Biblio::Isis - access your data in CDS/ISIS using perl

-= Biblio::Isis perl module with example scripts.
Biblio-Isis-0.24.tar.gz 40 Kb
-=> Latest source is always available from Subversion repository

Index

NAME

Top

Biblio::Isis - Read CDS/ISIS, WinISIS and IsisMarc database

SYNOPSIS

Top

  use Biblio::Isis;

  my $isis = new Biblio::Isis(
  	isisdb => './cds/cds',
  );

  for(my $mfn = 1; $mfn <= $isis->count; $mfn++) {
	print $isis->to_ascii($mfn),"\n";
  }

DESCRIPTION

Top

This module will read ISIS databases created by DOS CDS/ISIS, WinIsis or IsisMarc. It can be used as perl-only alternative to OpenIsis module which seems to depriciate it's old XS bindings for perl.

It can create hash values from data in ISIS database (using to_hash), ASCII dump (using to_ascii) or just hash with field names and packed values (like ^asomething^belse).

Unique feature of this module is ability to include_deleted records. It will also skip zero sized fields (OpenIsis has a bug in XS bindings, so fields which are zero sized will be filled with random junk from memory).

It also has support for identifiers (only if ISIS database is created by IsisMarc), see to_hash.

This module will always be slower than OpenIsis module which use C library. However, since it's written in perl, it's platform independent (so you don't need C compiler), and can be easily modified. I hope that it creates data structures which are easier to use than ones created by OpenIsis, so reduced time in other parts of the code should compensate for slower performance of this module (speed of reading ISIS database is rarely an issue).

METHODS

Top

new

Open ISIS database

 my $isis = new Biblio::Isis(
 	isisdb => './cds/cds',
	read_fdt => 1,
	include_deleted => 1,
	hash_filter => sub {
		my ($v,$field_number) = @_;
		$v =~ s#foo#bar#g;
	},
	debug => 1,
	join_subfields_with => ' ; ',
 );

Options are described below:

isisdb

This is full or relative path to ISIS database files which include common prefix of .MST, and .XRF and optionally .FDT (if using read_fdt option) files.

In this example it uses ./cds/cds.MST and related files.

read_fdt

Boolean flag to specify if field definition table should be read. It's off by default.

include_deleted

Don't skip logically deleted records in ISIS.

hash_filter

Filter code ref which will be used before data is converted to hash. It will receive two arguments, whole line from current field (in $_[0]) and field number (in $_[1]).

debug

Dump a lot of debugging output even at level 1. For even more increase level.

join_subfields_with

Define delimiter which will be used to join repeatable subfields. This option is included to support lagacy application written against version older than 0.21 of this module. By default, it disabled. See to_hash.

ignore_empty_subfields

Remove all empty subfields while reading from ISIS file.

count

Return number of records in database

  print $isis->count;

fetch

Read record with selected MFN

  my $rec = $isis->fetch(55);

Returns hash with keys which are field names and values are unpacked values for that field like this:

  $rec = {
    '210' => [ '^aNew York^cNew York University press^dcop. 1988' ],
    '990' => [ '2140', '88', 'HAY' ],
  };

mfn

Returns current MFN position

  my $mfn = $isis->mfn;

to_ascii

Returns ASCII output of record with specified MFN

  print $isis->to_ascii(42);

This outputs something like this:

  210	^aNew York^cNew York University press^dcop. 1988
  990	2140
  990   88
  990	HAY

If read_fdt is specified when calling new it will display field names from .FDT file instead of numeric tags.

to_hash

Read record with specified MFN and convert it to hash

  my $hash = $isis->to_hash($mfn);

It has ability to convert characters (using hash_filter) from ISIS database before creating structures enabling character re-mapping or quick fix-up of data.

This function returns hash which is like this:

  $hash = {
    '210' => [
               {
                 'c' => 'New York University press',
                 'a' => 'New York',
                 'd' => 'cop. 1988'
               }
             ],
    '990' => [
               '2140',
               '88',
               'HAY'
             ],
  };

You can later use that hash to produce any output from ISIS data.

If database is created using IsisMarc, it will also have to special fields which will be used for identifiers, i1 and i2 like this:

  '200' => [
             {
               'i1' => '1',
               'i2' => ' '
               'a' => 'Goa',
               'f' => 'Valdo D\'Arienzo',
               'e' => 'tipografie e tipografi nel XVI secolo',
             }
           ],

In case there are repeatable subfields in record, this will create following structure:

  '900' => [ {
  	'a' => [ 'foo', 'bar', 'baz' ],
  }]

Or in more complex example of

  902	^aa1^aa2^aa3^bb1^aa4^bb2^cc1^aa5

it will create

  902   => [
	{ a => ["a1", "a2", "a3", "a4", "a5"], b => ["b1", "b2"], c => "c1" },
  ],

This behaviour can be changed using join_subfields_with option to new, in which case to_hash will always create single value for each subfield. This will change result to:

This method will also create additional field 000 with MFN.

There is also more elaborative way to call to_hash like this:

  my $hash = $isis->to_hash({
  	mfn => 42,
	include_subfields => 1,
  });

Each option controll creation of hash:

mfn

Specify MFN number of record

include_subfields

This option will create additional key in hash called subfields which will have original record subfield order and index to that subfield like this:

  902   => [ {
	a => ["a1", "a2", "a3", "a4", "a5"],
	b => ["b1", "b2"],
	c => "c1",
	subfields => ["a", 0, "a", 1, "a", 2, "b", 0, "a", 3, "b", 1, "c", 0, "a", 4],
  } ],

join_subfields_with

Define delimiter which will be used to join repeatable subfields. You can specify option here instead in new if you want to have per-record control.

hash_filter

You can override hash_filter defined in new using this option.

tag_name

Return name of selected tag

 print $isis->tag_name('200');

read_cnt

Read content of .CNT file and return hash containing it.

  print Dumper($isis->read_cnt);

This function is not used by module (.CNT files are not required for this module to work), but it can be useful to examine your index (while debugging for example).

unpack_cnt

Unpack one of two 26 bytes fixed length record in .CNT file.

