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From "苗启广" <...@souvenirchina.com>
Subject Re: cvs commit: db-ojb/xdocs faq.xml
Date Sat, 09 Aug 2003 08:51:43 GMT


 2003-08-09 06:31:00 д
>of you ? Could you tell me ? Thanks~~ 
>arminw      2003/08/08 23:31:26
>
>  Modified:    xdocs    faq.xml
>  Log:
>  repair links
>  
>  Revision  Changes    Path
>  1.27      +81 -76    db-ojb/xdocs/faq.xml
>  
>  Index: faq.xml
>  ===================================================================
>  RCS file: /home/cvs/db-ojb/xdocs/faq.xml,v
>  retrieving revision 1.26
>  retrieving revision 1.27
>  diff -u -r1.26 -r1.27
>  --- faq.xml	30 Jun 2003 13:46:24 -0000	1.26
>  +++ faq.xml	9 Aug 2003 06:31:26 -0000	1.27
>  @@ -10,61 +10,67 @@
>   
>    <body>
>   
>  -  <section name="Frequently Asked Questions" anchor="faq">
>  +  <section name="Frequently Asked Questions">
>     <p><b>General</b></p>
>     <ul>
>  -    <li><a href="#FAQ3">Why OJB? Why do we need another O/R mapping tool?</a></li>
>  -    <li><a href="#FAQ8">How is OJB related to ODMG and JDO?</a></li>
>  -    <li><a href="#FAQ17">What are the OJB design principals?</a></li>
>  -    <li><a href="#FAQ18">Where can I learn more about Object/Relational
mapping in general?</a></li>
>  -    <li><a href="#FAQ34">How OJB performance compares to native JDBC programming?</a></li>
>  -    <li><a href="#FAQ35">How OJB performance compares to other O/R mapping
tools?</a></li>
>  +    <li><a href="#Why OJB? Why do we need another O/R mapping tool?">Why
OJB? Why do we need another O/R mapping tool?</a></li>
>  +    <li><a href="#How is OJB related to ODMG and JDO?">How is OJB related
to ODMG and JDO?</a></li>
>  +    <li><a href="#What are the OJB design principals?">What are the OJB
design principals?</a></li>
>  +    <li><a href="#Where can I learn more about Object/Relational mapping in
general?">Where can I learn more about Object/Relational mapping in general?</a></li>
>  +    <li><a href="#How OJB performance compares to native JDBC programming?">How
OJB performance compares to native JDBC programming?</a></li>
>  +    <li><a href="#How OJB performance compares to other O/R mapping tools?">How
OJB performance compares to other O/R mapping tools?</a></li>
>       <li><a href="#Is OJB ready for production environments?">Is OJB ready
for production environments?</a></li>
>     </ul>
>   
>     <p><b>Getting started</b></p>
>      <ul>
>  -    <li><a href="#FAQ1">Help! I'm having problems installing and using
OJB!</a></li>
>  -    <li><a href="#FAQ2">Help! I still have serious problems installing
OJB!</a></li>
>  -    <li><a href="#FAQ4">Does OJB support my RDBMS?</a></li>
>  -    <li><a href="#FAQ33">What are the OJB internal tables for?</a></li>
>  +    <li><a href="#Help! I'm having problems installing and using OJB!">Help!
I'm having problems installing and using OJB!</a></li>
>  +    <li><a href="#Help! I still have serious problems installing OJB!">Help!
