<s>
db4o	B-Language
(	O
database	O
for	O
objects	O
)	O
was	O
an	O
embeddable	O
open-source	B-Application
object	B-Application
database	I-Application
for	O
Java	B-Language
and	O
.NET	B-Application
developers	O
.	O
</s>
<s>
In	O
October	O
2014	O
,	O
Actian	O
declined	O
to	O
continue	O
to	O
actively	O
pursue	O
and	O
promote	O
the	O
commercial	O
db4o	B-Language
product	O
offering	O
for	O
new	O
customers	O
.	O
</s>
<s>
The	O
term	O
object-oriented	B-Application
database	I-Application
system	I-Application
dates	O
back	O
to	O
around	O
1985	O
,	O
though	O
the	O
first	O
research	O
developments	O
in	O
this	O
area	O
started	O
during	O
the	O
mid-1970s	O
.	O
</s>
<s>
The	O
first	O
commercial	O
object	B-Application
database	I-Application
management	I-Application
systems	I-Application
were	O
created	O
in	O
the	O
early	O
1990s	O
;	O
these	O
added	O
the	O
concept	O
of	O
native	O
database	O
driven	O
persistence	O
into	O
the	O
field	O
of	O
object-oriented	B-Language
development	O
.	O
</s>
<s>
The	O
second	O
wave	O
of	O
growth	O
was	O
observed	O
in	O
the	O
first	O
decade	O
of	O
the	O
21st	O
century	O
,	O
when	O
object-oriented	B-Application
databases	I-Application
written	O
completely	O
in	O
an	O
object-oriented	B-Language
language	I-Language
appeared	O
on	O
the	O
market	O
.	O
</s>
<s>
db4o	B-Language
is	O
one	O
of	O
the	O
examples	O
of	O
such	O
systems	O
written	O
completely	O
in	O
Java	B-Language
and	O
C#	B-Application
.	O
</s>
<s>
The	O
db4o	B-Language
project	O
was	O
started	O
in	O
2000	O
by	O
chief	O
architect	O
Carl	O
Rosenberger	O
,	O
shipping	O
in	O
2001	O
.	O
</s>
<s>
It	O
was	O
used	O
in	O
enterprise	O
and	O
academic	O
applications	O
prior	O
to	O
its	O
commercial	O
announcement	O
in	O
2004	O
by	O
newly	O
created	O
private	O
company	O
Db4objects	B-Language
Inc	O
.	O
</s>
<s>
In	O
2008	O
db4o	B-Language
was	O
purchased	O
by	O
Versant	O
corporation	O
,	O
which	O
marketed	O
it	O
as	O
open-source	B-Application
bi-licensed	O
software	O
:	O
commercial	O
and	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
(	O
GPL	B-License
)	O
.	O
</s>
<s>
db4o	B-Language
represents	O
an	O
object-oriented	B-Application
database	I-Application
model	I-Application
.	O
</s>
<s>
One	O
of	O
its	O
main	O
goals	O
is	O
to	O
provide	O
an	O
easy	O
and	O
native	O
interface	O
to	O
persistence	O
for	O
object	B-Language
oriented	I-Language
programming	I-Language
languages	I-Language
.	O
</s>
<s>
Development	O
with	O
db4o	B-Language
database	O
does	O
not	O
require	O
a	O
separate	O
data	B-Application
model	I-Application
creation	O
,	O
the	O
application	O
's	O
class	O
model	O
defines	O
the	O
structure	O
of	O
the	O
data	O
.	O
</s>
<s>
db4o	B-Language
attempts	O
to	O
avoid	O
the	O
object/relational	B-Architecture
impedance	I-Architecture
mismatch	I-Architecture
by	O
eliminating	O
the	O
relational	O
layer	O
from	O
a	O
software	O
project	O
.	O
</s>
<s>
db4o	B-Language
is	O
written	O
in	O
Java	B-Language
and	O
.NET	B-Application
and	O
provides	O
the	O
respective	O
