124 lines
9.2 KiB
HTML
124 lines
9.2 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="DRDA and CDRA support" />
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<meta name="abstract" content="One of the interesting possibilities in a distributed relational database is that the database might not only span different types of computers, but those computers might be in different countries or regions. The same servers, such as iSeries servers, can encode data differently depending on the language used on the server." />
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<meta name="description" content="One of the interesting possibilities in a distributed relational database is that the database might not only span different types of computers, but those computers might be in different countries or regions. The same servers, such as iSeries servers, can encode data differently depending on the language used on the server." />
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<meta name="DC.subject" content="Character Data Representation Architecture (CDRA), with DRDA, DRDA (Distributed Relational Database Architecture) support, with CDRA, Distributed Relational Database Architecture (DRDA) support, character conversion, encoding, character conversion, data, CCSID (coded character set identifier), code page, EBCDIC" />
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<meta name="keywords" content="Character Data Representation Architecture (CDRA), with DRDA, DRDA (Distributed Relational Database Architecture) support, with CDRA, Distributed Relational Database Architecture (DRDA) support, character conversion, encoding, character conversion, data, CCSID (coded character set identifier), code page, EBCDIC" />
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<meta name="DC.Relation" scheme="URI" content="rbal1intro.htm" />
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<meta name="DC.Relation" scheme="URI" content="../nls/rbagsglobalmain.htm" />
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<meta name="DC.Relation" scheme="URI" content="rbal1ccsid.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="rbal1drdacdra" />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>DRDA and
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CDRA support</title>
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</head>
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<body id="rbal1drdacdra"><a name="rbal1drdacdra"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">DRDA and
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CDRA support</h1>
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<div><p>One of the interesting possibilities in a distributed relational
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database is that the database might not only span different types of computers,
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but those computers might be in different countries or regions. The same servers,
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such as <span class="keyword">iSeries™ server</span>s, can encode
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data differently depending on the language used on the server.</p>
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<p>Different types of servers encode data differently. For instance, an S/390<sup>®</sup>,
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an <span class="keyword">iSeries server</span>, and a PS/2<sup>®</sup> system encode
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numeric data in their own unique formats. In addition, an S/390 and an <span class="keyword">iSeries server</span> use the EBCDIC encoding scheme
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to encode character data, while a PS/2 system uses an ASCII encoding scheme.</p>
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<p>For numeric data, these differences do not matter. Unlike systems that
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provide DRDA<sup>®</sup> support
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automatically convert any differences between the way a number is represented
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in one computer system to the way it is represented in another. For example,
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if an <span class="keyword">iSeries</span> application program
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reads numeric data from a DB2 Universal Database™ for iSeries database, <span class="keyword">DB2<sup>®</sup> UDB for iSeries</span> sends the numeric data in S/390 format
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and the <span class="keyword">i5/OS™</span> database
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management system converts it to <span class="keyword">iSeries</span> numeric
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format.</p>
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<p>However, the handling of character data is more complex, but this too can
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be handled within a distributed relational database. </p>
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<div class="section"><h4 class="sectiontitle">Character conversion with CDRA</h4><p>Not only can there
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be differences in encoding schemes, such as Extended Binary Coded Decimal
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Interchange Code (EBCDIC) versus American Standard Code for Information Interchange
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(ASCII), but there can also be differences related to language.</p>
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<p>For
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instance, systems configured for different languages can assign different
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characters to the same code, or different codes to the same character. For
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example, a system configured for U.S. English can assign the same code to
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the character } that a system configured for the Danish language assigns to
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å. But those two systems can assign different codes to the same character
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such as $.</p>
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<p>If data is to be shared across different servers, character
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data needs to be seen by users and applications the same way. In other words,
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a PS/2 user
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in New York and an <span class="keyword">iSeries server</span> user
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in Copenhagen both need to see a $ as a $, even though $ might be encoded
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differently in each server. Furthermore, the user in Copenhagen needs to see
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a }, if that is the character that was stored at New York, even though the
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code might be the same as a Danish å. In order for this to happen, the $ must
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be converted to the proper character encoding for a PS/2 system (that is, U.S. English character
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set, ASCII), and converted back to Danish encoding when it goes from New York
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to Copenhagen (that is, Danish character set, EBCDIC). This sort of character
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conversion is provided for by <span class="keyword">iSeries server</span> as
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well as the other IBM<sup>®</sup> distributed relational database managers. This conversion
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is done in a coherent way in accordance with the Character Data Representation
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Architecture (CDRA).</p>
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<p>CDRA specifies the way to identify the attributes
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of character data so that the data can be understood across servers, even
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if the servers use different character sets and encoding schemes. For conversion
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to happen across servers, each server must understand the attributes of the
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character data it is receiving from the other server. CDRA specifies that
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these attributes be identified through a coded character set identifier (CCSID).
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All character data in DB2 Universal Database for z/OS<sup>®</sup>, DB2
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Universal Database™ for VM, and the <span class="keyword">i5/OS</span> database
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management systems have a CCSID, which indicates a specific combination of
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encoding scheme, character set, and code page. All character data in an Extended
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Services<sup>®</sup> environment has a code page only (but the other database managers
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treat that code page identification as a CCSID). A <dfn class="term">code page</dfn> is
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a specific set of assignments between characters and internal codes.</p>
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<p>For
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example, CCSID 37 means encoding scheme 4352 (EBCDIC), character set 697 (Latin,
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single-byte characters), and code page 37 (USA/Canada country extended code
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page). CCSID 5026 means encoding scheme 4865 (extended EBCDIC), character
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set 1172 with code page 290 (single-byte character set for Katakana/ Kanji),
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and character set 370 with code page 300 (double-byte character set for Katakana/Kanji).</p>
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<p>DRDA-enabled
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systems include mechanisms to convert character data between a wide range
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of CCSID-to-CCSID pairs and CCSID-to-code page pairs. Character conversion
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for many CCSIDs and code pages is already built into these products. For more
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information on CCSIDs supported by <span class="keyword">iSeries</span>,
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see the <span class="keyword">i5/OS</span> globalization
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topic. For a description of the use of CCSIDs on the <span class="keyword">iSeries server</span>,
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see coded character set identifier (CCSID).</p>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rbal1intro.htm" title="Distributed relational database support on the iSeries server consists of an implementation of IBM Distributed Relational Database Architecture (DRDA) and integration of other SQL clients by use of Application Requester Driver (ARD) programs.">Introduction to distributed database programming</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="../nls/rbagsglobalmain.htm">i5/OS globalization</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="rbal1ccsid.htm" title="Support for the national language of any country requires the proper handling of a minimum set of characters.">Coded character set identifier</a></div>
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</div>
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</div>
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</body>
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</html>
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