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5 The Apache Tomcat Servlet/JSP Container
Hongqing Liu71898292014-10-15 13:31:32 +0800[diff] [blame^]6 " border="0"></a></td><td><h1><font face="arial,helvetica,sanserif">Apache Tomcat 6.0</font></h1><font face="arial,helvetica,sanserif">Version 6.0.41, May 19 2014</font></td><td><!--APACHE LOGO--><a href="http://www.apache.org/"><img src="./images/asf-logo.gif" align="right" alt="Apache Logo" border="0"></a></td></tr></table><table border="0" width="100%" cellspacing="4"><!--HEADER SEPARATOR--><tr><td colspan="2"><hr noshade="noshade" size="1"></td></tr><tr><!--LEFT SIDE NAVIGATION--><td width="20%" valign="top" nowrap="nowrap" class="noPrint"><p><strong>Links</strong></p><ul><li><a href="index.html">Docs Home</a></li><li><a href="http://wiki.apache.org/tomcat/FAQ">FAQ</a></li></ul><p><strong>User Guide</strong></p><ul><li><a href="introduction.html">1) Introduction</a></li><li><a href="setup.html">2) Setup</a></li><li><a href="appdev/index.html">3) First webapp</a></li><li><a href="deployer-howto.html">4) Deployer</a></li><li><a href="manager-howto.html">5) Manager</a></li><li><a href="realm-howto.html">6) Realms and AAA</a></li><li><a href="security-manager-howto.html">7) Security Manager</a></li><li><a href="jndi-resources-howto.html">8) JNDI Resources</a></li><li><a href="jndi-datasource-examples-howto.html">9) JDBC DataSources</a></li><li><a href="class-loader-howto.html">10) Classloading</a></li><li><a href="jasper-howto.html">11) JSPs</a></li><li><a href="ssl-howto.html">12) SSL</a></li><li><a href="ssi-howto.html">13) SSI</a></li><li><a href="cgi-howto.html">14) CGI</a></li><li><a href="proxy-howto.html">15) Proxy Support</a></li><li><a href="mbeans-descriptor-howto.html">16) MBean Descriptor</a></li><li><a href="default-servlet.html">17) Default Servlet</a></li><li><a href="cluster-howto.html">18) Clustering</a></li><li><a href="balancer-howto.html">19) Load Balancer</a></li><li><a href="connectors.html">20) Connectors</a></li><li><a href="monitoring.html">21) Monitoring and Management</a></li><li><a href="logging.html">22) Logging</a></li><li><a href="apr.html">23) APR/Native</a></li><li><a href="virtual-hosting-howto.html">24) Virtual Hosting</a></li><li><a href="aio.html">25) Advanced IO</a></li><li><a href="extras.html">26) Additional Components</a></li><li><a href="maven-jars.html">27) Mavenized</a></li></ul><p><strong>Reference</strong></p><ul><li><a href="RELEASE-NOTES.txt">Release Notes</a></li><li><a href="config/index.html">Configuration</a></li><li><a href="api/index.html">Javadocs</a></li><li><a href="http://tomcat.apache.org/connectors-doc/">JK 1.2 Documentation</a></li></ul><p><strong>Apache Tomcat Development</strong></p><ul><li><a href="building.html">Building</a></li><li><a href="changelog.html">Changelog</a></li><li><a href="http://wiki.apache.org/tomcat/TomcatVersions">Status</a></li><li><a href="developers.html">Developers</a></li><li><a href="architecture/index.html">Architecture</a></li><li><a href="funcspecs/index.html">Functional Specs.</a></li></ul></td><!--RIGHT SIDE MAIN BODY--><td width="80%" valign="top" align="left" id="mainBody"><h1>Apache Tomcat 6.0</h1><h2>JNDI Datasource HOW-TO</h2><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Table of Contents"><!--()--></a><a name="Table_of_Contents"><strong>Table of Contents</strong></a></font></td></tr><tr><td><blockquote>
Hongqing Liufd5ee812014-05-10 16:32:51 +0800[diff] [blame]7<ul><li><a href="#Introduction">Introduction</a></li><li><a href="#DriverManager,_the_service_provider_mechanism_and_memory_leaks">DriverManager, the service provider mechanism and memory leaks</a></li><li><a href="#Database_Connection_Pool_(DBCP)_Configurations">Database Connection Pool (DBCP) Configurations</a><ol><li><a href="#Installation">Installation</a></li><li><a href="#Preventing_database_connection_pool_leaks">Preventing database connection pool leaks</a></li><li><a href="#MySQL_DBCP_Example">MySQL DBCP Example</a></li><li><a href="#Oracle_8i,_9i_&_10g">Oracle 8i, 9i &amp; 10g</a></li><li><a href="#PostgreSQL">PostgreSQL</a></li></ol></li><li><a href="#Non-DBCP_Solutions">Non-DBCP Solutions</a></li><li><a href="#Oracle_8i_with_OCI_client">Oracle 