Copyright (C) 2003-2006 Jeffrey I Cohen. All rights reserved, worldwide.
NAME
Genezzo - an extensible database system
DESCRIPTION
The Genezzo modules implement a hierarchy of persistent
hashes using a fixed amount of memory and disk. This system is
designed to be easily configured and extended with custom functions,
persistent storage representations, and novel data access methods.
In its current incarnation it supports a limited subset of SQL with
a command line tool [gendba] and a partial DBI-style interface.
REQUIREMENTS
Perl 5.6
INSTALLATION
If you can read this, then you figured out how to uncompress and
untar the archive.
perl Makefile.PL # constructs the makefile
make
make test
make install # (as superuser [optional])
If you install Genezzo, you should be able to run the line-mode tool
directly by typing "gendba.pl" at the command line.
You also should be able to run scripts from the directory containing
this file, something like:
perl -Iblib/lib lib/Genezzo/gendba.pl
USAGE
line mode available via (/usr/bin) gendba.pl.
Try:
gendba.pl -help
gendba.pl -man
or:
perl -Iblib/lib lib/Genezzo/gendba.pl -help
perl -Iblib/lib lib/Genezzo/gendba.pl -man
for more information.
The GenDBI module supports a subset of DBI-style calls. See
dbi_example.pl for some sample usage.
Try:
perl -Iblib/lib demo/dbi_example.pl # runs an example
perldoc Genezzo::GenDBI
for more information.
The simplest way to create an instance of a Genezzo database is to use:
gendba.pl -init
This command will create a new database and login to the
command-line.
SQL SUPPORT -- see LIMITATIONS
EXPRESSIONS: The Genezzo parser can handle expressions composed of
column names, numeric or quoted string constants,
logical constants like TRUE, FALSE and NULL,
concatenation, scalar functions, and basic arithmetic
like '+', '-', '*', '/'. However, logical expressions
using AND, OR, and NOT are only legal in the WHERE clause.
INSERT:
INSERT INTO tablename VALUES (expr [, expr ...]);
INSERT INTO tablename (colname [, colname ...]) VALUES (expr [, expr ...]);
INSERT INTO tablename SELECT ... FROM ...
UPDATE:
UPDATE tablename SET colname = expr [, colname = expr ...] [WHERE ...]
DELETE:
DELETE FROM tablename [WHERE ...]
SELECT: The Genezzo parser can parse complex SELECT statements,
but the execution engine can only handle simple SELECTS
and basic joins.
SELECT * FROM tablename [WHERE ...]
SELECT COUNT(*) FROM tablename
SELECT ECOUNT(*) FROM tablename
SELECT * FROM t1, t2 WHERE t1.col1 = t2.col1
SELECT expr [[AS] column_alias] [, expr [[AS] column_alias]]
FROM tablename
[WHERE ...]
CREATE TABLE:
CREATE TABLE tablename (colname coltype [, colname coltype ...]);
CREATE INDEX:
CREATE INDEX iname on tablename (colname [, colname ...]);
ALTER TABLE ADD CONSTRAINT: supports primary and unique key and
check constraints. NOT NULL and foreign keys are not currently
supported, though you can implement NOT NULL as
CHECK (colname IS NOT NULL). The CHECK expression is equivalent
to a WHERE clause. A table can have multiple CHECK constraints,
but currently only one key constraint.
ALTER TABLE tablename
ADD [CONSTRAINT constraint_name]
PRIMARY KEY (colname [, colname ...]);
ALTER TABLE tablename
ADD [CONSTRAINT constraint_name]
UNIQUE (colname [, colname ...]);
ALTER TABLE tablename
ADD [CONSTRAINT constraint_name]
CHECK (conditional_expression);
ADDFILE: Not really a SQL command, but an extension to grow the
datafiles. See "addfile help".
DROP: drop a table or index.
COMMIT: write changes to disk.
SYNC: write changes to disk like "commit", but don't end a transaction.
ROLLBACK: discard all uncommitted changes.
DESCRIBE:
DESCRIBE tablename
EXPLAIN PLAN: dump parsing and plan information for any SQL command,
including CREATE and ALTER TABLE. Does not require a
"plan table". Can perform partial explanations for
invalid statements, such as missing tables/columns, etc.
