An emerging trend in Social Networking sites and Web portals is the opening up of their APIs to external application developers. For example, the Facebook Platform, Google Gadgets and Yahoo! Widgets allow developers to design their own applications, which can then can be integrated with the platform and shared with other users. However, current APIs are targeted towards developers with programming expertise and database knowledge; they are not accessible to a large class of users who do not have a programming/database background, but would nevertheless like to create new applications. To address this need, we have developed the AppForge system, which provides a WYSIWYG application development platform. Users can graphically specify the components of webpages inside a Web browser, and the corresponding database schema and application logic will be automatically generated on the fly by the system. The WYSIWYG interface gives instantaneous feedback on what users have created and allows them to run, test and continuously refine their applications. AppForge has been used to create prototype versions of a variety of applications such as an event planning system, a recruiting system, an item trading system and an online course management system. We have also conducted a small and preliminary user study to identify and fix some of the usability aspects of AppForge.

We describe a novel programming model for building, extending, and personalizing web-based data-driven applications.

Data-driven web applications are usually structured in three tiers with different programming models at each tier. This division forces developers to manually partition application functionality across the tiers, resulting in complex logic, suboptimal partitioning, and expensive re-partitioning of applications. In this paper, we introduce a unified platform for automatic partitioning of data-driven web applications. Our approach is based on Hilda[41, 46], a high-level declarative programming language with a unified data and programming model for all the layers of the application. Based on run-time properties of the application, Hilda's run time system automatically partitions the application between the tiers to improve response time while adhering to memory and/ or processing constraints at the clients. We evaluate our methodology with traces from a real application and with TPC-W, and our results show that automatic partitioning outperforms manual partitioning without the associated development overhead.

We propose Hilda, a high-level language for developing data-driven web applications. The primary benefits of Hilda over existing development platforms are: (a) it uses a unified data model for all layers of the application, (b) it is declarative, (c) it models both application queries and updates, (d) it supports structured programming for web sites, and (e) it enables conflict detection for concurrent updates. We also describe the implementation of a simple proof-ofconcept Hilda compiler, which translates a Hilda application program into Java Servlet code.

The XQuery 1.0 and XPath 2.0 Full-text (XQFT) language has been developed by the W3C to extend XQuery and XPath with full-text search capabilities. XQFT allows users to specify a mix of structured and complex full-text predicates, and also allows users to score/rank such queries. The power and flexibility of XQFT gives rise to two interesting questions. First, is it possible to efficiently integrate a full-function XML query language with sophisticated full-text search? Second, is it possible to score and rank arbitrary XQuery and XQFT queries? In this demonstration, we present evidence that it is indeed possible to achieve the above goals. We demonstrate the Quark open-source data management system and show how we can seamlessly and efficiently integrate structured and unstructured search over XML data. In particular, we demonstrate (a) techniques for efficiently evaluating keyword search over virtual XML views, and (b) a framework for scoring both structured and full-text predicates.

Current application development tools provide completely different programming models for the application server (e.g., Java and J2EE) and the client web browser (e.g., JavaScript and HTML). Consequently, the application developer is forced to partition the application code between the server and client at the time of writing the application. However, the partitioning of the code between the client and server may have to be changed during the evolution of the application for performance reasons (it may be better to push more functionality to the client), for correctness reasons (data that conflicts with multiple clients cannot always be pushed to clients), and for supporting clients with different computing power (browsers on desktops vs. PDAs). Since the client and server use different programming models, moving application code from client to server (and vice versa) reduces programmer productivity and also has the potential to introduce concurrency bugs. In this demonstration, we advocate an alternative solution to this problem: we propose developing applications using a unified declarative high-level language called Hilda, and show how a Hilda compiler can automatically (and correctly) partition Hilda code between the client and the server using a real Course Management System application. We illustrate our techniques using two clients: a powerful laptop machine and a less powerful PDA.