I still have serious problems installing OJB!</a></li>
>  +    <li><a href="#Does OJB support my RDBMS?">Does OJB support my RDBMS?</a></li>
>  +    <li><a href="#What are the OJB internal tables for?">What are the OJB
internal tables for?</a></li>
>   
>   	</ul>
>   
>     <p><b>OJB APIs</b></p>
>     <ul>
>  -    <li><a href="#FAQ9">What are the differences between the PersistenceBroker
API and the ODMG API? Which one should I use in my applications?</a></li>
>  -    <li><a href="#FAQ15">I don't like OQL, can I use the PersistenceBroker
Queries within ODMG?</a></li>
>  -    <li><a href="#FAQ16">The OJB JDO implementation is not finished, how
can I start using OJB?</a></li>
>  -
>  +    <li><a href="#What are the differences between the PersistenceBroker API
and
>  +     the ODMG API? Which one should I use in my applications?">
>  +        What are the differences between the PersistenceBroker API and
>  +     the ODMG API? Which one should I use in my applications?</a></li>
>  +    <li><a href="#I don't like OQL, can I use the PersistenceBroker Queries
within ODMG?">
>  +        I don't like OQL, can I use the PersistenceBroker Queries within ODMG?</a></li>
>  +    <li><a href="#The OJB JDO implementation is not finished, how can I start
using OJB?">
>  +        The OJB JDO implementation is not finished, how can I start using OJB?</a></li>
>     </ul>
>   
>     <p><b>Howto</b></p>
>     <ul>
>  -    <li><a href="#FAQ5">How to use OJB with my RDBMS?</a></li>
>  -    <li><a href="#FAQ32">What the best settings for maximal performance?</a></li>
>  -    <li><a href="#FAQ6">How to page and sort?</a></li>
>  -    <li><a href="#FAQ7">What about performance and memory usage if thousands
of objects matching a query are returned as a Collection?</a></li>
>  -    <li><a href="#FAQ11">When is it helpful to use Proxy Classes?</a></li>
>  -    <li><a href="#FAQ12">How can I convert data between RDBMS and OJB?</a></li>
>  -    <li><a href="#FAQ13">How can I trace and/or profile SQL statements
executed by OJB?</a></li>
>  -    <li><a href="#FAQ14">How does OJB manage foreign keys?</a></li>
>  -    <li><a href="#FAQ19">How can Collections of primitive typed elements
be mapped?</a></li>
>  -
>  -    <li><a href="#FAQ20">How could class 'myClass' represent a collection
of 'myClass' objects</a></li>
>  -    <li><a href="#FAQ37">Needed to put user/password of database connection
in repository file?</a></li>
>  -    <li><a href="#FAQ21">Many different database user - How do they login?</a></li>
>  -    <li><a href="#FAQ22">How do I use multiple databases within OJB?</a></li>
>  -    <li><a href="#FAQ23">How does OJB handle connection pooling?</a></li>
>  -    <li><a href="#FAQ24">Can I directly obtain a <code>java.sql.Connection</code>
within OJB?</a></li>
>  -    <li><a href="#FAQ25">Is it possible to perform my own sql-queries in
OJB?</a></li>
>  -    <li><a href="#FAQ31">Start OJB without a repository file?</a></li>
>  -    <li><a href="#FAQ26">Connect to database at runtime?</a></li>
>  -    <li><a href="#FAQ27">Add new persistent objects (<code>class-descriptor</code>)
at runtime?</a></li>
>  -    <li><a href="#FAQ28">Global metadata changes at runtime?</a></li>
>  -    <li><a href="#FAQ29">Per thread metadata changes at runtime?</a></li>
>  -    <li><a href="#FAQ30">Is it possible to use OJB within EJB's?</a></li>
>  -	<li><a href="#FAQ36">Can OJB handle ternary (or higher) associations?</a></li>
>  +    <li><a href="#How to use OJB with my RDBMS?">How to use OJB with my
RDBMS?</a></li>
>  +    <li><a href="#What are the best settings for maximal performance?">What
are the best settings for maximal performance?</a></li>
>  +    <li><a href="#How to page and sort?">How to page and sort?</a></li>
>  +    <li><a href="#What about performance and memory usage if thousands of
objects matching a query are returned as a Collection?">
>  +        What about performance and memory usage if thousands of
>  +        objects matching a query are returned as a Collection?</a></li>
>  +    <li><a href="#When is it helpful to use Proxy Classes?">When is it