8i with OCI client</a><ol><li><a href="#Oracle_8i_with_OCI_client/Introduction">Introduction</a></li><li><a href="#Putting_it_all_together">Putting it all together</a></li></ol></li><li><a href="#Common_Problems">Common Problems</a><ol><li><a href="#Intermittent_Database_Connection_Failures">Intermittent Database Connection Failures</a></li><li><a href="#Random_Connection_Closed_Exceptions">Random Connection Closed Exceptions</a></li><li><a href="#Context_versus_GlobalNamingResources">Context versus GlobalNamingResources</a></li><li><a href="#JNDI_Resource_Naming_and_Realm_Interaction">JNDI Resource Naming and Realm Interaction</a></li></ol></li></ul>
8</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Introduction"><strong>Introduction</strong></a></font></td></tr><tr><td><blockquote>
9
10<p>JNDI Datasource configuration is covered extensively in the
11JNDI-Resources-HOWTO. However, feedback from <code>tomcat-user</code> has
12shown that specifics for individual configurations can be rather tricky.</p>
13
14<p>Here then are some example configurations that have been posted to
15tomcat-user for popular databases and some general tips for db usage.</p>
16
17<p>You should be aware that since these notes are derived from configuration
18and/or feedback posted to <code>tomcat-user</code> YMMV :-). Please let us
19know if you have any other tested configurations that you feel may be of use
20to the wider audience, or if you feel we can improve this section in anyway.</p>
21
22<p>
23<b>Please note that JNDI resource configuration changed somewhat between
24Tomcat 5.0.x and Tomcat 5.5.x.</b> You will most likely need to modify older
25JNDI resource configurations to match the syntax in the example below in order
26to make them work in Tomcat 6.x.x.
27</p>
28
29<p>
30Also, please note that JNDI DataSource configuration in general, and this
31tutorial in particular, assumes that you have read and understood the
32<a href="config/context.html">Context</a> and
33<a href="config/host.html">Host</a> configuration references, including
34the section about Automatic Application Deployment in the latter reference.
35</p>
36</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="DriverManager, the service provider mechanism and memory leaks"><!--()--></a><a name="DriverManager,_the_service_provider_mechanism_and_memory_leaks"><strong>DriverManager, the service provider mechanism and memory leaks</strong></a></font></td></tr><tr><td><blockquote>
37
38<p><code>java.sql.DriverManager</code> supports the
39<a href="http://docs.oracle.com/javase/6/docs/api/index.html?java/sql/DriverManager.html">service
40provider</a> mechanism. This feature is that all the available JDBC drivers
41that announce themselves by providing a <code>META-INF/services/java.sql.Driver</code>
42file are automatically discovered, loaded and registered,
43relieving you from the need to load the database driver explicitly before
44you create a JDBC connection.
45However, the implementation is fundamentally broken in all Java versions for
46a servlet container environment. The problem is that
47<code>java.sql.DriverManager</code> will scan for the drivers only once.</p>
48
49<p>The <a href="config/listeners.html">JRE Memory Leak Prevention Listener</a>
50that is included with Apache Tomcat solves this by triggering the drivers scan
51during Tomcat startup. This is enabled by default. It means that only
52libraries visible to the listener such as the ones in
53<code>$CATALINA_BASE/lib</code> will be scanned for database drivers.
54If you are considering disabling this feature, note that
55the scan would be triggered by the first web application that is
56using JDBC, leading to failures when this web application is reloaded
57and for other web applications that rely on this feature.
58</p>
59
60<p>Thus, the web applications that have database drivers in their
61<code>WEB-INF/lib</code> directory cannot rely on the service provider
62mechanism and should register the drivers explicitly.</p>
63
64<p>The list of drivers in <code>java.sql.DriverManager</code> is also
65a known source of memory leaks. Any Drivers registered
66by a web application must be deregistered when the web application stops.
