Screenshot of a web application in development mode
|Developer(s)||The Seaside Team|
|Platform||IA-32, x86-64, ARM|
Seaside provides a component architecture in which web pages are built as trees of individual, stateful components, each encapsulating a small part of a page. Seaside uses continuations to model multiple independent flows between different components. Thus, it is a continuation-based web framework based on the ability to manipulate the execution stack of some implementations of Smalltalk.
A distinctive feature of Seaside is its integrated development environment, providing access to development tools and debugging support within an application. In development-mode, unhandled errors are reported to the web page; developers can access and alter the program code and state directly from the web page, allowing bug identifying and fixing processes to occur within an integrated development environment (IDE).
A Seaside application is a set of interacting components. Each one stores state across page views and can render itself to the HTML stream. Thus, it is straightforward to write a component once and then reuse it elsewhere in an application. Seaside also supports the notion of tasks, which allow a programmer to describe the high-level logic of component interaction.
Seaside is not template-oriented, and does not offer generating or using HTML templates; HTML markup is generated programmatically. (The Seaside-based Pier content-management framework does offer wiki-markup syntax for templating.) Seaside uses callbacks on closures to specify actions to be taken when clicking on a link or submitting a form. The developers and users of Seaside argue that this helps enforce separation of structure (markup) from content and presentation (Cascading Style Sheets (CSS)). Seaside's combination of components, callbacks, and closures can significantly reduce the semantic gap between a complex workflow and its representation in code.
Over the last few years, some best practices have come to be widely accepted in the web development field:
- Share as little state as possible.
- Use clean, carefully chosen, and meaningful URLs.
- Use templates to separate the model from the presentation.
Seaside deliberately breaks all of these rules. Avi Bryant describes it as a 'heretical' framework. He argues that this careful and reasoned rejection of the conventional wisdoms of web development has led to a very effective model for developing web applications.
The main development of Seaside is implemented in Pharo Smalltalk. Ports for other Smalltalk dialects exist. The original develoment of Seaside was done on Squeak in the early 2000's. Michel Bany implemented ports to VisualWorks through Seaside version 2.7; Cincom Systems supports Seaside as part of VisualWorks as of early 2008. Instantiations announced Seaside support in its VA Smalltalk version 8.0. As of February 2009, VA Smalltalk 8.0 is in beta. Esteban Maringolo maintained the 2.8 port, plus some other add-ons (such as script.aculo.us) for Dolphin Smalltalk X6. Gemstone Systems implemented a port to Gemstone/S. A port of 2.8 was completed for GemStone, and a preliminary version of 3.0 runs on GNU Smalltalk 3.0a and later.
- Compared to other web frameworks, Seaside is memory intensive. One session could accumulate several hundred kilobytes of RAM. A later release, version 2.8, significantly reduces this size (e.g., a formerly typical 200 KB size becomes 50 KB).
- Seaside does not follow representational state transfer (REST) by default. Instead, Uniform Resource Locators (URLs) hold session key information, and meaningful URLs must be generated explicitly.
Open-source projects using it
- Magritte – a meta-description framework with a tight integration into Seaside
- Pier – a content management system and high level application framework for Seaside
- ADK Project
Proprietary projects using it
- The Seaside Team
- Seaside – a Multiple Control Flow Web Application Framework
- IBM DeveloperWorks: Crossing borders: Continuations, Web development, Java programming
- Seaside: A Flexible Environment for Building Dynamic Web Applications
- Debugging Seaside Applications
- Avi Bryant explains why Seaside doesn't use templates
- Web Application Frameworks: A Comparative Study
- Screencast: Seaside Comet Chat Application
- "'Web Heresies: The Seaside Framework' Session notes, OSCON 2006". Archived from the original on 2014-08-30.CS1 maint: BOT: original-url status unknown (link)
- "Seaside 2.9 is current implemented on Pharo that serves as a reference implementation."
- Seaside for Dolphin Smalltalk blog
- Seaside 2.8
- Does Seaside run on GNU Smalltalk, GNU Smalltalk FAQ
- Jon Udell article in InfoWorld Archived 2007-02-12 at the Wayback Machine