A World Wide Web Interface to CTAN
Norman Walsh O'Reilly and Associates, 90 Sherman Street, Cambridge, MA 02140, U.S.A. [email protected]
Abstract There are a lot of different software packages, style files, fonts, etc., in the CTAN archves. Finding the things you need in a timely fashion can be difficult, as I found out while writing Making TEX Work. The ability to combine descriptions of packages with the directory listings from CTAN could help alleviate some of the difficulty. The HyperText Markup Language (HTML) is the document structuring language of the World Wide Web and it provides one possible means of combining different views of the archive into a single vision. The CTAN-Web project is my attempt to provide this vision.
Introduction familiar with it, is an extremely flexible and power- ful editor (it's most common on UNIX workstations, A functioning TEX system is really a large collection but versions exist for MS-DOS, Windows, OS/2, VMS, of programs that interact in subtle ways. Process- and a few other platforms). One of the editing modes ing even a relatively simple document like ths one of emacs, called dired, allows you to "edit" directo- requires several programs (TEX, a previewer, and a ries (a directory listing appears in a window on the printer driver at the very least), most of which read screen). In dired mode, the editing keys let you re- input files or can be configured in other ways. It was name, copy, delete, view, and edit files, among other Making this complexity that lead me to start writing things. Ange-ftp is an extension for emacs that lets TEX Work (Walsh 1994),a book I hoped would unravel you edit remote file systems via ftp in dired-mode. many of these intricacies (end of plug ;-). This lets me load the /tex-archi ve/macros direc- Making TEX Work, In the process of writing I tory from ftp. shsu .edu into an emacs buffer and looked at a lot of the software packages, style files, view files simply by pointing to them and pressing fonts, etc., in the CTAN archives. It really made me "v". Ange-ftp handles all of the transactions with the appreciate how much stuff the TEX user community ftp client in the background. Ange-ftp made gather- has made freely avdable. By my estimates there are ing information from README files much easier. more than 3 1,000files in more than 2,300 directories in /tex-archive on ftp. shsu. edu. Inspiration My first challenge was to find the things that I wanted to write about. This was a long process What I really wanted wasn't an easier way to browse that involved coordmating (at least mentally) the lists directories, no matter how grateful I was to have that, of files in the upper-level CTAN directories, entries but a way of combining the TeX-i ndex and other de- from David Jones' TeX-i ndex, descriptions main- scriptions with a directory listing in some coherent tained by the CTAN archivists, my own intuitions way. A typical interaction with CTAN, in my experi- about what was available, and the tidbits that I had ence, goes something like ths: I need a widget, that's collected over the years from Info-TeX postings. It under the something directory. Oh! There are sev- was occasionally tedious, but it was never really dif- eral things hke that. This one looks interesting. Nope ficult (at least technically). that's not it. How about this one. Yeah, that's better. When the book was beginning to fall into place Still, is ths other one better? Nope. Ok, I'll try the and I was starting to try to track down all the loose second one. ends, I came to a realization: in the early days, fmd- I fmd this sort of interaction tedious via ftp. ing thngs had been an end as well as a means. Now, As it happens, I was also beginning to explore with pressure mounting on an almost daily basis the World Wide Web (WWW) at the same time, moti- to finish, I discovered just how hard it was to find vated, in part, by experimentation with LATEXZHTML things on CTAN. This is not a criticism of the CTAN and other tools that translate TEX documents into archivists in any way. Without their foresight and HTML for online documentation projects. Might this diligent efforts, the task could easily become impos- be the answer, I wondered.. .? After several days of sible. It's just a fact: there's a lot of stuff out there. hacking, the first incarnation of CTAN-Web was born; One tool became invaluable in my daily efforts: the CTAN-Web home page is shown in Color Example ange-ftp for GNU emacs. GNU emacs, if you aren't 16.
