based development.

Here is an example of including an action from a template:

or from an action:

list()

Nitro server pages can include fragments at ‘Compile’ time or at ‘RunTime’ time. <!– compile time include (static include) –> <?include href=“myfile.inc” /> <!– run time include (dynamic include) –> <include href=“myfile.inc” />

Shaders, XSLT templates

Nitro features a fully programmable source transformation pipeline. A transformation stage in this pipeline is called a Shader. An example shader transforms an XHTML document with embeded ruby-code processing instructions to a Ruby method. Another shader might be an XSLT stage.

Nitro promotes the usage of XSLT for web templates. The functional nature of XSL is ideal for the Web. Moreover, the engine efficiently precompiles the xsl transformation along with other transformations (for example localization) essentially providing a computationally free transformation step.

Multiple Platforms

Runs on Linux and Windows. Has not been tested under MacOSX and other Unices.

Multiple Adaptors

Nitro supports multiple web server configurations. Out of the box it supports WEBrick (pure ruby), Lighttpd (fastcgi), Apache (fastcgi). More options will be available in the future.

Minimum configuration

Configuration files are kept to the absolute minimum. The target is to have no configuration files at all.

Distributed State

Nitro provides a powerfull distributed state mechanism that utilizes the DRb library. A typicall use of this infrastructure is to provide distributed sessions when running your application over a server cluster. Distributed sessions are fully transparent to the developer.

Request Filters

The develpoper has full access to the request handling pipeline. Request filters are a powerfull mechanism for customized processing of special requests. Example filters are the autologin filter, a gzip filter etc.

Moreover, Nitro provides the fine-grained filtering method pioneered by Rails where you can attach single methods, blocks, objects or modules, before, after or arrounf actions.

Parts

Parts are organized modules of web services. A Web Framework that integrates a large collection of parts (User management, Blog, Fora, CMS, Personalization, ..) will be released by Navel. Other libraries of parts are expected from the Ruby community when the Part API is finalized.

Hierarchical Caching

Nitro provides a well designed and efficient caching mechanism. Caching will be provided at the following levels: * DB Cache * Object Cache (deserialized objects) * Fragment Caching (cache generated sub-parts of a page, or a page) * HTTP 1.1 Caching (downstream caching of whole pages)

The engine calculates intra-page dependencies automatically. A variety of invalidation strategies can be implemented.

Multi phase evaluation

Experimental, facilitates efficient HTTP1.1 caching.

Programmatic xhtml rendering.

options = [‘Male’, ‘Female’] o.select(:name => ‘sex’) { o.options(options, selected = 1) }

or

options = { ‘Male’ => ‘m’, ‘Female’ => ‘f’ } o.select(:name => ‘sex’) { o.options(options, selected = 1) }

Automatic validation.

class User prop_accessor :name, :password, String validate_confirmation :password validate_length :name, :range => 2..12 end

u = User.new(…) unless u.valid? p u.errors.on(:name) p u.errors end

Support for ‘nice’ urls.

Experimental.

Advanced debuging features

* When running in debug mode, all exceptions raised are logged to a special debug panel in the current page. Find out the offending file and line from the exception dump, fix the bug, refresh the page. * in-process console: inject an irb session to a running application server. You can use the irb console to investigate all variables and code in your running server process.

* integrates the ‘breakpoint’ library by Florian Gross. The Breakpoint library provides the convenience of being able to inspect and modify state, diagnose bugs all via IRB by simply setting breakpoints in your applications by the call of a method.

UI Components

Nitro is distributed with a collection of usefull UI components to make form based application development easier (for example an efficient, database-aware Pager component).

Path overloading

Experimental.

Localization

Nitro supports efficient localization of web applications.

