...
DS-COMPOSITE
...
datastream
...
Content
...
Models
...
may
...
contain
...
this
...
reserved
...
datastream.
...
It
...
lists
...
the
...
datastreams
...
that
...
must
...
exist
...
in
...
subscribing
...
data
...
objects,
...
and
...
the
...
few
...
requirements
...
on
...
them.
...
#DSCompositeSchema
...
The
...
schema
...
for
...
the
...
datastream
...
can
...
be
...
seen
...
below.
| Code Block |
|---|
<xsd:schema targetNamespace="info:fedora/fedora-system:def/dsCompositeModel#" xmlns="info:fedora/fedora-system:def/dsCompositeModel#" xmlns:xsd="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xsd:element name="dsCompositeModel"> <xsd:complexType> <xsd:sequence> <xsd:element minOccurs="0" maxOccurs="unbounded" ref="dsTypeModel"/> </xsd:sequence> </xsd:complexType> </xsd:element> <xsd:element name="dsTypeModel"> <xsd:complexType> <xsd:sequence> <xsd:element minOccurs="0" maxOccurs="unbounded" ref="form"/> </xsd:sequence> <xsd:attribute name="ID" use="required" type="xsd:NCName"/> </xsd:complexType> </xsd:element> <xsd:element name="form"> <xsd:complexType> <xsd:attribute name="FORMAT_URI" use="optional" type="xsd:anyURI"/> <xsd:attribute name="MIME" use="optional"/> </xsd:complexType> </xsd:element> </xsd:schema> |
The
...
content
...
of
...
a
...
DS-COMPOSITE
...
datastream
...
could
...
look
...
like
...
this
| Code Block |
|---|
<dsCompositeModel xmlns="info:fedora/fedora-system:def/dsCompositeModel#"> <dsTypeModel ID="DC"> <form MIME="text/xml"/> </dsTypeModel> <dsTypeModel ID="ORIGIN"> <form MIME="text/xml"/> </dsTypeModel> </dsCompositeModel> [ |
...
Allowing
...
extensions
...
in
...
DS-COMPOSITE
...
Since
...
Fedora
...
already
...
use
...
DS-COMPOSITE
...
to
...
declare
...
the
...
existence
...
of
...
datastreams,
...
it
...
is
...
the
...
natural
...
location
...
to
...
specify
...
restrictions
...
on
...
the
...
contents
...
of
...
datastreams.
...
Unfortunately,
...
the
...
schema
...
for
...
the
...
DS-COMPOSITE
...
datastream
...
does
...
not
...
allow
...
for
...
any
...
extra
...
content,
...
To
...
that
...
effect,
...
we
...
have
...
made
...
a
...
small
...
change
...
to
...
the
...
schema.
| Code Block |
|---|
<xsd:schema targetNamespace="info:fedora/fedora-system:def/dsCompositeModel#" xmlns="info:fedora/fedora-system:def/dsCompositeModel#" xmlns:xsd="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xsd:element name="dsCompositeModel"> <xsd:complexType> <xsd:sequence> <xsd:element minOccurs="0" maxOccurs="unbounded" ref="dsTypeModel"/> </xsd:sequence> </xsd:complexType> </xsd:element> <xsd:element name="dsTypeModel"> <xsd:complexType> <xsd:sequence> <xsd:element minOccurs="0" maxOccurs="unbounded" ref="form"/> <!--Changes begin--> <xsd:element minOccurs="0" maxOccurs="1" ref="extensions"> <!--Changes end--> </xsd:element> </xsd:sequence> <xsd:attribute name="ID" use="required" type="xsd:NCName"/> </xsd:complexType> </xsd:element> <!-- Changes begin --> <xsd:element name="extensions"> <xsd:complexType> <xsd:sequence> <xsd:any namespace="##any" processContents="skip" minOccurs="0" maxOccurs="unbounded"/> </xsd:sequence> <xsd:attribute name="name" use="optional"/> </xsd:complexType> </xsd:element> <!--Changes end--> <xsd:element name="form"> <xsd:complexType> <xsd:attribute name="FORMAT_URI" use="optional" type="xsd:anyURI"/> <xsd:attribute name="MIME" use="optional"/> </xsd:complexType> </xsd:element> </xsd:schema> |
With
...
this
...
changed
...
schema,
...
the
...
contents
...
could
...
look
...
like
...
this:
| Code Block |
|---|
<dsCompositeModel xmlns="info:fedora/fedora-system:def/dsCompositeModel#"> <dsTypeModel ID="DC"> <form MIME="text/xml"/> <extensions name="SCHEMA"> </extensions> </dsTypeModel> <dsTypeModel ID="ORIGIN"> <form MIME="text/xml"/> <extensions name="SCHEMA"> </extensions> </dsTypeModel> </dsCompositeModel> |
What
...
is
...
noteworthy
...
here
...
is
...
that
...
the
...
<dsTypeModel>
...
and
...
the
...
<form>
...
elements
...
are
...
left
...
unchanged.
...
The
...
Fedora
...
code,
...
working
...
with
...
DS-COMPOSITE
...
only
...
looks
...
for
...
these
...
tags,
...
so
...
the
...
new
...
schema
...
will
...
not
...
cause
...
conflicts,
...
and
...
the
...
extensions
...
will
...
be
...
quietly
...
ignored.
...
This
...
is
...
exactly
...
as
...
we
...
want,
...
this
...
change
...
should
...
not
...
make
...
our
...
objects
...
incompatible
...
with
...
an
...
unmodified
...