67Tomcat will attempt to automatically discover and deregister any
68JDBC drivers loaded by the web application class loader when the web
69application stops.
70However, it is expected that applications do this for themselves via
71a <code>ServletContextListener</code>.
72</p>
73
74</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Database Connection Pool (DBCP) Configurations"><!--()--></a><a name="Database_Connection_Pool_(DBCP)_Configurations"><strong>Database Connection Pool (DBCP) Configurations</strong></a></font></td></tr><tr><td><blockquote>
75
76<p>The default database connection pool implementation in Apache Tomcat
77relies on the libraries from the
78<a href="http://commons.apache.org/">Apache Commons</a> project.
79The following libraries are used:
80</p>
81
82<ul>
83<li>Commons DBCP</li>
84<li>Commons Pool</li>
85</ul>
86
87<p>
88These libraries are located in a single JAR at
89<code>$CATALINA_HOME/lib/tomcat-dbcp.jar</code>. However,
90only the classes needed for connection pooling have been included, and the
91packages have been renamed to avoid interfering with applications.
92</p>
93
94<p>DBCP 1.3 provides support for JDBC 3.0.</p>
95
96<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Installation"><strong>Installation</strong></a></font></td></tr><tr><td><blockquote>
97
98<p>See the <a href="http://commons.apache.org/dbcp/configuration.html">
99DBCP documentation</a> for a complete list of configuration parameters.
100</p>
101
102</blockquote></td></tr></table>
103
104<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Preventing database connection pool leaks"><!--()--></a><a name="Preventing_database_connection_pool_leaks"><strong>Preventing database connection pool leaks</strong></a></font></td></tr><tr><td><blockquote>
105
106<p>
107A database connection pool creates and manages a pool of connections
108to a database. Recycling and reusing already existing connections
109to a database is more efficient than opening a new connection.
110</p>
111
112<p>
113There is one problem with connection pooling. A web application has
114to explicitly close ResultSet's, Statement's, and Connection's.
115Failure of a web application to close these resources can result in
116them never being available again for reuse, a database connection pool "leak".
117This can eventually result in your web application database connections failing
118if there are no more available connections.</p>
119
120<p>
121There is a solution to this problem. The Apache Commons DBCP can be
122configured to track and recover these abandoned database connections. Not
123only can it recover them, but also generate a stack trace for the code
124which opened these resources and never closed them.</p>
125
126<p>
127To configure a DBCP DataSource so that abandoned database connections are
128removed and recycled add the following attribute to the
129<code>Resource</code> configuration for your DBCP DataSource:
130</p>
131
132<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>removeAbandoned="true"</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
133
134<p>
135When available database connections run low DBCP will recover and recycle
136any abandoned database connections it finds. The default is <code>false</code>.
137</p>
138
139<p>
140Use the <code>removeAbandonedTimeout</code> attribute to set the number
141of seconds a database connection has been idle before it is considered abandoned.
142</p>
143
144<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>removeAbandonedTimeout="60"</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
145
146<p>
147The default timeout for removing abandoned connections is 300 seconds.
148</p>
149
150<p>
151The <code>logAbandoned</code> attribute can be set to <code>true</code>
152if you want DBCP to log a stack trace of the code which abandoned the
153database connection resources.
154</p>
155<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>logAbandoned="true"</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
156<p>
157The default is <code>false</code>.
158</p>
159
160</blockquote></td></tr></table>
161
162<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="MySQL DBCP Example"><!--()--></a><a name="MySQL_DBCP_Example"><strong>MySQL DBCP Example</strong></a></font></td></tr><tr><td><blockquote>
163
164<h3>0. Introduction</h3>
165<p>Versions of <a href="http://www.mysql.com/products/mysql/index.html">MySQL</a> and JDBC
166drivers that have been reported to work:
167</p>
168<ul>
169<li>MySQL 3.23.47, MySQL 3.23.47 using InnoDB,, MySQL 3.23.58, MySQL 4.0.1alpha</li>
170<li><a href="http://www.mysql.com/products/connector-j">Connector/J</a> 3.0.11-stable (the official JDBC Driver)</li>
171<li><a href="http://mmmysql.sourceforge.net">mm.mysql</a> 2.0.14 (an old 3rd party JDBC Driver)</li>
172</ul>
173
174<p>Before you proceed, don't forget to copy the JDBC Driver's jar into <code>$CATALINA_HOME/lib</code>.</p>
175
176<h3>1. MySQL configuration</h3>
177<p>
178Ensure that you follow these instructions as variations can cause problems.
