What is the PHP/Java Bridge?
----------------------------

  The PHP/Java Bridge is a network protocol which can be used to
  connect a native script engine, for example PHP, with a Java or ECMA
  335 VM.

  Please read the http://php-java-bridge.sf.net for more information.


Overview
--------

  The generic PHP/Java Bridge implementation is distributed as a web
  archive called "JavaBridge.war". It is a zip archive which contains
  the libraries "JavaBridge.jar", "php-script.jar" and "script-api.jar".

  The PHP/Java Bridge web application contains two servlets. The
  "PhpJavaServlet" handles requests from remote PHP clients running in
  Apache/IIS or from the command line:

    Apache/IIS/console::PHP <--> PhpJavaServlet

  The second servlet, PhpCGIServlet, can handle requests from internet
  clients directly. It can start PHP as a FastCGI or CGI sub component:

    internet browser <--> PhpCGIServlet <--> php-cgi <--> PhpJavaServlet


  Furthermore the bridge supports standalone Java applications through
  the JSR223 script API.


Build and execution instructions:
---------------------------------

  Type java -jar JavaBridge.war to extract the JavaBridge.jar from
  the web archive. 

  Double-click on JavaBridge.jar and select SERVLET_LOCAL:8080 to
  start a servlet engine listening on the local host interface. Type
  java -jar JavaBridge.jar --help to see the list of available options.

  Use the following code to access Java from your PHP scripts:

    <?php
    require_once("http://localhost:8080/JavaBridge/java/Java.inc");
    $s = new Java("java.lang.String", "hello");
    ...
    ?>


   To build and install an optimized implementation which doesn't need
   any Java, download and unpack the source download archive and type:

     phpize && ./configure && make && make install

  The optimized implementation uses persistent connections via "named
  pipes" and runs up to 10 times faster than the generic implementation.

------------------------------------
   Permanently activate the module
   -------------------------------

  Installation for the web:

  Copy the JavaBridge.war file into the autodeploy folder
  of the J2EE server or servlet engine.

  Example for Apache/Tomcat on Linux:

    cp JavaBridge.war /usr/share/tomcat5/webapps/


  Installation for standalone Java J2SE applications:

  Copy the JavaBridge.jar, php-script.jar and script-api.jar to
  the java.ext.dirs. Example for JDK1.6 on Linux:

    cp ext/*.jar /usr/java/packages/lib/ext/

---------------------------------------------
  Starting the PHP/Java Bridge automatically
  ------------------------------------------

  For the web:

  Start the J2EE server or servlet engine as a service. The
  Apache/Tomcat servlet engine automatically installs as a service on
  Windows and Linux.


  In standalone J2SE applications the bridge starts automatically
  when the JSR223 context is accessed.
  
---------------------------------------------
  Translating Java into PHP PEAR classes
  --------------------------------------

  Java libraries can be translated into PEAR classes using the command:

    java -jar JavaBridge.jar --convert /path/to/PEAR/repository ARCHIVE.JAR

  or, if you have configured the PHP/Java extension to run without Java:

    modules/java --convert /path/to/PEAR/repository ARCHIVE.JAR


  Example for Apache/Lucene:

     modules/java --convert /usr/share/pear /usr/share/java/lucene.jar

  <?php
     require_once("lucene/All.php")
     $searcher = new org_apache_lucene_search_IndexSearcher(getcwd());
     $term = new org_apache_lucene_index_Term("name", "test.php");
     $phrase = new org_apache_lucene_search_PhraseQuery();
     $phrase->add($term);

     $hits = $searcher->search($phrase);
     $iter = $hits->iterator();

     while($iter->hasNext()) {
       $next = $iter->next();
       $name = $next->get("name");
       echo "found: $name\n";
     }
  ?>

---------------------------------------------
  AS/Servlet with PHP CGI/FastCGI
  -------------------------------

  Read the following instructions only if you don't want to use
  Apache or IIS.

  Please deploy the JavaBridge.war into the Tomcat or J2EE server
  (please see or FAQ section on http://php-java-bridge.sf.net), then
  visit http://localhost:8080/JavaBridge and run the supplied JSP and
  PHP examples.