TUGboat, Volume 15 (1994),No. 3 -Proceedings of the 1994 Annual Meeting Norman Walsh
What is the World Wide Web? A detaded exploration of structured documen- tation principles is beyond the scope of this article, The WWW is a vast collection of network-accessible however, a few words may help clarify the picture; information. In an effort to make ths mforma- users famdiar with QXare already famdiar with tion manageable, protocols have been developed for structured documentation. cross-referencing the Web and software written to The key notion is that structures (characters, browse documents in the Web. One of the most pop- words, phrases, sentences, paragraphs, lists, chap- ular browsers is Mosaic, a browser from the NCSA.] ters, etc.) in a document should be identified by WWW documents use hypertext to make traversing meaning rather than appearance. For example, here between documents transparent, allowing the user to is a sentence that you might find in an installation follow a stream of ideas without regard to where the guide (this sentence is coded in TEX): embodiment of the ideas exists in the Web. Hypertext links allow you to build dynamic rela- Use the {\bf cd} command to change to the tionships between documents. For example, select- (\it /usr/tmp/i nstall} di rectory. ing a marked word or phrase in the current document The same sentence might be coded in a struc- can &splay more information about the topic, or a tured way like this: list of related topics. Use the
TUGboat, Volume 15 (1994),No. 3 -Proceedings of the 1994 Annual Meeting A World Wide Web Interface to CTAN
The CTAN-Web also has the following features: Handling the descriptions. In order to quickly lo- asare made directly to other online refer- cate descriptions for the various packages, I maintain ences in the Web. For example, the online help the collection of descriptions in a directory structure files provided in the i nfo/html he1 p directory that parallels the CTAN archives. Each description are also avdable as WWW documents on the file is written in a mixture of TEX and HTML (a mixture net. This fact is exploited in the descriptions of is used so that it may one day be possible to produce these files by creating a hypertext link directly a printed version of the Web). For example, the cur- to the online help. rent description of l atex-help-html .zip is shown In addition, font samples can be displayed for in Figure 1. several METAFONT fonts (viewing font samples Retrieving Nes from the archives. One of the first requires a browser that understands CIF Mesh2 problems that had to be solved was how files would The CTAN-Web documents are indexed. Users be retrieved from the archves. Whde it's easy to can perform online queries for material based create a link to a file at an ftp site, in the case of upon any word that appears as a filename or in CTAN-Web that isn't sufficient because CTAN exists the online description of any file. Simple con- at several sites. The lmk really needs to be made to ditional searches can also be performed (for ex- the closest ftp site. ample, "x or y" or "x and y"). Although I suppose it is possible to identify the A query for "verbatim and plain" finds 5 files closest ftp site from the user's host id, that seemed and 9 dire~tories.~ impractical. The following compromise was selected Each instance of a file that appears in more than instead: rather than linking files directly to an ftp one place in the archive is identified. For ex- site, they are linked to a script. The document ample, any reference to the file verbatim. sty server (httpd) provides a facility for malung links identifies all 7 instances of it in the archive. that cause a program to be executed; the output pro- duced by this program is then displayed as a WWW Want to know whch files were modified withn document. By passing the name of the file requested the last 12 days? Or between 1 Jan and 31 Jan by the user as an argument to the script, it was pos- of 1993? Information about the age of each file sible to write a retrieval script that dynamically con- is maintained in a separate database, accessi- structs a "retrieval document." The retrieval docu- ble via a script run by the CTAN-Web server. ment contains links to the requested file at each of This allows you to perform online queries of the the CTAN hosts. It is then possible for the user to archive by age. select the closest host. An example of the retrieval A "permuted index" is constructed each time document created for README. archive-features is the Web is built. This allows you to quickly lo- shown in Figure 2. cate files by name. Selecting a link Within the retrieval document A list of files added or modified in the last 7 or causes the browser to actually retrieve the file via 30 days is also constructed each time the Web anonymous ftp from the selected site. is built. Documents in the Web. There are three kinds of A tree (hierarchical) view of the archve is also documents in the CTAN-Web and within each docu- available. The tree view provides a fast means ment there are several lunds of lmks. of "wallung" down into the lower levels of the Directory documents. There is one directory docu- archve. ment in the Web for each directory in the archve. Reaching CTAN-Web Each directory document lists all of the files in the directory it represents along with their associated de- You can reach the CTAN-Web pages by usingthe URL: scriptions. http://jasper.ora.com/ctan.html Directory names in each document are linked to the corresponding directory documents. File names Behind the Scenes are llnked to filename documents (described below) or to the retrieval script, depending on whether the For those who are curious, this section provides a brief description of how the CTAN-Web is con- file occurs multiple times in the archive. structed. The Web is now rebullt on a daily ba- The directory document for the tex-archive/ macros directory is shown in Figure 3. sis using the most recent information from the Tree documents. There is one tree document in the ftp. shsu edu server. . Web for each directory in the archive that contains Samples for all the METAFONT fonts will be subdirectories. The tree document displays three generated shortly. levels of hierarchy starting at the directory it repre- In the Web built on 20 May 1994. sents.
TUGboat, Volume 15 (1994), No. 3 -Proceedings of the 1994 Annual Meeting Norman Walsh
An HTML version of the LaTeX help file created by George Greenwade. This is the version provided online at jasper.ora. com. It is also available in VMS format (formatted ASCII), TeXinfo format, HTML format, and as a Microsoft Windows help file. < P> The LaTeX he1 p fi1e is a1 so TUGboat, Volume 15 (1994), No. 3 -Proceedings of the 1994 Annual Meeting A World Wide Web Interface to CTAN Figure 2: Example of a retrieval document. Figure 3: The CTAN :/macros directory. Figure 4: The tex-archi ve/macros tree document Figure 5: The verbati m . sty filename document TUGboat, Volume 15 (1994), No. 3 -Proceedings of the 1994 Annual Meeting