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<chapter xml:id='chap-synchronization'

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<title>Synchronization</title>

<para>The synchronization engine is the core of OpenIDM.</para>

<para/>

<sect1>

<title>Configuration</title>

<para>Configuration of the synchronization service is provided through the following configuration object:</para>

<sect2>

<title>Usage</title>

<example>

<literallayout class="monospaced">

<code><![CDATA[

}]]>

</code>

</literallayout>

</example>

</sect2>

<sect2>

<title>Properties</title>

<variablelist>

<varlistentry>

<term>mappings</term>

<listitem>

<para>array of object-mapping objects, required</para>

<para>Specifies the mappings between objects that the synchronization engine manages.</para>

</listitem>

</varlistentry>

</variablelist>

</sect2>

<sect2>

<title>object-mapping object</title>

<para/>

<para>Specifies the configuration of each mapping.</para>

<sect3>

<title>Usage</title>

<example>

<literallayout class="monospaced">

<code><![CDATA[

}]]>

</code>

</literallayout>

</example>

</sect3>

<sect3>

<title>Properties</title>

<variablelist>

<varlistentry>

<term>name</term>

<listitem>

<para>string, required</para>

<para>Uniquely names the object mapping. Used in the link object identifier.</para>

</listitem>

</varlistentry>

<varlistentry>

<term>source</term>

<listitem>

<para>string, required</para>

<para>Specifies the path of the source object set. Example: "managed/user".</para>

</listitem>

</varlistentry>

<varlistentry>

<term>target</term>

<listitem>

<para>string, required</para>

<para>Specifies the path of the target object set. Example: "system/ldap/account".</para>

</listitem>

</varlistentry>

<varlistentry>

<term>validSource</term>

<listitem>

<para>script object, optional</para>

<para>A script that determines if a source object is valid to be mapped. The script yields a boolean value; true indicates the source object is valid; false can be used to defer mapping until some condition is met. In the root scope, the source object is provided in the "source" property. If the script is not specified, then all source objects are considered valid.</para>

</listitem>

</varlistentry>

<varlistentry>

<term>validTarget</term>

<listitem>

<para>script object, optional</para>

<para>A script used during reconciliation that determines if a target object is valid to be mapped. The script yields a boolean value; true indicates the target object is valid; false indicates that the target object should not be included in reconciliation. In the root scope, the source object is provided in the "target" property. If the script is not specified, then all target objects are considered valid for mapping.</para>

</listitem>

</varlistentry>

<varlistentry>

<term>targetCorrelation</term>

<listitem>

<para>target-correlation object, optional</para>

<para>A script that builds a query object and script that filters the result when a source object has no linked target. See the correlation object section below.</para>

</listitem>

</varlistentry>

<varlistentry>

<term>properties</term>

<listitem>

<para>array of property-mapping objects, optional</para>

<para>Specifies mappings between source object properties and target object properties, with optional transformation scripts.</para>

</listitem>

</varlistentry>

<varlistentry>

<term>policies</term>

<listitem>

<para>array of policy objects, optional</para>

<para>Specifies a set of link conditions and associated actions to take in response. </para>

</listitem>

</varlistentry>

<varlistentry>

<term>onCreate</term>

<listitem>

<para>script object, optional</para>

<para>A script to execute when a target object is to be created, after property mappings have been applied. In the root scope, the source object is provided in the "source" property, projected target object in the "target" property and the link situation that led to the create operation in "situation". The _id property in the target object can be modified, allowing the mapping to select an identifier; if not set then the identifier is expected to be set by the target object set. If the script throws an exception, then target object creation is aborted.</para>

</listitem>

</varlistentry>

<varlistentry>

<term>onUpdate</term>

<listitem>

<para>script object, optional</para>

<para>A script to execute when a target object is to be updated, after property mappings have been applied. In the root scope, the source object is provided in the "source" property, projected target object in the "target" property, link situation that led to the update operation in "situation". If the script throws an exception, then target object update is aborted.</para>

</listitem>

</varlistentry>

</variablelist>

</sect3>

</sect2>

<sect2>

<title>target-correlation object </title>

<para/>

<para>Provides the mechanism to locate an existing target object to link to a source object when a link between the two is qualified. Can provide more than one candidate, which will result in the "AMBIGUOUS" situation, documented below. </para>

<sect3>

<title>Usage</title>

<example>

<literallayout class="monospaced">

<code><![CDATA[

}]]>

</code>

</literallayout>

</example>

</sect3>

<sect3>

<title>Properties</title>

<variablelist>

<varlistentry>

<term>query</term>

<listitem>

<para>script object, required</para>

<para>A script that builds the query that will be performed on the target object set. The format of the query and the result are at defined by the target object set. In the root scope, the source object is provided in the "source" property. </para>

</listitem>

</varlistentry>

<varlistentry>

<term>filter</term>

<listitem>

<para>script object, required</para>

<para>Filters the executed query result, yielding an array of target object identifiers. The query result is provided in the "result" property in the root scope.</para>

