<?xml version='1.0' encoding='iso-8859-1'?>
<!-- $Revision: 1.23 $ -->
<!-- Purpose: database.abstract -->
<!-- Membership: pecl -->
<!-- State: experimental -->

<reference id="ref.sdo">
 <title>SDO Functions</title>
 <titleabbrev>SDO</titleabbrev>

 <partintro>
  <section id="sdo.intro">
   &reftitle.intro;   
   <para>
    Service Data Objects (SDOs) enable PHP applications to work with
    data from different sources (like a database query, an XML file, 
    and a spreadsheet) using a single interface.
   </para>
   <para>
    Each different kind of data source requires a Data Access Service 
    (DAS) to provide access to the data in the data source.
    In your PHP application, you use a DAS to create an SDO 
    instance that represents some data in the data source.  You can then 
    set and get values in the SDO instance using the standard SDO 
    interface.  Finally, you use a DAS to write the modified data back
    to a data source, typically the same one.
   </para>
   <para>
    See the
    <link linkend="sdo.das.table">list of Data Access Services</link>
    for details on those
    currently available.  In addition to the provided DASs, SDO also
    provides interfaces to enable others to be implemented 
    (see the section on <link linkend="sdo.class.sdo-das-spis">SDO Data
    Access Services Interface</link> for more details).
   </para>
    <para>
     This extension is derived from concepts taken from the
     <ulink url="&url.ibm.sdo;">Service Data Objects specification</ulink>.
     It includes a version of the
     <ulink url="&url.apache.tuscany;">Apache Tuscany</ulink> SDO 2.0 for C++ project.
   </para>

   <section id="sdo.intro.structure">
    <title>The Structure of a Service Data Object</title>
    <para>
     A Service Data Object instance is made up of a tree of data objects.
     The tree is defined by containment relationships between the data 
     objects.  For example, a Company data object might consist of a number 
     of Department data objects and therefore the Company would have 
     a containment relationship to the Departments.  
    </para>
    <para> An SDO may also have non-containment references between data objects in the
     tree. For example, one Employee data object might reference another Employee to
     identify a career mentor. 
    </para>
    <para>
     As well as data objects referencing each other, they can also have
     primitive properties.  For example, the Company data object might
     have a property called "name" of type string, for holding the name
     of the company (for example, "Acme").
    </para>
    <para> Each of these properties of a data object - containment relationships,
     non-containment references, or primitive properties - may be many-valued or
     single-valued. In the above examples, Departments is many-valued and
    the Company name is single-valued.
    </para>
    <para> In PHP, each SDO data object is represented as a PHP object. The properties of the
     data object can be accessed using either object syntax or associative array syntax.
     We'll see some examples of this later.
    </para>
   </section>
  </section>

  <section id="sdo.requirements">
   &reftitle.required;
   <para> The SDO extension requires PHP 5.1 or higher. It also requires the libxml2 library.
    Normally libxml2 will already be installed, but if not, it can be downloaded from
    <ulink url='&url.libxml;'>&url.libxml;</ulink>.
   </para>
  </section>

  <section id="sdo.installation">
   &reftitle.install;
   <procedure id='sdo.install.unix'>
     <title>Unix systems</title>
     <step>
      <para> You can download and install the latest stable release of all three SDO
       components - the SDO core, the XML DAS and the Relational DAS - with the command:
       <screen> <![CDATA[
pecl install sdo
]]>
       </screen>
      </para>
      <para> This command will build the SDO and XML shared libraries as well as installing
       the PHP files that make the Relational DAS.
      </para>
      <para>
       If you want to use the latest beta version, then instead run:
       <screen> 
<![CDATA[
pecl install sdo-beta
]]>
       </screen>
     </para>
    </step>
    <step>
     <para> The
      <command>pecl</command> command automatically installs the SDO and SDO_DAS_XML
      modules into your PHP extensions directory. To enable the SDO extensions you must add
      the following lines to &php.ini;:
      <screen> <![CDATA[
extension=sdo.so
extension=sdo_das_xml.so
]]>
      </screen>
     </para>
     <para> For more information about building PECL packages, consult the
      <link linkend="install.pecl">PECL installation</link> section of the manual.
     </para>
    </step>
    </procedure>
   
   <procedure id='sdo.install.win32'>
    <title>Windows</title>
    <step>
     <para>
      The latest DLLs for the SDO core and the XML DAS can be 
      downloaded from 
      <ulink url='&url.pecl.win.ext;php_sdo.dll'>php_sdo.dll</ulink> and 
      <ulink url='&url.pecl.win.ext;php_sdo_das_xml.dll'>php_sdo_das_xml.dll</ulink> respectively.
     </para>
     <para> 
      Note that currently the <ulink url='&url.pecl.win;'>pecl4win</ulink> site does not provide 
      these binaries at the current release level; you can only download the latest level.
     </para>
    </step>    
    <step>
     <para> The
      <command>pecl</command> command automatically installs the SDO and SDO_DAS_XML
      modules into your PHP extensions directory. To enable the SDO extensions you must add
      the following lines to &php.ini;:
      <screen>
       <![CDATA[
extension=php_sdo.dll
extension=php_sdo_das_xml.dll
]]>
      </screen>
     </para>
    </step>
    <step>
     <para> The Relational DAS can be downloaded and installed with the command:
      <screen>
      <![CDATA[
pecl install -B sdo
]]>
      </screen>
     </para>
     <para> The Relational DAS is written in PHP. You may need to update your
      <link linkend="ini.include-path">include_path</link> in &php.ini; to point to
      the directory that contains
      <filename>sdo/DAS/Relational</filename>.
     </para>
    </step>
   </procedure>
   