Here is definition of record:

 off key	description				size
  0: IDTYPE	BTree type				s
  2: ORDN	Nodes Order				s
  4: ORDF	Leafs Order				s
  6: N		Number of Memory buffers for nodes	s
  8: K		Number of buffers for first level index	s
 10: LIV	Current number of Index Levels		s
 12: POSRX	Pointer to Root Record in N0x		l
 16: NMAXPOS	Next Available position in N0x		l
 20: FMAXPOS	Next available position in L0x		l
 24: ABNORMAL	Formal BTree normality indicator	s
 length: 26 bytes

This will fill $self object under cnt with hash. It's used by read_cnt.

BUGS

Top

Some parts of CDS/ISIS documentation are not detailed enough to exmplain some variations in input databases which has been tested with this module. When I was in doubt, I assumed that OpenIsis's implementation was right (except for obvious bugs).

However, every effort has been made to test this module with as much databases (and programs that create them) as possible.

I would be very greatful for success or failure reports about usage of this module with databases from programs other than WinIsis and IsisMarc. I had tested this against ouput of one isis.dll-based application, but I don't know any details about it's version.

VERSIONS

Top

As this is young module, new features are added in subsequent version. It's a good idea to specify version when using this module like this:

  use Biblio::Isis 0.23

Below is list of changes in specific version of module (so you can target older versions if you really have to):

0.24

Added ignore_empty_subfields

0.23

Added hash_filter to to_hash

Fixed bug with documented join_subfields_with in new which wasn't implemented

0.22

Added field number when calling hash_filter

0.21

Added join_subfields_with to new and to_hash.

Added include_subfields to to_hash.

0.20

Added $isis->mfn, support for repeatable subfields and $isis->to_hash({ mfn => 42, ... }) calling convention

AUTHOR

Top

	Dobrica Pavlinusic
	CPAN ID: DPAVLIN
	dpavlin@rot13.org
	http://www.rot13.org/~dpavlin/

This module is based heavily on code from LIBISIS.PHP library to read ISIS files V0.1.1 written in php and (c) 2000 Franck Martin <franck@sopac.org> and released under LGPL.

COPYRIGHT

Top

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

The full text of the license can be found in the LICENSE file included with this module.

SEE ALSO

Top

Biblio::Isis::Manual for CDS/ISIS manual appendix F, G and H which describe file format

OpenIsis web site http://www.openisis.org

perl4lib site http://perl4lib.perl.org

CDS/ISIS manual appendix F, G and H

NAME

CDS/ISIS manual appendix F, G and H

DESCRIPTION

This is partial scan of CDS/ISIS manual (appendix F, G and H, pages 257-272) which is than converted to text using OCR and proofread. However, there might be mistakes, and any corrections sent to dpavlin@rot13.org will be greatly appreciated.

This digital version is made because current version available in ditial form doesn't contain details about CDS/ISIS file format and was essential in making the Biblio::Isis manpage module.

This extract of manual has been produced in compliance with section (d) of WinIsis LICENCE for receiving institution/person which say:

 The receiving institution/person may:
 (d) Print/reproduce the CDS/ISIS manuals or portions thereof,
     provided that such copies reproduce the copyright notice;

CDS/ISIS Files

This section describes the various files of the CDS/ISIS system, the file naming conventions and the file extensions used for each type of file. All CDS/ISIS files have standard names as follows:

  nnnnnn.eee

where:

nnnnnn

is the file name (all file names, except program names, are limited to a maximum of 6 characters)

.eee

is the file extension identifying a particular type of file.

Files marked with * are ASCII files which you may display or print. The other files are binary files.

A. System files

System files are common to all CDS/ISIS users and include the various executable programs as well as system menus, worksheets and message files provided by Unesco as well as additional ones which you may create.

CDS/ISIS Program

The name of the program file, as supplied by Unesco is

  ISIS.EXE

Depending on the release and/or target computer, there may also be one or more overlay files. These, if present, have the extension OVL. Check the contents of your system diskettes or tape to see whether overlay files are present.

System menus and worksheets

All system menus and worksheets have the file extension FMT and the names are built as follows:

  pctnnn.FMT

where:

p

is the page number (A for the first page, B for the second, etc.)

c

is the language code (e.g. E for English), which must be one of those provided for in the language selection menu xXLNG.

t

is X for menus and Y for system worksheets

nnn

is a unique identifier

For example the full name of the English version of the menu xXGEN is AEXGEN.FMT.

The page number is transparent to the CDS/ISIS user. Like the file extension the page number is automatically provided by the system. Therefore when a CDS/ISIS program prompts you to enter a menu or worksheet name you must not include the page number. Furthermore as file names are restricted to 6 characters, menus and worksheets names may not be longer than 5 characters.

System menus and worksheets may only have one page.

The language code is mandatory for system menus and standard system worksheets. For example if you want to link a HELP menu to the system menu EXGEN, its name must begin with the letter E.

The X convention is only enforced for standard system menus. It is a good practice, however, to use the same convention for menus that you create, and to avoid creating worksheets (including data entry worksheets) with X in this position, that is with names like xXxxx.

Furthermore, if a data base name contains X or Y in the second position, then the corresponding data entry worksheets will be created in the system worksheet directory (parameter 2 of SYSPAR.PAR) rather then the data base directory. Although this will not prevent normal operation of the data base, it is not recommended.