helpful to use Proxy Classes?</a></li>
>  +    <li><a href="#How can I convert data between RDBMS and OJB?">How can
I convert data between RDBMS and OJB?</a></li>
>  +    <li><a href="#How can I trace and/or profile SQL statements executed by
OJB?">How can I trace and/or profile SQL statements executed by OJB?</a></li>
>  +    <li><a href="#How does OJB manage foreign keys?">How does OJB manage
foreign keys?</a></li>
>  +    <li><a href="#How can Collections of primitive typed elements be mapped?">How
can Collections of primitive typed elements be mapped?</a></li>
>  +
>  +    <li><a href="#How could class 'myClass' represent a collection of 'myClass'
objects">How could class 'myClass' represent a collection of 'myClass' objects</a></li>
>  +    <li><a href="#Needed to put user/password of database connection in repository
file?">Needed to put user/password of database connection in repository file?</a></li>
>  +    <li><a href="#Many different database user - How do they login?">Many
different database user - How do they login?</a></li>
>  +    <li><a href="#How do I use multiple databases within OJB?">How do I
use multiple databases within OJB?</a></li>
>  +    <li><a href="#How does OJB handle connection pooling?">How does OJB
handle connection pooling?</a></li>
>  +    <li><a href="#Can I directly obtain a java.sql.Connection within OJB?">Can
I directly obtain a <code>java.sql.Connection</code> within OJB?</a></li>
>  +    <li><a href="#Is it possible to perform my own sql-queries in OJB?">Is
it possible to perform my own sql-queries in OJB?</a></li>
>  +    <li><a href="#Start OJB without a repository file?">Start OJB without
a repository file?</a></li>
>  +    <li><a href="#Connect to database at runtime?">Connect to database
at runtime?</a></li>
>  +    <li><a href="#Add new persistent objects (class-descriptors) at runtime?">Add
new persistent objects (<code>class-descriptor</code>) at runtime?</a></li>
>  +    <li><a href="#Global metadata changes at runtime?">Global metadata
changes at runtime?</a></li>
>  +    <li><a href="#Per thread metadata changes at runtime?">Per thread metadata
changes at runtime?</a></li>
>  +    <li><a href="#Is it possible to use OJB within EJB's?">Is it possible
to use OJB within EJB's?</a></li>
>  +	<li><a href="#Can OJB handle ternary (or higher) associations?">Can OJB
handle ternary (or higher) associations?</a></li>
>   	<li><a href="#How to map a list of Strings">How to map a list of Strings</a></li>
>   	<li><a href="#How to set up Optimistic Locking">How to set up Optimistic
Locking</a></li>
>   	<li><a href="#How to use OJB in a cluster">How to use OJB in a cluster</a></li>
>  @@ -74,7 +80,7 @@
>   
>      </ul>
>   
>  -   <subsection name="Help! I'm having problems installing and using OJB!" anchor="FAQ1">
>  +   <subsection name="Help! I'm having problems installing and using OJB!">
>       <p>
>        Please read the <a href="quickstart.html">OJB Quick Start</a> document.
OJB is a
>        powerful and complex system - installing and configuring OJB is not a trivial
task.
>  @@ -89,7 +95,7 @@
>       </p>
>      </subsection>
>   
>  -   <subsection name="Help! I still have serious problems installing OJB!" anchor="FAQ2">
>  +   <subsection name="Help! I still have serious problems installing OJB!">
>       <p>
>   	 The following answer is quoted from the OJB user-list. It is from a
>   	 reply to a user who had serious problems getting started with OJB.
>  @@ -173,7 +179,7 @@
>       </p>
>      </subsection>
>   
>  -   <subsection name="Why OJB? Why do we need another O/R mapping tool?" anchor="FAQ3">
>  +   <subsection name="Why OJB? Why do we need another O/R mapping tool?">
>       <p>
>        here are some outstanding OJB features:
>        <ul>
>  @@ -245,27 +251,27 @@
>       </p>
>      </subsection>
>   
>  -   <subsection name="What are the OJB design principals?" anchor="FAQ17">
>  +   <subsection name="What are the OJB design principals?">
>       <p>
>       OJB has a "pattern driven" design.
