JSS: A few notes for the technically inclined user
- Search words are folded to lowercase and stemmed
(e.g. final "s", "ing", and "ed" are removed).
- Short words with 3 letters or less that are not capitalized in
the original text are not indexed.
How JSS works
JSS uses a simple inverted word list. Each individual word that
appears in the corpus of documents is associated with a list of
documents (or a list of pages) in which the word apprears.
The inverted word list is encoded in string literals in
source code that runs in the browser. For CDROM-based collections,
this provides a machine-independent search capability without requiring
any software installation, and without requiring a Java virtual machine.
For web-based collections, this provides a simple search capability,
without requiring any server-side software installation, and
without consuming any server resources.
JSS is the simplest way to provide search capabilities for CDROM
document collections, and for Web sites with no access to CGI scripts.
Inverted Word List Encoding
source files. The encoding scheme is as follows. Each document or page
is identified by an ID number. For each word, a list of ID numbers of
documents in which the word appears is built. The list is sorted in
ascending order. This list is transformd into a list of differences
between successive IDs. This list is then encoded using a very simple
entropy coder. Small numbers up to 170 are encoded as single-byte
non-escaped characters taken from the printable ISO-latin set. Larger
numbers are escaped with the space character and encoded with two
Indexing your Collection with JSS
There are two ways to index a collection with JSS. The easiest one is
to use the Bib2Web
conversion server. Bib2Web is a free web service that allows you to
build and index a collection of documents in PostScript, TIFF, PDF, or
DjVu formats. Bib2Web has the considerable advantage of having a
built-in OCR engine (which is particularly useful for scanned
documents). No software installation is required.
The second possibility is to install the JSS
package. This package includes the jssindex program which
provides a very simple way to make a document collection searchable.
jssindex is a script written in the Lush language. To use the JSS indexer
package, you must first download and install
Lush. Lush runs on GNU/Linux, Unix,
and Windows under Cygwin.
To index collections of documents in the DjVu format with JSS, you
must download and install the DjVuLibre package.