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    10 <!DOCTYPE concept

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

    12 <concept id="GUID-C705B0D5-055A-5DAA-9C6E-2FC3519FA50C" xml:lang="en"><title>Publish

    13 and Subscribe Overview</title><shortdesc>This topic explains the overview of publish and subscribe.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <section id="GUID-5F3F1973-C819-436F-A9E2-B02E62F94A29"><title>Purpose</title> <p>Allows global variables to be set and retrieved,

    15 and allows subscribers to be notified that variables have changed. Note that

    16 you may find such global variables referred to as properties.</p> </section>

    17 <section id="GUID-40E87759-7EF6-4503-95CF-9297D2EC2AB1"><title>Architectural relationships</title> <p>Publish and Subscribe

    18 is implemented on the Kernel side and is accessed from the user side through

    19 the <xref href="GUID-C4776034-D190-3FC4-AF45-C7F195093AC3.dita"><apiname>RProperty</apiname></xref> handle.</p> </section>

    20 <section id="GUID-70948A73-79DA-4033-94D0-E6B2046E55B3"><title>Description</title> <p>Publish and Subscribe has three main

    21 components: properties, publishers and subscribers.</p> <p><b>Properties</b> </p> <p>A property is a single data value, that can be either a single 32-bit

    22 value or a variable length set of bytes referred to as a byte array. A byte

    23 array has a maximum size defined by <xref href="GUID-C4776034-D190-3FC4-AF45-C7F195093AC3.dita#GUID-C4776034-D190-3FC4-AF45-C7F195093AC3/GUID-57E64054-610A-31D1-AD7F-E2F9F9FC1DCB"><apiname>RProperty::KMaxPropertySize</apiname></xref>.</p> <p><b>Publishers</b> </p> <p>Publishers are threads that define and update a

    24 property.</p> <p><b>Subscribers</b> </p> <p>Subscribers

    25 are threads that listen for changes to a property, and can get the current

    26 value of a property. Typically, a thread gets the value of a property when

    27 notified of changes.</p> </section>

    28 </conbody></concept>