System messages files

System messages and prompts are stored in standard CDS/ISIS data bases. All corresponding data base files (see below) are required when updating a message file, but only the Master file is used to display messages.

There must be a message data base for each language supported through the language selection menu xXLNG.

The data base name assigned to message data bases is xMSG (where x is the language code).

System tables

System tables are used by CDS/ISIS to define character sets. Two are required at present:

ISISUC.TAB*

defines lower to upper-case translation

ISISAC.TAB*

defines the alphabetic characters.

System print and work files

Certain CDS/ISIS print functions do not send the output directly to the printer but store it on a disk file from which you may then print it at a convenient time. These files have all the file extension LST and are reused each time the corresponding function is executed.

In addition CDS/ISIS creates temporary work files which are normally automatically discarded at the end of the session. If the session terminates abnormally, however, they will not be deleted. A case of abnormal termination would be a power failure while you are using a CDS/ISIS program. Also these files, however, are reused each time, so that you do not normally need to delete them manually. Work files all have the extension TMP.

The print and work files created by CDS/ISIS are given below:

IFLIST.LST*

Inverted file listing file (produced by ISISINV)

WSLIST.LST*

Worksheet/menu listing file (produced by ISISUTL)

xMSG.LST*

System messages listing file (produced by ISISUTL)

x.LST*

Printed output (produced by ISISPRT when printing no print file name is supplied)

SORTIO.TMP

Sort work file 1

SORTII.TMP

Sort work file 2

SORTI2.TMP

Sort work file 3

SORTI3.TMP

Sort work file 4

SORT20.TMP

Sort work file 5

SORT2I.TMP

Sort work file 6

SORT22.TMP

Sort work file 7

SORT23.TMP

Sort work file 8

TRACE.TMP*

Trace file created by certain programs

ATSF.TMP

Temporary storage for hit lists created during retrieval

ATSQ.TMP

Temporary storage for search expressions

B. Data Base files

  1. mandatory files, which must always be present. These are normally established when the data base is defined by means of the ISISDEF services and should never be deleted;

  2. auxiliary files created by the system whenever certain functions are performed. These can periodically be deleted when they are no longer needed.

  3. user files created by the data base user (such as display formats), which are fully under the user's responsibility.

Each data base consists of a number of physically distinct files as indicated below. There are three categories of data base files:

In the following description xxxxxx is the 1-6 character data base name.

Mandatory data base files

xxxxxx.FDT*

Field Definition Table

xxxxxx.FST*

Field Select Table for Inverted file

xxxxxx.FMT*

Default data entry worksheet (where p is the page number).

Note that the data base name is truncated to 5 characters if necessary

xxxxxx.PFT*

Default display format

xxxxxx.MST

Master file

xxxxxx.XRF

Crossreference file (Master file index)

xxxxxx.CNT

B*tree (search term dictionary) control file

xxxxxx.N01

B*tree Nodes (for terms up to 10 characters long)

xxxxxx.L01

B*tree Leafs (for terms up to 10 characters long)

xxxxxx.N02

B*tree Nodes (for terms longer than 10 characters)

xxxxxx.L02

B*tree Leafs (for terms longer than 10 characters)

xxxxxx.IFP

Inverted file postings

xxxxxx.ANY*

ANY file

Auxiliary files

xxxxx.STW*

Stopword file used during inverted file generation

xxxxxx.LN1*

Unsorted Link file (short terms)

xxxxxx.LN2*

Unsorted Link file (long terms)

xxxxxx.LKl*

Sorted Link file (short terms)

xxxxxx.LK2*

Sorted Link file (long terms)

xxxxxx.BKP

Master file backup

xxxxxx.XHF

Hit file index

xxxxxx.HIT

Hit file

xxxxxx.SRT*

Sort convertion table (see ``Uppercase conversion table (1SISUC.TAB)'' on page 227)

User files

yyyyyy.FST*

Field Select tables used for sorting

yyyyyy.PFT*

Additional display formats

yyyyyy.FMT*

Additional data entry worksheets

yyyyyy.STW*

Additional stopword files

yyyyyy.SAV

Save files created during retrieval

The name of user files is fully under user control. However, in order to avoid possible name conflicts it is advisable to establish some standard conventions to be followed by all CDS/ISIS users at a given site, such as for example to define yyyyyy as follows:

  xxxyyy

where:

xxx

is a data base identifier (which could be the first three letters of the data base name if no two data bases names are allowed to begin with the same three letters)

yyy

a user chosen name.

Master file structure and record format

A. Master file record format

The Master record is a variable length record consisting of three sections: a fixed length leader; a directory; and the variable length data fields.

Leader format

The leader consists of the following 7 integers (fields marked with * are 31-bit signed integers):

MFN*

Master file number

MFRL

Record length (always an even number)

MFBWB*

Backward pointer - Block number

MFBWP

Backward pointer - Offset

BASE

Offset to variable fields (this is the combined length of the Leader and Directory part of the record, in bytes)

NVF

Number of fields in the record (i.e. number of directory entries)

STATUS

Logical deletion indicator (0=record active; 1=record marked for deletion)

MFBWB and MFBWP are initially set to 0 when the record is created. They are subsequently updated each time the record itself is updated (see below).

Directory format

The directory is a table indicating the record contents. There is one directory entry for each field present in, the record (i.e. the directory has exactly NVF entries). Each directory entry consists of 3 integers:

TAG

Field Tag

POS

Offset to first character position of field in the variable field section (the first field has POS=0)

LEN

Field length in bytes

The total directory length in bytes is therefore 6*NVF; the BASE field in the leader is always: 18+6*NVF.

Variable fields

This section contains the data fields (in the order indicated by the directory). Data fields are placed one after the other, with no separating characters.