179</p>
180
181<p>Create a new test user, a new database and a single test table.
182Your MySQL user <strong>must</strong> have a password assigned. The driver
183will fail if you try to connect with an empty password.
184</p>
185<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
186mysql&gt; GRANT ALL PRIVILEGES ON *.* TO javauser@localhost
187 -&gt; IDENTIFIED BY 'javadude' WITH GRANT OPTION;
188mysql&gt; create database javatest;
189mysql&gt; use javatest;
190mysql&gt; create table testdata (
191 -&gt; id int not null auto_increment primary key,
192 -&gt; foo varchar(25),
193 -&gt; bar int);
194</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
195<blockquote>
196<strong>Note:</strong> the above user should be removed once testing is
197complete!
198</blockquote>
199
200<p>Next insert some test data into the testdata table.
201</p>
202<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
203mysql&gt; insert into testdata values(null, 'hello', 12345);
204Query OK, 1 row affected (0.00 sec)
205
206mysql&gt; select * from testdata;
207+----+-------+-------+
208| ID | FOO | BAR |
209+----+-------+-------+
210| 1 | hello | 12345 |
211+----+-------+-------+
2121 row in set (0.00 sec)
213
214mysql&gt;
215</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
216
217<h3>2. Context configuration</h3>
218<p>Configure the JNDI DataSource in Tomcat by adding a declaration for your
219resource to your <a href="config/context.html">Context</a>.</p>
220<p>For example:</p>
221<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
222&lt;Context&gt;
223
224 &lt;!-- maxActive: Maximum number of database connections in pool. Make sure you
225 configure your mysqld max_connections large enough to handle
226 all of your db connections. Set to -1 for no limit.
227 --&gt;
228
229 &lt;!-- maxIdle: Maximum number of idle database connections to retain in pool.
230 Set to -1 for no limit. See also the DBCP documentation on this
231 and the minEvictableIdleTimeMillis configuration parameter.
232 --&gt;
233
234 &lt;!-- maxWait: Maximum time to wait for a database connection to become available
235 in ms, in this example 10 seconds. An Exception is thrown if
236 this timeout is exceeded. Set to -1 to wait indefinitely.
237 --&gt;
238
239 &lt;!-- username and password: MySQL username and password for database connections --&gt;
240
241 &lt;!-- driverClassName: Class name for the old mm.mysql JDBC driver is
242 org.gjt.mm.mysql.Driver - we recommend using Connector/J though.
243 Class name for the official MySQL Connector/J driver is com.mysql.jdbc.Driver.
244 --&gt;
245
246 &lt;!-- url: The JDBC connection url for connecting to your MySQL database.
247 --&gt;
248
249 &lt;Resource name="jdbc/TestDB" auth="Container" type="javax.sql.DataSource"
250 maxActive="100" maxIdle="30" maxWait="10000"
251 username="javauser" password="javadude" driverClassName="com.mysql.jdbc.Driver"
252 url="jdbc:mysql://localhost:3306/javatest"/&gt;
253
254&lt;/Context&gt;
255</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
256
257<h3>3. web.xml configuration</h3>
258
259<p>Now create a <code>WEB-INF/web.xml</code> for this test application.</p>
260<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
261&lt;web-app xmlns="http://java.sun.com/xml/ns/j2ee"
262 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
263 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
264http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
265 version="2.4"&gt;
266 &lt;description&gt;MySQL Test App&lt;/description&gt;
267 &lt;resource-ref&gt;
268 &lt;description&gt;DB Connection&lt;/description&gt;
269 &lt;res-ref-name&gt;jdbc/TestDB&lt;/res-ref-name&gt;
270 &lt;res-type&gt;javax.sql.DataSource&lt;/res-type&gt;
271 &lt;res-auth&gt;Container&lt;/res-auth&gt;
272 &lt;/resource-ref&gt;
273&lt;/web-app&gt;
274</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
275
276<h3>4. Test code</h3>
277<p>Now create a simple <code>test.jsp</code> page for use later.