   <procedure id='sdo.build.linux.steps'>
    <title>Building SDO on Linux</title>
    <para> This section describes how to build the SDO core and XML DAS on Linux. You would
     only need to know how to do this if you wish to build a recent version that you have checked
     out of CVS.
    </para>
    <step>
     <para>
      Change to the main extension directory:
      <command>cd &lt; wherever your sdo code is &gt;</command>
     </para>
    </step>
    <step>
     <para>
      Run <command>phpize</command>, which will set up the environment to
      compile both SDO and the XML Data Access Service.
     </para>
    </step>
    <step>
     <para>
      Next, run <command>./configure; make; make install</command>. 
      Please note, you may need to login as root to install the extension.
     </para>
    </step>
    <step>
     <para>
      Make sure that these modules are loaded by PHP, by adding
      <command>extension=sdo.so</command> and
      <command>extension=sdo_das_xml.so</command> to your
      &php.ini; file in the same order. 
     </para>
    </step>
   </procedure>
  </section>

  <section id="sdo.das.table">
   <title>Data Access Services</title>
   <para>
    The table below lists the currently provided SDO Data Access Services:
    <informaltable>
     <tgroup cols='2'>
      <thead>
       <row>
        <entry>DAS Name</entry>
        <entry>Description</entry>
       </row>
      </thead>
      <tbody>
       <row>
        <entry>
         <link linkend="ref.sdo-das-xml">SDO_DAS_XML</link>
        </entry>
        <entry>
         An XML Data Access Service supporting reading/writing
         SDOs as XML documents.
        </entry>
       </row>
       <row>
        <entry>
         <link linkend="ref.sdo.das.rel">SDO_DAS_Relational</link>
        </entry>
        <entry>
         A PDO-based Data Access Service supporting reading/writing SDO 
         to relational databases.  
         Implements an optimistic concurrency policy for updates.
        </entry>
       </row>
      </tbody>
     </tgroup>
    </informaltable>
   </para>
  </section>

  <section id='sdo.limitations'>
   <title>Limitations</title>
   <procedure id='sdo.limitations.implementation'>
    <title>Implementation Limitations</title>
    <para>
     The following are limitations in the current SDO implementation:
    </para>
    <step>
     <para>
      There is no support for multi-byte character sets.
      This will be considered, depending on community requirements,
      in the Unicode-enabled version of PHP.
      See <link linkend="ref.unicode">Unicode Functions</link>.
     </para>
    </step>
   </procedure>
   <procedure id='sdo.limitations.sdo'>
    <title>SDO Limitations</title>
    <para>
     The following SDO 2.0 concepts are not supported in the current 
     PHP implementation.
     It is not necessarily the case that these will all be added over time.
     Their inclusion will depend on community requirements.
    </para>
    <step>
     <para>
      Bi-directional relationships.
     </para>
    </step>
    <step>
     <para>
      Type and property alias names.
     </para>
    </step>
    <step>
     <para>
      Read-only properties.
     </para>
    </step>
    <step>
     <para> 
      The Helper classes defined in SDO 2.0 are not directly implemented. 
      However equivalent function is provided in a more natural way for PHP. 
      For example the function of <command>CopyHelper::copy()</command> 
      is provided by applying the PHP
      <link linkend='language.oop5.cloning'>clone</link> keyword to a data object.
     </para>
    </step>
   </procedure>
  </section>

  <section id='sdo.examples'>
   &reftitle.examples;
   <para>
    The examples below assume an SDO created with the schema
    and instance information shown below, using the XML Data Access Service.
   </para>
   <para>
    The instance document below describes a single company, 
    called 'MegaCorp', which contains a single department, 
    called 'Advanced Technologies'.
    The Advanced Technologies department contains three employees.
    The company employeeOfTheMonth is referencing the second employee,
    'Jane Doe'.
   </para>
   <para>
    <programlisting role="xml">
<![CDATA[
<?xml version="1.0" encoding="UTF-8" ?> 
<company xmlns="companyNS" name="MegaCorp" 
  employeeOfTheMonth="E0003">
  <departments name="Advanced Technologies" location="NY" number="123">
    <employees name="John Jones" SN="E0001"/>
    <employees name="Jane Doe" SN="E0003"/>
    <employees name="Al Smith" SN="E0004" manager="true"/>
  </departments>
</company>
]]>
    </programlisting>
   </para>
   <para> The root element of the schema is a company. The company contains departments, and
    each department contains employees. Each element has a number of attributes to store
    things like name, serial number, and so on. Finally, the company also has an IDREF
    attribute which identifies one of the employees as the 'employeeOfTheMonth'.
   </para>
   <para>
    <programlisting role="xml">
<![CDATA[
<xsd:schema  
  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  xmlns:sdo="commonj.sdo"
  xmlns:sdoxml="commonj.sdo/xml"
  xmlns:company="companyNS"
  targetNamespace="companyNS">
  <xsd:element name="company" type="company:CompanyType"/>
  <xsd:complexType name="CompanyType">
    <xsd:sequence>
      <xsd:element name="departments" type="company:DepartmentType" 
        maxOccurs="unbounded"/>
    </xsd:sequence>
    <xsd:attribute name="name" type="xsd:string"/>
    <xsd:attribute name="employeeOfTheMonth" type="xsd:IDREF" 
      sdoxml:propertyType="company:EmployeeType"/> 
  </xsd:complexType>
  <xsd:complexType name="DepartmentType">
    <xsd:sequence>
      <xsd:element name="employees" type="company:EmployeeType"  
        maxOccurs="unbounded"/>
    </xsd:sequence>
    <xsd:attribute name="name" type="xsd:string"/>
    <xsd:attribute name="location" type="xsd:string"/>
    <xsd:attribute name="number" type="xsd:int"/>
  </xsd:complexType>
  <xsd:complexType name="EmployeeType">
    <xsd:attribute name="name" type="xsd:string"/>
    <xsd:attribute name="SN" type="xsd:ID"/>
    <xsd:attribute name="manager" type="xsd:boolean"/>
  </xsd:complexType>
</xsd:schema>
]]>
    </programlisting>
   </para>
   <para>The XML Data Access Service maps the schema to an SDO. Attributes such as "name"
    become primitive properties, the sequence of employees becomes a many-valued
    containment relationship, and so on. Note that the containment relationships are
    expressed as one complex type within another, whereas non-containment references are
    expressed in terms of ID and IDREF, with a special
    <command>sdoxml:propertyType</command> attribute specifying the type of the
    non-containment reference.
   </para>
  </section>