</listitem>

</varlistentry>

</variablelist>

</sect3>

</sect2>

<sect2>

<title>property object</title>

<para/>

<para>Specifies how the value of a target property is determined.</para>

<sect3>

<title>Usage</title>

<example>

<literallayout class="monospaced">

<code><![CDATA[

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</code>

</literallayout>

</example>

</sect3>

<sect3>

<title>Properties</title>

<variablelist>

<varlistentry>

<term>target</term>

<listitem>

<para>string, required</para>

<para>Specifies the path of the property in the target object to map to.</para>

</listitem>

</varlistentry>

<varlistentry>

<term>source</term>

<listitem>

<para>string, optional</para>

<para>Specifies the path of the property in the source object to map from. If not specified, then the target property value will be derived from the script or default value.</para>

</listitem>

</varlistentry>

<varlistentry>

<term>script</term>

<listitem>

<para>script object, optional</para>

<para>An script to determine the target property value. The root scope contains value of the source property in the "source" property (if specified). The resulting value yielded by the script is stored in the target property. </para>

</listitem>

</varlistentry>

<varlistentry>

<term>default</term>

<listitem>

<para>any value, optional</para>

<para>Specifies the value to assign to the target property if a non-null value is not established by "source" and/or "transform". If not specified, the default value is null.</para>

</listitem>

</varlistentry>

</variablelist>

</sect3>

</sect2>

<sect2>

<title>policy object</title>

<para/>

<para>Specifies a link condition and the associated actions to take in response. </para>

<sect3>

<title>Usage</title>

<example>

<literallayout class="monospaced">

<code><![CDATA[

}]]>

</code>

</literallayout>

</example>

</sect3>

<sect3>

<title>Properties</title>

<variablelist>

<varlistentry>

<term>situation</term>

<listitem>

<para>string, required</para>

<para>Specifies the situation for which an associated action is to be defined. For a set of valid situation and default actions, see the Situations section, below.</para>

</listitem>

</varlistentry>

<varlistentry>

<term>action</term>

<listitem>

<para>string or script object, required</para>

<para>Specifies the action to perform. If a script is specified, the script is executed and is expected to yield a string containing the action to perform. For a set of valid actions, see the Actions section, below.</para>

</listitem>

</varlistentry>

</variablelist>

</sect3>

</sect2>

<sect2>

<title>Situations</title>

<para/>

<para>The following conditions are supported:</para>

<para/>

<para>"CONFIRMED" (qualifies=1, link=1, target=1)</para>

<para>The mapping qualifies for a target object and there is an existing link to a target object. Detected during change events and reconciliation. Default action: "IGNORE".</para>

<para/>

<para>"FOUND" (qualifies=1, link=0, target=1)</para>

<para>The mapping qualifies for a target object, there is no link to a target object, and there is a single correlated target object to link. Detected during change events and reconciliation. Default action: "LINK".</para>

<para/>

<para>"ABSENT" (qualifies=1, link=0, target=0)</para>

<para>The mapping qualifies for a target object, there is no link to a target object, and there is no correlated target object to link. Detected during change events and reconciliation. Default action: "CREATE".</para>

<para/>

<para>"AMBIGUOUS" (qualifies=1, link=0, target&gt;1)</para>

<para>The mapping qualifies for a target object, there is no link to a target object, but there is more than one correlated target object to link. Detected during change events and reconciliation. Default action: "EXCEPTION".</para>

<para/>

<para>"MISSING" (qualifies=1, link=1, target=0)</para>

<para>The mapping is qualified for a target object and there is a qualified link to a target object, but the target object is missing. Only detected during reconciliation and synchronous operations. Default action: "EXCEPTION".</para>

<para/>

<para>"UNQUALIFIED" (qualifies=0, link=1)</para>

<para>The mapping is not qualified for a target object and there is a link to an existing target object. Detected during change events and reconciliation. Default action: "DELETE".</para>

<para/>

<para>"UNASSIGNED" (qualifies=0, link=0, target=1)</para>

<para>There is target object for which there is no link. Only detected during reconciliation. Default action: "EXCEPTION".</para>

<para/>

</sect2>

<sect2>

<title>Actions</title>

<para/>

<para>"CREATE"</para>

<para>A target object is projected, created and linked.</para>

<para/>

<para>"LINK"</para>

<para>A correlated target object is linked and updated.</para>

<para/>

<para>"UNLINK"</para>

<para>A linked target object is unlinked and updated.</para>

<para/>

<para>"DELETE"</para>

<para>The linked target object is unlinked and deleted.</para>

<para/>

<para>"IGNORE"</para>

<para>No change to existing link state is made. If there is no linked target object to update as a result, no updates are applied.</para>

<para/>

<para>"EXCEPTION"</para>

<para>The condition is flagged as an exception. This aborts any change event. In reconciliation, the condition is reported as exceptional.</para>

