在Tomcat中通过JOTM支持JTA

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     define subcomponents such as "Valves" at this level.
     Documentation at /docs/config/server.html
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<Server port="8005" shutdown="SHUTDOWN">

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              pathname="conf/tomcat-users.xml" />
     <!--
		数据库连接池配置
	 -->
    <Resource name="jdbc/ExampleDB" auth="Container" type="javax.sql.DataSource"
              maxActive="100" maxIdle="30" maxWait="10000"
              username="APP" password="APP" driverClassName="org.apache.derby.jdbc.ClientDriver"
              url="jdbc:derby://localhost:1527/springside-example;create=true"/>
              
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		标明此链接使用上面配置的名称为tomcatThreadPool的连接池，无属性共享连接不会生效 -->
    <Connector port="8080" protocol="HTTP/1.1" redirectPort="8443" 
               connectionTimeout="20000" 
               executor="tomcatThreadPool" 
               acceptCount="100"
               useBodyEncodingForURI="true"
               enableLookups="false"
                />
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               maxThreads="150" scheme="https" secure="true"
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               backlog="100"
               useBodyEncodingForURI="true"
               enableLookups="false"
               />


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   <Engine name="Catalina" defaultHost="localhost" jvmRoute="cluster1">

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             resourceName="UserDatabase"/>

      <!-- Define the default virtual host
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       -->
      <Host name="localhost"  appBase="webapps"
            unpackWARs="true" autoDeploy="true"
            xmlValidation="false" xmlNamespaceAware="false">

		<!--
			配置虚拟目录，例如：http://localhost:8080	
		-->
		<Context path="/" docBase="D:\workspace\code\HBJH\web"></Context>
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        <!--
        <Valve className="org.apache.catalina.authenticator.SingleSignOn" />
        -->

        <!-- Access log processes all example.
             Documentation at: /docs/config/valve.html -->
        <!--
        <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"  
               prefix="localhost_access_log." suffix=".txt" pattern="common" resolveHosts="false"/>
        -->

      </Host>
    </Engine>
  </Service>
</Server>

Tomcat6 Support JTA with JOTM
1.place jotm jars into tomcat6/lib
2. create a file named "carol.properties" in tomcat6/lib with following content:
   carol.protocols=jrmp
   carol.start.jndi=false
  carol.start.ns=false
  carol.jvm.rmi.local.call=false
carol.jndi.java.naming.factory.url.pkgs=org.apache.naming
3.edit tomcat's server.xml:
<Context ...>
       <Transaction factory="org.objectweb.jotm.UserTransactionFactory" jotm.timeout="60"/>
</Context>
4.modify datasource define in server.xml:
<Resource auth="Container" factory="org.objectweb.jndi.DataSourceFactory" driverClassName="com.mysql.jdbc.Driver"...
5.modify spring config:
<bean id="transactionManager" class="org.springframework.transaction.jta.JtaTransactionManager"/>
support JMS Transaction:
<jms:jca-listener-container transaction-manager="transactionManager">
        <jms:listener destination="..." ref="..." />
</jms:jca-listener-container>
JOTM发布了2.14,而官网以及网上大部分资料为2.0*

JOTM2.14的Build-Jdk: 1.5.0_10，tomcat6中可以直接使用，无需再自行打包。

如果只是为了在tomcat6中使用UserTransaction,仅需如下设置

tomcat_home/conf中设置context.xml:
<Resource name="jdbc/TEST_DS"
auth="Container"
type="javax.sql.DataSource"
factory="org.objectweb.jotm.datasource.DataSourceFactory"
driverClassName="oracle.jdbc.driver.OracleDriver"
url="jdbc:oracle:thin:@XXX:1521:xxx"
username="xxx" password="xxx" maxActive="20" maxIdle="10"
maxWait="-1" />

<Resource name="UserTransaction"
auth="Container"
type="javax.transaction.UserTransaction" />

<Transaction factory="org.objectweb.jotm.UserTransactionFactory"
jotm.timeout="60" />

在tomcat_home/conf中加入carol.properties
carol.protocols=jrmp
carol.jvm.rmi.local.call=true
carol.start.jndi=false
carol.start.ns=false
carol.jndi.java.naming.factory.url.pkgs=org.apache.naming