  <section id="sdo.sample.getset">
   <title>Setting and Getting Property Values</title>
   <para> The following examples assume
    <command>$company</command> is the root of a tree of data objects created from the
    schema and instance document shown above.
   </para>
   <para>
    <example>
     <title>Access via property name</title>
     <para>
      Data object properties can be accessed using the object property
      access syntax.  The following sets the company name to 'Acme'.
     </para>
     <programlisting role="php" id="sdo.examples.propname">
<![CDATA[
<?php
  $company->name = 'Acme';
?>
]]>
     </programlisting>
    </example>
   </para>

   <para>
    <example>
     <title>Access via property name as array index</title>
     <para>We can also access properties using associative array syntax. The simplest
      form of this uses the property name as the array index. For example, the following sets
      the company name and gets the employeeOfTheMonth.
     </para>
     <programlisting role="php" id="sdo.examples.simplexpath">
<![CDATA[
<?php
  $company['name'] = 'UltraCorp';
  $eotm = $company['employeeOfTheMonth'];
?>
]]>
     </programlisting>
    </example>
   </para>

   <para>
    <example>
     <title>Data Object iteration</title>
     <para>
      We can iterate over the properties of a data object using foreach.
      The following iterates over the properties of the employee of the month.
     </para>
     <programlisting role="php" id="sdo.examples.doiter">
<![CDATA[
<?php
  $eotm = $company->employeeOfTheMonth;
  foreach ($eotm as $name => $value) {
      echo "$name: $value\n";
  }
?>
]]>
     </programlisting>
     <para> 
      which will output:
     </para>     
     <programlisting id="sdo.examples.doiter-output">
<![CDATA[
name: Jane Doe
SN: E0003
]]>
     </programlisting>
     <para> 
      The 'manager' property is not output, because it has not been set.
     </para>
    </example>
   </para>
   
   <para>
    <example>
     <title>Access many-valued property by name</title>
     <para> Many-valued data object properties can also be accessed using the object
      property name syntax. The following gets the list of departments.
     </para>
     <programlisting role="php" id="sdo.examples.mvpname">
<![CDATA[
<?php
  $departments = $company->departments;
?>
]]>
     </programlisting>
    </example>
   </para>
   
   <para>
    <example>
     <title>Many-valued element access</title>
     <para>
      We can access individual elements of many-valued properties using array
      syntax. The following accesses the first department in the company.
     </para>
     <programlisting role="php" id="sdo.examples.mvaccess">
<![CDATA[
<?php
  $ad_tech_dept = $company->departments[0];
?>
]]>
     </programlisting>
    </example>
   </para>

   <para>
    <example>
     <title>Many-valued property iteration</title>
     <para>
      Many-valued properties can also be iterated over using
      foreach.  The following iterates over the company's departments.
     </para>
     <programlisting role="php" id="sdo.examples.mvpiter">
<![CDATA[
<?php
  foreach ($company->departments as $department) {
    // ...
  }
?>
]]>
     </programlisting>
     <para>
      Each iteration will assign the next department in the
      list to the variable <command>$department</command>.
     </para>
    </example>
   </para>

   <para>
    <example>
     <title>Chained property access</title>
     <para> We can chain property references on a single line. 
      The following sets and gets the name of the first department.
     </para>
     <programlisting role="php" id="sdo.examples.nestedprop">
<![CDATA[
<?php
  $company->departments[0]->name = 'Emerging Technologies';
  $dept_name = $company->departments[0]->name;
?>
]]>
     </programlisting>
     <para>Using the associative array syntax, this is equivalent to</para>
     <programlisting role="php" id="sdo.examples.chainarray">
<![CDATA[
<?php
  $company['departments'][0]['name'] = 'Emerging Technologies';
  $dept_name = $company['departments'][0]['name'];
?>
]]>
     </programlisting>
     <para> In either case, the dept_name variable is set to 'Emerging Technologies'.
     </para>
    </example>
   </para>

   <para>
    <example>
     <title>XPath navigation</title>    
     <para> The associative array index can be an XPath-like expression. Valid
      expressions are defined by an augmented sub-set of XPath.
     </para>
     <para>
      Two forms of indexing into many-valued properties are supported.  
      The first is the standard XPath array syntax with the indexing
      starting at one, the second is an SDO extension to XPath with an index
      starting at zero.  The standard syntax is:
     </para>
     <programlisting role="php" id="sdo.examples.xpath1nav">
<![CDATA[
<?php
  $jane_doe = $company["departments[1]/employees[2]"];
?>
]]>
     </programlisting>    
     <para>and the SDO XPath extension syntax is:</para> 
     <programlisting role="php" id="sdo.examples.xpath0nav">
<![CDATA[
<?php
  $jane_doe = $company["departments.0/employees.1"];
?>
]]>
     </programlisting>
     <para>
      Both these examples get the second employee from the first department.
     </para>
    </example>
   </para>

   <para>
    <example>
     <title>XPath querying</title>
     <para>
      We can use XPath to query and identify parts of a data object based
      on instance data.  The following retrieves the manager from the
      'Advanced Technologies' department.
     </para>
     <programlisting role="php" id="sdo.examples.xpathquery">
      <![CDATA[
<?php
 $ad_tech_mgr = 
  $company["departments[name='Advanced Technologies']/employees[manager=true]"];
?>
]]>
     </programlisting>
    </example>
   </para>

