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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html">
<TITLE>VM Bridge FAQ</TITLE>
</HEAD>
<H1>VM Bridge FAQ</H1>
This file contains answers to frequently asked questions. Please see <a href="http:https://php-java-bridge.sourceforge.net/pjb">http:https://php-java-bridge.sourceforge.net</a> for more information.
<H2>General questions</H2>
<H4>Which alternatives exist?</H4>
<p>There are at least 4 other php to java bridges which offer a similar API. One was distributed with PHP 4.0.0 and has been discontinued. Two other bridges are proprietary software, built into a vendor-specific framework from Zend or a J2EE application server from Caucho.
Furthermore IBM's Zero framework for Eclipse contains a PHP interpreter written in pure Java and a php to java bridge which can call Java methods in-process.</p>
<p>The only free alternatives are SOAP and XML-RPC, which are up to 50 times slower than the XML protocol implementation used by this VM Bridge.</p>
<H4>How do I enable the Java extension in my php.ini file?</H4>
<p>A Java extension does not exist, so you can't enable it.</p>
<p>The VM Bridge is a network protocol, it requires a running Java VM, for example the servlet container Apache/Tomcat. Or, if you want to call PHP libraries from Java, a running PHP container, e.g. Apache or IIS.</p>
<H4>What do I need to communicate with Java?</H4>
<p>Only the PHP code from <code>Java.inc</code> and a running Java application, for example <code>JavaBridge.jar</code>, or a running Java servlet, for example <code>JavaBridge.war</code>.</p>
<p>Test code:
<blockquote>
<code>
<?php require_once("http:https://localhost:8080/JavaBridge/java/Java.inc"); <br>
echo java("java.lang.System")->getProperties(); ?>
</code>
</blockquote>
</p>
<H4>What do I need to communicate with PHP?</H4>
<p>Only the PHP code from <code>JavaProxy.php</code> within your PHP web application, the Java libraries <code>JavaBridge.jar</code>, <code>php-script.jar</code> and <code>php-servlet.jar</code>, and a <code>ContextLoaderListener</code> declaration in your <code>WEB-INF/web.xml</code></p>
<p>Test code:
<blockquote>
<code>
<% javax.script.ScriptEngine e = php.java.script.servlet.EngineFactory.getInvocablePhpScriptEngine (this, application, request, response, new java.net.URI("http:https://yourIntranetHost:80/yourPhpWebApp/JavaProxy.php"));<br>
out.println("yourIntranetHost running PHP version: " + (String)((javax.script.Invocable)e).invokeFunction("phpversion", new Object[]{}));<br>
((java.io.Closeable)e).close();
%>
</code>
</blockquote>
</p>
<H4>Which versions are supported?</H4>
<ul>
<li>PHP >= 5.1.2. PHP >= 5.3 recommended.</li>
<li>Java >= 1.4. Java >= 6 recommended.</li>
<li>J2EE >= 1.3.</li>
</ul>
<H4>Why doesn't the bridge throw a java.lang.RuntimeException or Error as a PHP JavaException by default?</H4>
<p>
All exceptions crossing the php/java container <strong>must</strong> be declared. If you want to catch <code>java.lang.RuntimeException</code> or <code>java.lang.Error</code> from PHP code, add a "throws" declaration. Example:
<blockquote>
<code>
public Object calculateValue(...) throws RuntimeException;
</code>
</blockquote>
It is a good programming practice to not allow <code>java.lang.RuntimeException</code> and <code>java.lang.Error</code> to cross an application container boundary. A JEE "enterprise java beans" container for example will terminate a transaction immediately if it encounters an exception derived from Error or RuntimeException.
</p>
<p>
However, since PHP/Java Bridge version 5.5.3 the bridge reports a java.lang.RuntimeException/Error as a PHP JavaException if the option <code>JAVA_PREFER_VALUES</code> is set. Please see the NEWS entry for version 5.5.3 from the PHP/Java Bridge documentation download for details.
</p>
<H4>Do I need a Java Application Server or Servlet Engine?</H4>
<p>Yes, Java needs an execution environment. Experienced users may use the execution environment built into JavaBridge.jar, see <code>java -jar JavaBridge.jar --help</code> for help.
</p>
<p>
You can also add PHP support to your standalone Java application by
adding the following line to its main class:
<blockquote>
<code>
static final php.java.bridge.JavaBridgeRunner runner = php.java.bridge.JavaBridgeRunner.getInstance(8087);
</code>
</blockquote>
The above code opens the port 8087, so that local PHP scripts can call
methods/procedures from your Java application, as long as your Java
application is running.
</p>
<p>The third option is the standard JSR 223 script interface, which
allows one to execute PHP code/scripts from Java applications.