  If the parameter name "use_fast_cgi" is set to "Autostart" in the
  web.xml, and a fcgi server does not listen on port 9667, and a fcgi
  binary can be found as either /usr/bin/php-cgi or c:/php/php-cgi.exe,
  then the back end automatically starts the Fast-CGI server on this
  computer. With the command:

    cd $HOME
    export REDIRECT_STATUS="200"
    export X_JAVABRIDGE_OVERRIDE_HOSTS="/"
    export PHP_FCGI_CHILDREN="5"
    export PHP_FCGI_MAX_REQUESTS="5000"
    /usr/bin/php-cgi -d allow_url_include=On -b 127.0.0.1:9667

  On Windows the command is:

    set REDIRECT_STATUS "200"
    set X_JAVABRIDGE_OVERRIDE_HOSTS "/"
    set PHP_FCGI_CHILDREN "5"
    set PHP_FCGI_MAX_REQUESTS "5000"
    launcher.exe php-cgi \\.\pipe\JavaBridge@9667 -d allow_url_include=On


  The PHP FastCGI server starts when the VM or the web context starts,
  it stops when the VM or web context terminates.


  If that failed, the bridge searches for a CGI binary called:
  
    php-cgi-<architecture>-<os>.exe or

    php-cgi-<architecture>-<os>.sh or

    php-cgi-<architecture>-<os>

  in the directory WEB-INF/cgi/. On Unix the binary must be executable. It
  is therefore recommended to always use a wrapper .sh script, for example:

  #!/bin/sh
  # This wrapper script reconstructs the executable permissions
  # which some zip or .war implementations do not preserve
  chmod +x ./php-cgi-i386-linux
  exec ./php-cgi-i386-linux

  Please see the README located in the directory WEB-INF/cgi/ for
  details.

  The <architecture> and <os> values are calculated as follows:

    System.getProperty("os.arch").toLowerCase();
    System.getProperty("os.name").toLowerCase();

  Please see the output of test.php for details.


  It is also possible to adjust the php_exec setting (see
  WEB-INF/web.xml), for example:

      <param-name>php_exec</param-name>
      <param-value>/usr/local/bin/php-cgi</param-value>

  or

      <param-name>php_exec</param-name>
      <param-value>c:/PHP/php-cgi.exe</param-value>

  In case your application server denies calling the CGI binary,
  either start apache or IIS or start a fast CGI server on port 9667
  as a separate process, for example from a service script. 

  On Unix the bridge uses named pipes. On Windows, where standard
  named pipes are not available, the bridge uses TCP sockets. If your
  application server denies socket accept/resolve, please either run the
  AS on a Unix operating system or add the following lines to your AS
  policy file (for example ...\domains\domain1\config\server.policy):

    grant {
      permission java.net.SocketPermission  "*", "accept,resolve";
    };


------------------------------------
  Recognized CFLAGS
  -----------------

   The build scripts of the native implementation recognize the
   following CFLAGS:

   * -DJAVA_COMPILE_DEBUG: Enables the assert() statement and other
     debug code.
   
   * -DJAVA_COMPILE_DEBUG -O0 -g3: Include full debug information into
     the binary.

   * -m64: Build 64 bit code. Required if you run a 64 bit JVM.

   * -m32: Build 32 bit code. Required if you run a 32 bit JVM on a 64
     bit system.

   * -DCFG_JAVA_SOCKET_INET: Disables local ("unix domain") sockets on
      systems which support them. 

  Example: make CFLAGS="-O0 -g3"

------------------------------------
  Log level
  ---------

  You can set the java.log_level to 7 values:

   0: Log nothing, not even fatal errors.

   1: Log fatal system errors such as "out of memory error".

   2: Log java exceptions.

   3: Log verbose, e.g.: "JavaBridge version x.y.z started"

   4: Log debug messages, including the c/s communication protocol.

   5: Log method invocations, including method selection.

   6: Reserved for internal use. Log messages which may be useful
      to debug certain parts of the bridge.

  The default log level is 2.  If java.log_level is missing, the
  back end uses the "default" log level supplied when the back end was
  started (the second argument after java -jar JavaBridge.jar ...).

  The log4j viewer "Chainsaw" can be used to automatically capture the
  log from the bridge, regardless in which environment it is
  running. log4j.jar must be in the Java VM's java.ext.dirs (usually
  jre/lib/ext), Chainsaw must be running and the back end must have
  been started without a log file argument or with the .ini option
  java.log_file="@127.0.0.1:4445". Chainsaw can be started with e.g.:

   /opt/jdk1.5/bin/java -cp /opt/jdk1.5/jre/lib/ext/log4j.jar \
                                               org.apache.log4j.chainsaw.Main

------------------------------------
  Security Enhanced Linux
  -----------------------

  SELinux is an implementation of a flexible and fine-grained
  mandatory access control architecture implemented in the Linux kernel.

