Spicey: An ER-based Web Framework for Curry

Description

Spicey is a framework to support the implementation of web-based systems in the multi-paradigm declarative language Curry. Spicey generates an initial implementation from an entity-relationship (ER) description of the underlying data. The generated implementation contains operations to create and manipulate entities of the data model, supports authentication, authorization, session handling, and the composition of individual operations to user processes. Furthermore, the implementation ensures the consistency of the database w.r.t. the data dependencies specified in the ER model, i.e., updates initiated by the user cannot lead to an inconsistent state of the database.

Example

As an example, we consider the implementation of a web log system with Spicey. A "blog" consists of "Entry" articles having title, text, author, and date as attributes, and "Comments" to each entry. Furthermore, there are a number of "Tags" to classify Entry articles. The complete entity-relationship model of this blog structure can be specified in Curry by a data term.

From this ER specification, Spicey generates the source code of a web-based system that provides access to the data via standard web browsers. For instance, here is a snapshot of the web interface generated by Spicey for the blog description:

Spicey generates also forms to insert new entities or edit the attributes of existing ones. If an entity is related to other entities, the form allows the manipulation of these relations. For instance, each Entry of the blog can be related to multiple tags. Therefore, a form to edit an Entry also allows to select related tags, as shown below:

Beyond the basic CRUD (create/read/update/delete) functionality, a Spicey applications has also infrastructures for many features of web-based systems, like session management (storing of session data), authentication, authorization, or complex user processes. These aspects are described in the documents shown below.

The implementation of Spicey is freely available. Spicey is implemented in Curry and uses various libraries and tools available in the PAKCS implementation of Curry. Thus, you should have PAKCS (Version 1.9.2(9) of September 2010 or later) installed in order to use Spicey. The implementation is available as a gzipped tar file (see the README file in the distribution for further instructions how to use the system).

An ER-based Framework for Declarative Web Programming (PADL 2010)

This conference paper introduces the basic ideas of Spicey and its implementation.

Paper on Spicey

This is an expanded version of the previous paper. It provides some more details about Spicey and its implementation.

Master Thesis (in German)

This is a master thesis on Spicey, written by Sven Koschnicke. This thesis contains details about the design and implementation of Spicey.