</p>
<H4>Ho do I enable logging?</H4>
<p>
Copy <code>log4j.jar</code> into <code>java.ext.dirs</code>. Example for JDK 6:
<blockquote>
<code>
cp log4j.jar /usr/java/packages/lib/ext
</code>
</blockquote>
</p>
<p>
Start the log4j viewer. Example for JDK 6:
<blockquote>
<code>
/opt/jdk1.6/bin/java org.apache.log4j.chainsaw.Main
</code>
</blockquote>
</p>
<p>
Start the application server with the options <code>-Dphp.java.bridge.default_log_level=LEVEL</code>. Example for tomcat:
<blockquote>
<code>
JAVA_HOME=/opt/jdk1.6 JAVA_OPTS="-Dphp.java.bridge.default_log_level=5" bin/catalina.sh run
</code>
</blockquote>
Example for the standalone container:
<blockquote>
<code>
java -Dphp.java.bridge.default_log_level=5 -jar JavaBridge.jar SERVLET:8080
</code>
</blockquote>
</p>
<H4>How can I set Java options?</H4>
<p>
With the -D flag. See <code>java -jar JavaBridge.jar --help for details. If tomcat is being used, one can set these options as follows:
<blockquote>
<code>
JAVA_OPTS="-D... -D..." /opt/tomcat/bin/catalina.sh run
</code>
</blockquote>
</p>
<H4>How can I increase the memory available to Java?</H4>
<p>
Use a VM >= 1.6 and add more RAM to your computer. Older Java versions
support the <code>Xmx</code> flag:
<blockquote>
<code>
java -Xmx512M ... -jar JavaBridge.jar SERVLET:8080
</code>
</blockquote>
</p>
<H4>How can I set PHP options?</H4>
<p>
With a <code>define</code> before a PHP library is loaded. Global options can also be set in the <code>php.ini</code> file. Use phpinfo() to see the location of this file.
</p>
<H4>How can I configure the bridge?</H4>
<p>Useful options which can be set before the Java.inc is loaded are:
<blockquote>
<code>
define ("JAVA_PREFER_VALUES", false);<br>
define ("JAVA_HOSTS", "127.0.0.1:8080");<br>
require_once ("java/Java.inc");<br>
...
</code>
</blockquote>
Please see the Options.inc for details.
</p>
<p>Server-side options can be set in the
php.java.bridge.global.properties file, see the JavaBridge.jar zip
file (contained in the JavaBridge.war zip file) for details.
</p>
<H4>Can I use Java libraries without installing java?</H4> <p>Yes. On a GNU operating system (e.g.: GNU/Linux, GNU/windows (aka "cygwin"), ...) you can use the GCC compiler to compile Java classes to native code.
Simply compile the C based extension and omit the
<code>--with-java=</code> configure option. The bridge will use the
<code>libgcj</code> library, which is part of the GNU gcc compiler. This library also uses much less system
resources (memory, files) than a "real" Java VM.</p>
<p>GCJ support has been removed in PHP/Java Bridge version 6. If
you want to compile JavaBridge.jar to native code, please use PHP/Java
Bridge version 5.5.4 instead.</p>
<H4>I can't load the resource or file from the current working directory!?!</H4>
<p>
The "current working directory" is not useful, as the Java back end may be running
on a different server or from a different working directory. Use a full path or a URL resource instead.
</p>
<H4>I get a blank page or some other error!?!</H4>
<p>
Check the PHP error log, see your <code>php.ini</code> file for details. If the command:
<blockquote>
<code>
echo '<?php require_once("http:https://localhost:8080/JavaBridge/java/Java.inc"); echo java("java.lang.System")->getProperties();?>' | php -n -d allow_url_include=On
</code>
</blockquote>
works in the shell but not within apache, then there's something wrong with your <code>php.ini</code> file.
</p>
<H4>Can I use Python instead of PHP?</H4>
<p>Yes, see the examples folder from the source download.</p>
<H4>Can I access Mono or .NET libraries using the pure PHP implementation?</H4>
<p>Yes, PHP/Java Bridge version < 6 contains a PHP library
"Mono.inc" generated from "Java.inc" and a "MonoBridge.exe" generated
from "JavaBridge.jar". If you want to compile from source, use the
configure option <code>--with-mono</code>.</p>
<p>Mono/.NET support has been removed in PHP/Java Bridge version
6. If you want to access Mono/.NET libraries, please use PHP/Java
Bridge version 5.5.4 instead.</p>
<H4>What does a "protocol error ..." mean?</H4>
<p>That your Java has problems, for example an OutOfMemoryError. Check the back end (Tomcat/J2EE/...) log for details.</p>
<p>It could also indicate a setup problem. If you use a servlet back end but haven't set the <code>java.servlet</code> or <code>JAVA_SERVLET</code> option, the PHP library <code>Java.inc</code> will confuse the HTML response from the servlet engine with the XML protocol used by the bridge.</p>
<H4>Does it support PHP 4?</H4>
<p>Start a simple socket listener and use the following "Java" class:
<blockquote>
<code>
<?php<br>
// The following is the "Java" class definition, stripped down to fit<br>
// into one line. To use this sample start Java with: java -jar<br>
// JavaBridge.jar INET:9267. Then type: php sample.php<br>
//<br>
class P{var$Pc="<C v=\"%s\" p=\"I\">",$PC="</C>",$Pi="<I v=\"%d\" m=\"%s\" p=\"I\">",$PI="</I>",$Ps="<S v=\"%s\"/>",$Pl="<L v=\"%d\" p=\"%s\"/>",$Po="<O v=\"%d\"/>",$c;function str($s){fwrite($this->c,sprintf($this->Ps,$s));}function obj($s){fwrite($this->c,sprintf($this->Po,$s->j));}function P(){$this->c=fsockopen("127.0.0.1",9267);}function cB($s){fwrite($this->c,sprintf($this->Pc,$s));}function cE(){fwrite($this->c,$this->PC);}function iB($o,$m){fwrite($this->c,sprintf($this->Pi,$o,$m));}function iE(){fwrite($this->c,$this->PI);}function v($s){if(is_object($s))$this->obj($s);else$this->str((string)$s);}function res(){$r=sscanf(fread($this->c,8192),"%s v=\"%[^\"]\"");return$r[1];}}function gP(){static$p;if(!$p)$p=new P();return$p;}class Java{var$j,$p;function Java(){if(!func_num_args())return;$this->p=gP();$ar=func_get_args();$this->p->cB(array_shift($ar));foreach($ar as$arg)$this->p->v($arg);$this->p->cE();$ar=sscanf($this->p->res(),"%d");$this->j=$ar[0];}function __call($m,$a,&$rv){$this->p->iB($this->j,$m);foreach($a as$arg)$this->p->v($arg);$this->p->iE();$p=new Java();$ar=sscanf($this->p->res(),"%d");$p->j=$ar[0];$p->p=$this->p;$rv=$p;return true;}function toString(){$this->p->iB("","castToString");$this->p->v($this);$this->p->iE();return base64_decode($this->p->res());}}overload("Java");<br>
<br>
<br>
// Test<br>
$i1 = new Java("java.math.BigInteger", "1");<br>
$i2 = new Java("java.math.BigInteger", "2");<br>
$i3 = $i1->add($i2);<br>
echo $i3->toString() . "\n";<br>
?><br>
</code>
</blockquote>
</p>
<H2>Class loading questions</H2>
<a name="java-require"></a>
<H4>Why has java_require() been deprecated?</H4>
<p>
Because Java doesn't have a module system.