Example - "explain plan for select * from t1;"
or even complex sql like:
Explain plan for
select * from t1
where c1 in (select avg(c2) from t2)
having avg(c3) > ((select min(c4)
from (select c5 from t3
union
select c6 from t4)
) + 5) * 7 / min(c7) ;
STARTUP/SHUTDOWN:
LIMITATIONS
General: No locking/multiuser support, bind variables,
incomplete DBI support.
SELECT: Simple queries only -- no ORDER BY, GROUP BY,
HAVING, subqueries, set functions (UNION, INTERSECT).
Only basic FROM clause joins: FROM t1, t2, ... are
supported.
No aggregation functions other than COUNT(*), ECOUNT(*).
COUNT and ECOUNT do not accept a WHERE clause.
ALTER TABLE: no foreign key, NULL/NOT NULL constraints.
CREATE TABLE: Only numeric and character datatypes are accepted.
Datatype length and precision are not enforced.
Numeric columns will accept arbitrary character input,
but will attempt to use numeric (versus character)
comparisons. No table or column constraints.
No CREATE TABLE AS SELECT.
EXAMPLES
Some very basic SQL create/drop/describe table, select, insert, update
and delete syntax is supported, and like standard SQL, table and
column names are case-insensitive unless quoted. More complex SQL
parses, but is ignored. While many scalar SQL functions are available,
the only supported aggregation functions are count(*) and ecount(*),
a non-blocking count estimation function. The database also
supports commit to force changes to disk, and a crude rollback.
NOTE: Data definition (such as create table or ct) must be manually
committed to keep the database in a consistent state. Uncommitted
inserts and updates will only be block-consistent -- there is no
guarantee that the data will get flushed to disk, and no
guarantee whether the changes will or will not take effect.
rem Some simple SELECTs
select * from _col1;
select rid, rownum, tname, colname from _col1;
select count(*) from _col1;
select ecount(*) from _col1;
rem SELECTs with WHERE, perl and SQL style.
select * from _tab1 where tname =~ m/col/;
select * from _tab1 where tid < 5;
select * from _tab1 where numcols > 3 AND numcols < 6;
rem basic joins
select * from _tab1, _col1 where _tab1.tid = _col1.tid
and _tab1.tname =~ m/col/;
rem Column aliases and Expressions
select tid as Table_ID, tname Name, (tid+1)/2 from _tab1;
rem Basic INSERT
insert into test1 values ('a','b','c','d');
insert into test1(col2, col1) values ('a','b','c','d');
rem CREATE TABLE and INSERT...SELECT
create table test2(col1 char, col2 char);
insert into test2 (col1) select col1 from test1;
rem DELETE with WHERE
delete from test1 where col1 < 'bravo' and col2 > 5;
rem UPDATE with WHERE (no subqueries supported)
update test2 set col2 = 'foo' where col2 is null;
commit
By default, the database will autostart -- the gendba.pl command will
connect to an active, updateable instance. The shutdown command will
reset the database to a read-only mode that only provides read access
to certain dictionary tables. The startup command will restart the
database.
The Genezzo parser also supports the Feeble query language, as
described by gendba.pl -man. Briefly, the commands are ct (create
table), dt (drop table), i (insert), u (update), d (delete), s
(select). The following example creates a table EMP with two
columns, ENAME (as character) and ID (as number), inserts five rows,
and counts them.
ct EMP ENAME=c ID=n
i EMP bob 1 orville 2 wilbur 3 harry 4 luke 5
s EMP count
s EMP ecount
commit
While the SQL update and delete commands support a WHERE clause, the
Feeble "u" and "d" commands only work via rowid. For example:
gendba 10> s EMP rid rownum *
rid rownum ename id
___ ______ _____ __
1/33/1 1 bob 1
1/33/2 2 orville 2
1/33/3 3 wilbur 3
1/33/4 4 harry 4
1/33/5 5 luke 5
5 rows selected.
gendba 11> d EMP 1/33/1
deleted 1 rows from table emp.
gendba 12> u EMP 1/33/5 margo 66
updated 1 rows in table emp.
gendba 13> !10
s EMP rid rownum *
rid rownum ename id
___ ______ _____ __
1/33/2 1 orville 2
1/33/3 2 wilbur 3
1/33/4 3 harry 4
1/33/5 4 margo 66
4 rows selected.
