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<concept xml:lang="en" id="GUID-F4875493-6501-56FC-90E5-5EEAA89A72C3"><title>Persistent Storage Overview</title><shortdesc>Provides application data persistence between sessions. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody><section id="GUID-D2371A03-C03A-5B5B-B7B3-0F2BB591C5B5"><title>Purpose</title> <p>The Persistent Storage collection contains various solutions to the problem of persisting application data. </p> </section> <section id="GUID-E8C28A02-B3AA-565D-8D57-B6544E084FED"><title>Architecture</title> <p>The components of the Persistent Storage collection are mainly independent of each other from an architectural point of view. The only exception to this is that the relational database functionality provided by DBMS makes use of stores. However, that is a matter of implementation: the two components are alternative solutions to data persistence and are not used in combination. </p> </section> <section id="GUID-050F9EDA-D865-5A9D-9724-A77E110B9EE5"><title>Description</title> <p>The functionality of each component is threefold: </p> <ul><li id="GUID-230C8DC2-B0D6-5B8C-83F0-B8C2106A9B15"><p>Writing application data to memory, </p> </li> <li id="GUID-C3EA82BF-D383-5EC8-9678-47A8C1C2F16E"><p>Reading application data from memory, and </p> </li> <li id="GUID-6B42679F-23EF-5103-A127-30A8DAF5BE50"><p>Managing data integrity when several applications are reading from or writing to memory using the same component. </p> </li> </ul> </section> <section id="GUID-0B1E079A-053A-5353-B893-80937B1BA008"><title>Components</title> <ul><li id="GUID-E2B97EA3-DC57-52DE-BC78-5652445B2932"><p>Central Repository persists application data using repositories created at build time. </p> </li> <li id="GUID-821D0353-2FC8-5BB5-A688-DFED76DC5911"><p>Store persists application data using data streams. </p> </li> <li id="GUID-DB2F0354-F487-5788-AB77-1F777731B778"><p>DBMS persists application data using relational databases. </p> </li> <li id="GUID-AD472637-B65F-5EF9-944D-DD20D5C6E34F"><p>SQL persists application data using relational databases. </p> </li> <li id="GUID-C363166D-9786-52D6-8CF5-33E17BF690DE"><p>SQLite persists application data using relational databases. </p> </li> </ul> </section> <section><title>Using Persistent Storage</title> <p>The components of this collection are all used for the same purpose, persisting application data. They differ in the strategy used and in their implementation. </p> </section> </conbody><related-links><link href="GUID-CBC57511-7F28-596A-9763-5674EB41BCAC.dita"><linktext>Central Repository
                Overview</linktext> </link> <link href="GUID-13C95985-D16F-5A9E-A7F8-CAB637C4C6ED.dita"><linktext>DBMS Overview</linktext> </link> <link href="GUID-33241691-7362-5FA1-A3B0-C3FA550E5E09.dita"><linktext>Store Overview</linktext> </link> <link href="GUID-22844C28-AB5B-5A6F-8863-7269464684B4.dita"><linktext>Symbian SQL Overview</linktext> </link> <link href="GUID-5CA62D99-15E2-5556-966F-CFC3FCE3B246.dita"><linktext>SQLite 3 Overview</linktext> </link> </related-links></concept>