</p>
<p>
For example a library "lucene-2.3.1.jar" required by application B,
cannot be loaded if an older version of the library, required by
application A, is already cached.<br>
An attempt to link the library anyway will cause "NoClassDefFound" or "NoSuchMethod" errors at runtime. Or some procedures may throw checked exceptions even though they haven't declared them.
</p>
<p>
To protect PHP developers from Java's "<a href="http:https://en.wikipedia.org/wiki/JAR_hell">jar hell</a>", I have removed the
dynamic class loading mechanism from PHP/Java Bridge version 6.0;
java_require() issues a warning.
</p>
<p>
A proper Java module system must use special Java VM hooks, which don't
exist until now.
</p>
<H4>How do I load Java libraries?</H4>
<p>You should link your Java application as described in the
<a href="http:https://php-java-bridge.sourceforge.net/pjb/standalone.php">Java standalone</a>
or
<a href="http:https://php-java-bridge.sourceforge.net/pjb/webapp.php">Java webapps</a>
documents.
</p>
<H4>Where can I store my java libraries for the VM Bridge?</H4>
<p>In your web application <code>WEB-INF/lib</code> directory.</p>
<p> If libraries should be available globally, store them in <code>java.ext.dirs</code>, for example in <code>/usr/share/java/ext</code>.</p>
<H4>Why do I get a ClassNotFoundException?</H4>
<p>You probably haven't loaded the relevant Java library. Or the
class doesn't exist or it is not public or it throws a java.lang.Error
during initialization. Check which library exports the feature and add the library to your web application WEB-INF/lib directory.</p>
<a name="java-dll-hell"></a>
<H4>Why do I get a NoClassDefFoundError?</H4>
<p>Because Java doesn't have a module system.</p>
<p>All libraries and their dependencies must be loaded by one, and only one class loader.</p>
<p>Please read the previous sentence until you understand what it means; for example a simple file system copy(!) operation may be the cause for a NoClassDefFoundError.</p>
<p><em>Please do not report NoClassDefFoundErrors to the mailing list or via the bug tracker. This is not a bug and we cannot help you any further!</em></p>
<H4>How do I load impure Java libraries?</H4>
<p>You can't. Java libraries must be pure Java.</p>
<p> Please read the
documentation of your J2EE server, Servlet engine or Java VM to see if and
how the environment can handle impure Java libraries. A common approach is to store the Java part in <code>java.ext.dirs</code> and the native part in <code>java.library.path</code>.</p>
<H2>J2EE/Servlet questions</H2>
<a name="php-extensions">
<H4>I want to ship my own PHP web application. Where do I put PHP and PHP extensions?</H4>
<p>
PHP binaries go to <code>WEB-INF/cgi/</code> and should be named <code>php-cgi-ARCHITECTURE-OS.exe</code> (Windows) or <code>php-cgi-ARCHITECTURE-OS</code> (Linux/Unix).
</p>
<p>
PHP extensions go to <code>WEB-INF/cgi/ARCHITECTORE-OS/ext</code>. The extension can be customized with a <code>WEB-INF/cgi/ARCHITECTURE-OS/conf.d/EXTENSION.ini</code> file.
<p>
Pure PHP libraries go to <code>WEB-INF/pear/</code>.
</p>
<p>
Example for the PHP mysql extension for Linux and Windows (i386/x86):
<blockquote>
<code>
WEB-INF --- cgi --- php-cgi-x86-windows.exe<br>
|<br>
--- x86-windows --- conf.d --- mysql.ini [extension="php_mysql.dll"]<br>
| |<br>
| --- ext --- php_mysql.dll<br>
|<br>
|<br>
--- php-cgi-i386-linux<br>
|<br>
--- i386-linux --- conf.d --- mysql.ini [extension="mysql.so"]<br>
|<br>
--- ext --- mysql.so<br>
</code>
</blockquote>
<a name="custom-servlet">
<H4>I have written my own servlet. How do I call it from PHP?</H4>
<p>
Add the following code to your servlet:
<blockquote>
<code>
public String hello() { return "hello from MyServlet"; }<br>
[...]<br>
protected void doPut (HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {<br>
IContextFactory ctx = new RemoteHttpServletContextFactory(this, getServletContext(), req, req, res);<br>
res.setHeader("X_JAVABRIDGE_CONTEXT", ctx.getId());<br>
res.setHeader("Pragma", "no-cache");<br>
res.setHeader("Cache-Control", "no-cache");<br>
try { ctx.getBridge().handleRequests(req.getInputStream(), res.getOutputStream()); } finally { ctx.destroy(); }<br>
}<br>
</code>
</blockquote>
</p>
<p>
Then copy the libraries <code>JavaBridge.jar</code> and <code>php-servlet.jar</code> to your <code>WEB-INF/lib</code> directory and re-deploy your web application.