APIs	O
.	O
</s>
<s>
It	O
can	O
run	O
on	O
any	O
operating	O
system	O
that	O
supports	O
Java	B-Language
or	O
.NET	B-Application
.	O
</s>
<s>
It	O
is	O
offered	O
under	O
licenses	O
including	O
GPL	B-License
,	O
the	O
db4o	B-Language
Opensource	O
Compatibility	O
License	O
(	O
dOCL	O
)	O
,	O
and	O
a	O
commercial	O
license	O
for	O
use	O
in	O
proprietary	O
software	O
.	O
</s>
<s>
Developers	O
using	O
relational	B-Application
databases	I-Application
can	O
view	O
db40	O
as	O
a	O
complementary	O
tool	O
.	O
</s>
<s>
The	O
db4o-RDBMS	O
data	O
exchange	O
can	O
be	O
implemented	O
using	O
db4o	B-Language
Replication	B-Architecture
System	O
(	O
dRS	O
)	O
.	O
</s>
<s>
dRS	O
can	O
also	O
be	O
used	O
for	O
migration	O
between	O
object	O
(	O
db4o	B-Language
)	O
and	O
relational	O
(	O
RDBMS	O
)	O
technologies	O
.	O
</s>
<s>
As	O
an	O
embedded	B-Application
database	I-Application
db4o	B-Language
can	O
be	O
run	O
in	O
application	O
process	O
.	O
</s>
<s>
db4o	B-Language
contains	O
a	O
function	O
to	O
store	O
any	O
object	O
:	O
</s>
<s>
db4o	B-Language
is	O
designed	O
to	O
be	O
embedded	O
in	O
clients	O
or	O
other	O
software	O
components	O
invisible	O
to	O
the	O
end	O
user	O
.	O
</s>
<s>
Thus	O
,	O
db4o	B-Language
needs	O
no	O
separate	O
installation	O
mechanism	O
,	O
but	O
comes	O
as	O
a	O
single	O
library	O
file	O
with	O
a	O
footprint	O
of	O
around	O
670kB	O
in	O
the	O
.NET	B-Application
version	O
and	O
around	O
1MB	O
in	O
the	O
Java	B-Language
version	O
.	O
</s>
<s>
Client/server	O
version	O
allows	O
db4o	B-Language
to	O
communicate	O
between	O
client	O
and	O
server-side	O
applications	O
.	O
</s>
<s>
Due	O
to	O
a	O
feature	O
referred	O
to	O
as	O
"	O
Generic	O
Reflection	O
"	O
,	O
db4o	B-Language
can	O
work	O
without	O
implementing	O
persistent	O
classes	O
on	O
the	O
server	O
.	O
</s>
<s>
db4o	B-Language
supports	O
automatic	O
object	O
schema	O
evolution	O
for	O
the	O
basic	O
class	O
model	O
changes	O
(	O
field	O
name	O
deletion/addition	O
)	O
.	O
</s>
<s>
This	O
feature	O
can	O
be	O
viewed	O
as	O
an	O
advantage	O
over	O
relational	B-Architecture
model	I-Architecture
,	O
where	O
any	O
change	O
in	O
the	O
schema	O
results	O
in	O
mostly	O
manual	O
code	O
review	O
and	O
upgrade	O
to	O
match	O
the	O
schema	O
changes	O
.	O
</s>
<s>
Rather	O
than	O
using	O
string-based	O
APIs	O
(	O
such	O
as	O
SQL	B-Language
,	O
OQL	B-Language
,	O
JDOQL	O
,	O
EJB	B-Language
QL	I-Language
,	O
and	O
SODA	O
)	O
,	O
Native	O
Queries	O
(	O
NQ	O
)	O
allow	O
developers	O
to	O
simply	O
use	O
the	O
programming	O
language	O
itself	O
(	O
e.g.	O
,	O
Java	B-Language
,	O
C#	B-Application
,	O
or	O
VB.NET	O
)	O
to	O
access	O
the	O
database	O
and	O
thus	O
avoid	O
a	O
constant	O
,	O
productivity-reducing	O
context	O
switch	O
between	O
programming	O
language	O
and	O
data	O
access	O
API	O
.	O
</s>
<s>
Native	O
Queries	O
also	O
provide	O
type	B-Language
safety	I-Language
,	O
as	O
well	O
as	O
remove	O
the	O
need	O
to	O
sanitize	O
against	O
code	O
injection	O
(	O
see	O