Download

The latest version of Nitro can be found at

www.rubyforge.com/projects/nitro

Documentation for Nitro can be found at

www.rubyforge.com/projects/nitro

Requirements

Nitro requires the following applications or libraries:

Ruby 1.8.1 and greater

www.ruby-lang.org Version 1.8.2 is recomended

The following applications or libraries are OPTIONAL:

PostgreSQL

www.postgres.org Used for Database driven web applications.

MySQL

www.mysql.org Used for Database driven web applications.

Ruby-psql

www.postgresql.jp/interfaces/ruby/archive/ruby-postgres-0.7.1.tar.gz Ruby interface to the PostgreSQL RDBMS.

Ruby-mysql

tmtm.org/ja/ruby/mysql/README_en.html Ruby interface to the MySQL RDBMS.

Ruby-XSLT

gregoire.lejeune.free.fr/ruby-xslt_0.4.0.tar.gz Used for XSLT based templates.

Apache 2.0

www.apache.org Used to host application in production environments.

Lighttpd

www.lighttpd.net/ A lean and efficient web server. A perfect companion to Nitro.

Ruby-fcgi

www.moonwolf.com/ruby/archive/ruby-fcgi-0.8.5.tar.gz Used for FCGI based applications.

FastCGI development kit

www.fastcgi.com/dist/fcgi.tar.gz Needed to compile the C-version of the ruby fcgi library.

Please install the required applications and libraries before continuing with the installation of Nitro.

Instalation

Nitro is distributed as a RubyGem. First of all make sure you have installed RubyGems on your system. Then run the following command:

gem install nitro

Then try to run the examples/tiny Example application.

A tar.gz distribution is also available on www.rubyforge.com/projects/nitro

Running the example applications

examples/tiny

A simple application that requires no external applications

$ cd nitro/examples/tiny

$ vi conf/apache.conf

edit user, group,DocumentRoot root as needed.

$vi conf/lhttpd.conf

edit as needed, or edit

$ vi run.rb

$ ruby run.rb

browse 127.0.0.1:8069

examples/blog

A simple Blog application to demonstrate xsl skins, Og models, xml dispatchers and more.

$ cd nitro/examples/blog

$ vi conf/apache.conf $ vi conf/lhttpd.conf

edit the configuration as needed.

$ vi run.rb

edit the postgresql user and password

if you wan to run this application with MySQL edit the configuration file to include

{ … :backend => “mysql” … }

instead.

there is no need to initialize the database, Og automatically takes cate of this.

$ ruby run.rb

this script starts the the blog application using the WEBrick adapter.

browse 127.0.0.1:8069

You can run the application in debug mode with the following command:

$ ruby run.rb –debug

Debuging Nitro applications

Have “tail -f” commands running on log/app.log in your application directory. Nitro will automatically display debugging and runtime information to these files. Debugging info will also be shown in the browser when running in debug mode.

Description of contents

bin Commands and wizards.

examples/ Various examples. ‘tiny’ is a minimal example, ‘blog’ is a fully working and nice looking Blog implementation, ‘no_xsl_blog’ is the same example without using XSLT, ‘og’ contains some Og examples and ‘flash’ is an example for generating binary content for a Nitro response.

lib/nitro Nitro library source files.

lib/og Og library source files.

lib/glue Common source files.

lib/parts Nitro Web Framework parts. A part is a module of functionality

test Unit and functional tests.

Running Tests

The easiest way to run the included unit tests is through Rake:

$ rake test_all

runs all the tests including database tests.

$ rake test

runs all tests except the database tests.

Rake can be found at rake.rubyforge.org

Support

For any questions regarding Nitro, feel free to ask on the ruby-talk mailing list (which is mirrored to comp.lang.ruby) or contact [email protected].

A Nitro specific mailing list is also available. Please subscribe to [email protected]. The homepage for this list is available here:

rubyforge.org/mailman/listinfo/nitro-general

Licence

Nitro (www.navel.gr/nitro) is copyrighted free software created and maintained by George Moschovitis ([email protected]) and released under the standard BSD Licence. For details consult the file LICENCE.