The Comprehensive TEX Archve Network (CTAN) George D. Greenwade Department of Economics and Business Analysis College of Business Administration Sam Houston State University Huntsville, TX, USA 77341-21 18 Voice: (409) 294-1265 FAX: (409) 294-3612 Internet: bed-gdg@SHSU. edu Abstract Ths paper outlines the concept, development, and use of the Comprehensive TEX Archive Network (CTAN) - a network-accessible archve for files related to the TEX family of document processing. The CTAN is a coordinated effort among consenting well-known archve sites which provides quick identification and retrieval files in a consistent manner from hosts on different continents, thereby reducing overall network load and increasing speed of retrieval. Moreover, it provides users with a parallel archive structure between hosts with holdings whch are generally synchronized to with 30 hours of one another. This is achieved by routinely mirroring one another's holdings, as well as mirroring other archves to maintain an up-to-date collection of files. Why a Comprehensive TEX Archive 1992, with the author as its Chair.' While a Network? variety of issues related to archving have been discussed (and broader guidelines, per se, will in all Since the inception of publicly-accessible network- likelihood be forthcoming), the concept of creating a based archves, TEX and its related packages, macros, systematically coordinated family of network-based and utilities have been available for retrieval by archve sites was tacitly agreed upon as a mechanism users via any number of techniques. The combina- for verifying that the ideas under discussion were tion of the growth of the Internet in recent years, the workable. Also, ths approach was viewed as a growth of publicly-accessible network-based archive mechanism for creating a more efficient design, sites, and the growth in the number of files asso- both theoretically and practically, to meet the needs ciated with TEX and it's affiliated packages and of the worldwide TEX community. programs, created a rather overwhelming number of files for users with network connections to sort General Consensus Notes From WG-TAG. Ger- through. In terms of "overwhelming," the number mane to the development of a set of archves in lieu of files available has been a significant boost for of a "hard and fast" set of guidelines for propagation users; however, in these same terms, the number to other hosts were the following concerns: of different versions available, their precise location on a given archive host, the user interface avdable to access these files, and the ability to efficiently identify the various pieces required to make the var- I would like to take this opportunity to formally ious iterations of TEX and its relatives work properly recognize the members of ths Working Group has evolved to be a non-trivial task. and publicly thank them for their efforts on any In recognition of these problems, the then- number of topics whch we have dealt with. These newly-created Technical Council of the TEX Users individuals are, in alphabetical order: Nelson Beebe, Group formed a Techcal Working Group on TEX Barbara Beeton, Karl Berry, Johannes L. Braams, Archive Guidelines (officially WG-92-05; informally David Carlisle, Michael J. Ferguson, Alan J. Hoenig, referred to as TWG-TAG) in the latter months of Don Hosek, David M. Jones, Pierre MacKay, David Osborne, Philip Taylor, Jon Radel, Sebastian Rahtz, Rainer Schoepf, Joachlm Schrod, and Elizabeth Tachkawa. TUGboat, Volume 14 (1993), No. 3 -Proceedings of the 1993 Annual Meeting The Comprehensive TEX Archve Network (CTAN) Existing archive hosts very likely have chosen Genesis of the Design and utilize a structure which is politically and Prior to defining the CTAN directory structure, ex- practically acceptable for their site. tensive discussion was undertaken by TWG-TAG While the concept of the Internet's File Trans- regarding the optimal directory hierarchy. Com- fer Protocol (ftp) for a user interface was on pared for use were the herarchical design used everyone's mind, access via alternate means on most ftp-accessible hosts now possessing a TEX (primarily electronic mail and hard media) had archive and the flat design used by a number of to be considered. mail-oriented hosts. For brevity's sake, allow it Very few hosts on the network possess a to be said that the hierarchcal design was cho- comprehensive archve of TEX-relatedmaterials; sen. Once this decision was made, comparisons thus, a design guideline whch includes all of existing archves were undertaken, primarily dimensions of TEX may not be proper for a focusing on the holdings of three major sites- specialized archive. Stuttgart University's ftp. uni -stuttgart. de, As- Even if a set of guidelines were developed, ton University's TeX. ac . u k, and Claremont Col- there is no way to ensure that every site lege's ymi r . cl aremont edu. The end result is which possesses some aspect of TEX in