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<TITLE>Writing Advanced Applications, Chapter 2: Examining a
Container-managed Bean</TITLE>
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<H2>Writing Advanced Applications<BR>
<FONT SIZE="3">Chapter 2 Continued: Examining a Container-Managed Bean</FONT></H2>
<FONT SIZE="-1">[<A HREF="code3.html"><<BACK</A>] [<A HREF="index.html#contents">CONTENTS</A>] [<A HREF="code5.html">NEXT>></A>]</FONT></DIV>
<P>
This section walks through the
<A HREF="./Code/registration/RegistrationBean.java">RegistrationBean.java</A>
code to show how easy it is to have the container manage persistent
data storage to an underlying medium such as a database (the default).
Chapter 3 modifies <CODE>RegistrationBean</CODE> to use
Bean-managed persistence to handle database access and manage transactions.
<UL>
<LI><FONT FACE="Verdana, Arial, Helvetica, sans-serif">
<A HREF="#member">Member Variables</A></FONT>
<LI><FONT FACE="Verdana, Arial, Helvetica, sans-serif">
<A HREF="#create">Create Method</A></FONT>
<LI><FONT FACE="Verdana, Arial, Helvetica, sans-serif">
<A HREF="#ctx">Entity Context Methods</A></FONT>
<LI><FONT FACE="Verdana, Arial, Helvetica, sans-serif">
<A HREF="#load">Load Method</A></FONT>
<LI><FONT FACE="Verdana, Arial, Helvetica, sans-serif">
<A HREF="#store">Store Method</A></FONT>
<LI><FONT FACE="Verdana, Arial, Helvetica, sans-serif">
<A HREF="#pool">Connection Pooling</A></FONT>
<LI><FONT FACE="Verdana, Arial, Helvetica, sans-serif">
<A HREF="#deployment">Deployment Descriptor</A></FONT>
</UL>
<HR>
<A NAME="member"></A>
<H3>Member Variables</H3>
A container-managed environment needs clues about which variables
are for persistent storage and which are not. In the Java<FONT SIZE="-2"><SUP>TM</SUP></FONT>
programming language, the <CODE>transient</CODE> keyword indicates
variables to not include when data in an object is serialized and
written to persistent storage. In the <CODE>RegistrationBean.java</CODE> class,
the <CODE>EntityContext</CODE> variable is marked <CODE>transient</CODE>
to indicate that its data not be written to the underlying storage
medium.
<P>
<CODE>EntityContext</CODE> data is not written to persistent storage
because its purpose is to provide information on the container's runtime
context. It, therefore, does not contain data on the registered user and should
not be saved to the underlying storage medium. The other variables are
declared <CODE>public</CODE> so the container in this example can discover them
using the Reflection API.
</FONT>
<PRE>
protected transient EntityContext ctx;
public String theuser, password, creditcard,
emailaddress;
public double balance;
</PRE>
<FONT FACE="Verdana, Arial, Helvetica, sans-serif">
<A NAME="create"></A>
<H3>Create Method</H3>
The Bean's <CODE>ejbCreate</CODE> method is called
by the container after the client program calls the
<CODE>create</CODE> method on the <CODE>remote</CODE>
interface and passes in the registration data.
This method assigns the incoming values to the member variables that
represent user data. The container handles storing and loading
the data, and creating new entries in the underlying storage medium.
</FONT>
<PRE>
public RegistrationPK ejbCreate(String theuser,
String password,
String emailaddress,
String creditcard)
throws CreateException, RemoteException {
this.theuser=theuser;
this.password=password;
this.emailaddress=emailaddress;
this.creditcard=creditcard;
this.balance=0;
</PRE>
<FONT FACE="Verdana, Arial, Helvetica, sans-serif">
<A NAME="ctx"></A>
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