<s>
XQuery	B-Language
API	I-Language
for	I-Language
Java	I-Language
(	O
XQJ	B-Language
)	O
refers	O
to	O
the	O
common	O
Java	B-Language
API	I-Language
for	O
the	O
W3C	O
XQuery	B-Language
1.0	O
specification	O
.	O
</s>
<s>
The	O
XQJ	B-Language
API	O
enables	O
Java	B-Language
programmers	O
to	O
execute	O
XQuery	B-Language
against	O
an	O
XML	B-Protocol
data	O
source	O
(	O
e.g.	O
</s>
<s>
an	O
XML	B-Application
database	I-Application
)	O
while	O
reducing	O
or	O
eliminating	O
vendor	O
lock	O
in	O
.	O
</s>
<s>
The	O
XQJ	B-Language
API	O
provides	O
Java	B-Language
developers	O
with	O
an	O
interface	O
to	O
the	O
XQuery	B-Language
Data	O
Model	O
.	O
</s>
<s>
Its	O
design	O
is	O
similar	O
to	O
the	O
JDBC	B-Language
API	I-Language
which	O
has	O
a	O
client/server	O
feel	O
and	O
as	O
such	O
lends	O
itself	O
well	O
to	O
Server-based	O
XML	B-Application
Databases	I-Application
and	O
less	O
well	O
to	O
client-side	O
XQuery	B-Language
processors	O
,	O
although	O
the	O
"	O
connection	B-General_Concept
"	O
part	O
is	O
a	O
very	O
minor	O
part	O
of	O
the	O
entire	O
API	O
.	O
</s>
<s>
Users	O
of	O
the	O
XQJ	B-Language
API	O
can	O
bind	O
Java	B-Language
values	O
to	O
XQuery	B-Language
expressions	O
,	O
preventing	O
code	O
injection	O
attacks	O
.	O
</s>
<s>
Also	O
,	O
multiple	O
XQuery	B-Language
expressions	O
can	O
be	O
executed	O
as	O
part	O
of	O
an	O
atomic	B-General_Concept
transaction	I-General_Concept
.	O
</s>
<s>
The	O
XQuery	B-Language
API	I-Language
for	I-Language
Java	I-Language
was	O
developed	O
at	O
the	O
Java	B-Language
Community	I-Language
Process	I-Language
as	O
JSR	B-Language
225	I-Language
.	O
</s>
<s>
It	O
had	O
some	O
big	O
technology	O
backers	O
such	O
as	O
Oracle	B-General_Concept
,	O
IBM	O
,	O
BEA	O
Systems	O
,	O
Software	O
AG	O
,	O
Intel	O
,	O
Nokia	O
and	O
DataDirect	O
.	O
</s>
<s>
Version	O
1.0	O
of	O
the	O
XQuery	B-Language
API	I-Language
for	I-Language
Java	I-Language
Specification	O
was	O
released	O
on	O
June	O
24	O
,	O
2009	O
,	O
along	O
with	O
JavaDocs	B-Language
,	O
a	O
reference	O
implementation	O
and	O
a	O
TCK	O
(	O
Technology	B-Language
Compatibility	I-Language
Kit	I-Language
)	O
which	O
implementing	O
vendors	O
must	O
conform	O
to	O
.	O
</s>
<s>
There	O
is	O
no	O
(	O
visible	O
)	O
activity	O
to	O
create	O
a	O
version	O
of	O
XQJ	B-Language
that	O
provides	O
support	O
for	O
XQuery	B-Language
3.0	O
or	O
3.1	O
,	O
for	O
example	O
by	O
providing	O
Java	B-Language
bindings	O
for	O
additions	O
to	O
the	O
data	O
model	O
such	O
as	O
functions	O
,	O
arrays	O
,	O
or	O
maps	O
.	O
</s>
<s>
XQJ	B-Language
allows	O
multiple	O
implementations	O
to	O
exist	O
and	O
be	O
used	O
by	O
the	O
same	O
application	O
.	O
</s>
<s>
XQJ	B-Language
connections	O
support	O
creating	O
and	O
executing	O
XQuery	B-Language
expressions	O
.	O
</s>
<s>
XQJ	B-Language
represents	O
XQuery	B-Language
expressions	O
using	O
one	O
of	O
the	O
following	O
classes	O
:	O
</s>
<s>
XQExpression	O
–	O
the	O
expression	O
is	O
sent	O
to	O
the	O
XQuery	B-Language
processor	O
every	O
time	O
.	O
</s>
<s>
XQuery	B-Language
expressions	O
return	O
a	O
result	O
sequence	O
of	O
XDM	O
items	O
which	O
in	O
XQJ	B-Language
are	O
represented	O
through	O
the	O
XQResultSequence	O
interface	O
.	O
</s>
<s>
XDM	O
type	O
information	O
in	O
XQJ	B-Language
can	O
be	O
retrieved	O
via	O
the	O
XQItemType	O
interface	O