The default database is stored in a fixed-size 160K file. You can
change the default filesize and the blocksize at database
initialization time. For example:
gendba.pl -init -define blocksize=8k -define dbsize=10M
to create a database with a 10 megabyte datafile using 8K blocks.
By default, this file is a fixed size, but it can be set to grow
using the "increase_by" settings added in version 0.18. Also, you can
add additional files to your database using the "addfile" command. By
default, each file is double the size of the previous. Type "addfile
help" for more options.
NEW FEATURES - Indexed Tables
Version 0.13 introduces an indexed-table type. An indexed table
treats the first column in the table definition as a unique, not-null
primary key. Note that an "Indexed Table" is distinct from an
ordinary table with a separate index, where you can assign a separate
index object to a particular column or group of columns.
gendba 9> ct EMP index id=n name=c
Create Table : emp
with unique index option
tablename : emp
column id : n (primary key)
column name : c
table emp created
gendba 10> i EMP 1 bob 2 orville 3 wilbur 4 harry 5 luke
inserted 5 rows into table emp.
gendba 11> s EMP rid *
rid id name
___ __ ____
1 1 bob
2 2 orville
3 3 wilbur
4 4 harry
5 5 luke
5 rows selected.
gendba 12> i EMP 1 bob 2 orville 3 wilbur 4 harry 5 luke
whisper: duplicate key 1
Failed to insert row 1 in table emp at lib/Genezzo/gendba.pl line 230
inserted 0 rows into table emp.
gendba 13> select tid, tname, otype from _tab1 where tname = 'emp'
tid tname otype
___ _____ _____
14 emp IDXTAB
1 row selected.
Notice that the first column is marked as a primary key when the
table is created, and the rids for indexed tables are the primary key,
not a physical block address.
Indexed tables have an object type of IDXTAB in the data dictionary
-- conventional tables are marked as TABLE.
WHERE clause processing has been enhanced to use equality predicates
(e.g. "SELECT * from EMP where id = 2") to drive index scans. Any
series of "AND"ed predicates is a candidate for an efficient index
search, but the use of an OR currently requires a full table scan.
CAVEATS: The index performance is pretty poor, for a couple reasons.
It should improve a lot.
NEW FEATURES - Indexes
Users can now define their own indexes. The dictionary
automatically maintains indexes on its own tables. In order to create
an index called EMP_I1 on the ID column of table EMP, the command is:
Create Index EMP_I1 on EMP (ID)
You can have arbitrary combinations of numeric and character keys.
RESTRICTIONS: only one index per table currently. Index keys must
be less than one-half of the db blocksize.
In version 0.15, the query engine will use the index to drive the
row fetch for a SELECT if the WHERE clause specifies an equality
predicate on the primary key. For example:
Select * from EMP where ID = 5
uses an index. In general, additional predicates may accompany the
equality expression as long as they are ANDed:
Select * from EMP where ID = 5 and ENAME =~ m/BOB/
However, the presence of ORs causes the plan to revert to a full
table scan:
Select * from EMP where ID = 5 or ID = 6
All user-defined indexes are non-unique. Unique indexes should be
created as unique constraints (fixed in version 0.22) using
ALTER TABLE.
NEW FEATURES - automatic tablespace and file growth
In version 0.18, datafiles are no longer a fixed size. The column
"increase_by" in table _tsfiles controls the behavior: if this column
is blank, null, or zero, the datafile size is fixed. If
"increase_by" is a non-zero number, the datafile will attempt to grow by
that many bytes if it runs out of free extents. If "increase_by" is a
percentage like "50%", the datafile is extended by the current size
multiplied by this percentage. The AddFile command now takes
"increase_by" as an optional argument.
Also in version 0.18, each tablespace can be configured to
automatically create new datafiles when the current datafile runs out
of free extents. The column "addfile" in table _tspace controls the
behavior: if the column is blank or null, then the tablespace must be
extended manually. If the "addfile" column contains a valid argument
list for the AddFile command, then this command will get invoked when
all of the current datafiles are full. Note that the datafiles can be
of a fixed size, or use the new "increase_by" parameter to grow to some
maximum size (currently 2G).