  A system component running on a SELinux kernel must declare
  exactly a) which resources of the operating system it needs in order
  to function properly and b) what it provides to other components.

  The PHP/Java Bridge distribution contains two policy files,
  "php-java-bridge.te" and "php-java-bridge.fc". The
  "php-java-bridge.te" declares the javabridge_t domain and the
  resources it requires.  httpd and user domains are granted connect, 
  read and write to the PHP/Java Bridge server socket, which is
  "@var/run/.php-java-bridge_socket" in the Linux abstract name-space,
  and file create/read/write in the tmp_t.  Everything else (connections
  to other servers, file access, ...) is currently denied.

  The "php-java-bridge.fc" contains the file contexts for the PHP/Java
  Bridge and the log.

  Installation instructions for RHEL 4 and Fedora Core 4:
  -------------------------------------------------------

   1. Install selinux-policy-targeted-sources-*.rpm, for example with
      the command:

        rpm -i selinux-policy-targeted-sources-1.17.30-2.19.noarch.rpm

   2. Update the policy files with the PHP/Java Bridge policy:

        su -c "sh security/update_policy.sh /etc/selinux/targeted/src/policy"

  Installation instructions for RHEL 5, Fedora Core 5 or above:
  -------------------------------------------------------------

  1. Create the binary policy with the command:

        cd security/module; make

  2. Inject the rules into the kernel, either the php-java-bridge-tomcat.pp 
     or the php-java-bridge.pp. For example:

        semodule -i php-java-bridge.pp 

  3. The rules apply to the javabridge_t domain. Another rule
     specifies that when an executable is called from the httpd_t domain
     and the executable is tagged as javabridge_exec_t, a domain transition
     to javabridge_t occurs. It is therefore important that RunJavaBridge
     is tagged with javabridge_exec_t and that it is called from the
     httpd_t domain. Furthermore the java executable must be a binary:

        chcon -t javabridge_exec_t /usr/lib/php/modules/RunJavaBridge
        chcon -t bin_t /usr/lib/php/modules/java

  4. The policy module can be removed with the command:
  
        semodule -r javabridge
  
  If the default policy is too restrictive and e.g. you want to use
  the PHP/Java Bridge to connect to your J2EE server, you can
  temporarily set the policy to "permissive", for example with the
  command "setenforce Permissive". Connect to the server, then extract
  the permissions from the audit log, for example with the command
  "audit2allow -l -i /var/log/audit/audit.log", then append them at the
  end of the "php-java-bridge.te" file and load the updated policy into
  the kernel. Don't forget to switch back, for example with "setenforce
  Enforcing".

  Please note that SEL security is orthogonal to the standard Unix 
  security. For example you could also put the java process into 
  a "jail"; set up a user account with restricted rights, change the 
  owner of RunJavaBridge and set the SUID bit:

        chown apache:apache /usr/lib/php/modules/RunJavaBridge
        chmod 6111 /usr/lib/php/modules/RunJavaBridge

  The java process would run with the limited rights of apache *and* be 
  protected by the SEL policy.

------------------------------------
  Security issues
  ---------------

  The bridge uses abstract local sockets, named pipes (located in
  /dev/shm/ or /tmp/) or local TCP sockets as communication channels.

  It is recommended to use the local back end on a Unix machine which
  supports abstract local ("unix domain") sockets or named pipes. On
  these systems the communication channel is not visible and cannot be
  attacked. If you are running a Security Enhanced Linux kernel, which
  is standard since RHEL4 or FC3, the back end is also protected by the
  SEL policy. The servlet back end uses a HTTP tunnel to execute one
  statement and then switches to named pipes for the rest of the
  communication.

  On other systems, such as Windows and Mac OSX, the bridge opens a
  local TCP port on 9167 (MonoBridge.exe) or 9267 (JavaBridge.jar), 9567
  (JavaBridge.war) or 9667 (FastCGI). Please make sure that the ports in
  the range [9167, ..., 9667] cannot be accessed from the internet.

------------------------------------
  Loading user classes and libraries
  ----------------------------------

  Java libraries should either be translated into PEAR classes (see
  above) or be installed in one of the following directories:
  java.ext.dirs or php.java.bridge.base/lib or, for the
  J2EE/servlet back end, WEB-INF/lib. Libraries in these directories are
  automatically loaded by a static loader whenever the JVM starts.

