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1 <?xml version="1.0" encoding="utf-8"?> |
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2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. --> |
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3 <!-- This component and the accompanying materials are made available under the terms of the License |
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4 "Eclipse Public License v1.0" which accompanies this distribution, |
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5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". --> |
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6 <!-- Initial Contributors: |
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7 Nokia Corporation - initial contribution. |
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8 Contributors: |
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9 --> |
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10 <!DOCTYPE concept |
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11 PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
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12 <concept id="GUID-E189B0C0-AAB5-5472-996B-91043DE0B6D4" xml:lang="en"><title>Package |
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13 Buffers Overview</title><shortdesc>Allows any value type (a T class) to be encapsulated as a descriptor, |
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14 for the purpose of inter-thread data transfer.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody> |
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15 <section id="GUID-D6ADB133-EB0D-41C5-B513-152ED052BA9F"><title>Architectural relationships</title> <p>The Client/Server API |
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16 expects data that is to be passed between threads to be encapsulated in a |
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17 descriptor. Package buffers provide a generic way for the thread providing |
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18 the data to do this. The thread receiving the data extracts the original data |
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19 from the package.</p> <p>APIs with client/server architectures, such as telephony |
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20 and Messaging, define specialised package buffer types that encapsulate the |
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21 particular data types that they require to pass between threads.</p> </section> |
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22 <section id="GUID-545604B3-1A3A-4236-AB40-F15E19D40487"><title>Description</title> <p>The API has two key concepts: package |
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23 buffer descriptor, and package pointer descriptor. </p> </section> |
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24 <section id="GUID-5B34C59B-3D61-48E9-9939-0259E1EC9A64"><title>Package buffer descriptor</title> <p>The package buffer descriptor |
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25 creates a new instance of the type to encapsulate and stores it within the |
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26 descriptor. The interface allows a reference to the encapsulated object to |
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27 be obtained, so that it can be accessed and modified.</p> <p>The package buffer |
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28 descriptor interface is provided by <xref href="GUID-C7A094BD-846F-3ED2-8CCE-C0743DB3712A.dita"><apiname>TPckgBuf</apiname></xref>.</p></section> |
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29 <section id="GUID-B12499C9-B385-43CF-8342-06B34150BE67"><title>Package pointer descriptor</title> <p>The package pointer |
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30 descriptor refers to an already existing object. It is otherwise used in a |
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31 similar way to the package buffer descriptor.</p> <p>The package pointer descriptor |
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32 interface is provided by <xref href="GUID-36B29964-420D-38D0-AF08-4DA70BED8B6E.dita"><apiname>TPckgC</apiname></xref> for const objects, and <xref href="GUID-4DFB8E64-81FF-3D3B-9694-CE51B11DA69A.dita"><apiname>TPckg</apiname></xref> for |
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33 non-const objects. </p> </section> |
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34 </conbody><related-links> |
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35 <link> |
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36 <desc><xref href="GUID-D0D27AEA-FDDB-5F6F-94F6-ADDF5910DC47.dita">Client/Server |
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37 Overview</xref></desc> |
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38 </link> |
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39 <link href="GUID-11EEFB3D-0414-5BEB-9D78-56A4B9154008.dita"><linktext>Using Descriptors</linktext> |
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40 </link> |
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41 </related-links></concept> |