Prior to version 0.69, the simplest way to alter tablespace settings
was the "bigdb.sql" script. This script is supplanted in version 0.69
by the alter_ts() utility function. The command:
select alter_ts() from dual;
will, by default, upgrade the SYSTEM tablespace to use a base file
size of 10M which automatically grows in 50% increments. For more
information, in gendba.pl line-mode please type:
help area=utility_functions alter_ts
NEW FEATURES - ALTER TABLE ADD CONSTRAINT
Version 0.20 supports ALTER TABLE ADD CONSTRAINT <name> CHECK (<check-text>).
The check-text is any basic where clause predicate. Example:
gendba 3> create table testcon (col1 c, col2 n);
table testcon created
gendba 4> alter table testcon add constraint cn1
check ((col2 > 5) AND col1 =~ m/(a|b|c)/)
Added constraint cn1 to table testcon
gendba 5> insert into testcon values ('a', 7);
inserted 1 row into table testcon.
gendba 6> insert into testcon values ('b', 8);
inserted 1 row into table testcon.
gendba 7> insert into testcon values ('d', 8);
WARNING: violated constraint cn1
must satisfy (col2 > 5) AND col1 =~ m/(a|b|c)/
WARNING: Failed to insert row 1 in table testcon
inserted 0 rows into table testcon.
gendba 8> insert into testcon values ('a', 1);
WARNING: violated constraint cn1
must satisfy (col2 > 5) AND col1 =~ m/(a|b|c)/
WARNING: Failed to insert row 1 in table testcon
inserted 0 rows into table testcon.
Version 0.22 supports
ALTER TABLE ADD CONSTRAINT <name> UNIQUE (<column-list>)
and
ALTER TABLE ADD CONSTRAINT <name> PRIMARY KEY (<column-list>
Version 0.22 only supports a single constraint or single index per
table, but version 0.23 supports multiple constraints and indexes
on a table.
Need to extend to fully support NULL/NOT NULL, FOREIGN KEY, plus
ENABLE/DISABLE.
NEW FEATURES - System/User Extensibility
Version 0.25 of Genezzo supports database extensibility. See
Genezzo::Havok for more details. The script "havok.sql" (now
deprecated) can be used to add extensibility tables to your database.
In version 0.58 a new function HavokUse supercedes the havok.sql
script, and the table user_extend is supplanted in version 0.59 by
Havok::UserFunctions.
NEW FEATURES - Improved error reporting, handling
Version 0.31 error reporting has been significantly reworked to be
more compatible with DBI. In particular, Genezzo::GenDBI->connect now
takes an optional attribute hash with PrintError and RaiseError, so
it will print messages using warn() or die(). In addition, it also
supports a GZERR argument is used to replace the internal Genezzo
error handlers. More documentation exists in GenDBI.pm. The DBI
standard err and errstr aren't supported yet.
NEW FEATURES - backward compatiblity
Version 0.32 supports a compatibility matrix - it can support version 0.31
databases. Genezzo can now maintain a list of which versions use the same
database format. Need to extend this capability to get automatic upgrade
between different database revisions.
NEW FEATURES - database export, rollback, quoted strings,
dynamic system extensions
Version 0.33 introduces genexpl.pl, a very, very basic data export
utility. A "rollback" command is now available, which will discard
all in-memory changes and replace them with the previous committed
results. Note that the buffer cache will automatically flush data
to disk when it is full, so rollback will not be able to restore
data in this case. Single-quoted strings in SQL expressions now
support backslash quoting, so 'foo\\bar\'s' is interpreted as
foo\bar's. Finally, a new Havok module called SysHook supports
extensions to basic Genezzo database functions. SysHook is
restructured in version 0.34.
NEW FEATURES - multiline SQL statements
Version 0.38 allows multiline SQL statements for SELECT, INSERT,
UPDATE, DELETE, and EXPLAIN in the gendba interactive line mode.
These statements must be terminated by a semicolon.
NEW FEATURES - Improved Parser
Version 0.39 uses a new parser based upon Parse::RecDescent
for SELECT statements. The new parser is stricter about
quoting conventions and identifier names -- standard identifiers
must start with an alpha character, or be specified in double quotes.
