and ISDN SYSTEMS

Computer Networks and ISDN System5 30 ( 199x1 63 l-633

Short Paper

Web development tools: a survey ’

Abstract

In this paper we review, classify, and assess 33 existing commercial products in the light of evaluation criteria based on the impact on the application development process, architecture. and user-perceived quality. From this review we draw requirements for new-generation development tools and show how current solutions match different application domains. ,CJ 19% Published by Elsevirr Science B.V. All rights reserved.

K~~nor-ds: Web development: CASE tools; Authoring tools; Database gateways

016Y-75~2/Y8/$1Y.00 G IYYX Published by Elsevier Science B.V. All rights reserved. P/I SOl69-7552~98~00021-x

1. Motivations

The tirst generation of Web development tools mostly addressed content production (e.g., by enabling visual editing of HTML pages) and is clearly insufficient to face the industrial-strength development of large applications. Very recently, a second generation of development tools has started spreading in the market. from three diflerent origins, which correspond to the core issues of modem Web application development: . vendors of productivity tools for the Web have started

integrating database connectivity and object-based components into their authoring environments:

. database vendors have provided facilities for exporting database content in Web-compatible format and for translating proprietary client-server applications for Web execution;

. hypermedia authoring tools are being extended to add both Web-compatible export capabilities and database connectivity. The goal of this paper is to take a snapshot of the

’ The full version of the paper is available at http://www.elet.poli mi.it/-fraterna/www7/wehtoolh.html 2 E-muil: tr~terna@elet.polimi.it

current situation of the software solutions for integrated Web-database development and demonstrate commonal- ities and dilferences among existing tools. which could help understanding the present state of the tool market. predicting its evolution, and assessing individual tools in light of their adequacy to specilic application require- ments. The base of the classitication is a set of 33 different commercial tools. listed in the full version of this paper.

2. Categories of Web development tools

The many tools available for Web development can be grouped into live basic categories. herein presented in order of increasing support to the structured development of Web applications.

Visual HTML editors and site managers are author- ing and site management environments originally con- ceived to alleviate the complexity of writing HTML code and of maintaining the pages of a Web site in the tile system. In a typical contiguration these products bundle a WYSIWYG HTML editor. which permits the user to design sophisticated HTML pages without programming. and a visual site manager, which displays in a graphical way the content of a Web site and supports functions

like page upload.deletion, and renaming, and broken link detection and repair. Among the products in this category there are Adobe SiteMill and PageMill, NetObject Inc.‘s Fusion. SoftQuad‘s HotMetal, Microsoft’s FrontPage. and many others. These tool are an excellent solution for mall- to medium-sized applications, where publishing database content is not the major issue. The lack of a schema of the application, i.e.. of an abstract representa- tion independent of content, forces the definition of the application features instance-by-instance and is a major obstacle to scale-up.

Hypermedia tools share the same focus on authoring as visual HTML editors but have a different origin, off- line hypermedia publishing. These products entered the market of Web-database development very recently and the interest in them is motivated by their non-conven- tional approach to application design and specific focus on navigation and presentation. The best known represen- tatives of this class of products are: Asymetrix’s Tool- book, Macromedia’s Director and Authorware. Formula Graphics Multimedia 97. and several others. Although ar- chitecturally immature. hypermedia tools permit designers to deliver very sophisticated user interfaces, which exhibit a degree of control over graphic accuracy and multimedia synchronization hardly available with other means. The inherent navigational design paradigm, coupled to very effective aids like guided tours and flexible access indices contribute to the deployment of applications which are close to the kind of communication found in high quality. hand-developed Web sites.

HTML-DBPL integrators explicitly address the merge of Web and databases and are very powerful, yet basic, products which can be used to implement appli- cations on top of large information bases: on the other hand. their use typically requires a substantial develop- ment effort. The exising solutions propose different ways ol‘ integrating HTML with a full-fledged database pro- gramming language (DBPL). yielding an intermediate application programming language. Examples of HTML extensions include: Cold Fusion by Allaire Inc.. Mi- crosoft’s Active Server Pages (ASP) and Internet Database Connector ([DC). StoryServer by Vignette Corporation. HTML-DBPL integrators are comparable to traditional client/server 3GLs. because they provide a high level programming interface masking lower-level architectural details: as such. they are often used to build more sophis- ticated products.