</p>
<p>
If your servlet is programmed so that it listens on localhost:8080/MyWebApp/MyServlet, set <code>JAVA_HOSTS</code> and <code>JAVA_SERVLET</code> to these values:
<blockquote>
<code>
<?php
define("JAVA_HOSTS", "localhost:8080");<br>
define("JAVA_SERVLET", "/MyWebApp/MyServlet");<br>
require_once("java/Java.inc");<br>
<br>
echo java_context()->getServlet()->hello();<br>
?>
</code>
</blockquote>
</p>
<a name="load-balancing">
<H4>How do I set up a load balancer for the VM Bridge cluster?</H4>
<p>
Set up the VM Bridge cluster as <a href="#cluster">described below</a>. The example uses two nodes named "carlos" and "diego". The HTTP server front end runs on the web server "timon".
</p>
<p>Install Apache 2.2.0 or higher.</p>
<p>Enable <code>proxy_module</code> and <code>proxy_balancer_module</code>. The following example is for Linux (lines marked with "+" should be added to the <code>conf/httpd.conf</code> file):
<blockquote>
<code>
LoadModule rewrite_module modules/mod_rewrite.so<br>
+ LoadModule proxy_module modules/mod_proxy.so<br>
+ LoadModule proxy_balancer_module modules/mod_proxy_balancer.so<br>
LoadModule cache_module modules/mod_cache.so<br>
</code>
</blockquote>
</p>
<p>
Add the following code to the bottom of your <code>conf/httpd.conf</code> file:
<blockquote>
<code>
ProxyPass /JavaBridge balancer:https://mycluster maxattempts=2<br>
<Proxy balancer:https://mycluster><br>
BalancerMember http:https://diego:8080/JavaBridge<br>
BalancerMember http:https://carlos:8080/JavaBridge<br>
</Proxy><br>
<Location /balancer-manager><br>
SetHandler balancer-manager<br>
Deny from all<br>
Allow from 127.0.0.1<br>
</Location><br>
</code>
</blockquote>
</p>
<p>Start the cluster nodes on "carlos" and "diego".</p>
<p>Browse to <code>http:https://timon/JavaBridge/</code> (note the trailing slash) and click on the test.php. Click on refresh. Check if both nodes respond.</p>
<p>Browse to <code>http:https://timon/JavaBridge/sessionSharing.php</code> and click on refresh. Check the cookie value.</p>
<p>Browse to <code>http:https://timon/balancer-manager/</code>.
<p>Please see the <code>mod_rewrite</code> documentation for more information how to rewrite incoming URLs.</p>
</a>
<a name="cluster">
<H4>Ho do I set up a tomcat cluster?</H4>
<p>
Download tomcat 5 or higher, a Java JRE 5 or higher and the VM Bridge 4.1.6 or higher.
</p>
<p>
The following example uses two nodes running on two machines called
"carlos" and "diego".
</p>
<p>
On all nodes: Extract the tomcat distribution into a directory.
</p>
<p>On <strong>"diego"</strong> add the following to <code>conf/server.xml</code>:
<blockquote>
<code>
<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"<br>
channelSendOptions="8"><br>
<Manager className="org.apache.catalina.ha.session.DeltaManager"<br>
expireSessionsOnShutdown="false"<br>
notifyListenersOnReplication="true"/><br>
<Channel className="org.apache.catalina.tribes.group.GroupChannel"><br>
<Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"<br>
address="<strong>diego</strong>"<br>
port="4000"<br>
autoBind="100"<br>
selectorTimeout="5000"<br>
maxThreads="6"/><br>
</Channel><br>
</Cluster><br>
</code>
</blockquote>
</p>
<p>On <strong>"carlos"</strong> add the following to <code>conf/server.xml</code>:
<blockquote>
<code>
<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"<br>
channelSendOptions="8"><br>
<Manager className="org.apache.catalina.ha.session.DeltaManager"<br>
expireSessionsOnShutdown="false"<br>
notifyListenersOnReplication="true"/><br>
<Channel className="org.apache.catalina.tribes.group.GroupChannel"><br>
<Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"<br>
address="<strong>carlos</strong>"<br>
port="4000"<br>
autoBind="100"<br>
selectorTimeout="5000"<br>
maxThreads="6"/><br>
</Channel><br>
</Cluster><br>
</code>
</blockquote>
</p>
<p>Copy the "JavaBridge.war" into the "webapps" directory on "diego" and "carlos" and start both nodes. For example with the command:
<blockquote>
<code>
JAVA_OPTS="-Dphp.java.bridge.promiscuous=true" JAVA_HOME=/usr/java/default bin/catalina.sh run
</code>
</blockquote>
</p>
<p>
Please see your HTTP server documentation and <a href="#load-balancing">the description above</a> how to set it up as a load balancer.
</p>
</a>
<a name="global-servlet">
<H4>I want to use PHP for all tomcat applications. Apache and IIS are not available, but performance is important. How do I install it?</H4>
</a>
<ol>
<li>
Download the PHP/Java Bridge binary.
<li>
Copy <code>JavaBridge.jar</code>, <code>php-servlet.jar</code> and <code>php-script.jar</code> from the <code>JavaBridge.war</code> zip archive to <code>$CATALINA_HOME/lib</code>.