278<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
279&lt;%@ taglib uri="http://java.sun.com/jsp/jstl/sql" prefix="sql" %&gt;
280&lt;%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %&gt;
281
282&lt;sql:query var="rs" dataSource="jdbc/TestDB"&gt;
283select id, foo, bar from testdata
284&lt;/sql:query&gt;
285
286&lt;html&gt;
287 &lt;head&gt;
288 &lt;title&gt;DB Test&lt;/title&gt;
289 &lt;/head&gt;
290 &lt;body&gt;
291
292 &lt;h2&gt;Results&lt;/h2&gt;
293
294&lt;c:forEach var="row" items="${rs.rows}"&gt;
295 Foo ${row.foo}&lt;br/&gt;
296 Bar ${row.bar}&lt;br/&gt;
297&lt;/c:forEach&gt;
298
299 &lt;/body&gt;
300&lt;/html&gt;
301</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
302</p>
303
304<p>That JSP page makes use of <a href="http://java.sun.com/products/jsp/jstl">JSTL</a>'s
305SQL and Core taglibs. You can get it from
306<a href="http://tomcat.apache.org/taglibs/standard/">Apache Tomcat Taglibs - Standard Tag Library</a>
307project &mdash; just make sure you get a 1.1.x release. Once you have JSTL,
308copy <code>jstl.jar</code> and <code>standard.jar</code> to your web app's
309<code>WEB-INF/lib</code> directory.
310
311</p>
312
313<p>Finally deploy your web app into <code>$CATALINA_BASE/webapps</code> either
314as a warfile called <code>DBTest.war</code> or into a sub-directory called
315<code>DBTest</code></p>
316<p>Once deployed, point a browser at
317<code>http://localhost:8080/DBTest/test.jsp</code> to view the fruits of
318your hard work.</p>
319
320</blockquote></td></tr></table>
321
322<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Oracle 8i, 9i & 10g"><!--()--></a><a name="Oracle_8i,_9i_&_10g"><strong>Oracle 8i, 9i &amp; 10g</strong></a></font></td></tr><tr><td><blockquote>
323<h3>0. Introduction</h3>
324
325<p>Oracle requires minimal changes from the MySQL configuration except for the
326usual gotchas :-)</p>
327<p>Drivers for older Oracle versions may be distributed as *.zip files rather
328than *.jar files. Tomcat will only use <code>*.jar</code> files installed in
329<code>$CATALINA_HOME/lib</code>. Therefore <code>classes111.zip</code>
330or <code>classes12.zip</code> will need to be renamed with a <code>.jar</code>
331extension. Since jarfiles are zipfiles, there is no need to unzip and jar these
332files - a simple rename will suffice.</p>
333
334<p>For Oracle 9i onwards you should use <code>oracle.jdbc.OracleDriver</code>
335rather than <code>oracle.jdbc.driver.OracleDriver</code> as Oracle have stated
336that <code>oracle.jdbc.driver.OracleDriver</code> is deprecated and support
337for this driver class will be discontinued in the next major release.
338</p>
339
340<h3>1. Context configuration</h3>
341<p>In a similar manner to the mysql config above, you will need to define your
342Datasource in your <a href="config/context.html">Context</a>. Here we define a
343Datasource called myoracle using the thin driver to connect as user scott,
344password tiger to the sid called mysid. (Note: with the thin driver this sid is
345not the same as the tnsname). The schema used will be the default schema for the
346user scott.</p>
347
348<p>Use of the OCI driver should simply involve a changing thin to oci in the URL string.
349</p>
350<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
351&lt;Resource name="jdbc/myoracle" auth="Container"
352 type="javax.sql.DataSource" driverClassName="oracle.jdbc.OracleDriver"
353 url="jdbc:oracle:thin:@127.0.0.1:1521:mysid"
354 username="scott" password="tiger" maxActive="20" maxIdle="10"
355 maxWait="-1"/&gt;
356</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
357
358<h3>2. web.xml configuration</h3>
359<p>You should ensure that you respect the element ordering defined by the DTD when you
360create you applications web.xml file.</p>
361<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
362&lt;resource-ref&gt;
363 &lt;description&gt;Oracle Datasource example&lt;/description&gt;
364 &lt;res-ref-name&gt;jdbc/myoracle&lt;/res-ref-name&gt;
365 &lt;res-type&gt;javax.sql.DataSource&lt;/res-type&gt;
366 &lt;res-auth&gt;Container&lt;/res-auth&gt;
367&lt;/resource-ref&gt;
368</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
369<h3>3. Code example</h3>
370<p>You can use the same example application as above (asuming you create the required DB
371instance, tables etc.) replacing the Datasource code with something like</p>
372<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
373Context initContext = new InitialContext();
374Context envContext = (Context)initContext.lookup("java:/comp/env");
375DataSource ds = (DataSource)envContext.lookup("jdbc/myoracle");
376Connection conn = ds.getConnection();
377//etc.