>       <a href="links.html#design">Please refer to this document for more details</a>
>       </p>
>      </subsection>
>   
>  -   <subsection name="Where can I learn more about Object/Relational mapping in general?"
anchor="FAQ18">
>  +   <subsection name="Where can I learn more about Object/Relational mapping in general?">
>       <p>
>       <a href="links.html#further readings on O/R mapping">We have a link list
pointing to further readings.</a>
>       </p>
>      </subsection>
>   
>   
>  -    <subsection name="How OJB performance compares to native JDBC programming?"
anchor="FAQ34">
>  +    <subsection name="How OJB performance compares to native JDBC programming?"
>
>       <p>
>           See section <a href="#FAQ32">faq max. performance</a> and <a
href="performance.html">Performance</a>.
>       </p>
>       </subsection>
>   
>  -    <subsection name="How OJB performance compares to other O/R mapping tools?"
anchor="FAQ35">
>  +    <subsection name="How OJB performance compares to other O/R mapping tools?"
>
>       <p>
>           See section <a href="#FAQ32">faq max. performance</a> and <a
href="performance.html">Performance</a>.
>       </p>
>  @@ -302,7 +308,7 @@
>       </subsection>
>   
>   
>  -   <subsection name="How can Collections of primitive typed elements be mapped?"
anchor="FAQ19">
>  +   <subsection name="How can Collections of primitive typed elements be mapped?"
>
>       <p>
>   		The first thing to ask is:
>   		How are these primitive typed elements (Strings are also treated as primitive types
here)
>  @@ -323,27 +329,27 @@
>      </subsection>
>   
>   
>  -   <subsection name="Does OJB support my RDBMS?" anchor="FAQ4">
>  +   <subsection name="Does OJB support my RDBMS?">
>       <p>
>        <A HREF="platforms.html">please refer to this document</A>.
>       </p>
>      </subsection>
>   
>  -   <subsection name="How to use OJB with my RDBMS?" anchor="FAQ5">
>  +   <subsection name="How to use OJB with my RDBMS?">
>       <p>
>        <A HREF="platforms.html">please refer to this document</A>.
>       </p>
>      </subsection>
>   
>   
>  -   <subsection name="What are the best settings for maximal performance?" anchor="FAQ32">
>  +   <subsection name="What are the best settings for maximal performance?" >
>       <p>
>       See <a href="performance.html">performance section</a>.
>       </p>
>       </subsection>
>   
>   
>  -   <subsection name="How to page and sort?" anchor="FAQ6">
>  +   <subsection name="How to page and sort?" >
>       <p>
>        Sorting can be configured by
>        org.apache.ojb.broker.query.Criteria::orderBy(column_name).
>  @@ -362,8 +368,7 @@
>       </p>
>      </subsection>
>   
>  -   <subsection name="What about performance and memory usage if thousands of
>  -    objects matching a query are returned as a Collection?" anchor="FAQ7">
>  +   <subsection name="What about performance and memory usage if thousands of objects
matching a query are returned as a Collection?" >
>       <p>
>        You can do two things to enhance performance if you have to process queries
>        that produce thousands of result objects:
>  @@ -395,7 +400,7 @@
>       </p>
>      </subsection>
>   
>  -   <subsection name="How is OJB related to ODMG and JDO?" anchor="FAQ8">
>  +   <subsection name="How is OJB related to ODMG and JDO?" >
>       <p>
>        ODMG is a standard API for Object Persistence specified by the ODMG
>        consortium (www.odmg.org).
>  @@ -462,7 +467,7 @@
>      </subsection>
>   
>      <subsection name="What are the differences between the PersistenceBroker API
and
>  -     the ODMG API? Which one should I use in my applications?" anchor="FAQ9">
>  +     the ODMG API? Which one should I use in my applications?" >
>       <p>
>        The PersistenceBroker (PB) provides a minimal API for transparent
>        persistence:
>  @@ -529,13 +534,13 @@
>       </p>
>      </subsection>
>   
>  -   <subsection name="What are the OJB internal tables for?" anchor="FAQ33">
>  +   <subsection name="What are the OJB internal tables for?" >
>       <p>
>        <a href="platforms.html">please refer to this document</a>.
