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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-1197F032-1B73-58E1-8B45-E5D58B9DF788" xml:lang="en"><title>Domain

    13 Management Policy DLL</title><shortdesc>This provides an implementation of the domain tree, and a suitable

    14 implementation of the <apiname>DmPolicy</apiname> class that the domain manager

    15 uses to access that tree.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    16 <p>A base port must supply a Domain Policy DLL that defines a domain tree.

    17 The domain manager uses the domain tree, which represents the domain hierarchy. </p>

    18 <p>The domain tree is a static structure that is defined by domain management

    19 policy at system initialization, and remains fixed after system initialization. </p>

    20 <p>The policy that governs the management of domains and its implementation

    21 is entirely up to the device. The only mandatory requirement that Symbian

    22 platform makes is that you supply a Domain Policy DLL. This provides an implementation

    23 of the domain tree, and a suitable implementation of the <xref href="GUID-15CAA28D-943B-3B92-B4E1-8AA466DFA407.dita"><apiname>DmPolicy</apiname></xref> class

    24 that the domain manager uses to access that tree. A default implementation

    25 is provided by Symbian platform. </p>

    26 <fig id="GUID-C902A1BA-C300-5A93-8385-F4D39FB6F86A">

    27 <image href="GUID-CE3C8A77-8797-53FB-984E-A91A413BA254_d0e363473_href.png" placement="inline"/>

    28 </fig>

    29 <p>The domain hierarchy itself is defined in terms of a simple array of <xref href="GUID-15A31C41-77E0-3E6D-B106-D4FBFA9A52C6.dita"><apiname>TDmDomainSpec</apiname></xref> objects.

    30 Each <codeph>TDmDomainSpec</codeph> item defines a domain, its characteristics,

    31 and its position in the domain hierarchy. A default domain hierarchy is supplied

    32 by Symbian platform, but domain management policy can define additional domain

    33 identifiers, <xref href="GUID-4F284AB0-85A5-3871-B973-8BCAB4AA91BC.dita"><apiname>TDmDomainId</apiname></xref> types, and consequently domains.

    34 The only requirement that the domain manager makes is that the root of the

    35 domain tree must have domain Id <codeph>KDmIdRoot</codeph>. </p>

    36 <fig id="GUID-7590D6B6-A264-58A6-8764-8491020B921C">

    37 <title>           Default domain tree          </title>

    38 <image href="GUID-32C58139-E341-5A15-B20C-D3EA4117AC6E_d0e363498_href.png" placement="inline"/>

    39 </fig>

    40 <p>The default domain hierarchy supplied by Symbian platform in <filepath>domainpolicy.cpp</filepath> is

    41 simply: </p>

    42 <codeblock id="GUID-89939191-2C55-54B5-BCBA-DA8D1430D849" xml:space="preserve">static const TDmDomainSpec    DomainHierarchy[] = 

    43     

    44     {

    45         { KDmIdRoot,    KDmIdNone,    KCapabilityWriteSystemData, EPwActive,    100000 /* 100ms */    },

    46         { KDmIdApps,    KDmIdRoot,    KCapabilityNone,            EPwActive,    100000 /* 100ms */    },

    47         { KDmIdUiApps,    KDmIdRoot,    KCapabilityNone,            EPwActive,    100000 /* 100ms */    },

    48         { KDmIdNone,    KDmIdNone,    0,                            EPwActive,    0    }

    49     };

    50     </codeblock>

    51 <p>The domain manager uses the domain tree specification (i.e. the <codeph>TDmDomainSpec</codeph> array)

    52 to build its own internal representation of the domain hierarchy. It calls <xref href="GUID-15CAA28D-943B-3B92-B4E1-8AA466DFA407.dita#GUID-15CAA28D-943B-3B92-B4E1-8AA466DFA407/GUID-A3E21E8F-5920-3DBD-B735-D4B8DE8E382D"><apiname>DmPolicy::GetDomainSpecs()</apiname></xref> to

    53 access the domain tree specification, and calls <xref href="GUID-15CAA28D-943B-3B92-B4E1-8AA466DFA407.dita#GUID-15CAA28D-943B-3B92-B4E1-8AA466DFA407/GUID-5A1DD864-7059-3322-8DF2-BB7A53237CB6"><apiname>DmPolicy::Release()</apiname></xref> to

    54 free that specification. The default implementation of <codeph>GetDomainSpecs()</codeph> simply

    55 returns a pointer to the specification, which means that the default implementation

    56 of <codeph>Release()</codeph> has nothing to do, and is indeed empty. </p>

    57 </conbody></concept>