在tomcat_home/lib中加入
carol.jar
howl.jar
jotm-core.jar
jotm-datasource.jar
ow2-connector-1.5-spec.jar
ow2-jta-1.1-spec.jar
xapool.jar

调用程式为
Context ctx = new InitialContext();
DataSource ds = (DataSource)
ctx.lookup("java:comp/env/jdbc/TEST_DS");
UserTransaction ut = (UserTransaction)
ctx.lookup("java:comp/UserTransaction");
java.sql.Connection conn = ds.getConnection();
ut.begin();
ut.commit(); or ut.rollback();
程式最小依赖包为
jotm-core.jar
jotm-client.jar
jotm-datasource.jar
ow2-jta-1.1-spec.jar
xapool.jar


在Tomcat中通过JOTM支持JTA
因为需要将项目从IBM WebSphere Application Server移植到Tomcat上开发，所以研究了一下在Tomcat中通过JNDI查找和使用JDBC及JTA的方法。

Tomcat 是Servlet容器，但它也提供了一个JNDI InitialContext实现，因此用户可以像在J2EE应用程序服务器中一样在Tomcat中使用JNDI查找JDBC数据源。不过在事务处理方面，Tomcat本身并不支持JTA(Java Transaction API)，所以需要借助其他的方案。
JOTM(Java Open Transaction Manager)是ObjectWeb的一个开源JTA实现，它本身也是开源应用程序服务器JOnAS(Java Open Application Server)的一部分，为其提供JTA支持和分布式事务管理。JOTM同样可以为Tomcat提供JTA支持，以下将对相关的配置进行简单说明，使用的相应版本为：

Tomcat 5.5.x
JOTM 2.0.x
Oracle 9i

1. 配置Tomcat环境

在$TOMCAT_HOME/conf/context.xml文件中添加以下内容：

<Resource name="jdbc/framework" auth="Container"
type="javax.sql.DataSource"
factory="org.objectweb.jndi.DataSourceFactory"
username="user" password="pwd"
driverClassName="oracle.jdbc.driver.OracleDriver"
url="jdbc:oracle:thin:@172.18.136.200:1521:ORADB"
maxActive="30" maxIdle="30"/>

<Transaction factory="org.objectweb.jotm.UserTransactionFactory"
jotm.timeout="60"/>

2. 添加所需的JAR文件

下载JOTM，将以下文件添加到$TOMCAT_HOME/common/lib/：
jotm.jar
jotm_jrmp_stubs.jar
jotm_iiop_stubs.jar
ow_carol.jar
jta-spec1_0_1.jar
jts1_0.jar
objectweb-datasource.jar
xapool.jar
howl.jar
connector-1_5.jar
同时，还需要添加相应数据库的JDBC包，例如Oracle的classes12.jar

3. 配置JOTM

新建一个carol.properties文件，置于$TOMCAT_HOME/common/classes/，文件内容如下：

# JNDI (Protocol Invocation)
carol.protocols=jrmp

# Local RMI Invocation
carol.jvm.rmi.local.call=true

# do not use CAROL JNDI wrapper
carol.start.jndi=false

# do not start a name server
carol.start.ns=false

# Naming Factory
carol.jndi.java.naming.factory.url.pkgs=org.apache.naming

这样JOTM将不会使用CAROL JNDI wrapper，从而可以避免类装载错误的发生

4. 说明

4.1 JOTM目前的版本在JDK1.5或以上可能无法正常运行，解决的方法有两个：使用JDK1.5重新编译carol库，或者将Tomcat运行在JDK1.4中

4.2 <Transaction>是Tomcat 5中的新标记，对于不支持此标记的老版本，需要使用以下语句代替事务资源的声明：

<!-- Resource configuration for UserTransaction
use JOTM
-->
<Resource name="UserTransaction" auth="Container"
type="javax.transaction.UserTransaction"
factory = "org.objectweb.jotm.UserTransactionFactory"
jotm.timeout = "60"/>

4.3 需要注意的是，使用<Resource>节点声明的资源默认上下文前缀是"java:comp/env"，而使用< Transaction>节点时则是"java:comp"。因此，当使用4.2的方式声明用户事务时，相应的JNDI查找代码也应该改为 UserTransaction ut = (UserTransaction)initCtx.lookup("java:comp/env/UserTransaction");