SQL	B-Language
Injection	I-Language
)	O
.	O
</s>
<s>
LINQ	B-Language
support	O
is	O
fully	O
integrated	O
in	O
db4o	B-Language
for	O
.NET	B-Application
version	O
3.5	O
.	O
</s>
<s>
LINQ	B-Language
allows	O
the	O
creation	O
of	O
object-oriented	B-Language
queries	O
of	O
any	O
complexity	O
with	O
the	O
benefit	O
of	O
compile-time	O
checking	O
,	O
IDE	O
Intellisense	O
integration	O
and	O
automated	O
refactoring	O
.	O
</s>
<s>
Due	O
to	O
integration	O
with	O
some	O
open-source	B-Application
libraries	O
db4o	B-Language
also	O
allows	O
optimized	O
LINQ	B-Language
queries	O
on	O
Compact	O
Framework	O
.	O
</s>
<s>
LINQ	B-Language
can	O
be	O
used	O
both	O
against	O
relational	O
and	O
object	O
data	O
storage	O
,	O
thus	O
providing	O
a	O
bridge	O
between	O
them	O
.	O
</s>
<s>
The	O
drawbacks	O
and	O
difficulties	O
faced	O
by	O
other	O
Object	B-Application
Databases	I-Application
also	O
apply	O
to	O
Db4o	B-Language
:	O
</s>
<s>
Other	O
things	O
that	O
work	O
against	O
ODBMS	B-Application
seem	O
to	O
be	O
the	O
lack	O
of	O
interoperability	O
with	O
a	O
great	O
number	O
of	O
tools/features	O
that	O
are	O
taken	O
for	O
granted	O
concerning	O
SQL	B-Language
,	O
including	O
but	O
not	O
limited	O
to	O
industry	O
standard	O
connectivity	O
,	O
reporting	O
tools	O
,	O
OLAP	B-Application
tools	O
,	O
and	O
backup	B-Protocol
and	I-Protocol
recovery	I-Protocol
standards	O
.	O
</s>
<s>
Object	B-Application
databases	I-Application
also	O
lack	O
a	O
formal	O
mathematical	O
foundation	O
,	O
unlike	O
the	O
relational	B-Architecture
model	I-Architecture
,	O
and	O
this	O
in	O
turn	O
leads	O
to	O
weaknesses	O
in	O
their	O
query	B-Language
support	O
.	O
</s>
<s>
However	O
,	O
some	O
ODBMSs	O
fully	O
support	O
SQL	B-Language
in	O
addition	O
to	O
navigational	O
access	O
,	O
e.g.	O
</s>
<s>
Objectivity/SQL	O
++	O
,	O
Matisse	O
,	O
and	O
InterSystems	B-Application
CACHÉ	O
.	O
</s>
<s>
Disadvantages	O
specific	O
to	O
Db4o	B-Language
may	O
include	O
:	O
</s>
<s>
"	O
There	O
is	O
no	O
general	O
query	B-Language
language	I-Language
like	O
SQL	B-Language
which	O
can	O
be	O
used	O
for	O
data	O
analyzing	O
or	O
by	O
other	O
applications	O
.	O
</s>
<s>
Replication	B-Architecture
cannot	O
be	O
done	O
administratively	O
—	O
i.e.	O
</s>
<s>
one	O
needs	O
to	O
program	O
an	O
application	O
to	O
achieve	O
replication	B-Architecture
.	O
</s>
<s>
"	O
This	O
is	O
contrary	O
to	O
most	O
RDBMS	O
,	O
where	O
administrators	O
manage	O
servers	O
and	O
replication	B-Architecture
between	O
them.	O
"	O
</s>
<s>
db4o	B-Language
supported	O
Java	B-Language
's	O
JDK	O
1.1.x	O
through	O
6.0	O
and	O
runs	O
on	O
Java	B-Language
EE	I-Language
and	O
Java	B-Language
SE	I-Language
.	O
</s>
<s>
db4o	B-Language
also	O
runs	O
with	O
Java	B-Language
ME	I-Language
dialects	O
that	O
support	O
reflection	O
,	O
such	O
as	O
CDC	B-Language
,	O
Personal	O
Profile	O
,	O
Symbian	B-Operating_System
OS	I-Operating_System
,	O
SavaJe	O
and	O
Zaurus	B-Operating_System
.	O
</s>
<s>
Depending	O
on	O