   <para>
    <example>
     <title>Creating child data objects</title>
     <para>
      A data object can be a factory for its child data objects.  
      A child data object is automatically part of the data graph.  
      The following add a new employee to the 'Advanced Technologies' 
      department.
     </para>
     <programlisting role="php" id="sdo.examples.create">
<![CDATA[
<?php
  $ad_tech_dept = $company["departments[name='Advanced Technologies']"];
  $new_hire = $ad_tech_dept->createDataObject('employees');
  $new_hire->name = 'John Johnson';
  $new_hire->SN = 'E0005';
  $new_hire->manager = false;
?>
]]>
     </programlisting>
    </example>
   </para>

   <para>
    <example>
     <title>Unset a primitive property</title>
     <para>
      We can use the <function>isset</function> and
      <function>unset</function> functions to test and remove items
      from the data object.
     </para>
     <para>
      The following clears the name of the first department.
     </para>
     <programlisting role="php" id="sdo.examples.unsetprim">
<![CDATA[ 
<?php
  unset($company->departments[0]->name);
?>
]]>
     </programlisting>
    </example>
   </para>
      
   <para>
    <example>
     <title>Unset a data object</title>
     <para>
      unset can also be used to remove a data object from the tree.
      The following example shows John Jones leaving the company. 
     </para>
     <programlisting role="php" id="sdo.examples.unsetdo">
<![CDATA[ 
<?php
  unset($company->departments[0]->employees[0]);
?>
]]>
     </programlisting>
    </example>
   </para>
   
   <para>
    <example>
     <title>Unset a referenced data object</title>
     <para>
      The following removes the 'employeeOfTheMonth' from the company.
      If this were a containment relationship then the
      employee would be removed from the company 
      (probably not a good idea to sack your best employee each month!), 
      but since this is a non-containment reference, 
      the employee being referenced will remain in the 
      department in the company,
      but will no longer be accessible via the employeeOfTheMonth property.
     </para>
     <programlisting role="php" id="sdo.examples.unsetrefdo">
<![CDATA[ 
<?php
  if (isset($company->employeeOfTheMonth)) {
    unset($company->employeeOfTheMonth);
  }
?>
]]>
     </programlisting>
    </example>
   </para>
   
   <para>
    <example>
     <title>Access via property index</title>
     <para> Data object properties can be accessed via their property index using array
      syntax. The property index is the position at which the property's definition
      appears in the model (in this case the xml schema). We can see from the schema listing
      above that the company name attribute is the second company property (the SDO
      interface makes no distinction between XML attributes and elements). The following
      sets the company name to 'Acme', with the same result as
      <link linkend="sdo.examples.propname">Access via property name</link>
     </para>
     <programlisting role="php" id="sdo.examples.propindex">
<![CDATA[
<?php
  $company[1] = 'Acme';
?>
]]>
     </programlisting>
     <para> Using the index directly in this way is likely to be fragile. Normally the
      property name syntax should be preferred, but the property index may be required
     in special cases.
     </para>
    </example>
   </para>

  </section>

  <section id="sdo.sample.sequence">
   <title>Working with Sequenced Data Objects</title>
   <para>
    Sequenced data objects are SDOs which can track property
    ordering across the properties of a data object. They can also
    contain unstructured text elements (text element which do not
    belong to any of the SDO's properties).  Sequenced data objects are
    useful for working with XML documents which allow unstructured text (i.e.
    mixed=true) or if the elements can be interleaved (
    <![CDATA[<A/><B/><A/>]]>).  This can occur for example when
    the schema defines maxOccurs>1 on a
    element which is a complexType with a choice order indicator.
   </para>
   <para>
    The examples below assume an SDO created with the following schema
    and instance information, using the XML Data Access Service.
   </para>
   <para>
    The schema below describes the format of a letter.  The letter can
    optionally contain three properties; date, firstName, and lastName.
    The schema states <command>mixed="true"</command> which means that
    unstructured text can be interspersed between the three properties.
   </para>
   <para>
    <programlisting role="xml">
<![CDATA[
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  xmlns:letter="http://letterSchema"
  targetNamespace="http://letterSchema">
  <xsd:element name="letters" type="letter:FormLetter"/>
  <xsd:complexType name="FormLetter" mixed="true">
    <xsd:sequence>
      <xsd:element name="date" minOccurs="0" type="xsd:string"/>
      <xsd:element name="firstName" minOccurs="0" type="xsd:string"/>
      <xsd:element name="lastName" minOccurs="0" type="xsd:string"/>
    </xsd:sequence>
  </xsd:complexType>
</xsd:schema>
          ]]>
    </programlisting>
   </para>

   <para>
    The following is an instance letter document.  It contains the
    three letter properties; date, firstName and lastName, and has
    unstructured text elements for the address and letter body.
   </para>
   <para>
    <programlisting role="xml">
<![CDATA[
<letter:letters xmlns:letter="http://letterSchema">
  <date>March 1, 2005</date>
  Mutual of Omaha
  Wild Kingdom, USA
  Dear
  <firstName>Casy</firstName>
  <lastName>Crocodile</lastName>
  Please buy more shark repellent.
  Your premium is past due.
</letter:letters>
          ]]>
    </programlisting>
   </para>
   <para>
    When loaded, the letter data object will have the sequence and
    property indices shown in the table below:
    <informaltable>
     <tgroup cols='3'>
      <thead>
       <row>
        <entry>Sequence Index</entry>
        <entry>Property Index:Name</entry>
        <entry>Value</entry>
       </row>
      </thead>
      <tbody>
       <row>
        <entry>0</entry>
        <entry>0:date</entry>
        <entry>March 1, 2005</entry>
       </row>
       <row>
        <entry>1</entry>
        <entry>-</entry>
        <entry>Mutual of Omaha</entry>
       </row>
       <row>
        <entry>2</entry>
        <entry>-</entry>
        <entry>Wild Kingdom, USA</entry>
       </row>
       <row>
        <entry>3</entry>
        <entry>-</entry>
        <entry>Dear</entry>
       </row>
       <row>
        <entry>4</entry>
        <entry>1:firstName</entry>
        <entry>Casy</entry>
       </row>
       <row>
        <entry>5</entry>
        <entry>2:lastName</entry>
        <entry>Crocodile</entry>
       </row>
       <row>
        <entry>6</entry>
        <entry>-</entry>
        <entry>Please buy more shark repellent.</entry>
       </row>
       <row>
        <entry>7</entry>
        <entry>-</entry>
        <entry>Your premium is past due.</entry>
       </row>
      </tbody>
     </tgroup>
    </informaltable>
   </para>