5. 测试
假设数据库中已经做了相应配置，可以使用如下jsp页面进行测试：
<!--test.jsp-->
<%@page contentType="text/html;charset=GB2312"%>
<%@page import="java.sql.*"%>
<%@page import="javax.sql.*"%>
<%@page import="javax.naming.*"%>
<%@page import="javax.transaction.UserTransaction"%>
<%
ResultSet rs = null;
Statement stmt = null;
UserTransaction ut = null;
Connection conn = null;
try {
Context initCtx = new InitialContext();
Context envCtx = (Context) initCtx.lookup("java:comp/env");
DataSource ds = (DataSource) envCtx.lookup("jdbc/framework");
ut = (UserTransaction)initCtx.lookup("java:comp/UserTransaction");
conn = ds.getConnection();

ut.begin();
System.out.println("<<< beginning the transaction >>>");

stmt = conn.createStatement(
// ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE
);
rs = stmt.executeQuery("SELECT PRICE FROM TM_PRODUCT WHERE ID=1");
rs.next();
} catch(Exception e) {e.printStackTrace();}
%>
<html>
<body>
Original price:
<%=rs.getString("price")%>
<br>After update:
<%
PreparedStatement pstmt = conn.prepareStatement("update tm_product set price=? where id=1");
pstmt.setInt(1,101);
pstmt.executeUpdate();
rs = stmt.executeQuery("SELECT PRICE FROM TM_PRODUCT WHERE ID=1");
rs.next();
%>
<%=rs.getString("price")%>
<br>After Rollback:
<%
System.out.println("<<< rolling back the transaction >>>");
ut.rollback();//Or ut.commit();
rs = stmt.executeQuery("SELECT PRICE FROM TM_PRODUCT WHERE ID=1");
rs.next();
%>
<%=rs.getString("price")%>
<%conn.close();%>
</body>
</html>

为tomcat分配内存
这里要分配的是允许java使用的最大内存大小，要根据MAS服务器实际配置而定。建议配置如下：
  1G内存：JAVA_OPTS='-Xms512m -Xmx512m'
  2G内存：JAVA_OPTS='-Xms512m -Xmx1024m'
  4G内存：JAVA_OPTS='-Xms512m -Xmx2048m'
用vi打开/opt/tomcat/bin/catalina.sh，在开头加入：
JAVA_OPTS='-Xms512m -Xmx512m'
保存退出。

Tomcat默认可以使用的内存为128MB，在较大型的应用项目中，这点内存是不够的，轻微时，会使系统性能急剧下降，严重时,将导致系统无法运行，影响系统的稳定性。当内存不够用时，常见的问题就是报tomcat内存益处错误，从儿导致客户端包500错误的，如下：解决方法主要是加大TOMCAT可利用内存，并在程序当中加大内存使用。因此根据应用的需求，有必要调整JVM使用内存的大小。现在将手工修改tomcat内存的方法及注意事项列出，希望能对新人有所帮助。
tomcat提供了两种安装模式，即免安装（*.zip）和安装（*.exe）方式。针对不同的安装方式下修改tomcat内存大小的方法几注意问题（windows环境）：
方式1：当选择安装方式时，可以在安装tomcat的过程进行设置tomcat初始化内存的大小。但是假如说在安装时没有选择，或者应用改变了，需要增加tomcat内存时怎么半呢？此时，我们就要手工修改tomcat的一些文件了：
看了很多网上的资料，都是说修改<CATALINA_HOME>\bin\catalina.bat文件的内容，即在里面增加一行代码：
set JAVA_OPTS=-Xms512m -Xmx512m //表示初始化最小可用内存和最大可用内存都是512MB（修改相应值即可）

