Lasso Fundamentals

Welcome to Lasso Server, a powerful and comprehensive tool for building and hosting data-driven web applications. This chapter introduces important concepts and information you should know before starting to use Lasso Server or Lasso Developer.

Lasso Server (and Lasso Developer) is server-side software that runs along with any FastCGI capable web server. It adds a suite of dynamic functionality and database connectivity to your web site. This functionality empowers you to build and serve just about any dynamic web application that you need with maximum productivity and ease.

Lasso Server works by receiving requests from the web server and routing those requests to specific server-side resources. Generally, these local resources are files written in the Lasso language. Lasso can be easily embedded in templates with HTML, XML or other data types. Lasso Server manages processing and executing these files and responding to the client with the resulting data. The details of programming in the Lasso language are covered in the Lasso 9 Language Guide also included with this product.

Architecture

Lasso Runtime

The Lasso runtime is a language platform designed from the ground up with the single purpose of hosting on-line applications. It was engineered with a focus on scalability and performance. Lasso's threading model is integrated with its transparent event driven IO sub-system to make efficient use of hardware with multiple CPUs and to ensure that network requests are served promptly under heavy load.

The Lasso runtime system manages the dynamic compilation of Lasso language code down to native machine code with integrated caching schemes and automatic optimization of the most frequently used methods and object types. It also supports a flexible array of options for ahead of time code compilation into dynamically loaded libraries as well as stand-alone executables for Mac OS X and Linux platforms.

Though the Lasso runtime can operate in the role of a quick command line utility, it is designed with features to support the needs of a "stay running" application process. Internally, such an application consists of a set of sub-processes, or threads, each waiting to receive messages and sleeping until such messages arrive. Each thread maintains its own set of variables and a thread can not directly access the variables of another thread.

Lasso Language

This version of the Lasso language builds upon many years of success with providing a versatile and full featured programming language. Lasso is a dynamically typed object-oriented language with close ties to its database abstraction layer. The language integrates closely to the Lasso runtime to give access to the lower level operating system in a uniform and performance minded manner. It improves upon this by already including many of the most useful 3rd party libraries, data sources, technologies and protocols.

Lasso's type system combines the dynamic nature of scripting languages, with some of the safety and features normally only available in statically typed languages. Types can be extended through a "traits" system, promoting code reuse, and methods are open to multiple-dispatch, which uses type annotations to provide pattern matching over method calls.

New types and methods can be added at runtime, which means that a running system is not required to be brought down for most changes. This is helpful not only during development, but also while a system is in-service and urgent, well tested patches need to be applied.

Object types and methods can be compiled ahead of time using the Lasso compiler (lassoc). The result of this compilation is a dynamic library which can be loaded automatically on-demand the first time the type or method is required. This helps keep unused data out of memory, improves startup time, and lets an application be built and deployed in a modular manner.

Lasso Server

Lasso Server is a suite of tools and methodologies for developing, serving and administering data-driven web sites written in the Lasso language. Lasso Server operates with any FastCGI supporting web server, such as Apache, IIS, lighttpd and WebSTAR. A full compliment of methods and objects are included for accessing web server parameters and variables as well as for encoding and decoding data and for responding to requests.[p]

Lasso Server provides an object model for programmatically building response documents in addition to a simple template mode for creating or customizing HTML, XML, PDF or any other sort of data on the fly. This system is designed to make it easy to separate logic from presentation.

Lasso Server provides easy to use, yet powerful control over content type and character encoding. Combined with the Lasso language's highly integrated support for Unicode strings, Lasso Server can readily serve content for any language using just one string object and API.

Also provided is built-in support for logging, bulk email sending, users and groups security, sessions and more, plus integration with many 3rd party libraries much as curl, OpenSSL and SQLite. Lasso Server brings a rich set of tools together into one package.

The Lasso Admin application is included with Lasso Server. This application provides administrative access to a running system. It gives access to database configuration, users and groups, sessions, email queues, error logs and more. Lasso Admin provides a unified access point for the server administrator to monitor and configure the operations of the server.

Lasso Developer

Lasso Developer is a free of charge, single-user edition of Lasso Server that can be used by a single developer to create and test interactive Web sites on their own machine. Lasso Developer has a client IP addresses limitation and per minute transaction limit. Lasso Developer is designed for authoring and demoing web sites and is the perfect way for getting started with Lasso Server.

Any installation of Lasso Server will default to Lasso Developer functionality when it is run without a valid serial number.