378</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
379</blockquote></td></tr></table>
380
381
382<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="PostgreSQL"><strong>PostgreSQL</strong></a></font></td></tr><tr><td><blockquote>
383<h3>0. Introduction</h3>
384<p>PostgreSQL is configured in a similar manner to Oracle.</p>
385
386<h3>1. Required files </h3>
387<p>
388Copy the Postgres JDBC jar to $CATALINA_HOME/lib. As with Oracle, the
389jars need to be in this directory in order for DBCP's Classloader to find
390them. This has to be done regardless of which configuration step you take next.
391</p>
392
393<h3>2. Resource configuration</h3>
394
395<p>
396You have two choices here: define a datasource that is shared across all Tomcat
397applications, or define a datasource specifically for one application.
398</p>
399
400<h4>2a. Shared resource configuration</h4>
401<p>
402Use this option if you wish to define a datasource that is shared across
403multiple Tomcat applications, or if you just prefer defining your datasource
404in this file.
405</p>
406<p><i>This author has not had success here, although others have reported so.
407Clarification would be appreciated here.</i></p>
408
409<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
410&lt;Resource name="jdbc/postgres" auth="Container"
411 type="javax.sql.DataSource" driverClassName="org.postgresql.Driver"
412 url="jdbc:postgresql://127.0.0.1:5432/mydb"
413 username="myuser" password="mypasswd" maxActive="20" maxIdle="10" maxWait="-1"/&gt;
414</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
415<h4>2b. Application-specific resource configuration</h4>
416
417<p>
418Use this option if you wish to define a datasource specific to your application,
419not visible to other Tomcat applications. This method is less invasive to your
420Tomcat installation.
421</p>
422
423<p>
424Create a resource definition for your <a href="config/context.html">Context</a>.
425The Context element should look something like the following.
426</p>
427
428<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
429&lt;Context&gt;
430
431&lt;Resource name="jdbc/postgres" auth="Container"
432 type="javax.sql.DataSource" driverClassName="org.postgresql.Driver"
433 url="jdbc:postgresql://127.0.0.1:5432/mydb"
434 username="myuser" password="mypasswd" maxActive="20" maxIdle="10"
435maxWait="-1"/&gt;
436&lt;/Context&gt;
437</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
438
439<h3>3. web.xml configuration</h3>
440<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
441&lt;resource-ref&gt;
442 &lt;description&gt;postgreSQL Datasource example&lt;/description&gt;
443 &lt;res-ref-name&gt;jdbc/postgres&lt;/res-ref-name&gt;
444 &lt;res-type&gt;javax.sql.DataSource&lt;/res-type&gt;
445 &lt;res-auth&gt;Container&lt;/res-auth&gt;
446&lt;/resource-ref&gt;
447</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
448
449<h4>4. Accessing the datasource</h4>
450<p>
451When accessing the datasource programmatically, remember to prepend
452<code>java:/comp/env</code> to your JNDI lookup, as in the following snippet of
453code. Note also that "jdbc/postgres" can be replaced with any value you prefer, provided
454you change it in the above resource definition file as well.
455</p>
456
457<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
458InitialContext cxt = new InitialContext();
459if ( cxt == null ) {
460 throw new Exception("Uh oh -- no context!");
461}
462
463DataSource ds = (DataSource) cxt.lookup( "java:/comp/env/jdbc/postgres" );
464
465if ( ds == null ) {
466 throw new Exception("Data source not found!");
467}
468</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
469
470</blockquote></td></tr></table>
471</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Non-DBCP Solutions"><!--()--></a><a name="Non-DBCP_Solutions"><strong>Non-DBCP Solutions</strong></a></font></td></tr><tr><td><blockquote>
472<p>
473These solutions either utilise a single connection to the database (not recommended for anything other
474than testing!) or some other pooling technology.