Only identifiers can be unquoted. String literals must be in single
quotes. The parser does make an exception for dictionary tables like
_tab1 and _col1, which do *not* need to quoted. Boolean operations
must use AND and OR, not && and ||. || is the SQL string concatenation
operation. The count estimation function ECOUNT must be specified as
ecount(*) in the select list.
While the parser is smarter, the execution phase is not improved. The
only supported aggregation functions are count(*) or ecount(*) in the
select list. Having, Group By, and Order By are still missing.
Version 0.40 allows arbitrary expressions in SELECT lists, e.g:
Select tid+5/2 from _tab1;
Version 0.41 adds support for the literals TRUE, FALSE, and NULL,
and extends the new parser to cover ALTER TABLE, DELETE, and INSERT.
INSERT can now handle arbitrary expressions, e.g:
Insert into mytable values (1+1, 2*2, 3/4);
Version 0.42 adds arbitrary expression support to UPDATE, and marks
the complete switchover to the new parser.
Version 0.43 adds case-insensitive table and column names.
NEW FEATURES - Raw Device support
Version 0.44 and 0.45 add support for raw io devices.
NEW FEATURES - Additional User-supplied Preferences and File Header Info
In Version 0.47, users can supply arbitrary command-line definitions
for the dictionary preference table or fileheader info using
-define and -fileheader_define, respectively.
NEW FEATURES - Object-Oriented SysHooks
In Version 0.47, a single package can load multiple functions as
a set of class methods, versus package methods.
NEW FEATURES - Tablespaces
In Version 0.51, users can create additional tablespaces (collections
of datafiles for storage) for tables and indexes. By default, all
tables and indexes are created in the SYSTEM tablespace. The command
"CREATE TABLESPACE tablespace_name" creates a new, empty tablespace.
You must add files to the tablespace use "addfile tsname=..." or "af
tsname=..." before it can be used. See "addfile help" for more details.
CREATE TABLE and CREATE INDEX now take a new TABLESPACE option. Note
that key constraints on a table inherit its tablespace. A table or
index can only be stored in a single tablespace, and they cannot be
moved to a different tablespace. Additional files may be added to any
tablespace at any time. Currently, there is no support for DROP
TABLESPACE, or taking tablespace offline. Example:
gendba 1> create tablespace ts1
gendba 2> addfile tsname=ts1
gendba 3> create table mytab (col1 char) tablespace ts1
NEW FEATURES - Joins
In Version 0.52, basic joins are supported.
NEW FEATURES - DUAL table
In version 0.58, Genezzo provides a single-row DUAL table which is
useful for evaluating expressions, e.g.:
gendba 1> select (((5+5)/4)*32) from dual;
(((5+5)/4)*32)
______________
80
1 row selected.
NEW FEATURES - HavokUse function for System/User Extensibility
In version 0.58, the HavokUse function supercedes the havok.sql and
syshook.sql scripts. HavokUse operates on Havok modules in a
fashion analogous to the way perl "use" loads perl modules. Havok
modules now use a metadata document similar to the MakeMaker META.yml
which lists module dependencies, table definitions, etc. For example,
to load Genezzo::Havok::SysHook, use the command:
Select HavokUse('Genezzo::Havok::SysHook') from dual;
If the havok and sys_hook tables do not exist, HavokUse will create
and update these tables. If the tables already exist, HavokUse will
do nothing, but return successfully. See the Havok module for more
details. Note that the "select" statement is now invoking
dictionary actions which may create and update new tables, and which
may need to be committed. Also, prior to version 0.71, HavokUse
only performs partial initialization -- it is still necessary to
commit, shutdown and restart to activate the new Havok modules.
Modules created after version 0.71 can use add_user_function and
add_sys_hook to dynamically load new functionality.
NEW FEATURES - Havok::UserFunctions, standard SQL scalar functions
Previously, all standard perl functions could be invoked in a SQL
statement, and additional SQL functions were optionally added via
Havok::UserExtend. In version 0.59, Havok::UserExtend has been
deprecated and replaced with Havok::UserFunctions, and Genezzo only
supports functions defined in the new user_functions table. This
table is preloaded when the database is created with many common
perl and sql functions.
The perl functions which are available in SQL are:
chomp, chop, chr, crypt, index, lc, lcfirst, length, ord, pack,
reverse, rindex, sprintf, substr, uc, ucfirst, abs, atan2, cos, exp,
hex, int, log10 (to avoid confusion between natural log and base10),
oct, rand, sin, sqrt, srand, and perl_join (which is renamed to
avoid a conflict with the SQL JOIN operation).