Web form editors, report writers, and database publishing wizards take quite a database-centric ap- proach to Web-database integration, by addressing the migration of client/server, form-based application to the Web: these tools aim at augmenting the implementor’s

productivity in such tasks as form editing, report writ- ing, and event-based programming; they offer a higher level of support with respect to HTML-DBPL integrators. but still concentrate only on the implementation phase. Among the reviewed products. we cite: Microsoft’s Visual InterDev. Visual Basic 5, and Access97. Oracle Developer 2000, Borland’s IntraBuilder. Sybase’s PowerBuilder, Ap- ple’s WebObjects. NetDynamics, Asymetrix SuperCede Database Edition. and Allaire’s Cold Fusion Application Wizards.

Finally, Model-driven Web generators are those prod- ucts (actually one product!) that provide a complete cov- erage of all the development activities. from analysis to implementation, by leveraging state-of-the-art software engineering techniques. An outstanding representative of this category is the Oracle Web Development Suite, which comprises Designer 3000. a CASE tool for generating Web applications from augmented Entity-Relationship di- agrams. Other examples of this approach are a few re- search prototypes, namely Autoweb 121, HSDL 131. RMC [Il. and OOHDM 141.

The situation for Web development that emerges from the review is typical of a not yet mature technology (it could be easily compared to the 00 tool market in the eighties): most products have a limited focus (implemen- tation, with some provision for design); a few tools are trying to cover the lifecycle in a broader way, but they do so by approaching development from an innatural angle. typically using models and abstractions drawn from other lields. notably databases.

This scenario opens many research opportunities: l Conceptual modelling: a conceptual model for a Web

application should give peer dignity to structure. be- havior, navigation. and presentation. These perspec- tives should remain orthogonal.

. CASE support: with the proper models. a higher level of assistance could be reached. Among the missing features we mention: mapping Web conceptual models (not only structure) to database schemata, reverse-engi- neering database applications into Web applications (not only forms), language- and device-independent application generation. model-level reuse.

. Restructuring: application customiration and evolu- tion requires mechanisms to restructure existing Web applications to adapt them to different users or to changes in the requirements: restructuring is a well- known issue in the database tield. but is still not fully understood for Web applications. In principle, Web conceptual models and tools could be extended to sup- port a notion of view suited to Web applications. which should allow restructuring presentation and navigation, as well as structure.

3. Conclusions

An attempt can be done to match tool categories and application requirements:

. SI~KI~/ ,s(dt, hrr,sir7r.rs-to-7~,srr qydiutiom: this cate- gory includes such applications as companies’ points of presence, infocenters, and so on. Visual editors and site managers seem the appropriate solution, because they ensure the high-level of visual accuracy necessary for targeting the general public, coupled to produc- ttvity tools reducing the development effort. This role could be undermined in the near future by hypermedia authoring tools. which share the same focus on presen- tation quality and are even more effective in the design of navigational and multimedia interfaces. The current limit to the applicability of both these classes of solu- tions is the size of the information base: if this has to be hept in a database, then presently these tools do not provide the adequate mean\ to integrate database and Web design. implementation and maintenance.

. lrltnr-hr.sir7es.s or hr~sil7es.~-tc)-busi~less upplicdon.s: this category comprises all legacy information systems and EDI applications and is characterized by users already trained to the transactional and form-based interaction paradigm. Web form editors and database publishing wizards offer a powerful opportunity for migrating existing applications to Intranets. and this technical advantage largely balances the limited ex- ploitation of the communication capabilities of the Web.

. Oqe ,scde hll.sir7es.s-to-Lrser cpp1icution.s: this is the most challenging area. comprising such applications as electronic commerce and virtual libraries. Presently. no specitic product is fully addressing the analysis. design, implementation and evolution of this kind of application. which require the same communication paradigm and interface quality as small scale LIW-

oriented applications and the same performance and scalability as intranet applications. In this scenario. neutral. implementation-oriented products like HTML- DBPL integrators seem the most adequate choice. al- though development and maintenance with the\e tools still requires a substantial coding effort.

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