475</p>
476</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Oracle 8i with OCI client"><!--()--></a><a name="Oracle_8i_with_OCI_client"><strong>Oracle 8i with OCI client</strong></a></font></td></tr><tr><td><blockquote>
477<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Oracle 8i with OCI client/Introduction"><!--()--></a><a name="Oracle_8i_with_OCI_client/Introduction"><strong>Introduction</strong></a></font></td></tr><tr><td><blockquote>
478<p>Whilst not strictly addressing the creation of a JNDI DataSource using the OCI client, these notes can be combined with the
479Oracle and DBCP solution above.</p>
480<p>
481In order to use OCI driver, you should have an Oracle client installed. You should have installed
482Oracle8i(8.1.7) client from cd, and download the suitable JDBC/OCI
483driver(Oracle8i 8.1.7.1 JDBC/OCI Driver) from <a href="http://otn.oracle.com/">otn.oracle.com</a>.
484</p>
485<p>
486After renaming <code>classes12.zip</code> file to <code>classes12.jar</code>
487for Tomcat, copy it into <code>$CATALINA_HOME/lib</code>.
488You may also have to remove the <code>javax.sql.*</code> classes
489from this file depending upon the version of Tomcat and JDK you are using.
490</p>
491</blockquote></td></tr></table>
492
493<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Putting it all together"><!--()--></a><a name="Putting_it_all_together"><strong>Putting it all together</strong></a></font></td></tr><tr><td><blockquote>
494<p>
495Ensure that you have the <code>ocijdbc8.dll</code> or <code>.so</code> in your <code>$PATH</code> or <code>LD_LIBRARY_PATH</code>
496 (possibly in <code>$ORAHOME\bin</code>) and also confirm that the native library can be loaded by a simple test program
497using <code>System.loadLibrary("ocijdbc8");</code>
498</p>
499<p>
500You should next create a simple test servlet or jsp that has these
501<strong>critical lines</strong>:
502</p>
503<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>
504DriverManager.registerDriver(new
505oracle.jdbc.driver.OracleDriver());
506conn =
507DriverManager.getConnection("jdbc:oracle:oci8:@database","username","password");
508</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>
509<p>
510where database is of the form <code>host:port:SID</code> Now if you try to access the URL of your
511test servlet/jsp and what you get is a
512<code>ServletException</code> with a root cause of <code>java.lang.UnsatisfiedLinkError:get_env_handle</code>.
513</p>
514<p>
515First, the <code>UnsatisfiedLinkError</code> indicates that you have
516<ul>
517<li>a mismatch between your JDBC classes file and
518your Oracle client version. The giveaway here is the message stating that a needed library file cannot be
519found. For example, you may be using a classes12.zip file from Oracle Version 8.1.6 with a Version 8.1.5
520Oracle client. The classeXXXs.zip file and Oracle client software versions must match.
521</li>
522<li>A <code>$PATH</code>, <code>LD_LIBRARY_PATH</code> problem.</li>
523<li>It has been reported that ignoring the driver you have downloded from otn and using
524the classes12.zip file from the directory <code>$ORAHOME\jdbc\lib</code> will also work.
525</li>
526</ul>
527</p>
528<p>
529Next you may experience the error <code>ORA-06401 NETCMN: invalid driver designator</code>
530</p>
531<p>
532The Oracle documentation says : "Cause: The login (connect) string contains an invalid
533driver designator. Action: Correct the string and re-submit."
534
535Change the database connect string (of the form <code>host:port:SID</code>) with this one:
536<code>(description=(address=(host=myhost)(protocol=tcp)(port=1521))(connect_data=(sid=orcl)))</code>
537</p>
538<p>
539<i>Ed. Hmm, I don't think this is really needed if you sort out your TNSNames - but I'm not an Oracle DBA :-)</i>
540</p>
541</blockquote></td></tr></table>
542</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Common Problems"><!--()--></a><a name="Common_Problems"><strong>Common Problems</strong></a></font></td></tr><tr><td><blockquote>
543<p>Here are some common problems encountered with a web application which
544uses a database and tips for how to solve them.</p>
545
546<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Intermittent Database Connection Failures"><!--()--></a><a name="Intermittent_Database_Connection_Failures"><strong>Intermittent Database Connection Failures</strong></a></font></td></tr><tr><td><blockquote>
547<p>
548Tomcat runs within a JVM. The JVM periodically performs garbage collection
549(GC) to remove java objects which are no longer being used. When the JVM
550performs GC execution of code within Tomcat freezes. If the maximum time
551configured for establishment of a database connection is less than the amount
552of time garbage collection took you can get a database connection failure.