<para/>

</sect2>

<sect2>

<title>script object</title>

<para/>

<sect3>

<title>Usage</title>

<example>

<literallayout class="monospaced">

<code><![CDATA[

}]]>

</code>

</literallayout>

</example>

<para/>

</sect3>

<sect3>

<title>Properties</title>

<variablelist>

<varlistentry>

<term>type</term>

<listitem>

<para>string, required</para>

<para>Specifies the type of script to be executed. Presently, only "text/javascript" is supported.</para>

</listitem>

</varlistentry>

<varlistentry>

<term>source</term>

<listitem>

<para>string, required</para>

<para>Specifies the source code of the script to be executed.</para>

</listitem>

</varlistentry>

</variablelist>

</sect3>

</sect2>

</sect1>

<sect1>

<title>Links</title>

<para>To maintain links between source and target objects in mappings, an object set is stored in the repository. The object set identifier follows this scheme:</para>

<para/>

<para>links/{mapping}</para>

<para/>

<para>{mapping}</para>

<para>This is the name of the mapping for which links are managed.</para>

<para/>

<sect2>

<title>Schema</title>

<example>

<para>The structure of a link entry is:</para>

<literallayout class="monospaced">

<code><![CDATA[

}]]>

</code>

</literallayout>

</example>

<sect3>

<title>Properties</title>

<variablelist>

<varlistentry>

<term>sourceId</term>

<listitem>

<para>string, required</para>

<para>The value of an object's _id property, which identifies the source object that is linked to a target object.</para>

</listitem>

</varlistentry>

<varlistentry>

<term>targetId</term>

<listitem>

<para>string, required</para>

<para>The value of an object's _id property, which identifies the target object that is linked to a source object.</para>

</listitem>

</varlistentry>

<varlistentry>

<term>reconId</term>

<listitem>

<para>string or null</para>

<para>The identifier of the last reconciliation job that processed this link. Is used during reconciliation to detect orphan source and target objects.  </para>

</listitem>

</varlistentry>

</variablelist>

</sect3>

</sect2>

<sect2>

<title>Queries</title>

<para/>

<para>The following queries will be required for a link object set.</para>

<para/>

<para>Find link(s) for a given source object identifier (step 1):</para>

<para>SELECT * FROM links/{mapping} WHERE sourceId = {value}</para>

<para>Note: While only one result makes sense, this query is intended to allow multiple results so that this scenario can be handled as an exception.</para>

<para/>

<para>Select link(s) for a given target object identifier (step 2):</para>

<para>SELECT * FROM links/{mapping} WHERE targetId = {value}</para>

<para>Note: While only one result makes sense, this query is intended to allow multiple results so that this scenario can be handled as an exception.</para>

<para/>

<para>Find orphan source and target links (step 3):</para>

<para>SELECT * FROM links/{mapping} WHERE reconId &lt;&gt; {value}</para>

<para/>

</sect2>

</sect1>

<sect1>

<title>Reconciliation</title>

<para>Reconciliation is performed on a per-mapping basis. The process of reconciliation for a given mapping is broken down into the following process:</para>

<orderedlist>

<listitem>

<para>Iterate through all objects for the object set specified as "source". For each source object: look for link to target object in link object set, perform correlation query (if defined). Conclude what the link condition is. Determine action to perform based on policy defined for condition. Perform action. Store reconId identifier in mapping to indicate that mapping was processed. Write results somewhere.</para>

</listitem>

<listitem>

<para>Iterate through all object identifiers for the object set specified as "target". For each identifier: find the target in the link object set. If reconId is "mine" then that target has already been processed correctly in step 1. If unrecognized reconId or link object does not exist, then source is missing. Determine action to perform based on policy defined for condition. Perform the action. Store reconId identifier in mapping (if applicable) to indicate that the mapping was processed. Write results somewhere.  </para>

</listitem>

<listitem>

<para>Iterate through all link objects. If "my" reconId, skip. If unrecognized reconId, then source and/or target are missing. Determine action to perform based on policy. Perform action. Store reconId identifer in mapping to indicate it was processed in this run.</para>

</listitem>

</orderedlist>

<para>This should catch and allow processing for all conditions.</para>

<para/>

</sect1>

<sect1>

<title>REST API</title>

<para>External synchronized objects should expose an API to request immediate synchronization. The form should be:</para>

<para/>

<para>Request</para>

<para>POST /openidm/system/xml/account/jsmith?action=sync HTTP/1.1</para>

<para>…</para>

<para/>

<para>Response (success)</para>

<para>HTTP/1.1 204 No Content</para>

<para>…</para>

<para/>

<para>Response (synchronization failure)</para>

<para>HTTP/1.1 409 Conflict</para>

<para>…</para>

<para/>

<para>[JSON representation of error]</para>

<para/>

</sect1>

</chapter>