   <para>
    To ensure sequence indices are maintained, sequenced data objects
    should be manipulated through the SDO_Sequence interface.  
    This allows the data object's instance data to be manipulated 
    in terms of the sequence index as opposed to the property index 
    (shown in the table above).  
    The following examples assume the letter instance has been 
    loaded into a data object referenced by the variable
    <command>$letter</command>.
    <example>
     <title>Getting the SDO_Sequence interface</title>
     <para>
      We obtain a data object's sequence using the
      <function>getSequence</function>
      method. The follow gets the
      sequence for the letter data object.
     </para>
     <programlisting role="php" id="sdo.examples.seqinterface">
<![CDATA[ 
<?php
  $letter_seq = $letter->getSequence();
?>
]]>
     </programlisting>
    </example>
   </para>
   <para>
    All subsequent examples assume that the
    <command>$letter_seq</command>
    variable has been assigned the sequence for the letter data object.
   </para>

   <para>
    <example>
     <title>Get/set sequence values</title>
     <para>
      We can get and set individual values (including unstructured text)
      using the sequence index.  
      The following sets the firstName to 'Snappy' and gets the last 
      sequence values (the unstructured text, 'Your premium is past due.').
     </para>
     <programlisting role="php" id="sdo.examples.getsetseq">
<![CDATA[ 
<?php
  $letter_seq[4] = 'Snappy';
  $text = $letter_seq[count($letter_seq) - 1];
?>
]]>
     </programlisting>
    </example>
   </para>

   <para>
    <example>
     <title>Sequence iteration</title>
     <para>
      We can iterate through the individual sequence values using foreach.
      The following runs through the individual values in sequence order.
     </para>
     <programlisting role="php" id="sdo.examples.seqiter">
<![CDATA[ 
<?php
  foreach ($letter->getSequence() as $value) {
    // ...
  }
?>
]]>
     </programlisting>
    </example>
   </para>

   <para>
    <example>
     <title>Sequence versus Data Object</title>
     <para>
      Setting values through the data object interface may result in the
      value not being part of the sequence.  A value set through the data
      object will only be accessible through the sequence if the property was
      already part of the sequence. The following example sets the
      lastName through the data object and gets it through the sequence.
      This is fine because lastName already exists in the sequence.  If
      it had not previously been set, then lastName would be set to
      'Smith', but would not be part of the sequence.
     </para>
     <programlisting role="php" id="sdo.examples.seqvsdo">
<![CDATA[ 
<?php
  $letter[2] = 'Smith';
  $last_name = $letter_seq[5];
?>
]]>
     </programlisting>
    </example>
   </para>

   <para>
    <example>
     <title>Adding to a sequence</title>
     <para>
      We can add new values to a sequence using the
      <link linkend='function.SDO-Sequence-insert'><function>SDO_Sequence::insert</function></link>
      method.  The following examples assume that the 'firstName' and 
      'lastName' properties are initially unset.
     </para>
     <programlisting role="php" id="sdo.examples.seqadd">
<![CDATA[ 
<?php
  // Append a firstName value to the sequence
  // value: 'Smith'
  // sequence index: NULL (append)
  // propertyIdentifier: 1 (firtName property index)
  $letter_seq->insert('Smith', NULL, 1);

  // Append a lastName value to the sequence
  // value: 'Jones'
  // sequence index: NULL (append)
  // propertyIdentifier: 'lastName' (lastName property name)
  $letter_seq->insert('Jones', NULL, 'lastName');

  // Append unstructured text
  // value: 'Cancel Subscription.'
  // sequence index: absent (append)
  // propertyIdentifier: absent (unstructured text)
  $letter_seq->insert('Cancel Subscription.');

  // Insert new unstructured text.  Subsequent sequence values
  // are shifted up.                                       
  // value: 'Care of:'
  // sequence index: 1 (insert as second element)
  // propertyIdentifier: absent (unstructured text)
  $letter_seq->insert('Care of:', 1);
?>
]]>
     </programlisting>
    </example>
   </para>

   <para>
    <example>
     <title>Removing from a sequence</title>
     <para>
      We can use the <function>isset</function>  and
      <function>unset</function> functions to test and remove items
      from the sequence (Note: <function>unset</function> currently
      leaves the values in the data object, but this behaviour is
      likely to change to also remove the data from the data object).
      A sequence behaves like a contiguous list; therefore, removing
      items from the middle will shift entries at higher indices
      down. The following example tests to see if the first sequence
      element is set and unsets it if is.
     </para>
     <programlisting role="php" id="sdo.examples.seqremove">
<![CDATA[ 
<?php
  if (isset($letter_seq[0])) {
    unset($letter_seq[0]);
  }
?>
]]>
     </programlisting>
    </example>
   </para>

  </section>


  <section id="sdo.sample.reflection">
   <title>Reflecting on Service Data Objects</title>
   <para>
    SDOs have a knowledge of the structure they have been created to 
    represent (the model).  For example, a Company SDO created using 
    <link linkend="sdo.examples">the Company XML schema</link> above
    would only be permitted to contain DepartmentType data objects 
    which in turn could only contain EmployeeType data objects.
   </para>
   <para>
    Sometimes it is useful to be able to access this model information at 
    runtime.  For example, this could be used to automatically generate 
    a user interface for populating a data object.  The model information 
    is accessed using reflection.  
   </para>