如在catalina.bat的
rem ----- Execute The Requested Command
echo Using CATALINA_BASE: %CATALINA_BASE%
echo Using CATALINA_HOME: %CATALINA_HOME%
echo Using CATALINA_TMPDIR: %CATALINA_TMPDIR%
echo Using JAVA_HOME: %JAVA_HOME%
这一栏改为
rem ----- Execute The Requested Command
set JAVA_OPTS=-Xms512m -Xmx512m
echo Using CATALINA_BASE: %CATALINA_BASE%
echo Using CATALINA_HOME: %CATALINA_HOME%
echo Using CATALINA_TMPDIR: %CATALINA_TMPDIR%
echo Using JAVA_HOME: %JAVA_HOME%
就可以将JAVA虚拟机分配内存 508.0625MB的!
但是很多人修改后，发现修改并没有起作用，即通过windows的服务启动tomcat时，实际的内存还是默认的，修改的设置并没有起作用；而通过<CATALINA_HOME>\bin\startup.bat 启动却是生效的。这是为什么呢？因为在安装过程中，JVM的初始化参数已经写在注册表中了，由于没有修改注册表中相关参数，所以以windows服务方式启动时，修改的并没有生效。而通过<CATALINA_HOME>\bin\startup.bat 启动直接是通过<CATALINA_HOME>\bin\catalina.bat文件中的配置的。你需要重新加载到系统服务中才生效，或者你手工在注册表中查找修改启动值，加载到服务中的时候参数已经配置好了，自己修改artup.bat不会改变注册表中的参数设置。

解决方法：修改注册表中的参数，加入JVM初始化内存的参数：
HKEY_LOCAL_MACHINE\SOFTWARE\Apache Software Foundation\Tomcat Service Manager\Tomcat5\Parameters\JavaOptions
值为
-Dcatalina.home="C:\ApacheGroup\Tomcat 5.0"
-Djava.endorsed.dirs="C:\ApacheGroup\Tomcat 5.0\common\endorsed"
-Xrs
如加入 -Xms512m -Xmx800m

方式2：针对免安装的用户，也可以通过将tomcat注册为windows的一个服务的方式来实现：‘
我们可以对service.bat文件做一些其他修改，使tomcat更加能满足我们各种不同需求时的要求
1. 如果让tomcat编译jsp文件，就在PR_CLASSPATH中加入J2SDK的tools.jar
修改前：
set PR_CLASSPATH=%CATALINA_HOME%\bin\bootstrap.jar
修改后：
set PR_CLASSPATH=%JAVA_HOME%\lib\tools.jar;%CATALINA_HOME%\bin\bootstrap.jar
2.要使用一个特定的JVM，就要修改jvm的参数；要使注册的windows服务的启动方式为自动，增加--Startup Automatic，这个是比较常用的；要用定制的server.xml配置文件并且传递多个参数给StartClass，要修改StartParams的值，各个值之间用分号分隔：
修改前：
"%EXECUTABLE%" //IS//%SERVICE_NAME% --Jvm auto
--StartClass org.apache.catalina.startup.Bootstrap --StopClass org.apache.catalina.startup.Bootstrap
--StartParams start --StopParams stop
修改后：
"%EXECUTABLE%" //IS//%SERVICE_NAME% --Jvm "%JAVA_HOME%\jre\bin\server\jvm.dll"
--StartClass org.apache.catalina.startup.Bootstrap --StopClass org.apache.catalina.startup.Bootstrap
--StartParams "-config;%CUSTOM_SERVERXML_FILE%;-nonaming;start" --StopParams stop
--Startup Automatic
3. 指定最大和最小的内存限制，要增加jvm的初始参数
修改前：
"%EXECUTABLE%" //US//%SERVICE_NAME% --JvmOptions
"-Dcatalina.base=%CATALINA_BASE%;-Dcatalina.home=%CATALINA_HOME%;-Djava.endorsed.dirs=%CATALINA_HOME%\common\endorsed"
--StartMode jvm --StopMode jvm
修改后：
"%EXECUTABLE%" //US//%SERVICE_NAME% --JvmOptions
"-Xms128M;-Xmx256M;-Dcatalina.base=%CATALINA_BASE%;-Dcatalina.home=%CATALINA_HOME%;-Djava.endorsed.dirs=%CATALINA_HOME%\common\endorsed"
--StartMode jvm --StopMode jvm
4.有时注册windows服务成功后，但是启动服务时显示“发生服务特定错误: 0.”
就是因为jvm没有指定，修改Jvm auto为Jvm "%JAVA_HOME%\jre\bin\server\jvm.dll"后重新注册windows服务就可以启动了。


java -server -Xms512m -Xmx512m -XX:MaxNewSize=256m