<li>
Add the following 9 lines marked with a <code>+</code> to the tomcat <code>$CATALINA_HOME/conf/web.xml</code> web app:
<blockquote>
<code>
<br>
<<em>web-app</em> xmlns=... >
<br><br>
+ <listener><listener-class>php.java.servlet.ContextLoaderListener</listener-class></listener><br>
+ <servlet><servlet-name>PhpJavaServlet</servlet-name><servlet-class>php.java.servlet.PhpJavaServlet</servlet-class><br>
+ </servlet><br>
+ <servlet><servlet-name>PhpCGIServlet</servlet-name><servlet-class>php.java.servlet.fastcgi.FastCGIServlet</servlet-class><br>
+ <init-param><param-name>prefer_system_php_exec</param-name><param-value>On</param-value></init-param><br>
+ <init-param><param-name>php_include_java</param-name><param-value>On</param-value></init-param><br>
+ </servlet><br>
+ <servlet-mapping><servlet-name>PhpJavaServlet</servlet-name><url-pattern>*.phpjavabridge</url-pattern> </servlet-mapping><br>
+ <servlet-mapping><servlet-name>PhpCGIServlet</servlet-name><url-pattern>*.php</url-pattern></servlet-mapping><br>
...<br>
<br>
<<em>/web-app</em>>
</code>
</blockquote>
<li>
Start tomcat.
</ol>
To test the above settings, add a file <code>test.php</code>:
<blockquote>
<code>
<?php echo java("java.lang.System")->getProperties(); ?>
</code>
</blockquote>
to some web context, for example "examples", and browse to <code>http:https://yourHost.com:8080/examples/test.php</code>.
<p>
In case you don't need to access Java from all of your scripts, you can set the <code>php_include_java</code> option to <code>Off</code> and <code>require_once("java/Java.inc")</code>, if needed.
<p>
<a name="php-web-app">
<H4>How do I create a standalone PHP web application for distribution and how can users deploy it into tomcat?</H4>
</a>
<p>
Create a directory <code>myApplication</code>, create the directories <code>myApplication/WEB-INF/lib/</code> and <code>myApplication/WEB-INF/cgi/</code>.
Download the J2EE binary and copy the <code>JavaBridge.jar</code> and the <code>php-servlet.jar</code> from the JavaBridge.war to the <code>myApplication/WEB-INF/lib/</code> folder. Copy the contents of the <code>cgi</code> folder to <code>myApplication/WEB-INF/cgi/</code>. Create the file <code>myApplication/WEB-INF/web.xml</code> with the following content:
<blockquote>
<code>
<br>
<web-app><br>
<!-- PHP Servlet --><br>
<servlet><br>
<servlet-name>PhpJavaServlet</servlet-name><br>
<servlet-class>php.java.servlet.PhpJavaServlet</servlet-class><br>
</servlet><br>
<!-- PHP CGI processing servlet, used when Apache/IIS are not available --><br>
<servlet><br>
<servlet-name>PhpCGIServlet</servlet-name><br>
<servlet-class>php.java.servlet.fastcgi.FastCGIServlet</servlet-class><br>
</servlet><br>
<br>
<!-- PHP Servlet Mapping --><br>
<servlet-mapping><br>
<servlet-name>PhpJavaServlet</servlet-name><br>
<url-pattern>*.phpjavabridge</url-pattern><br>
</servlet-mapping><br>
<!--PHP CGI Servlet Mapping --><br>
<servlet-mapping><br>
<servlet-name>PhpCGIServlet</servlet-name><br>
<url-pattern>*.php</url-pattern><br>
</servlet-mapping><br>
<br>
<!-- Welcome files --><br>
<welcome-file-list><br>
<welcome-file>index.php</welcome-file><br>
</welcome-file-list><br>
</web-app><br>
</code>
</blockquote>
</p>
<p>
<p>
Copy the files <code>sessionSharing.jsp</code> and <code>sessionSharing.php</code> from the <code>JavaBridge.war</code> to <code>myApplication</code> and create <code>myApplication.war</code>, for example with the commands: <code>cd myApplication; jar cf ../myApplication.war *</code>. </p>
<p>The web archive can now be distributed, copy it to the tomcat <code>webapps</code> directory and re-start tomcat. Visit <code>http:https://localhost/myApplication/sessionSharing.php</code> and <code>http:https://localhost/myApplication/sessionSharing.jsp</code>.
</p>
<a name="tomcat-security">
<H4>I want to use Tomcat's security manager, how do I install the bridge?</H4>
</a>
<p>
Install the PHP/Java Bridge for all web application as described <a href="#global-servlet">here</a>.
</p>
<a name="php-jsp-session-sharing">
<H4>I want to use Apache/IIS as a front-end and tomcat as a back end. How do I enable PHP and JSP for all my applications?</H4>
</a>
<p> Set up Apache or IIS so that it forwards requests to the back
end. Please see <a href="#load-balancing">the description above</a>
for details.
</p>
<H4>Does the
bridge run native code within my servlet engine or application
server?</H4> <p>No. The bridge back end is written in pure java, it
doesn't use any native code. Native PHP runs within Apache, IIS, or a
FCGI server. If the PHP instance crashes, an error page is
returned to the client and the Apache, IIS, CGI container usually starts a new PHP instance for the next
request.</p>
<H4>The EJB example works with the Sun J2EE server, but in JBoss I get a ClassCastException, what's wrong?</H4>
<p>It's a JBoss problem, although this problem may also appear in other application servers which do not strictly separate the application/bean domains. The JavaBridge.war already contains the <code>documentClient.jar</code> as a library, so JBoss references the library classes instead of the bean classes. Just remove the <code>documentClient.jar</code> from the <code>JavaBridge.war</code>, re-deploy <code>JavaBridge.war</code> and run the test again.