   <para>
    <example>
     <title>Reflecting on a Data Object</title>
     <para>
      The following example shows how we can reflect on an empty Employee 
      data object.
     </para>
     <programlisting role="php" id="sdo.examples.reflection">
<![CDATA[ 
<?php
  // Create the employee data object (e.g. from an XML Data Access Service)
  $employee = ...;
  $reflection = new SDO_Model_ReflectionDataObject($employee);
  print($reflection);
?>
]]>
     </programlisting>
     &example.outputs;

     <screen>
<![CDATA[
object(SDO_Model_ReflectionDataObject)#4 { - ROOT OBJECT - Type { 
companyNS:EmployeeType[3] { commonj.sdo:String $name; 
commonj.sdo:String $SN; commonj.sdo:Boolean $manager; } }
]]>
     </screen>
     <para>
      Using print on the SDO_Model_ReflectionDataObject writes out the data 
      object's model.  We can see from the output how the type 
      companyNS:EmployeeType has three properties and we can see the names 
      of the properties along with their types.  Note, the primitive types
      are listed as SDO types (e.g. commonj.sdo namespace, String type).  
      It is worth noting that this is the SDO model and when these are 
      surfaced to an application they can be treated as the PHP equivalent 
      types (e.g. string and boolean).
     </para>
    </example>
   </para>

   <para>
    <example>
     <title>Accessing the type information</title>
     <para>
      We can query the type information of a data object using reflection.  
      The following example checks the type corresponds to a data object
      rather than a primitive and then iterates through the properties of
      the type, writing out the name of each property ($type and $property 
      are SDO_Model_Type and SDO_Model_Property objects, respectively).
     </para>
     <programlisting role="php" id="sdo.examples.reflection.type">
<![CDATA[ 
<?php
    // Create the employee data object (e.g. from an XML Data Access Service)
    $employee = ...;
    $reflection = new SDO_Model_ReflectionDataObject($employee);
    $type = $reflection->getType();
    if (! $type->isDataType()) {
        foreach ($type->getProperties() as $property) {
            print $property->getName() . "\n";
        }
    }
?>
]]>
     </programlisting>
     &example.outputs;
     <screen>
<![CDATA[
name
SN
manager
]]>
     </screen>
    </example>
   </para>

  </section>





  <!-- class definition section -->
  <section id='sdo.classes'>
   &reftitle.classes;
   <para>
    SDO consists of three sets of interfaces.  The first set covers those
    interfaces for use by typical SDO applications.  These are identified 
    by the package prefix 'SDO_'.  The second set is those used to reflect 
    on, and work with, the model of a data object.  These are identified 
    by the package prefix 'SDO_Model_'.  Finally, the third set are those 
    use by Data Access Service implementations and are identified by the 
    package prefix 'SDO_DAS_'.  The majority of SDO users will not need to 
    use or understand the 'SDO_Model_' and 'SDO_DAS_' interfaces.
   </para>

   <section id='sdo.class.sdo-apis'>
    <title>SDO Application Programmer Interface</title>

    <section id='sdo.class.sdo-dataobject'>
     <title>
      <classname>SDO_DataObject</classname>
     </title>
     <para>
      The main interface through which data objects are manipulated.  In
      addition to the methods below, SDO_DataObject extends the
      ArrayAccess, SDO_PropertyAccess (defines <function>__get</function> /
      <function>__set</function> methods for property access overloading),
      Iterator, and Countable interfaces.
     </para>
     <section id='sdo.class.SDO_DataObject.methods'> &reftitle.methods;
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-DataObject-getSequence'>getSequence</link>
         - get the sequence for the data object
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DataObject-createDataObject'>createDataObject</link>
         - create a child data object
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DataObject-clear'>clear</link>
         - unset the properties of a data object
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DataObject-getContainer'>getContainer</link>
         - get the container (also known as 'parent') of this data object
        </para>
       </listitem>      
       <listitem>
        <para>
         <link linkend='function.SDO-DataObject-getTypeName'>getTypeName</link>
         - get the name of the type for this data object
        </para>
       </listitem>     
       <listitem>
        <para>
         <link linkend='function.SDO-DataObject-getTypeNamespaceURI'>getTypeNamespaceURI</link>
         - get the namespace URI of the type for this data object
        </para>
       </listitem>
      </itemizedlist>
     </section>
    </section>

    <section id='sdo.class.sdo-sequence'>
     <title>
      <classname>SDO_Sequence</classname>
     </title>
     <para>
      The interface through which sequenced data objects can be accessed
      to preserve ordering across a data object's properties and 
      to allow unstructured text.  
      SDO_Sequence preserves contiguous indices and therefore inserting 
      or removing elements may shift other elements up or
      down. In addition to the methods below, SDO_Sequence extends the
      ArrayAccess, Iterator and Countable interface.
     </para>
     <section id='sdo.class.SDO_Sequence.methods'>
      &reftitle.methods;
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-Sequence-getProperty'>getProperty</link> 
         - get the property for a given sequence index
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-Sequence-move'>move</link>
         - move an element from one property index to another
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-Sequence-insert'>insert</link>
         - insert a new value into the sequence
        </para>
       </listitem>
      </itemizedlist>
     </section>
    </section>

    <section id='sdo.class.sdo-list'>
     <title>
      <classname>SDO_List</classname>
     </title>
     <para>
      The interface through which many-valued properties are manipulated.
      In addition to the method defined below, SDO_List extends ArrayAccess,
      Iterator and Countable.  SDO_List preserves contiguous indices and
      therefore inserting or removing elements may shift other elements
      up or down.
     </para>
     <section id='sdo.class.SDO-List.methods'>
      &reftitle.methods;
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-List-insert'>insert</link> 
         - insert a new value into the list
        </para>
       </listitem>
      </itemizedlist>
     </section>
    </section>