B. Control record

The first record in the Master file is a control record which the system maintains automatically. This is never accessible to the ISIS user. Its contents are as follows (fields marked with * are 31-bit signed integers):

CTLMFN*

always 0

NXTMFN*

MFN to be assigned to the next record created in the data base

NXTMFB*

Last block number allocated to the Master file (first block is 1)

NXTMFP

Offset to next available position in last block

MFTYPE

always 0 for user data base file (1 for system message files)

(the last four fields are used for statistics during backup/restore).

C. Master file block format

The Master file records are stored consecutively, one after the other, each record occupying exactly MFRL bytes. The file is stored as physical blocks of 512 bytes. A record may begin at any word boundary between 0-498 (no record begins between 500-510) and may span over two or more blocks.

As the Master file is created and/or updated, the system maintains an index indicating the position of each record. The index is stored in the Crossreference file (.XRF)

D. Crossreference file

The XRF file is organized as a table of pointers to the Master file. The first pointer corresponds to MFN 1, the second to MFN 2, etc.

Each pointer consists of two fields:

RECCNT*
MFCXX1*
MFCXX2*
MFCXX3*
XRFMFB

(21 bits) Block number of Master file block containing the record

XRFMFP

(11 bits) Offset in block of first character position of Master record (first block position is 0)

which are stored in a 31-bit signed integer (4 bytes) as follows:

  pointer = XRFMFB * 2048 + XRFMFP

(giving therefore a maximum Master file size of 500 Megabytes).

Each block of the XRF file is 512 bytes and contains 127 pointers. The first field in each block (XRFPOS) is a 31-bit signed integer whose absolute value is the XRF block number. A negative XRFPOS indicates the last block.

Deleted records are indicated as follows:

XRFMFB < 0 and XRFMFP > 0

logically deleted record (in this case ABS(XRFMFB) is the correct block pointer and XRFMFP is the offset of the record, which can therefore still be retrieved)

XRFMFB = -1 and XRFMFP = 0

physically deleted record

XRFMFB = 0 and XRFMFP = 0

inexistent record (all records beyond the highest MFN assigned in the data base)

E. Master file updating technique

Creation of new records

New records are always added at the end of the Master file, at the position indicated by the fields NXTMFB/NXTMFP in the Master file control record. The MFN to be assigned is also obtained from the field NXTMFN in the control record.

After adding the record, NXTMFN is increased by 1 and NXTMFB/NXTMFP are updated to point to the next available position. In addition a new pointer is created in the XRF file and the XRFMFP field corresponding to the record is increased by 1024 to indicate that this is a new record to be inverted (after the inversion of the record 1024 is subtracted from XRFMFP).

Update of existing records

Whenever you update a record (i.e., you call it in data entry and exit with option X from the editor) the system writes the record back to the Master file. Where it is written depends on the status of the record when it was initially read.

There was no inverted file update pending for the record

This condition is indicated by the following:

On XRF XRFMFP < 512 and

On MST MFBWB = 0 and MFBWP = 0

In this case, the record is always rewritten at the end of the Master file (as if it were a new record) as indicated by NXTMFB/NXTMFP in the control record. In the new version of the record MFBWB/MFBWP are set to point to the old version of the record, while in the XRF file the pointer points to the new version. In addition 512 is added to XRFMFP to indicate that an inverted file update is pending. When the inverted file is updated, the old version of the record is used to determine the postings to be deleted and the new version is used to add the new postings. After the update of the Inverted file, 512 is subtracted from XRFMFP, and MFBWB/MFBWP are reset to 0.

An inverted file update was pending

This condition is indicated by the following:

On XRF XRFMFP > 512 and

On MST MFBWB > 0

In this case MFBWB/MFBWP point to the version of the record which is currently reflected in the Inverted file. If possible, i.e. if the record length was not increased, the record is written back at its original location, otherwise it is written at the end of the file. In both cases, MFBWB/MFBWP are not changed.

Deletion of records

Record deletion is treated as an update, with the following additional markings:

On XRF XRFMFB is negative

On MST STATUS is set to 1

F. Master file reorganization

As indicated above, as Master file records are updated the MST file grows in size and there will be lost space in the file which cannot be used. The reorganization facilities allow this space to be reclaimed by recompacting the file.

During the backup phase a Master file backup file is created (.BKP). The structure and format of this file is the same as the Master file (.MST), except that a Crossreference file is not required as all the records are adjacent. Records marked for deletion are not backed up. Because only the latest copy of each record is backed up, the system does not allow you to perform a backup whenever an Inverted file update is pending for one or more records.

During the restore phase the backup file is read sequentially and the program recreates the MST and XRF file. At this point alt records which were marked for logical deletion (before the backup) are now marked as physically deleted (by setting XRFMFB = -1 and XRFMFP = 0. Deleted records are detected by checking holes in the MFN numbering.

Inverted file structure and record formats

A. Introduction

The CDS/ISIS Inverted file consists of six physical files, five of which contain the dictionary of searchable terms (organized as a B*tree) and the sixth contains the list of postings associated with each term. In order to optimize disk storage, two separate B*trees are maintained, one for terms of up to 10 characters (stored in files .N01/.L01) and one for terms longer than 10 characters, up to a maximum of 30 characters (stored in files .N02/.L02). The file CNT contains control fields for both B*trees. In each B*tree the file .N0x contains the nodes of the tree and the .L0x file contains the leafs. The leaf records point to the postings file .IFP.

The relationship between the various files is schematically represented in Figure 67.

The physical relationship between these six files is a pointer, which represents the relative address of the record being pointed to. A relative address is the ordinal record number of a record in a given file (i.e. the first record is record number 1, the second is record number 2, etc.). The file .CNT points to the file .N0x, .N0x points to .L0x, and .L0x points to .IFP. Because the .IFP is a packed file, the pointer from .L0x to .IFP has two components: the block number and the offset within the block, each expressed as an integer.

