Mercurial > hg > digilib
annotate doc/src/site/markdown/digilib-short.md @ 1655:7310735dd5b5
Refactoring of the configuration docs
| author | Frank Sachsenheim <funkyfuture@riseup.net> |
|---|---|
| date | Thu, 17 Aug 2017 16:20:23 +0200 |
| parents | 7770ac493446 |
| children |
| rev | line source |
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| 1273 | 1 # A short introduction to digilib |
| 2 | |
| 3 ## digilib -- how does it work? | |
| 4 | |
| 5 The image server digilib is a state-less web-based client-server | |
| 6 application for interactive viewing and manipulation of images. | |
| 7 | |
| 8 ## Frontend and Scaler server | |
| 9 | |
| 10 digilib consists mainly of two parts, the image server component proper, | |
| 11 called "Scaler" and a client-side part that runs in the users web | |
| 12 browser. | |
| 13 | |
| 14  | |
| 15 | |
| 16 The users browser sends an HTTP request for a certain (zoomed, scaled, | |
| 17 rotated) image to the Scaler server and the server returns the image | |
| 18 data as HTTP response. | |
| 19 | |
| 20 To complete the schematics of figure 1 we must also take into account | |
| 21 that the client-side part consisting of HTML and Javascript code has | |
| 22 also been requested and loaded from a frontend-web server into the users | |
| 23 browser. | |
| 24 | |
| 25  | |
| 26 | |
| 27 To date there are several frontend implementations for digilib like the | |
| 28 current "jquery" version that only requires static HTML and Javascript and the | |
| 29 older "greyskin" version (grey buttons, implemented in JSP) that come with | |
| 30 the default [digilib distribution][1] or the "[Zogilib][2]" frontend version | |
| 31 implemented in ZOPE. | |
| 32 | |
| 33 The frontend-server and the Scaler-server do not have to run | |
| 34 on the same machine and often there are several frontends that use the | |
| 35 same Scaler server. | |
| 36 | |
| 37 ### Request formats | |
| 38 | |
| 39 The format of the HTTP requests for the frontend and the | |
| 40 Scaler server can be completely different. The HTML and Javascript code | |
| 41 of the frontend just has to generate the correct request for the Scaler | |
| 42 to produce the desired image. Most of the current frontend implementations | |
| 43 share some or all of the parameters with the Scaler API. | |
| 44 | |
| 45 ### Scaler | |
| 46 | |
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47 The [Scaler API](scaler-api.html) is documented on the digilib.sourceforge.net |
| 1273 | 48 pages. Here is a minimal version: |
| 49 | |
| 50 The Scaler servlet takes parameters in the HTTP request format: | |
| 1402 | 51 `Scaler?param1=value1¶m2=value2&...` Unknown parameters |
| 1273 | 52 will be silently ignored. |
| 53 | |
| 54 Recognised parameters: | |
| 55 | |
| 1402 | 56 - `fn` path to file or directory. All paths are relative to the configured base directory |
| 1273 | 57 (digilib-config parameter `basedir-list`). |
| 58 - `pn` page number. Index into the (alphabetically sorted) | |
| 59 directory given by the path. Starts with 1. Ignored if the path | |
| 60 points to a file. Default: 1. | |
| 61 - `dw` destination image width (pixels). If omitted the image is | |
| 62 scaled to fit `dh.` | |
| 63 - `dh` destination image height (pixels). If omitted the image | |
| 64 is scaled to fit `dw`. | |
| 65 - `wx` relative x offset of the image area to be sent (0 <= | |
| 66 `wx` <= 1). Default: 0. | |
| 67 - `wy` relative y offset of the image area to be sent (0 <= | |
| 68 `wy` <= 1). Default: 0. | |
| 69 - `ww` relative width of the image area to be sent (0 <= `ww` | |
| 70 <= 1). Default: 1. | |
| 71 - `wh` relative height of the image area to be sent (0 <= `wh` | |
| 72 <= 1). Default: 1. | |
| 1402 | 73 - The image to be loaded can be specified by `fn` parameter and the optional |
| 1273 | 74 index `pn` |
| 75 - if `fn` points to a directory then the file with the index `pn` | |
| 76 (in alphabetical order according to ASCII) will be loaded | |
| 77 - if `fn` points to a file (with or without extension) then this | |
| 78 file will be loaded | |
| 79 | |
| 80 The image will be scaled equally in horizontal and vertical direction | |
| 81 such that the resulting image does not exceed the rectangle [`dw`,`dh`]. | |
| 82 If only either height or width is given the image is scaled to match | |
| 83 only the given parameter. The size of the resulting image in the other | |
| 84 parameter is determined by the aspect ratio of the image. | |
| 85 | |
| 86 An example for a Scaler URL is: | |
| 1402 | 87 `http://digilib.mpiwg-berlin.mpg.de/digitallibrary/Scaler?fn=experimental/digilib-test/images&wh=0.1712&ww=0.1282&wy=0.1681&wx=0.6895&dw=862&dh=904` |
| 1273 | 88 such a URL can be used as src attribute to an img element in the |
| 89 frontend HTML. | |
| 90 | |
|
1279
828b6c8b1b19
changed links in documentation (and poms) to new sourceforge site.
robcast
parents:
1273
diff
changeset
|
91 [1]: https://sourceforge.net/p/digilib/code/ci/default/tree/webapp/src/main/webapp |
| 1273 | 92 |
| 93 [2]: http://itgroup.mpiwg-berlin.mpg.de/cgi-bin/cvsweb.cgi/zogiLib/ |