553</p>
554
555<p>To collect data on how long garbage collection is taking add the
556<code>-verbose:gc</code> argument to your <code>CATALINA_OPTS</code>
557environment variable when starting Tomcat. When verbose gc is enabled
558your <code>$CATALINA_BASE/logs/catalina.out</code> log file will include
559data for every garbage collection including how long it took.</p>
560
561<p>When your JVM is tuned correctly 99% of the time a GC will take less
562than one second. The remainder will only take a few seconds. Rarely,
563if ever should a GC take more than 10 seconds.</p>
564
565<p>Make sure that the db connection timeout is set to 10-15 seconds.
566For the DBCP you set this using the parameter <code>maxWait</code>.</p>
567
568</blockquote></td></tr></table>
569
570<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Random Connection Closed Exceptions"><!--()--></a><a name="Random_Connection_Closed_Exceptions"><strong>Random Connection Closed Exceptions</strong></a></font></td></tr><tr><td><blockquote>
571<p>
572These can occur when one request gets a db connection from the connection
573pool and closes it twice. When using a connection pool, closing the
574connection just returns it to the pool for reuse by another request,
575it doesn't close the connection. And Tomcat uses multiple threads to
576handle concurrent requests. Here is an example of the sequence
577of events which could cause this error in Tomcat:
578</p>
579<pre>
580 Request 1 running in Thread 1 gets a db connection.
581
582 Request 1 closes the db connection.
583
584 The JVM switches the running thread to Thread 2
585
586 Request 2 running in Thread 2 gets a db connection
587 (the same db connection just closed by Request 1).
588
589 The JVM switches the running thread back to Thread 1
590
591 Request 1 closes the db connection a second time in a finally block.
592
593 The JVM switches the running thread back to Thread 2
594
595 Request 2 Thread 2 tries to use the db connection but fails
596 because Request 1 closed it.
597</pre>
598<p>
599Here is an example of properly written code to use a database connection
600obtained from a connection pool:
601</p>
602<pre>
603 Connection conn = null;
604 Statement stmt = null; // Or PreparedStatement if needed
605 ResultSet rs = null;
606 try {
607 conn = ... get connection from connection pool ...
608 stmt = conn.createStatement("select ...");
609 rs = stmt.executeQuery();
610 ... iterate through the result set ...
611 rs.close();
612 rs = null;
613 stmt.close();
614 stmt = null;
615 conn.close(); // Return to connection pool
616 conn = null; // Make sure we don't close it twice
617 } catch (SQLException e) {
618 ... deal with errors ...
619 } finally {
620 // Always make sure result sets and statements are closed,
621 // and the connection is returned to the pool
622 if (rs != null) {
623 try { rs.close(); } catch (SQLException e) { ; }
624 rs = null;
625 }
626 if (stmt != null) {
627 try { stmt.close(); } catch (SQLException e) { ; }
628 stmt = null;
629 }
630 if (conn != null) {
631 try { conn.close(); } catch (SQLException e) { ; }
632 conn = null;
633 }
634 }
635</pre>
636
637</blockquote></td></tr></table>
638
639<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Context versus GlobalNamingResources"><!--()--></a><a name="Context_versus_GlobalNamingResources"><strong>Context versus GlobalNamingResources</strong></a></font></td></tr><tr><td><blockquote>
640<p>
641 Please note that although the above instructions place the JNDI declarations in a Context
642 element, it is possible and sometimes desirable to place these declarations in the
643 <a href="config/globalresources.html">GlobalNamingResources</a> section of the server
644 configuration file. A resource placed in the GlobalNamingResources section will be shared
645 among the Contexts of the server.
646</p>
647</blockquote></td></tr></table>
648
649<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="JNDI Resource Naming and Realm Interaction"><!--()--></a><a name="JNDI_Resource_Naming_and_Realm_Interaction"><strong>JNDI Resource Naming and Realm Interaction</strong></a></font></td></tr><tr><td><blockquote>
650<p>
651 In order to get Realms to work, the realm must refer to the datasource as
652 defined in the &lt;GlobalNamingResources&gt; or &lt;Context&gt; section, not a datasource as renamed
653 using &lt;ResourceLink&gt;.
654</p>
655</blockquote></td></tr></table>
656
657</blockquote></td></tr></table></td></tr><!--FOOTER SEPARATOR--><tr><td colspan="2"><hr noshade="noshade" size="1"></td></tr><!--PAGE FOOTER--><tr><td colspan="2"><div align="center"><font color="#525D76" size="-1"><em>
658 Copyright &copy; 1999-2014, Apache Software Foundation
659 </em></font></div></td></tr></table></body></html>