B. Format of .CNT file

This file contain two 26-byte fixed length records (one for each B*tree) each containing 10 integers as follows (fields marked with * are 31-bit signed integers):

IDTYPE

B*tree type (1 for .N01/.L01, 2 for .N02/.L02)

ORDN

Nodes order (each .N0x record contains at most 2*ORDN keys)

ORDF

Leafs order (each .L0x record contains at most 2*ORDF keys)

N

Number of memory buffers allocated for nodes

K

Number of buffers allocated to lst level index (K < N)

LIV

Current number of index levels

POSRX*

Pointer to Root record in .N0x

NMAXPOS*

Next available position in .N0x file

FMAXPOS*

Next available position in .L0x file

ABNORMAL

Formal B*tree normality indicator (0 if B*tree is abnormal, 1 if B*tree is normal). A B*tree is abnormal if the nodes file .N0x contains only the Root.

ORDN, ORDF, N and K are fixed for a given generated system. Currently these values are set as follows:

ORDN = 5; ORDF = 5; N = 15; K = 5 for both B*trees

                  +--------------+
                  | Root address |
                  +-------|------+
                          |                          .CNT file
                          |                      -------------
                          |                          .N0x file
              +-----------V--------+
              | Key1 Key2 ... Keyn |                   Root
              +---|-------------|--+
                  |             |
            +-----+             +------+
            |                          |
 +----------V----------+     +---------V----------+ 1st level
 | Key1  Key2 ... Keyn | ... | Key1 Key2 ... Keyn |   index
 +--|------------------+     +-----------------|--+
    |                                          :
    :                                  +-------+
    |                                  |
 +--V------------------+     +---------V----------+ last level
 | Key1  Key2 ... Keyn | ... | Key1 Key2 ... Keyn |   index
 +---------|-----------+     +---------|----------+
           |                           |
           |                           |         -------------
           |                           |             .L0x file
 +---------V-----------+     +---------V----------+
 | Key1  Key2 ... Keyn | ... | Key1 Key2 ... Keyn |
 +--|------------------+     +--------------------+
    |
    |                                            -------------
    |                                                .IPF file
 +--V----------------------------------+
 | P1  P2  P3 ..................... Pn |
 +-------------------------------------+

Figure 67: Inverted file structure

The other values are set as required when the B*trees are generated.

C. Format of .N0x files

These files contain the indexes) of the dictionary of searchable terms (.N01 for terms shorter than 11 characters and .N02 for terms longer than 10 characters). The .N0x file records have the following format (fields marked with * are 31-bit signed integers):

POS*

an integer indicating the relative record number (1 for the first record, 2 for the second record, etc.)

OCK

an integer indicating the number of active keys in the record ( 1 <= OCK <= 2*ORDN )

IT

an integer indicating the type of B*tree (1 for .N01, 2 for .N02)

IDX

an array of ORDN entries (OCK of which are active), each having the following format:

KEY

a fixed length character string of length .LEx (LE1 =10, LE2 = 30)

PUNT

a pointer to the .N0x record (if PUNT > 0) or .L0x record (if PUNT < 0) whose IDX(1).KEY = KEY. PUNT = 0 indicates an inactive entry. A positive PUNT indicates a branch to a hierarchically lower level index. The lowest level index (PUNT < 0) points the leafs in the .L0x file.

D. Format of .L0x files

These files contain the full dictionary of searchable terms (.L01 for terms shorter than 11 characters and .L02 for terms longer than 10 characters). The .L0x file records have the following format (fields marked with * are 31-bit signed integers):

POS*

an integer indicating the relative record number (1 for the first record, 2 for the second record, etc.)

OCK

an integer indicating the number of active keys in the record (1 < OCK <= 2*ORDF)

IT

an integer indicating the type of B*tree (1 for .N01, 2 for .N02)

PS*

is the immediate successor of IDX[OCK].KEY in this record (this is used to speed up sequential access to the file)

IDX

an array of ORDN entries (OCK of which are active), each having the following format:

KEY

a fixed length character string of length LEx (LE1=10, LE2=30)

INFO

a pointer to the .IFP record where the list of postings associated with KEY begins. This pointer consists of two 31-bit signed integers as follows:

INFO[1]*

relative block number in .IFP

INFO[2]*

offset (word number relative to 0) to postings list

E. Format of .IFP file

This file contains the list of postings for each dictionary term. Each list of postings has the format indicated below. The file is structured in blocks of 512 characters, where (for an initially loaded and compacted file) the lists of postings for each term are adjacent, except as noted below.

The general format of each block is:

IFPBLK

a 31-bit signed integer indicating the Block number of this block (blocks are numbered from 1)

IFPREC

An array of 127 31-bit signed integers

IFPREC[1] and FPREC[2] of the first block are a pointer to the next available position in the .IFP file.

Pointers from .L0x to .IFP and pointers within .IFP consist of two 31-bit signed integers: the first integer is a block number, and the second integer is a word offset in IFPREC (e.g. the offset to the first word in IFPREC is 0). The list of postings associated with the first search term will therefore start at 1/0.

Each list of postings consists of a header (5 double-words) followed by the actual list of postings (8 bytes for each posting). The header has the following format (each field is a 31-bit signed integer):

IFPNXTB*

Pointer to next segment (Block number)

IFPNXTP*

Pointer to next segment (offset)

IFPTOTP*

Total number of postings (accurate only in first segment)

IFPSEGP*

Number of postings in this segment (IFPSEGP <= IFPTOTP)

IFPSEGC*

Segment capacity (i.e. number of postings which can be stored in this segment)

Each posting is a 64-bit string partitioned as follows:

PMFN

(24 bits) Master file number

PTAG

(16 bits) Field identifier (assigned from the FST)

POCC

(8 bits) Occurrence number

PCNT

(16 bits) Term sequence number in field

Each field is stored in a strict left-to-right sequence with leading zeros added if necessary to adjust the corresponding bit string to the right (this allows comparisons of two postings as character strings).