The SQL string functions are concat, greatest, initcap, least, lower,
and upper. The SQL math functions are cosh, ceil, floor, ln, sinh, tan,
and tanh (also note many standard SQL math functions are identical to their
perl counterparts, which are listed above). The SQL conversion
functions are ascii, instr, and nvl.
Version 0.67 has many fixes plus added support for the string
functions lpad, ltrim, rpad, rtrim, translate, replace, and soundex
and the math functions mod, power, round, sign, trunc, logN. Please
see Genezzo::Havok::SQLScalar or "help area=sql_functions" for more
information.
Version 0.69 adds the utility function add_user_function() which
simplifies the creation of new sql functions. In gendba.pl
line-mode please type:
help area=utility_functions add_user_function
for more information.
NEW FEATURES - improved genexp.pl
The version 0.60 database export (genexp.pl) now correctly handles table
constraints and indexes.
NEW FEATURES - Feeble/SQL compatible case-sensitivity
Prior to version 0.63, Feeble commands (ct, d, u, s) did not match
the SQL behavior for case-insensitive identifiers. For example, the
Feeble command:
"ct EMP COL1=c"
would create a table called EMP (uppercase) with a column COL1, while
the SQL command:
"create table EMP (COL1 char(10))"
would create a table called emp (lowercase) with a column col1.
This discrepancy would require the use of quoted identifiers in SQL
in order to reference uppercase or mixed case table or column names.
To facilitate interoperablity between Feeble and SQL, Feeble now
matches the SQL usage and legal naming restrictions for unquoted,
case-insensitive names, and uppercase or mixed case names are only
available using SQL quoted identifiers. Feeble does not support
quoted names.
NEW FEATURES - additional comparison functions IN, LIKE
In version 0.68, basic support for IN and LIKE comparison is
supported. IN only supports expression lists, not subqueries, e.g:
Select * from tab1 where col1 IN ('a', 'b', 'c');
Select * from tab2 where col2 NOT IN (22,33,44);
The LIKE operator supported as a function (versus a separate clause),
e.g:
Select * from tab1 where col3 LIKE ('foo%');
Select * from tab1 where col3 NOT LIKE ('#_foo_', '#');
The first argument to LIKE is a pattern which can take two special
matching characters -- a percent ('%') which is a wildcard (any number
of characters, including zero), and an underscore ('_') which matches
a single character. The optional second argument is an ESCAPE
character. If the '%' or '_' is prefixed with the ESCAPE character it
is treated as a literal. Note that LIKE comparisons are
case-sensitive.
NEW FEATURES - additional utility functions add_user_function, alter_ts
In version 0.69 utility functions simplify the tasks of adding new
user functions, and altering tablespaces for large databases.
In gendba.pl line-mode please type:
help area=utility_functions long=alter_ts add_user_function
for more information.
NEW FEATURES - improved HELP
In version 0.70 the help system is re-organized and enhanced. The
new help supports regex lookup, loadable help modules, and online
support for the SQL functions. In gendba.pl line-mode, try:
Help Help
or
Help area=sql
for more information.
NEW FEATURES - dynamic system hooks
Prior to version 0.71, the Genezzo::Havok::SysHook module required
direct modification of the sys_hook table. In version 0.71, the
function add_sys_hook can be used to dynamically add system hooks to a
running Genezzo instance. In gendba.pl line-mode please type:
help area=system_hooks add_sys_hook
for more information.
NEW FEATURES - self-managed extents
In version 0.72 the extent code keeps better track of block usage,
allowing the more efficient re-use of space from deleted rows.
INCOMPATIBLE CHANGES
Version 0.72 dictionary and block format is incompatible with
previous releases. No upgrade path is supported.
Version 0.48 thru 0.50 are compatible.
SEE ALSO
The project homepage at http://www.genezzo.com
AUTHOR
Original author: Jeffrey I Cohen <jcohen@genezzo.com>
Copyright (c) 2003-2007 Jeffrey I Cohen. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Address bug reports and comments to: jcohen@genezzo.com
For more information, please visit the Genezzo homepage
at http://www.genezzo.com