    <section id='sdo.class.sdo-datafactory'>
     <title>
      <classname>SDO_DataFactory</classname>
     </title>
     <para>
      The interface through which data objects can be created.  
      A Data Access Service is responsible for populating the model 
      (i.e. configuring the data factory with the type and structure 
      information for the data objects it can create.) 
      for the factory and can then optionally return an instance of, 
      or implement, the SDO_DataFactory interface.
     </para>
     <section id='sdo.class.SDO-DataFactory.methods'>
      &reftitle.methods;
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-DataFactory-create'>create</link> 
         - create a new data object
        </para>
       </listitem>
      </itemizedlist>
     </section>
    </section>
        
    <section id='sdo.class.sdo-exception'>
     <title>
      <classname>SDO_Exception</classname>
     </title>
     <para>
      An SDO_Exception is thrown when the caller's request cannot be completed.
      The subclasses of SDO_Exception are:
      <itemizedlist>
       <listitem>
        <para>SDO_PropertyNotSetException -
        the property specified exists but has not been set or does not have a
        default value
        </para>
       </listitem>
       <listitem>
        <para>SDO_PropertyNotFoundException -
        the property specified is not part of the data object's type
        </para>
       </listitem>
       <listitem>
        <para>SDO_TypeNotFoundException -
        the specified namespace URI or type name is unknown
        </para>
       </listitem>
       <listitem>
        <para>SDO_InvalidConversionException -
        conversion between the types of the assignment is not possible 
        </para>
       </listitem>
       <listitem>
        <para>SDO_IndexOutOfBoundsException -
        the numeric index into a data object, sequence or list is not in the
        valid range 
        </para>
       </listitem>
       <listitem>
        <para>SDO_UnsupportedOperationException -
        the request cannot be completed because it is not allowed,
        for example an attempt to set a read-only property.
        </para>
       </listitem>
      </itemizedlist>
     </para>
     <section id='sdo.class.SDO_Exception.methods'> &reftitle.methods;
     <para>One method is added to those inherited from the built in 
     <link linkend='language.exceptions.extending'>Exception</link> class:
     </para>
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-Exception-getCause'>getCause</link> 
         - get the cause of this SDO_Exception
        </para>
       </listitem>

      </itemizedlist>
     </section>
    </section>
    
   </section>



   <section id='sdo.class.sdo-model-apis'>
    <title>SDO Reflection Application Programmer Interfaces</title>

    <section id='sdo.class.sdo-reflectiondataobject'>
     <title>
      <classname>SDO_Model_ReflectionDataObject</classname>
     </title>
     <para>
      The main interface used to reflect on a data object instance 
      to obtain its model type and property information.  
      It is designed to follow the reflection pattern introduced in PHP 5.
     </para>
     <section id='sdo.class.SDO_Model_ReflectionDataObject.constructor'> 
       &reftitle.constructor;     
       <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-ReflectionDataObject-construct'>__construct</link>
         - construct a new SDO_Model_ReflectionDataObject.
        </para>
       </listitem>     
      </itemizedlist>
     </section>
     <section id='sdo.class.SDO_Model_ReflectionDataObject.methods'> 
       &reftitle.methods;
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-ReflectionDataObject-export'>export</link>
         - get a string describing the data object.
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-ReflectionDataObject-getType'>getType</link>
         - get the SDO_Model_Type for the data object.
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend=
          'function.SDO-Model-ReflectionDataObject-getInstanceProperties'>getInstanceProperties</link>
         - get the instance properties of the data object.
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend=
          'function.SDO-Model-ReflectionDataObject-getContainmentProperty'>getContainmentProperty</link>
         - get the property which defines the containment relationship to the data object.
        </para>
       </listitem>
      </itemizedlist>
     </section>
    </section>

    <section id='sdo.class.sdo-type'>
     <title>
      <classname>SDO_Model_Type</classname>
     </title>
     <para>
      The interface through which a data object's type information can be 
      retrieved.  This interface can be used to find out the type name and 
      namespace URI of the type, whether the type allow open content, and so 
      on.
     </para>
     <section id='sdo.class.SDO_Model_Type.methods'> &reftitle.methods;
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-Type-getName'>getName</link>
          - get the name of the type.
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-Type-getNamespaceURI'>getNamespaceURI</link>
         - get the namespace URI of the type.
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-Type-isInstance'>isInstance</link>
         - test for a data object being an instance of the type.
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-Type-getProperties'>getProperties</link>
         - get the properties of the type.
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-Type-getProperty'>getProperty</link>
         - get a property of the type.
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-Type-isDataType'>isDataType</link>
         - test to see if this type is a primitive scalar type.
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-Type-isSequencedType'>isSequencedType</link>
         - test to see if this is a sequenced type.
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-Type-isOpenType'>isOpenType</link>
         - test to see if this is an open type.
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-Type-isAbstractType'>isAbstractType</link>
         - test to see if this is an abstract type.
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-Model-Type-getBaseType'>getBaseType</link>
         - get the base type of this type (if one exists).
        </para>
       </listitem>
      </itemizedlist>
     </section>
    </section>