The list of postings is stored in ascending PMFN/PTAG/POCC/PCNT sequence. When the inverted file is loaded sequentially (e.g. after a full inverted file generation with ISISINV), each list consists of one or more adjacent segments. If IFPTOT <= 32768 then: IFPNXTB/IFPNXTP = 0/0 and IFPTOT = IFPSEGP = IFPSEGC.

As updates are performed, additional segments may be created whenever new postings must be added. In this case a new segment with capacity IFPTOTP is created and linked to other segments (through the pointer IFPNXTB/IFPNXTP) in such a way that the sequence PMFN/PTAG/POCC/PCNT is maintained. Whenever such a split occurs the postings of the segment where the new posting should have been inserted are equally distributed between this segment and the newly created segment. New segments are always written at the end of the file (which is maintained in IFPREC[1]/IFPREC[2] of the first .IFP block.

For example, assume that a new posting Px has to be inserted between P2 and P3 in the following list:

 +----------------------------+
 | 0 0 5 5 5 | P1 P2 P3 P4 P5 |
 +----------------------------+

after the split (and assuming that the next available position in .IFP is 3/4) the list of postings will consist of the following two segments:

 +----------------------------+
 | 3 4 5 3 5 | P2 P2 Px -- -- |
 +--|-------------------------+
    |
 +--V-------------------------+
 | 0 0 5 3 5 | P3 P4 P5 -- -- |
 +----------------------------+

In this situation, no new segment will be created until either segment becomes again full.

As mentioned above, the posting lists are normally stored one after the other. However, in order to facilitate access to the .IFP file the segments are stored in such a way that:

  1. the header and the first posting in each list (28 bytes) are never split between two blocks.

  2. a posting is never split between two blocks; if there is not enough room in the current block the whole posting is stored in the next block.

LICENCE

UNESCO has developed and owns the intellectual property of the CDS/ISIS software (in whole or in part, including all files and documentation, from here on referred to as CDS/ISIS) for the storage and retrieval of information.

For complete text of licence visit http://www.unesco.org/isis/files/winisislicense.html.

ChangeLog

2007-05-18 21:16:52 dpavlin r72

/trunk/lib/Biblio/Isis.pm: push version to 0.24

2007-05-18 21:16:43 dpavlin r71

/trunk/scripts/dump_isisdb.pl: added -v to dump script which will display erased records and empty subfields

2007-05-18 20:26:01 dpavlin r70

/trunk/lib/Biblio/Isis.pm: added ignore_empty_subfields [0.24_1]

2006-10-29 15:37:43 dpavlin r69

/trunk/t/2_isis.t, /trunk/lib/Biblio/Isis.pm: fixed bug with documented, but unimplemented new( join_subfields_with => 'foo' )

2006-08-26 23:09:20 dpavlin r68

/trunk/scripts/dump_isisdb.pl: changed options to -o offset and -l limit

2006-08-25 16:35:47 dpavlin r67

/trunk/lib/Biblio/Isis.pm: better eliminination of empty subfields

2006-08-25 10:20:58 dpavlin r66

/trunk/t/2_isis.t, /trunk/lib/Biblio/Isis.pm: added hash_filter to to_hash [0.23]

2006-07-13 13:34:30 dpavlin r65

/trunk/lib/Biblio/Isis.pm: documented that hash filter gets also a field number [0.22]

2006-07-13 13:27:27 dpavlin r64

/trunk/t/2_isis.t, /trunk/lib/Biblio/Isis.pm: hash_filter now accepts whole line from record and field number. Removed oddly placed implementation of regexpes (moved to WebPAC via hash_filter as it should...)

2006-07-13 09:13:25 dpavlin r63

/trunk/t/2_isis.t: added global replacements (which are not bound to subfield existence)

2006-07-10 12:01:04 dpavlin r62

/trunk/t/2_isis.t, /trunk/lib/Biblio/Isis.pm: added regexpes to new as option

2006-07-09 21:36:33 dpavlin r61

/trunk/t/2_isis.t, /trunk/lib/Biblio/Isis.pm: initial implementation of split_on_delimiters functionality needed for Webpac. It adds just regexpes hash to to_hash, but I'm still not quite satisfied with it.

2006-07-09 13:20:06 dpavlin r60

/trunk/MANIFEST, /trunk/Makefile.PL, /trunk/MANIFEST.SKIP: cpan target and tweaking of distribution files

2006-07-09 12:22:09 dpavlin r59

/trunk/lib/Biblio/Isis.pm: added link to Biblio::Isis::Manual

2006-07-09 12:18:44 dpavlin r58

/trunk/t/2_isis.t, /trunk/lib/Biblio/Isis.pm: test and fix join_subfields_with

2006-07-09 12:12:57 dpavlin r57

/trunk/t/2_isis.t, /trunk/lib/Biblio/Isis.pm: added join_subfields_with and include_subfields [0.21]

2006-07-08 16:03:52 dpavlin r56

/trunk/t/2_isis.t, /trunk/lib/Biblio/Isis.pm: to_hash now accept parametars

2006-07-08 14:21:49 dpavlin r55

/trunk/t/2_isis.t: add tests for to_hash and to_ascii

2006-07-07 23:45:12 dpavlin r54

/trunk/t/2_isis.t, /trunk/lib/Biblio/Isis.pm: added $isis->mfn, some documentation about version compatibility and few FIXME markers

2006-07-07 23:43:34 dpavlin r53

/trunk/Makefile.PL: better html creation

2006-07-07 22:33:06 dpavlin r52

/trunk/t/002_isis.t, /trunk/t/2_isis.t, /trunk/t/9_pod.t, /trunk/t/999_pod.t, /trunk/t/001_load.t, /trunk/t/1_load.t, /trunk/t/9_pod-coverage.t, /trunk/t/998_pod-coverage.t: renamed tests

2006-07-07 22:29:49 dpavlin r51

/trunk/t/002_isis.t: make test less chatty without debug

2006-07-07 21:11:01 dpavlin r50

/trunk/scripts/dump_isisdb.pl, /trunk/lib/Biblio/Isis.pm: support for repeatable subfields, version bump to 0.20

THIS MIGHT BE INCOMPATIBILE CHANGE for old programs if they always expect to get scalar for values in hash generated by to_hash.

