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<task id="GUID-0BD22FDB-1A5C-56AA-A7FC-BD2271B2F928" xml:lang="en"><title>Writing
a Backup Engine Client (CSBEClient)</title><shortdesc>The Backup Engine exports <apiname>conn::CSBEClient</apiname>,
which provides data to a host PC for backup and receives data from a host
PC while restoring data. Device creators can call this API to write a backup
server that handles PC requests for backup and restore. </shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>
<prereq><p>The <xref href="GUID-5CA933B9-7987-5DDE-AE12-B0D5AFD31451.dita">Backup
Engine Overview</xref> provides an overview of the backup and restore architecture
as well as components and APIs for using <xref href="GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2.dita#GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2/GUID-FB671D02-0F15-396F-9FB7-EE3E9372093C"><apiname>conn::CSBEClient</apiname></xref>.
It also shows that a backup server (<xref href="GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2.dita#GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2/GUID-FB671D02-0F15-396F-9FB7-EE3E9372093C"><apiname>conn::CSBEClient</apiname></xref>) interacts
with a host PC and the Backup Engine. </p> <p>The <xref href="GUID-7FDD9FEC-5017-5E5D-A50A-5F343A3C7F6C.dita">Backup
Engine Concepts</xref> introduces different types of backup and restore. </p> <p>The <xref href="GUID-C579E24C-2B8E-5646-B307-7967F50A0B84.dita">File Locks</xref> describes
the concepts of public data and private data. </p> </prereq>
<context id="GUID-039E9656-DF70-52DD-AF3A-05912737C1A9"><p>After a phone connects
to a PC, the phone user can select to back up or restore data from PC-side
software. The backup software on the device side responds to the requests
by working with a set of components. </p> <p>Requests during a backup or a
restore are usually initiated from a host PC to a backup server on a device.
The backup server handles the PC requests and calls <xref href="GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2.dita#GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2/GUID-FB671D02-0F15-396F-9FB7-EE3E9372093C"><apiname>conn::CSBEClient</apiname></xref> for
backup and restore. The <xref href="GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2.dita#GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2/GUID-FB671D02-0F15-396F-9FB7-EE3E9372093C"><apiname>conn::CSBEClient</apiname></xref> then interacts
with the Backup Engine which in turn calls data owner applications for data
request or supply. The backup server finally transfers the data to and from
the host PC. </p> <fig id="GUID-52D747F3-9EA8-5474-B854-A00A01D6B8F1">
<image href="GUID-414DD60D-C5C3-5A75-9DF7-8980F72CB485_d0e597578_href.jpg" placement="inline"/>
</fig> <p>In the CSBEClient API, <codeph>RequestDataL()</codeph> and <codeph>SupplyDataL()</codeph> are
two major functions for backup and restore: </p> <ul>
<li id="GUID-7641D61E-215C-5326-B05B-9367DB79AC4D"><p>For a backup, the backup
server calls the <codeph>CSBEClient::RequestDataL()</codeph> function which
gets the data from the Backup Engine. The backup server can then transfer
the data to the host for a backup. </p> </li>
<li id="GUID-85B681B6-842A-5A1A-BF77-9EC83B082F56"><p>For a restore, the backup
server gets the data from the host PC. The backup server then calls the <codeph>CSBEClient::SupplyDataL()</codeph> function
which supplies the data to the Backup Engine for a restore. </p> </li>
</ul> <p>A particular type of <xref href="GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2.dita#GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2/GUID-27BF6AEB-72A0-3E39-9598-AB97BE2569FC"><apiname>conn::CSBGenericTransferType</apiname></xref> is
passed to these functions depending on the data to be transferred, such as
a snapshot or incremental data. Refer to the <xref href="GUID-8BFC185E-91FD-5E04-A26C-728B06F31FDD-GENID-1-7-1-23-1-1-4-1-3-1-6-1-6-1.dita">Creating
transfer types</xref> section for an example. </p><p> The backup and restore
sections below describe the <xref href="GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2.dita#GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2/GUID-FB671D02-0F15-396F-9FB7-EE3E9372093C"><apiname>conn::CSBEClient</apiname></xref> function calls.
The sequence of the calls depends on the requests from the host PC and the
backup server, but the recommended sequence is listed below.</p> </context>
<steps-unordered id="GUID-23CB37EE-9978-5FCF-BBC2-B532FA1323FC">
<step id="GUID-8298F87B-6603-57DB-B2F4-08615F61442D"><cmd/>

<info><xref href="GUID-F40BA7EA-AF7E-5BCF-96DD-9C4D8E947F0C.dita">Writing a CSBEClient
for Backup</xref> describes the sequence of <xref href="GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2.dita#GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2/GUID-FB671D02-0F15-396F-9FB7-EE3E9372093C"><apiname>conn::CSBEClient</apiname></xref> functions
call for partial and incremental data backup. </info>
</step>
<step id="GUID-61CD02CF-7592-5F6E-9943-98BEB5397E69"><cmd/>
<info><xref href="GUID-A5ED089C-8831-5E25-AE7C-8E6F1C21D3BE.dita">Writing a CSBEClient
for Restore</xref>  describes the sequence of <xref href="GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2.dita#GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2/GUID-FB671D02-0F15-396F-9FB7-EE3E9372093C"><apiname>conn::CSBEClient</apiname></xref> functions
call for partial and incremental data restore. </info>
</step>
<step id="GUID-151F94B7-4A9F-5C58-8AE0-B15C83025801"><cmd/>
<info><xref href="GUID-8BFC185E-91FD-5E04-A26C-728B06F31FDD-GENID-1-7-1-23-1-1-4-1-3-1-6-1-6-1.dita">Creating Transfer
Types</xref> describes how to create a particular <xref href="GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2.dita#GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2/GUID-27BF6AEB-72A0-3E39-9598-AB97BE2569FC"><apiname>conn::CSBGenericTransferType</apiname></xref> transfer
data type. The data type is passed to the <xref href="GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2.dita#GUID-169BB4E2-5B0E-3719-A7B8-A3C0AAA602E2/GUID-FB671D02-0F15-396F-9FB7-EE3E9372093C"><apiname>conn::CSBEClient</apiname></xref> to
transfer the data from or to the Backup Engine. </info>
</step>
</steps-unordered>
</taskbody><related-links>
<link href="GUID-5CA933B9-7987-5DDE-AE12-B0D5AFD31451.dita"><linktext>Backup Engine
Overview</linktext></link>
<link href="GUID-743D2832-E73A-5184-A85D-306B2A6FFACC.dita"><linktext>Active Backup
Client</linktext></link>
</related-links></task>