>       </p>
>      </subsection>
>   
>  -   <subsection name="When is it helpful to use Proxy Classes?" anchor="FAQ11">
>  +   <subsection name="When is it helpful to use Proxy Classes?" >
>       <p>
>        Proxy classes can be used for &quot;lazy loading&quot; aka
>        &quot;lazy materialization&quot;. Using Proxy classes can help you in
>  @@ -565,7 +570,7 @@
>       </p>
>      </subsection>
>   
>  -   <subsection name="How can I convert data between RDBMS and OJB?" anchor="FAQ12">
>  +   <subsection name="How can I convert data between RDBMS and OJB?" >
>       <p>
>        For Example I have a DB column of type INTEGER but a class atribute of type
>        boolean. How can I provide an automatic mapping with OJB?
>  @@ -579,7 +584,7 @@
>   
>   
>   
>  -   <subsection name="How can I trace and/or profile SQL statements executed by OJB?"
anchor="FAQ13">
>  +   <subsection name="How can I trace and/or profile SQL statements executed by OJB?"
>
>       <p>
>      	 OJB  ships with out of the box support for P6Spy.
>   	 P6Spy is a JDBC proxy. It delegates all JDBC calls to the
>  @@ -605,7 +610,7 @@
>       </p>
>      </subsection>
>   
>  -   <subsection name="How does OJB manage foreign keys?" anchor="FAQ14">
>  +   <subsection name="How does OJB manage foreign keys?" >
>       <p>
>   	 Automatically! you just define 1:1, 1:n or m:n associations in the
>   	 repository_user.xml file.
>  @@ -617,7 +622,7 @@
>       </p>
>      </subsection>
>   
>  -   <subsection name="I don't like OQL, can I use the PersistenceBroker Queries within
ODMG?" anchor="FAQ15">
>  +   <subsection name="I don't like OQL, can I use the PersistenceBroker Queries within
ODMG?" >
>       <p>
>   	 Yes you can! The ODMG implementation relies on PB Queries internally!
>   	 Several users (including myself) are doing this.
>  @@ -652,7 +657,7 @@
>       </source>
>      </subsection>
>   
>  -   <subsection name="The OJB JDO implementation is not finished, how can I start
using OJB?" anchor="FAQ16">
>  +   <subsection name="The OJB JDO implementation is not finished, how can I start
using OJB?" >
>       <p>
>    	 I recommend to not use JDO now, but to use the existing ODMG api
>   	 for the time being.
>  @@ -704,7 +709,7 @@
>      </subsection>
>   
>   
>  -   <subsection name="Needed to put user/password of database connection in repository
file?" anchor="FAQ37">
>  +   <subsection name="Needed to put user/password of database connection in repository
file?" >
>      <p>
>      There is no need to put user/password in the repository file (more exact in the
>      <code>jdbc-connection-descriptor</code>). You can pass this
>  @@ -728,7 +733,7 @@
>      </subsection>
>   
>   
>  -<subsection name="How could class 'myClass' represent a collection of 'myClass'
objects" anchor="FAQ20">
>  +<subsection name="How could class 'myClass' represent a collection of 'myClass'
objects" >
>      <p>
>       OJB can handle such recursive associations without problems.
>       <ul>
>  @@ -755,7 +760,7 @@
>      </subsection>
>   
>   
>  -    <subsection name="Many different database user - How do they login?" anchor="FAQ21">
>  +    <subsection name="Many different database user - How do they login?" >
>       <p>
>       There are two ways to do that. Define for each user a <code>jdbc-connection-descriptor</code>
>       (unattractive way, because we have to add each new user to repository file),
>  @@ -790,7 +795,7 @@
>       </subsection>
>   
>   
>  -    <subsection name="How do I use multiple databases within OJB?" anchor="FAQ22">
>  +    <subsection name="How do I use multiple databases within OJB?" >
>       <p>
>       Define for each database a <code>jdbc-connection-descriptor</code>,
use the
>       different <code>jcdAlias</code> names to match the according database.