2006-07-07 21:07:44 dpavlin r49

/trunk/t/002_isis.t: sync test with new data

2006-07-07 20:48:57 dpavlin r48

/trunk/data/winisis/BIBL.XRF, /trunk/data/winisis/BIBL.mst: fix difference at MFN 5, 225^a

2006-07-07 10:33:33 dpavlin r47

/trunk/t/002_isis.t: sane debug output

2006-07-07 10:25:02 dpavlin r46

/trunk/t/002_isis.t: dump rec in debug also

2006-07-06 20:31:46 dpavlin r45

/trunk/t/002_isis.t, /trunk/lib/Biblio/Isis.pm: better logging, use Data::Dump if available [0.14]

2006-07-06 11:02:37 dpavlin r44

/trunk/lib/Biblio/Isis.pm: skip empty results of hash_filter

2006-06-29 23:20:14 dpavlin r43

/trunk/scripts/dump_isisdb.pl: actually use -n argument for maximum records to dump

2005-12-09 14:50:52 dpavlin r42

/trunk/scripts/dump_isisdb.pl: added -d path and -n flags

2005-03-12 21:05:29 dpavlin r41

/trunk/lib/Biblio/Isis.pm: better support for ISIS files with null pointers (it will warn and not die)

2005-02-01 15:49:42 dpavlin r40

/trunk/Makefile.PL: I use Test::More and not Test::Simple

2005-01-27 22:01:17 dpavlin r39

/trunk/lib/Biblio/Isis.pm: carp and not croak if MST or XRF file isn't found (calling program will receive undef from new and warning will be issued).

2005-01-12 19:28:41 dpavlin r38

/trunk/t/002_isis.t, /trunk/t/001_load.t, /trunk/Makefile.PL: use File::Spec in attempt to support MacPerl

2005-01-07 20:57:56 dpavlin r37

/trunk/lib/Biblio/Isis, /trunk/t/999_pod.t, /trunk/Isis.pm, /trunk/MANIFEST, /trunk/lib, /trunk/lib/Biblio, /trunk/Makefile.PL, /trunk/lib/Biblio/Isis.pm, /trunk/MANIFEST.SKIP, /trunk/lib/Biblio/Isis/Manual.pod: re-organize directories, add CDS/ISIS manual -- part about file structure

2005-01-06 20:48:07 dpavlin r36

/trunk/t/002_isis.t, /trunk/scripts/bench.pl, /trunk/t/999_pod.t, /trunk/Isis.pm, /trunk/scripts/dump_isisdb.pl, /trunk/t/001_load.t, /trunk/MANIFEST, /trunk/Makefile.PL, /trunk/IsisDB.pm: renamed module to Biblio::Isis

2005-01-06 16:27:07 dpavlin r35

/trunk/IsisDB.pm: moved *_cnt function to end of module (so that documetation ends up at end)

2005-01-06 00:40:07 dpavlin r34

/trunk/IsisDB.pm: croak more, carp less (die on anything which is unrecoverable)

2005-01-05 21:23:04 dpavlin r33

/trunk/t/002_isis.t, /trunk/IsisDB.pm: - make filehandles locally scoped
- changed unpack to portable big-endian (so that it works on little-endian machines; tested with PearPC and OpenDarwin)
- added carps where missing
- added binmode when opening files
- any argument to 002_isis.t will show debugging output

2005-01-05 15:46:26 dpavlin r32

/trunk/t/002_isis.t, /trunk/scripts/bench.pl, /trunk/scripts/dump_isisdb.pl, /trunk/MANIFEST, /trunk/IsisDB.pm, /trunk/t/998_pod-coverage.t: new api version
- added count method (instead of calling maxmfn directly in object)
- added POD coverage test
- moved unpack_cnt to be separate method and document it

2005-01-02 22:14:54 dpavlin r31

/trunk/MANIFEST: fixed manifest

2005-01-02 02:41:30 dpavlin r30

/trunk/scripts/cmp.sh: fix

2005-01-01 22:39:27 dpavlin r29

/trunk/scripts/dump_isis.pl, /trunk/scripts/dump_isisdb.pl: renamed example script

2005-01-01 22:29:49 dpavlin r28

/trunk/t/002_isis.t: test read_cnt

2005-01-01 22:29:35 dpavlin r27

/trunk/IsisDB.pm: documentation improvement

2004-12-31 07:16:02 dpavlin r26

/trunk/IsisDB.pm: partial fix for physically deleted records, but logic could benefit from a bit more work since it's not totally complient with ISIS documentation.

2004-12-31 05:43:20 dpavlin r25

/trunk/t/002_isis.t, /trunk/data/winisis/BIBL.XRF, /trunk/IsisDB.pm, /trunk/data/winisis/BIBL.mst: major improvments and new version:
- implement logically deleted records (really!)
- re-ordered values tests using cmp_ok so that reporting is correct,
- return record in fetch even if it's in memory (bugfix)
- removed some obsolete code

2004-12-31 04:24:57 dpavlin r24

/trunk/data/winisis/BIBL.FDT: add missing FDT file

2004-12-31 04:21:21 dpavlin r23

/trunk/IsisDB.pm: important fix: identifiers should be first two characters and than ^, otherwise, leave them alone.