</p><p>
In JBoss' default setup the code:
<blockquote>
<code>
// access the home interface<br>
$DocumentHome = java("DocumentHome");<br>
$PortableRemoteObject = java("javax.rmi.PortableRemoteObject");<br>
$home=$PortableRemoteObject->narrow($objref, $DocumentHome);<br>
</code>
</blockquote>
refences the <code>DocumentHome</code> from the library, which is assignment-incompatible to <code>DocumentHome</code> from the enterprise bean (<code>DocumentHome@WebAppClassLoader</code> != <code>DocumentHome@BeanClassLoader</code>), so you get a ClassCastException in <code>narrow</code>.
</p>
<p>
In contrast the Sun J2EE server correctly separates the beans/applications; the <code>$objref</code> is a unique proxy generated by a parent of the <code>WebAppClassLoader</code>, so that <code>narrow</code> can always cast the proxy to <code>DocumentHome@WebAppClassLoader</code>, even if a class with the same name is already available from the <code>WebAppClassLoader</code>.</p>
<H4>How do I install PHP into the Nutch, Spring, JSF, ..., Framework?</H4>
<p>By providing JSR 223 based PHP beans and a description how to manage them, as usual. The code
<blockquote>
<code>
javax.script.ScriptEngine e = <br>
php.java.script.EngineFactory.getInvocablePhpScriptEngine (this, <br>
application, <br>
request, response);<br>
</code>
</blockquote>
can be used to access the JSR 223 ScriptEngine from the framework, provided that a listener has been configured in the WEB-INF/web.xml:
<blockquote>
<code>
<listener>
<listener-class>php.java.servlet.ContextLoaderListener</listener-class>
</listener>
</code>
</blockquote>
</p>
<H2>General runtime questions</H2>
<H4>How do I include a local (*.asp, *.jsp, ...) resource?</H4>
<p>Use the <code><a href="http:https://us.php.net/manual/en/function.virtual.php">virtual()</a></code> or <code><a href="API/JavaBridge/_JavaBridge.inc.html#functionjava_virtual">java_virtual()</a></code> function.
</p>
<p><strong>Warning:</strong> Do not open a "loop back" url connection (e.g. via <code>fopen("http:https://localhost.../foo.asp")</code>) to include the <em>local</em> resource. This might exceed the HTTP server's pool size and create a deadlock!</p>
<H4>How do I reference a class w/o creating an instance?</H4>
<p>
With the <code>java</code> function, for example: <code>java("java.lang.System")</code>.
</p>
<p>The function is defined in <code>http:https://localhost:8080/JavaBridge/java/Java.inc</code> as:
<blockquote>
<code>
function java($clazz) {<br>
static $classMap = array();<br>
if(array_key_exists($clazz, $classMap)) return $classMap[$clazz];<br>
return classMap[$clazz]=new JavaClass($clazz);<br>
}
</code>
</blockquote>
</p>
<H4>Why does java_context()->getHttpServletRequest()->getSession() return null?</H4>
<p>
PHP scripts must explicitly allocate a session with <code><a href="API/JavaBridge/_JavaProxy.inc.html#functionjava_session">java_session()</a></code>. For example:
<blockquote>
<code>
java_session(); <br>
// now the (Remote-)HttpServletRequest knows about the session: <br>
echo java_context()->getHttpServletRequest()->getSession(); <br>
</code>
</blockquote>
</p>
<H4>Where is my output?</H4> <p><code>System.out</code> and
<code>System.err</code> are redirected to the server log file(s). When
PHP scripts are invoked from a java framework (Java Server Faces for
example), even the PHP output is redirected. For the standalone back
end the output appears in the
<code>/var/log/php-java-bridge.log</code> or in VMBridge.log, see
.ini option <code>java.log_file</code>. For the j2ee back end the
location of the log file(s) depends on the j2ee server
configuration.</p>
<H4>How do I make my script state (objects or variables) persistent?</H4>
<p>If you must code it yourself: with
e.g. <code>java_session()->put("buf", $stringBuffer)</code></p>
<H4>How many threads does the bridge start?</H4>
<p>Request-handling threads are started
from a thread pool, which limits the number of user requests to 20
(default), see system property
<code>php.java.bridge.threads</code>. All further requests have to
wait until one of the worker threads returns to the pool. </p>
<p>When running in a servlet engine, a <a
href="server/documentation/API/php/java/bridge/http/ContextServer.html">ContextServer</a>
is started which handles the pipe or local socket communication
channel. </p> <p>When java invokes local scripts outside of a HTTP
environment, the bridge starts a <a
href="server/documentation/API/php/java/bridge/http/HttpServer.html">HttpServer</a>,
a <a
href="server/documentation/API/php/java/bridge/http/ContextServer.html">ContextServer</a>
and a <a
href="server/documentation/API/php/java/script/HttpProxy.html">HttpProxy</a>. The
HttpProxy represents the PHP continuation and the HttpServer the
request-handling java continuation associated with the JSR223 script.
</p>
<H4>How do I access enums or inner classes?</H4>
With the <code>classname$inner</code> syntax. For example <br><br>
<code>
public interface php {<br>
public class java {<br>
public enum bridge {JavaBridge, JavaBridgeRunner};<br>
}<br>
}<br>
</code><br>
can be accessed with:<br><br>
<code>
<?php<br>
$bridge = new java('php$java$bridge');<br>
echo $bridge->JavaBridgeRunner;<br>
?><br>
</code><br>
The above code is not a good programming example but it demonstrates why a different syntax is used to access inner classes.