.	O
</s>
<s>
Atomic	O
XQuery	B-Language
items	O
can	O
be	O
easily	O
cast	O
to	O
Java	B-Language
primitives	O
via	O
XQItemAccessor	O
methods	O
such	O
as	O
getByte( )	O
and	O
getFloat( )	O
.	O
</s>
<s>
Also	O
XQuery	B-Language
items	O
and	O
sequences	O
can	O
be	O
serialized	O
to	O
DOM	B-General_Concept
,	O
SAX	B-Application
,	O
StAX	B-Language
and	O
the	O
generic	O
IO	O
and	O
classes	O
.	O
</s>
<s>
The	O
following	O
example	O
illustrates	O
creating	O
a	O
connection	B-General_Concept
to	O
an	O
XML	B-Application
Database	I-Application
,	O
submitting	O
an	O
XQuery	B-Language
expression	O
,	O
then	O
processing	O
the	O
results	O
in	O
Java	B-Language
.	O
</s>
<s>
Once	O
all	O
of	O
the	O
results	O
have	O
been	O
processed	O
,	O
the	O
connection	B-General_Concept
is	O
closed	O
to	O
free	O
up	O
all	O
resources	O
associated	O
with	O
it	O
.	O
</s>
<s>
The	O
following	O
example	O
illustrates	O
how	O
a	O
Java	B-Language
value	O
can	O
be	O
bound	O
to	O
an	O
external	O
variable	O
in	O
an	O
XQuery	B-Language
expression	O
.	O
</s>
<s>
Assume	O
that	O
the	O
connection	B-General_Concept
already	O
exists	O
:	O
</s>
<s>
Mapping	O
between	O
Java	B-Language
and	O
XQuery	B-Language
data	O
types	O
is	O
largely	O
flexible	O
,	O
however	O
the	O
XQJ	B-Language
1.0	O
specification	O
does	O
have	O
default	O
mapping	O
rules	O
mapping	O
data	O
types	O
when	O
they	O
are	O
not	O
specified	O
by	O
the	O
user	O
.	O
</s>
<s>
These	O
mapping	O
rules	O
bear	O
great	O
similarities	O
to	O
the	O
mapping	O
rules	O
found	O
in	O
JAXB	B-Language
.	O
</s>
<s>
The	O
following	O
table	O
illustrates	O
the	O
default	O
mapping	O
rules	O
for	O
when	O
binding	O
Java	B-Language
values	O
to	O
external	O
variables	O
in	O
XQuery	B-Language
expressions	O
.	O
</s>
<s>
The	O
following	O
is	O
a	O
list	O
of	O
Native	B-Application
XML	I-Application
Databases	I-Application
which	O
are	O
known	O
to	O
have	O
XQuery	B-Language
API	I-Language
for	I-Language
Java	I-Language
implementations	O
.	O
</s>
<s>
DataDirect	O
provide	O
XQJ	B-Language
adapters	B-Device
for	O
relational	B-Application
databases	I-Application
,	O
by	O
translating	O
XQuery	B-Language
code	O
into	O
SQL	B-Language
on	O
the	O
fly	O
,	O
then	O
converting	O
SQL	B-Application
result	I-Application
sets	I-Application
into	O
a	O
format	O
suitable	O
for	O
XQJ	B-Language
to	O
process	O
further	O
.	O
</s>
<s>
The	O
following	O
is	O
a	O
list	O
of	O
non-database	O
XQuery	B-Language
processors	O
which	O
provide	O
an	O
XQuery	B-Language
API	I-Language
for	I-Language
Java	I-Language
interface	O
(	O
typically	O
allowing	O
query	O
against	O
documents	O
parsed	O
from	O
XML	B-Protocol
in	O
filestore	O
,	O
and	O
held	O
in	O
memory	O
as	O
DOM	B-General_Concept
or	O
similar	O
trees	O
)	O
.	O
</s>
<s>
The	O
specification	O
is	O
marked	O
as	O
"	O
Copyright	O
©	O
2003	O
,	O
2006	O
-	O
2009	O
Oracle	B-General_Concept
.	O
</s>
<s>
Secondly	O
,	O
the	O
license	O
does	O
not	O
meet	O
the	O
criteria	O
to	O
qualify	O
as	O
an	O
open	O
source	O
license	O
(	O
see	O
Open	B-License
Source	I-License
Definition	I-License
)	O
,	O
because	O
of	O
the	O
ban	O
on	O
making	O
extensions	O
and	O
modifications	O
.	O
</s>
<s>
This	O
has	O
led	O
some	O
open	O
source	O
enthusiasts	O
to	O
challenge	O
whether	O
XQJ	B-Language
implementations	O
can	O
ever	O
be	O
considered	O
truly	O
open	O
source	O
.	O
</s>