2004-12-31 01:06:21 dpavlin r22

/trunk/t/002_isis.t: test to_ascii

2004-12-31 00:46:33 dpavlin r21

/trunk/t/002_isis.t: fetch tests

2004-12-30 23:17:00 dpavlin r20

/trunk/data/isismarc/isismarc, /trunk/data/isismarc/BIBL.mst, /trunk/data/winisis, /trunk/data/winisis/BIBL.l01, /trunk/data/winisis/BIBL.l02, /trunk/data/isismarc/isismarc/isismarc2.cip, /trunk/data/winisis/BIBL.N01, /trunk/data/winisis/BIBL.N02, /trunk/data/winisis/BIBL.XRF, /trunk/data/isismarc/BIBL.IFP, /trunk/data/winisis/BIBL.mst, /trunk/data, /trunk/data/isismarc/isismarc/fdt21.xrf, /trunk/data/isismarc/isismarc/fdt21.mst, /trunk/data/isismarc, /trunk/data/winisis/BIBL.IFP, /trunk/data/isismarc/isismarc/pft21.fst, /trunk/data/isismarc/isismarc/fmt21.xrf, /trunk/data/isismarc/isismarc/pft21.xrf, /trunk/data/isismarc/isismarc/fmt21.mst, /trunk/data/winisis/BIBL.CNT, /trunk/data/isismarc/BIBL.XRF, /trunk/data/isismarc/isismarc/pft21.mst: added test data

2004-12-30 23:16:20 dpavlin r19

/trunk/t/002_isis.t, /trunk/t/001_load.t, /trunk/IsisDB.pm: added real test (beginning of...) and changed some confesses to croak

2004-12-30 22:40:53 dpavlin r18

/trunk/Makefile.PL, /trunk/IsisDB.pm: Deduce file names and extensions using glob case insesitive. This fixes potential problem with extension names. Extracted code to read .CNT file into read_cnt function.

2004-12-30 19:45:14 dpavlin r17

/trunk/scripts/cmp.sh: small script to compare output from IsisDB with OpenISIS

2004-12-30 17:16:34 dpavlin r16

/trunk/IsisDB.pm: clean up offset calculation (now works with ISIS databases from isis.dll), don't re-fetch MFN if in memory allready, dump debugging messages to STDERR

2004-12-29 22:46:40 dpavlin r15

/trunk/scripts/dump_isis.pl, /trunk/scripts/dump_openisis.pl, /trunk/MANIFEST, /trunk/IsisDB.pm: mostly documentation improvements, but also nicer output and field names output (using .FDT file) in to_ascii if read_fdt is specified

2004-12-29 20:11:34 dpavlin r14

/trunk/scripts/bench.pl, /trunk/Makefile.PL: benchmark hash creation for various implementations

2004-12-29 20:10:59 dpavlin r13

/trunk/scripts/dump_isis.pl, /trunk/scripts/dump_openisis.pl: added debug output which displays raw structures

2004-12-29 20:10:11 dpavlin r12

/trunk/IsisDB.pm: added to_hash method and hash_filter coderef to new constructor to filter data prior to unpacking ISIS data into hash.

2004-12-29 17:03:52 dpavlin r11

/trunk/Makefile.PL, /trunk/IsisDB.pm: documentation and dependency improvements, inline Read32 to get some more performance.

2004-12-29 16:04:07 dpavlin r10

/trunk/IsisDB.pm: skip fields with length 0, OpenIsis produce binary junk in this case.

2004-12-29 16:01:41 dpavlin r9

/trunk/scripts/dump_isis.pl, /trunk/IsisDB.pm: logically deleted records are by default skipped, but can be included using include_deleted option to new

2004-12-29 15:17:59 dpavlin r8

/trunk/IsisDB.pm: another speedup (7845.71/s)

2004-12-29 15:10:34 dpavlin r7

/trunk/scripts/dump_isis.pl, /trunk/scripts/bench.pl, /trunk/IsisDB.pm: added benchmarking script, some speedup (7029.54/s vs 5829.19/s), removed left-overs from php porting (dictionaries are not supported by this module), make dump_isis.pl arguments same as dump_openisis.pl, renamed GetMFN to fetch

2004-12-28 04:07:03 dpavlin r6

/trunk/Makefile.PL, /trunk/Changes: minor changes and cleanup, create Changes from Subversion repository log

2004-12-28 04:06:29 dpavlin r5

/trunk/t/999_pod.t: test pod

2004-12-28 04:06:04 dpavlin r4

/trunk/scripts/dump_isis.pl: print number of rows

2004-12-28 01:48:44 dpavlin r3

/trunk/IsisDB.pm: remove debugging

2004-12-28 01:41:45 dpavlin r2

/trunk/scripts/dump_isis.pl, /trunk/scripts/dump_openisis.pl, /trunk/t/001_load.t, /trunk/MANIFEST, /trunk/IsisDB.pm: first working version:
- add support for repeatable fields (so all hash values becomed arrays, even with single element)
- scripts to dump CDS/ISIS database using this module and OpenIsis
- to_ascii method which dumps ascii output of record

2004-12-28 00:43:04 dpavlin r1

/trunk/README, /trunk, /trunk/LICENSE, /trunk/t, /trunk/t/001_load.t, /trunk/MANIFEST, /trunk/Makefile.PL, /trunk/scripts, /trunk/Changes, /trunk/IsisDB.pm: Import of old code back from february to actually make it work.