its . a hybrid of the three directory structures, focus- archve would follow them since archves are a ing on top-level directories whch are somewhat function of local resources, support, and needs mnemonically-based directory names at ths level more than "network" demands. which, at least in the author's view, is pleasing. If a workable demonstration of the guidelines The structure is adequately diverse so that dvi- existed, more sites may voluntarily elect to related files (such as device drivers, dvi to output follow the ultimate guidelines. programs, and dvi viewers) are distinctly different No single site on the network possessed a from macros, and that macros are adequately cate- canonical listing, much less collection, of the gorized into the appropriate flavor of TEX for which latest relevant files available; therefore, any they are intended. The top-level directory herarchy guidelines developed would be hypothetical is presented in Appendix A. more than worlung. Conceptually, every file in the archve fits into It is necessary to make the structure as flexible one branch of ths directory herarchy (albeit the as possible, while at the same time ensuring directory mutually agreed to by the maintainers that files may be easily located by users via of the hosts involved in this project). Where a some consistent and logical design. file conceptually fits into more than one directory, As much as foreseeably possible, the structure efforts are made to ensure that the file properly should be extensible into evolving network appears where it should. retrieval and browsing technologies, such as Gopher, Mosaic, and other developing utilities. Coincidences of Consequence. A critical dimen- It is essential that the archives support users sion of ths project was its timing. Two hosts were from the variety of platforms under which TEX new machines; therefore, they were easily designed is available; while a given platform may be into whatever structure was agreed to. The main used for the archives themselves, it should not coincidences whch aided the success of ths project impose problems on any other platform which were: a user may wish to ultimately use the files on. Sebastian Rahtz, who was just beginning to At least initially, the concern was to provide put together the Aston "daughter" archve at a reliable archving directory herarchy from ftp . tex. ac. uk, began utilizing the directory with the project, as opposed to a production design by following the very rough outline of system herar~hy.~ the preliminary structure. Malung the struc- ture operational was a significant factor in more than a few subsequent decisions as it illustrated, in a close-to-production environ- ment, the strengths and weaknesses of the Please note that the concerns above are those then-tentative hierarchy. perceived by the author as the majority opinion and Sam Houston State University was just in- are not necessarily those of the TWG-TAG, nor are stalling its first Unix-based host and learn- they necessarily those of any one given member of ing its ihosyncrasies; however, its use as an the TWG-TAG. TUGboat, Volume 14 (1993),No. 3 -Proceedings of the 1993 Annual Meeting George D. Greenwade archive host was established soon after its in- disjoint and unrelated projects coming to fruition stallation. This was a preferable choice for an at approximately the same time, this project would archive host over SHSU's more established ftp likely still be in its planning stages. host, Niord. SHSU .edu, as it ran a compara- ble software to the other two hosts, and was The CTAN Hosts configurable for use as a mirror. David M. Jones had just released the first ver- By now, you're very likely aslung where these hosts sion of his index of TEX and ETEX macros, are on the network. The present CTAN hosts and providing the TWG-T.4G with a relatively com- their root CTAN directories are: prehensive listing of files, their authoritative ftp. uni -stuttgart. de /pub/tex/ location, current version, and other critical ftp.tex.ac.uk /pub/archive/ information. ftp.shsu.edu /tex-archive/ Joachirn Schrod's mirroring software for Unix Based at Stuttgart University germ an^),^ Aston Uni- hosts (which the CTAN hosts utilize) was being versity (EnglandL4and Sam Houston State University upgraded. Joachim was able to quickly address (United state^),^ respectively. a few specific problems resulting from its Whde the designs of the consulted archives massive use. were largely congruent, there were some modifi- Nelson Beebe was developing a few new ex- cations when compared to all existing archives. tensions to the ftp server software which was Rainier Schoepf, TEX archve manager at Stuttgart's adopted for use. Significant contributions were ftp. uni -stuttgart . de, was fully agreeable to his definitions which allow users to retrieve modifying the directory structure there based on recursive ZIP and ZOO archves of directory the recommendations which were developed.