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Leoni, M. C., Dolensky, M., Bentley, R., Goodwin, T., & Linde, T. 2003, in ASP Conf. Ser., Vol. 314 Astronomical Data Analysis Software and Systems XIII, eds. F. Ochsenbein, M. Allen, & D. Egret (San Francisco: ASP), 307

TWiki: A Collaboration Platform for VO Projects

M. C. Leoni, M. Dolensky
European Southern Observatory, Karl-Schwarzschild Str. 2, Garching bei München, D-85748, Germany

R. Bentley
Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK

T. Goodwin, T. Linde
University of Leicester, Dept of Physics & Astronomy, University Road, Leicester LE1 7RH, UK


Finding an easy way of sharing knowledge and experience in a geographically dispersed project team is not easy. The TWiki is a Web-based collaboration platform. It looks like a normal Internet web site, but everybody can change pages or add content by just using a browser. A revision control keeps track of changes.

Several Virtual Observatory projects use this type of web site to share info among project members and across projects. This is an experience report on the usage and maintenance of TWiki sites in Astronomy.

Even if at first it seems almost the opposite of how the Web and on-line communications "normally" work, it is intuitive and aspires to the Zen ideals known as Wabi-Sabi: "It finds beauty in the imperfect and ephemeral and constantly evolving".

1. Introduction

Working in a distributed team always means spending a lot of time trying to keep everybody up-to-date about what other members are doing, as well to keep people in touch with each other. The infrastructure aims at facilitating project communication, therefore helping to share knowledge, the status and vision of the project, to draft ideas, and to synchronize different teams.

The TWiki is a web-based collaboration tool that offers the possibility to use a web site like an enhanced white-board. TWiki was not invented by the Astronomy Community but it perfectly suites our needs.

The astronomy-related TWiki sites considered in this paper have all seen a constant increment both in the number of visitors and users, as well as in the amount of pages created/updated and files uploaded. These TWiki sites are ALMA, Astrogrid, Aus-VO, AVO, EGSO, IVOA (Table. 1).
\tabletypesize{\footnotesize }
IVOA & \makeURL{} \nl

2. WikiWords (i.e. Terminology)

A TWiki Web is a collection of pages grouped by some logical meaning.
A Topic means a wiki page with all its content.

3. Usage/Usability

Usage statistics are plotted in Fig. 1 and Fig. 2: The former describes the number of pages modified and the number of files uploaded, i.e. real interactions with the Twiki. The latter displays the number of pages visited in each month. To create these charts, only relevant Webs of each TWiki site were taken into account.

The simplicity of TWiki is mostly due to the fact that one can access and work on such a site simply by using a web-browser. It is not necessary to install any particular client software. To have an idea of how many users are really working with the TWiki, Table. 2 presents the number of collaborators who put material on the mentioned sites.

... \nl
IVOA &11 &19 &37 &52 &67 &71 &74 &78 &83 &93 \nl

4. Installation and Maintenance

The are only a few system requirements when setting up a TWiki server. Even though it was originally designed for Unix-like Operating Systems (and it is actually developed in a Linux/Apache environment) it works also on Microsoft Windows.

Implemented as CGI scripts in Perl, it works on port 80 without any special firewall requirements. To assure transparency a revision control system (RCS) keeps track of changes and all prior revisions are directly accessible. The e-mail notification service1 makes use of the Net::SMTP Perl module (alternatively sendmail).

Figure 1: Uploaded documents and modified pages.

5. Pros and Cons

5.1 Pros

- Easy to use, easy to maintain.
- Full public access on the Web.
- Simplified built-in markup language.
- Instant updates of the on-line material.
- Constant development to assure new features every month (with simple plug-in format to facilitate the installation phase).
- New plug-ins, provided by an archive user community, constantly enrich the functionality.

5.2 Cons

- The hardest piece is to get people to use it: ...Once they get started they can't live without it anymore.
- It is difficult to maintain a clear document structure since everybody can add pages and documents. So, the more active the user community, the bigger the mess that may result.
- Being a purely web based tool, the editor is a rather basic HTML form; there is a more advanced Javascript editor though.

Figure 2: Visited Topics on all six TWikis.


Wabi Sabi,


... service1
Inform users about changes in the TWiki Webs.

© Copyright 2004 Astronomical Society of the Pacific, 390 Ashton Avenue, San Francisco, California 94112, USA
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