>  @@ -798,7 +803,7 @@
>       </subsection>
>   
>   
>  -    <subsection name="How does OJB handle connection pooling?" anchor="FAQ23">
>  +    <subsection name="How does OJB handle connection pooling?" >
>       <p>
>       OJB does connection pooling per default, expect for datasources. Datasources never
will be pooled.
>       <br/>
>  @@ -817,7 +822,7 @@
>       </subsection>
>   
>   
>  -    <subsection name="Can I directly obtain a java.sql.Connection within OJB?" anchor="FAQ24">
>  +    <subsection name="Can I directly obtain a java.sql.Connection within OJB?" >
>       <p>
>       The PB-api enabled the possibility to obtain a connection from the current
>       used <code>PersistenceBroker</code> instance:
>  @@ -839,7 +844,7 @@
>       </subsection>
>   
>   
>  -    <subsection name="Is it possible to perform my own sql-queries in OJB?" anchor="FAQ25">
>  +    <subsection name="Is it possible to perform my own sql-queries in OJB?" >
>       <p>
>       There are serveral ways in OJB to do that.
>       <br/>
>  @@ -863,7 +868,7 @@
>       </subsection>
>   
>   
>  -    <subsection name="Start OJB without a repository file?" anchor="FAQ31">
>  +    <subsection name="Start OJB without a repository file?" >
>       <p>
>       It is possible to start OJB with an 'empty' repository.xml file:
>       <source><![CDATA[
>  @@ -883,7 +888,7 @@
>   
>   
>   
>  -    <subsection name="Connect to database at runtime?" anchor="FAQ26">
>  +    <subsection name="Connect to database at runtime?" >
>       <p>
>       You could add <code>jdbc-connection-descriptors</code> at runtime,
using
>       the <code>MetadataManager</code>:
>  @@ -911,7 +916,7 @@
>       </subsection>
>   
>   
>  -    <subsection name="Add a new persistent object (class-descriptor) at runtime?"
anchor="FAQ27">
>  +    <subsection name="Add new persistent objects (class-descriptors) at runtime?"
>
>       <p>
>       You could add <code>class-descriptors</code> at runtime, using
>       the <code>MetadataManager</code>:
>  @@ -939,21 +944,21 @@
>       </subsection>
>   
>   
>  -    <subsection name="Global metadata changes at runtime?" anchor="FAQ28">
>  +    <subsection name="Global metadata changes at runtime?" >
>       <p>
>       Please see section <a href="metadata.html">Metadata Handling</a> in
>       system documentation.
>       </p>
>       </subsection>
>   
>  -    <subsection name="Per thread metadata changes at runtime?" anchor="FAQ29">
>  +    <subsection name="Per thread metadata changes at runtime?" >
>       <p>
>       Please see section <a href="metadata.html">Metadata Handling</a> in
>       system documentation.
>       </p>
>       </subsection>
>   
>  -    <subsection name="Is it possible to use OJB within EJB's?" anchor="FAQ30">
>  +    <subsection name="Is it possible to use OJB within EJB's?" >
>       <p>
>       Yes, see <a href="deployment.html">deployment</a> instructions in the
docs.
>       Additional you can find some EJB example beans in package <code>org.apache.ojb.ejb</code>
>  @@ -961,7 +966,7 @@
>       </p>
>       </subsection>
>   
>  -    <subsection name="Can OJB handle ternary (or higher) associations?" anchor="FAQ36">
>  +    <subsection name="Can OJB handle ternary (or higher) associations?" >
>       <p>
>       	Yes, that's possible. Here is an example.
>   		With a ternary relationship there are three (or more) entities
>  
>  
>  
>
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