Fedora.
...
...
Schema
...
extensions
...
in
...
DS-COMPOSITE
...
Now
...
that
...
there
...
is
...
a
...
system
...
in
...
place
...
for
...
extensions
...
to
...
DS-COMPOSITE,
...
looking
...
at
...
extensions
...
become
...
worthwhile.
...
It
...
can
...
be
...
said
...
that
...
there
...
are
...
three
...
kinds
...
of
...
datastreams
...
in
...
a
...
Fedora
...
object:
...
1.
...
xml
...
embedded
...
in
...
the
...
object
...
2.
...
bytes
...
embedded
...
in
...
the
...
object
...
3.
...
external
...
file
...
referenced
...
by
...
URL.
...
The
...
schema
...
extension
...
will
...
only
...
concern
...
itself
...
with
...
the
...
first
...
option,
...
namely
...
the
...
xml
...
embedded
...
in
...
the
...
datastream.
...
For
...
XML,
...
there
...
already
...
exist
...
a
...
commonly
...
accepted
...
system
...
for
...
specifying
...
the
...
content,
...
i.e.
...
XML
...
Schema.
...
But
...
where
...
to
...
place
...
the
...
schema,
...
then?
...
Embedding
...
it
...
directly
...
in
...
DS-COMPOSITE
...
makes
...
for
...
a
...
very
...
unreadable
...
datastream.
...
Alternatively,
...
you
...
could
...
just
...
specify
...
an
...
URL
...
to
...
the
...
schema,
...
but
...
this
...
approach
...
have
...
problems
...
too.
...
Having
...
the
...
Content
...
Model
...
depend
...
on
...
schemas
...
defined
...
elsewhere,
...
perhaps
...
on
...
remote
...
servers,
...
mean
...
that
...
the
...
content
...
models
...
could
...
break
...
by
...
actions
...
totally
...
unrelated
...
to
...
the
...
repository.
...
The
...
best
...
way,
...
we
...
have
...
found,
...
is
...
to
...
embed
...
the
...
schema
...
in
...
a
...
datastream,
...
either
...
in
...
the
...
content
...
model
...
itself,
...
or
...
in
...
another
...
object.
...
To
...
that
...
purpose
...
we
...
have
...
defined
...
the
...
following
...
extension
...
schema
| Code Block |
|---|
<xsd:schema targetNamespace="http://ecm.sourceforge.net/types/dscompositeschema/0/1/#" xmlns="http://ecm.sourceforge.net/types/dscompositeschema/0/1/#" xmlns:xsd="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xsd:element name="schema"> <xsd:complexType> <xsd:attribute name="type" use="required" type="typetype"/> <xsd:attribute name="datastream" use="required" type="idType"/> <xsd:attribute name="object" use="optional" type="pidType"/> </xsd:complexType> </xsd:element> <xsd:simpleType name="typetype"> <xsd:restriction base="xsd:string"> <xsd:enumeration value="xsd"/> </xsd:restriction> </xsd:simpleType> <xsd:simpleType name="idType"> <xsd:restriction base="xsd:ID"> <xsd:maxLength value="64"/> </xsd:restriction> </xsd:simpleType> <xsd:simpleType name="pidType"> <xsd:restriction base="xsd:string"> <xsd:maxLength value="64"/> <xsd:pattern value="([A-Za-z0-9]|-|\.)+:(([A-Za-z0-9])|-|\.|~|_|(%[0-9A-F]{2}))+"/> </xsd:restriction> </xsd:simpleType> </xsd:schema> |
Using
...
that
...
extension,
...
the
...
DS-COMPOSITE
...
datastream
...
could
...
look
...
like
...
this
| Code Block |
|---|
<dsCompositeModel xmlns="info:fedora/fedora-system:def/dsCompositeModel#" xmlns:schema="http://ecm.sourceforge.net/types/dscompositeschema/0/1/#"> <!-- The DC datastream is declared. It's mime type must be text/xml. It must adhere to the xml schema residing in the DC_SCHEMA datastream in the "doms:DublinCore_Schema" object. --> <dsTypeModel ID="DC"> <form MIME="text/xml"/> <extensions name="SCHEMA"> <schema:schema type="xsd" datastream="DC_SCHEMA" object="info:fedora/doms:DublinCore_Schema"/> </extensions> </dsTypeModel> <!-- The ORIGIN datastream is declared. It's mime type must be text/xml. It must adhere to the xml schema residing in the ORIGIN_SCHEMA datastream in this content model--> <dsTypeModel ID="ORIGIN"> <form MIME="text/xml"/> <extensions name="SCHEMA"> <schema:schema type="xsd" datastream="ORIGIN_SCHEMA"/> </extensions> </dsTypeModel> </dsCompositeModel> |
For
...
the
...
DC
...
datastream,
...
the
...
schema
...
can
...
be
...
found
...
in
...
the
...
object
...
doms:DublinCore_Schema,
...
in
...
the
...
datastream
...
DC_SCHEMA.
...
For
...
the
...
ORIGIN
...
datastream
...
the
...
schema
...
is
...
found
...
in
...
the
...
content
...
model
...
object
...
itself,
...
in
...
the
...
datastream
...
ORIGIN_SCHEMA.
...
In
...
both
...
cases,
...
the
...
schema
...
is
...
of
...
type
...
"xsd".
...
The
...
type
...
attribute
...
should
...
allow
...
for
...
easy
...
extension
...
to
...
other
...
kinds
...
of
...
schemas.
...