<s>
Propel	B-Language
is	O
a	O
free	O
,	O
open-source	O
(	O
MIT	B-License
)	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
mapping	I-General_Concept
toolkit	O
written	O
in	O
PHP	B-Application
.	O
</s>
<s>
It	O
is	O
also	O
an	O
integral	O
part	O
of	O
the	O
PHP	B-Application
framework	O
Symfony	B-Language
and	O
was	O
the	O
default	O
ORM	O
up	O
to	O
,	O
and	O
including	O
version	O
1.2	O
.	O
</s>
<s>
The	O
Propel	B-Language
project	O
was	O
started	O
in	O
August	O
2003	O
,	O
with	O
the	O
availability	O
of	O
beta	O
versions	O
PHP	B-Application
version	O
5	O
.	O
</s>
<s>
With	O
version	O
5	O
,	O
PHP	B-Application
was	O
finally	O
able	O
to	O
provide	O
a	O
level	O
of	O
support	O
for	O
object-oriented	B-Language
programming	I-Language
that	O
both	O
made	O
projects	O
like	O
Propel	B-Language
possible	O
and	O
also	O
created	O
a	O
demand	O
for	O
these	O
hitherto-missing	O
components	O
of	O
large-scale	O
,	O
object-oriented	B-Language
architectures	O
.	O
</s>
<s>
Propel	B-Language
was	O
originally	O
based	O
on	O
the	O
Apache	O
Torque	O
project	O
,	O
which	O
was	O
a	O
Java	B-Language
language	I-Language
ORM	O
project	O
.	O
</s>
<s>
Propel	B-Language
's	O
primary	O
function	O
is	O
to	O
provide	O
a	O
mapping	O
between	O
PHP	B-Application
classes	O
and	O
database	O
tables	O
.	O
</s>
<s>
To	O
accomplish	O
this	O
Propel	B-Language
includes	O
a	O
generator	O
component	O
which	O
uses	O
source	O
code	O
generation	O
to	O
build	O
PHP	B-Application
classes	O
based	O
on	O
a	O
datamodel	O
definition	O
written	O
in	O
XML	B-Protocol
.	O
</s>
<s>
Propel	B-Language
also	O
includes	O
a	O
runtime	O
component	O
which	O
manages	O
connections	O
,	O
transactions	O
,	O
and	O
any	O
idiosyncratic	O
rules	O
that	O
describe	O
the	O
workings	O
of	O
the	O
RDBMS	O
being	O
used	O
with	O
Propel	B-Language
.	O
</s>