customer	O
demand	O
,	O
db4o	B-Language
will	O
also	O
run	O
on	O
dialects	O
without	O
reflection	O
,	O
such	O
as	O
CLDC	B-Language
,	O
MIDP	B-Language
,	O
BlackBerry	B-Operating_System
and	O
Palm	B-Operating_System
OS	I-Operating_System
.	O
</s>
<s>
db4o	B-Language
was	O
successfully	O
tested	O
on	O
JavaFX	B-Application
and	O
Silverlight	B-Application
.	O
</s>
<s>
db4o	B-Language
ran	O
on	O
Android	B-Application
.	O
</s>
<s>
db4o	B-Language
uses	O
a	O
custom	O
feature	O
called	O
"	O
generic	O
reflector	O
"	O
to	O
represent	O
class	O
information	O
,	O
when	O
class	O
definitions	O
are	O
not	O
available	O
,	O
which	O
allows	O
to	O
use	O
it	O
in	O
a	O
mixed	O
Java-.NET	O
environment	O
,	O
for	O
example	O
Java	B-Language
client	O
-	O
.NET	B-Application
server	I-Application
and	O
vice	O
versa	O
.	O
</s>
<s>
db4o	B-Language
provides	O
sources	O
of	O
documentation	O
:	O
tutorial	O
,	O
reference	O
documentation	O
,	O
API	O
documentation	O
,	O
online	O
paircasts	O
and	O
blogs	O
.	O
</s>
<s>
For	O
commercial	O
users	O
db4o	B-Language
suggests	O
dDN	O
(	O
db4o	B-Language
developer	O
network	O
)	O
subscription	O
with	O
guaranteed	O
24-hour	O
support	O
and	O
live	O
pairing	O
sessions	O
with	O
the	O
client	O
–	O
Xtreme	O
Connect	O
.	O
</s>
<s>
Object	O
Management	O
Enterprise	O
(	O
OME	O
)	O
is	O
a	O
db4o	B-Language
database	O
browsing	O
tool	O
,	O
which	O
is	O
available	O
as	O
a	O
plugin	O
to	O
Eclipse	O
and	O
MS	O
Visual	O
Studio	O
2005/2008	O
.	O
</s>
<s>
OME	O
provide	O
some	O
administrative	O
functions	O
as	O
indexing	B-Application
,	O
de-fragmentation	O
and	O
backup	B-Protocol
.	O
</s>
<s>
From	O
the	O
db4o	B-Language
version	O
7.8	O
OME	O
was	O
included	O
into	O
standard	O
db4o	B-Language
distribution	O
and	O
the	O
source	O
was	O
made	O
available	O
to	O
the	O
public	O
in	O
db4o	B-Language
svn	O
repository	O
.	O
</s>
<s>
db4o	B-Language
releases	O
development	O
,	O
production	O
and	O
stable	O
builds	O
.	O
</s>
<s>
db4o	B-Language
also	O
runs	O
a	O
continuous	O
build	O
,	O
which	O
is	O
triggered	O
by	O
any	O
new	O
change	O
committed	O
to	O
the	O
SVN	O
code	O
repository	O
.	O
</s>
<s>
db4o	B-Language
build	O
name	O
format	O
is	O
meant	O
to	O
provide	O
all	O
the	O
necessary	O
information	O
about	O
the	O
version	O
,	O
time	O
of	O
build	O
and	O
supported	O
platform	O
:	O
</s>
<s>
db4o	B-Language
–	O
name	O
of	O
the	O
product	O
,	O
i.e.	O
</s>
<s>
java	B-Language
–	O
Java	B-Language
version	O
of	O
db4o	B-Language
.	O
</s>
<s>
.NET	B-Application
version	O
is	O
identified	O
by	O
“	O
net	O
”	O
for	O
.NET	B-Application
2.0	O
releases	O
or	O
“	O
net35	O
”	O
for	O
.NET	B-Application
3.5	O
version	O
.	O
</s>
<s>
.NET	B-Application
version	O
includes	O
the	O
corresponding	O
Compact	O
Framework	O
release	O
.	O
</s>
<s>
db4o	B-Language
public	O
SVN	O
repository	O
is	O
also	O
available	O
for	O
the	O
developers	O
to	O
get	O
the	O
source	O
code	O
and	O
build	O
versions	O
locally	O
with	O
or	O
without	O
custom	O
modifications	O
.	O
</s>