</p>
<H4>How do I create a primitive array?</H4>
<p>
Primitive types are wrapped by associated java classes.
The following example uses <code>reflect.Array</code> to create a new <code>byte</code> array:<br><br>
<code>
$Byte = java("java.lang.Byte");<br>
$byte = $Byte->TYPE;<br>
$Array = java("java.lang.reflect.Array");<br>
$byteArray = $Array->newInstance($byte, 255);<br>
$System = java("java.lang.System");<br>
$length = $System->in->read($byteArray);<br>
$str = new Java("java.lang.String", $byteArray, 0, $length);<br>
echo "You have typed: $str\n";<br>
</code>
</p>
<a name="performance"></a> <H4>How fast is it?</H4> <p>
The following scripts were
executed on one 1.5 GHZ x86 cpu running RedHat Fedora 10 Linux and Sun jdk1.6.0_02.
We have tested "Mozilla Rhino" 1.6 release 2 from <a href="http:https://java.sun.com">JDK 1.6</a>, <a href="http:https://caucho.com">Caucho "Quercus" version 3.2.1</a>, the <a href="http:https://php-java-bridge.sf.net">PHP/Java Bridge version 5.4.4</a>, and <a href="http:https://php.net/manual/en/book.java.php">PHP 4's ext/java</a>.
</p>
The PHP code (<code>t11.php</code>):<br>
<p>
<code>
<?php<br>
$buf=new java("java.lang.StringBuilder");<br>
for ($i=0; $i<400000; $i++) $buf->append($i);<br>
echo $buf->length() . "\n";<br>
?>
</code>
</p>
Another PHP code is necessary for Quercus 3.2.1 because it cannot run the above standard PHP code correctly (<code>t12.php</code>):<br>
<p>
<code>
<?php<br>
$buf=new java("java.lang.StringBuilder");<br>
for ($i=0; $i<400000; $i++) $buf->append(new java("java.lang.String", $i));<br>
echo $buf->length() . "\n";<br>
?>
</code>
</p>
The ECMAScript ("Mozilla Rhino") code (<code>t11.js</code>):<br>
<p>
<code>
buf = new java.lang.StringBuilder();<br>
for(i=0; i<400000; i++) buf.append(new java.lang.Integer(i));<br>
print (buf.length());<br>
</code>
</p>
<p>
<center>
<TABLE
BORDER="1"
><COL><COL><COL><COL><THEAD
><TR
><TH
>Command</TH
><TH
>Script Engine</TH
><TH
>Communication Channel</TH
><TH
>Execution time (real, user, sys)</TH
></TR
></THEAD
<TR
><TD
>time jrunscript -l js t11.js</TD
><TD
><a href="http:https://java.sun.com">"Mozilla Rhino" 1.6 release 2</a></TD
><TD
>none (native code)</TD
><TD
>0m7.932s,<br>
0m7.701s,<br>
0m0.113s
</TD
></TR
>
<TR
><TD
>time jrunscript -classpath quercus.jar:resin-util.jar:servlet-api.jar -l quercus t12.php</TD
><TD
><a href="http:https://caucho.com">Quercus 3.2.1</a></TD
><TD
>none (native code)</TD
><TD
>0m7.134s,<br>
0m5.050s,<br>
0m1.934s
</TD
></TR
>
<TR
><TD
>time jrunscript -classpath JavaBridge.jar -l php t11.php</TD
><TD
><a href="http:https://php-java-bridge.sf.net">PHP/Java Bridge 5.4.4</a></TD
><TD
>named pipes (XML protocol)</TD
><TD
>0m16.059s,<br>
0m15.341s,<br>
0m0.197s
</TD
></TR
>
<TR
><TD
>php t11.php</TD
><TD
><a href="http:https://php.net/manual/en/book.java.php">PHP 4.4.7/PHP-Java extension</a></TD
><TD
>JNI (binary protocol)</TD
><TD
>0m57.689s,<br>
0m56.243s,<br>
0m0.467s
</TD
></TR
>
</TABLE
>
</center>
</p>
<p>
</p>
<H4>How does the bridge handle OutOfMemoryErrors?</H4>
<p>
OutOfMemoryErrors may happen because a cached object cannot be released, either because <p>
<ol>
<li> the object is permanently referenced by a request-handling thread or</li>
<li> the object has been entered into the session or application store or
the object is referenced by a thread outside of the scope of the VM Bridge.</li>
</ol>
</p>
</p>
<p>When a <code>java.lang.OutOfMemoryError</code> reaches the request-handling thread, the VM Bridge thread pool removes the thread from its pool and writes a message <code>FATAL: OutOfMemoryError</code> to the VM Bridge log file. The session store is cleaned and all client connections are terminated without confirmation.
</p>
<p>
If the OutOfMemoryError persists, this means that a thread outside of the VM Bridge has caused this error condition.
</p>
<p>
OutOfMemory conditions can be debugged by running the back end with e.g.:<br><br>
<code>
java -agentlib:hprof=heap=sites -jar JavaBridge.jar<br>
</code>
</p>
<H4>How can PHP classes extend Java classes and Java methods?</H4>
<p>
By using <a href="API/JavaBridge/_JavaProxy.inc.html#functionjava_closure"><code>java_closure()</code></a> and the <a href="http:https://en.wikipedia.org/wiki/Visitor_pattern">visitor pattern</a> for example.