    <section id='sdo.class.sdo-property'>
     <title>
      <classname>SDO_Model_Property</classname>
     </title>
     <para>
      The interface through which a data object's property information can 
      be retrieved.  This interface can be used to find out the type of a 
      property, whether a property has a default value, whether the 
      property is contained or reference by its parent, its cardinality, 
      and so on.
     </para>
     <section id='sdo.class.SDO_Model_Property.methods'> &reftitle.methods;
      <itemizedlist>
        <listitem>
         <para>
          <link linkend='function.SDO-Model-Property-getName'>getName</link>
          - get the name of the property.
         </para>
        </listitem>
        <listitem>
         <para>
          <link linkend='function.SDO-Model-Property-getType'>getType</link>
          - get the type of the property.
         </para>
        </listitem>
        <listitem>
         <para>
          <link linkend='function.SDO-Model-Property-isMany'>isMany</link>
          - test to see if the property is many-valued.
         </para>
        </listitem>
        <listitem>
         <para>
          <link linkend='function.SDO-Model-Property-isContainment'>isContainment</link>
          - test to see if the property describes a containment relationship.
         </para>
        </listitem>
        <listitem>
         <para>
          <link linkend='function.SDO-Model-Property-getContainingType'>getContainingType</link>
          - get the type which contains this property.
         </para>
        </listitem>
        <listitem>
         <para>
          <link linkend='function.SDO-Model-Property-getDefault'>getDefault</link>
          - get the default value for a property.
         </para>
        </listitem>
      </itemizedlist>
     </section>
    </section>



   </section>

   <section id='sdo.class.sdo-das-spis'>
    <title>
     SDO Data Access Service Developer Interfaces
    </title>

    <section id='sdo.class.sdodas-dataobject'>
     <title>
      <classname>SDO_DAS_DataObject</classname>
     </title>
     <para>
      The interface through which a Data Access Service can access 
      a data object's 
      <link linkend='sdo.class.sdodas-changesummary'>SDO_DAS_ChangeSummary</link>.
      The change summary is used by the Data Access Service to check for 
      conflicts when applying changes back to a data source.
     </para>
     <section id='sdo.class.SDO_DAS_DataObject.methods'> &reftitle.methods;
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-DataObject-getChangeSummary'>getChangeSummary</link> 
         - get the change summary for a data object
        </para>
       </listitem>

      </itemizedlist>
     </section>
    </section>

    <section id='sdo.class.sdodas-changesummary'>
     <title>
      <classname>SDO_DAS_ChangeSummary</classname>
     </title>
     <para>
      The interface through which the change history of a data
      object is accessed.  The change summary holds information for any
      modifications on a data object which occurred since logging
      was activated.  In the case of deletions and modifications, the old
      values are also held in the change summary.
     </para>
     <para>
      If logging is no longer active
      then the change summary only holds changes made up to the point when
      logging was deactivated.  
      Reactivating logging clears the change summary.
      This is useful when a set of changes have been written out by a
      DAS and the data object is to be reused.
     </para>
     <section id='sdo.class.SDO_DAS_ChangeSummary.methods'>
      &reftitle.methods;
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-ChangeSummary-beginLogging'>beginLogging</link> 
         - begin logging changes made to a data object
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-ChangeSummary-endLogging'>endLogging</link> 
         - end logging changes made to a data object
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-ChangeSummary-isLogging'>isLogging</link> 
         - test to see if change logging is on
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-ChangeSummary-getChangedDataObjects'>getChangedDataObjects</link> 
         - get a list of the data objects which have been changed
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-ChangeSummary-getChangeType'>getChangeType</link> 
         - get the type of change which has been made to a data object
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-ChangeSummary-getOldValues'>getOldValues</link> 
         - get a list of old values for a data object
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-ChangeSummary-getOldContainer'>getOldContainer</link> 
         - get the old container data object for a deleted data object
        </para>
       </listitem>
      </itemizedlist>
     </section>
    </section>

    <section id='sdo.class.sdodas-setting'>
     <title>
      <classname>SDO_DAS_Setting</classname>
     </title>
     <para>
      The interface through which the old value for a property is
      accessed. A list of settings is returned by the change summary method
      <link linkend='function.SDO-DAS-ChangeSummary-getOldValues'>
       <function>getOldValues</function>
      </link>.
     </para>
     <section id='sdo.class.SDO_DAS_Setting.methods'>
      &reftitle.methods;
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-Setting-getPropertyIndex'>getPropertyIndex</link> 
         - get the property index for the changed property
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-Setting-getPropertyName'>getPropertyName</link> 
         - get the property name for the changed property
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-Setting-getValue'>getValue</link> 
         - get the old value for the changed property
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-Setting-getListIndex'>getListIndex</link> 
         - get the list index for the old value if it was part of a 
         many-valued property
        </para>
       </listitem>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-Setting-isSet'>isSet</link>
         - test to see if the property was set prior to being modified
         </para>
       </listitem>
      </itemizedlist>
     </section>
    </section>

    <section id='sdo.class.sdodas-datafactory'>
     <title>
      <classname>SDO_DAS_DataFactory</classname>
     </title>
     <para>
      The interface for constructing the model for an SDO_DataObject.
      The SDO_DAS_DataFactory is an abstract class providing a static
      method which returns a concrete data factory implementation.
      The implementation is used by Data Access Services to create an 
      SDO model from their model.
      For example, a Relational Data Access Service might create and populate
      an SDO_DAS_DataFactory model based on a schema for a relational
      database.
     </para>
     <section id='sdo.class.SDO_DAS_DataFactory.methods'>
      &reftitle.methods;
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-DataFactory-getDataFactory'>getDataFactory</link> 
         - static methods for getting a concrete data factory instance
        </para>
       </listitem>
      </itemizedlist>
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-DataFactory-addType'>addType</link> 
         - add a new type to the SDO model
        </para>
       </listitem>
      </itemizedlist>
      <itemizedlist>
       <listitem>
        <para>
         <link linkend='function.SDO-DAS-DataFactory-addPropertyToType'>addPropertyToType</link> 
         - add a new property to a type definition in the SDO model
        </para>
       </listitem>
      </itemizedlist>
     </section>
    </section>
   </section>
  </section>

  &reference.sdo.constants;

 </partintro>

 &reference.sdo.functions;

</reference>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
indent-tabs-mode:nil
sgml-parent-document:nil
sgml-default-dtd-file:"../../../manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->