</p>
<p> In PHP 5.3 or above the following code can be used:
<blockquote>
<code>
use java\lang\String as JString;<br><br>
class String extends JString {<br>
function toString(){return "I am " . parent::toString();}<br>
function __toString() {return $this->toString();}<br>
}<br><br>
echo new String("foo");<br><br>
=> I am foo
</code>
</blockquote>
<H4>How can I convert a Java object into a PHP value?</H4>
<p>
With <code>java_values()</code>. For example:
<blockquote>
<code>
$ar = java("java.lang.reflect.Array")->newInstance(java("java.lang.Integer"), 2);<br>
$ar[0] = new java("java.lang.Integer", 2);$ar[1] = new java("java.lang.Integer", 5);<br>
print_r(java_values($ar));<br>
</code>
</blockquote>
</p>
<H4> How can I convert a PHP object into a Java object?</H4>
<p>
With <code>java_closure()</code>. For example:
<blockquote>
<code>
class Foo {<br>
function toString() {return "php::foo";}<br>
}<br>
$foo = new Foo();<br>
$jObj = java_closure($foo);<br>
$String = java("java.lang.String");<br>
echo $String->valueOf($jObj);<br>
</code>
</blockquote>
</p>
<H4>How do I call JSP tags from PHP?</H4>
<p>
Example:
<blockquote>
<code>
require_once("http:https://localhost:8080/JavaBridge/java/Java.inc");<br>
$tag = new Java("foo.bar.BazTag");<br>
<br>
$session = java_session();<br>
$ctx = java_context();<br>
$servlet = $ctx->getAttribute("php.java.servlet.Servlet");<br>
$response = $ctx->getAttribute("php.java.servlet.HttpServletResponse");<br>
$request = $ctx->getAttribute("php.java.servlet.HttpServletRequest");<br>
$factory = java("javax.servlet.jsp.JspFactory")->getDefaultFactory();<br>
$pc = $factory->getPageContext($servlet, $request, $response, null, true, 8192, false);<br>
<br>
$tag->setPageContext($pc);<br>
$value = $tag->doStartTag();<br>
if(($value != Java("javax.servlet.jsp.tagext.Tag")->SKIP_BODY) {<br>
if($value != Java("javax.servlet.jsp.tagext.Tag")->EVAL_BODY_INCLUDE)) {<br>
$tag->setBodyContent($pc->pushBody());<br>
$tag->doInitBody();<br>
}<br>
do {<br>
...<br>
} while($tag->doAfterBody() == Java("javax.servlet.jsp.tagext.BodyTag")->EVAL_BODY_AGAIN)<br>
}<br>
if($value != Java("javax.servlet.jsp.tagext.Tag")->EVAL_BODY_INCLUDE) $pc->popBody();<br>
$tag->doEndTag();<br>
</blockquote>
</code>
</p><p>
The generated content (if any) can be retrieved from the servlet output stream with:
<blockquote>
<code>
java_values($response->getBufferContents();
</code>
</blockquote>
</p>
<p>Please see the <code>php_java_lib/JspTag.php</code> and <code>tests.php5/tag.php</code> for details.</p>
<H4>How does the bridge support Java generics?</H4>
<p>
You can ignore the parameter type.
</p>
<p>
Java doesn't support real generics on byte-code level. The generics in JDK 1.5 and above are implemented as "erasures"; they are syntactic sugar, useful only for the Java compiler. The generated byte-code is the same as in JDK 1.4.
</p>
<H4>What about Java 5 varargs?</H4>
<p>
Pass them as a PHP array. Example:
</p>
<p>
<blockquote>
<code>
<?php require_once("http:https://localhost:8080/JavaBridge/java/Java.inc");<br>
$t1 = new java('Varargs$Test', 1);<br>
$t2 = new java('Varargs$Test', 2);<br>
echo java("Varargs")->varargs(array($t1, $t2));<br>
?>
</code>
</blockquote>
</p>
<p>
<blockquote>
<code>
public class Varargs {<br>
public static class Test {<br>
public int i;<br>
public Test (int i) {<br>
this.i = i;<br>
}<br>
public String toString() {<br>
return String.valueOf(i);<br>
}<br>
}<br>
public static String varargs(Test ...tests) {<br>
StringBuffer buf = new StringBuffer();<br>
for (Test test : tests) {<br>
buf.append(test);<br>
}<br>
return buf.toString();<br>
}<br>
}<br>
</code>
</blockquote>
</p>
<H4>NULL tests</H4>
<p>
Use <code>java_is_null($value)</code> or <code>is_null (java_values ($value))</code> to test for a (Java-) NULL value.
</p>
<H4>How do I start the bridge back end when there's another Java VM listening on port 8080?</H4>
<p>Simply deploy the VM Bridge web archive into the servlet engine or application server listening on port 8080. Or use a different port.</p>
<H4>What's the difference between SERVLET_LOCAL:8080 and INET_LOCAL:8080?</H4>
<p>The standalone option SERVLET_LOCAL emulates a servlet engine and starts a HTTP server which can select the fastest channel supported on this operating system. On Linux this is a named pipe created in /dev/shm or INET_LOCAL as a fall back.</p>
<p>INET_LOCAL always uses local TCP socket communication.</p>
<H4>Whenever I reboot my computer I have to start the bridge back end again. How can I automate this?</H4>
<p>Download and install a servlet engine or J2EE server as a Windows
or Unix service.</p>
<H4>Do I have to require Java.inc in each of my scripts? Isn't that very slow?</H4>
<p>In order to communicate with Java, a PHP "Java" class definition is needed. Here's a simple PHP "Java" class definition which fits into one line:
<blockquote>
<code>
<?php<br>
// The following is the "Java" class definition, stripped down to fit<br>
// into one line. To use this sample start Java with: java -jar<br>
// JavaBridge.jar INET:9267.Then type: php sample.php<br>