  The location of the php.java.bridge.base depends on the Java system
  property -Dphp.java.bridge.base. It defaults to user.home. When
  the standalone component is invoked as a sub component of Apache or
  IIS, php.java.bridge.base is initialized with the PHP .ini
  extension_dir setting, which is usually /usr/lib/php/modules or
  c:\php.
  
  Java libraries can also be loaded or re-loaded on demand by a
  dynamic loader. They should have the following file name:
  <name>-<version>.jar and be stored in a sub directory of the PHP
  extension_dir/lib/ directory or in a sub directory of the
  /usr/share/java directory. For example:

    /usr/share/java/batStore/batStore-1.0.jar.

  Java libraries can be created from .class files with the following
  command:

    jar cvf myLibrary-0.1.jar my/package/*.class 

  The dynamic loader can link java libraries into PHP files at
  run-time if the PHP files contain the command:

    java_require("<library1>;<libraryN>");

  Note that <library> can also be a directory containing .jar files.

  For example:

    <?php
      // process order
      java_require("j2ee.jar;myProject/myLibrary-0.1.jar");

      $proc = new Java("my.package.InputProcessor", ...);
      $proc->doSomething($_POST);
      ...
    ?>

  Minor upgrades of dynamic-loaded libraries can be installed at
  run-time. When the dynamic loader detects that the time stamp or the
  version number of the .jar file has changed, it automatically loads
  the new version.

  Disadvantages of the dynamic loader:

  * An attempt to load an impure java library immediately throws an
    UnsatisfiedLinkError.

  * Class loading via the dynamic loader is slower, because it
    cannot use the global VM class cache.

  * Libraries must be explicitly required by using the php
    java_require() procedure.

  Disadvantages of the static loader:

  * All java libraries are loaded when the Java- or Mono VM
    starts. For the PHP CLI component, which usually starts a new VM for
    each PHP invocation (unless java.hosts or java.socketname is set),
    this may cause a noticeable delay (a few 100 ms).

  * The static loader can only load libraries which are stored in the
    /usr/share/java/ext or in the php.java.bridge.base/lib directory. Hot
    deployment is not possible because all classes are loaded when the VM
    starts.

  * The standard directories /usr/share/java/ext or
    /usr/java/packages/lib/ext/ don't exist on Windows so that users must
    check the windows registry to find the "standard" java extension dir.

  It is recommended to store Java libraries which are API stable or
  use the java native interface into the php.java.bridge.base/lib
  directory or into java.ext.dirs. All other libraries can go into a
  project specific directory within php.java.bridge.base/lib/ or
  /usr/share/java/ and be loaded on-demand.

  Note that classes loaded from two different class loader instances
  cannot access each other. This means that, e.g., neither

    java_require("foo.jar");
    ...
    Class.forName("foo");  // wrong!

  nor 

    java_require("foo.jar"); java_require("bar.jar");
    $foo = new Java("foo");
    $foo->callWithBar(); // error!

  work as expected.

  In the first example the class was loaded from the bootstrap class
  loader, which cannot access foo.jar's class loader. In the second example
  foo and bar depend on each other, so that the call fails because bar
  cannot be accessed from foo.jar's class loader.

  The first example can be corrected by using the current class
  loader:

     java_require("foo.jar");
     ...
     Class.forName("foo",true,Thread.currentThread().getContextClassLoader());

  or simply:

      java_require("foo.jar");
      new JavaClass("foo");

  The second example can be corrected by loading the interconnected
  libraries from the same class loader:
   
     java_require("foo.jar;bar.jar");

------------------------------------
  Sun java platform issues
  ------------------------

  The sun java platform does not support java "modules". This causes
  certain problems when running java programs. When you compile a class
  foo which references a class bar and ship the class foo without
  providing bar, the sun java platform will not complain unless the user
  accidentally calls a method which references the non-existing class. If
  this happens, a "NoClassDefFound" error is thrown. This error may
  not(!) indicate which class is missing and it certainly does not
  indicate which external library is missing. The tests.php4 folder
  contains two tests, noClassDefFound.php and noClassDefFound2.php which
  demonstrate this.

  To avoid this problem please document *exactly* (including the
  version number) which external libraries (.jar files) your software
  needs. If you have written software where certain methods require an
  optional library, please document this in the method header.

  If receive this error when using a Java library, this may mean the
  following:

    * an old or different JDK than expected by the library is used,
      for example GNU Java instead of SUN or IBM Java.

    * java_require("foo.jar"); java_require("bar.jar"); was used instead of
      java_require("foo.jar;bar.jar"); to load two interconnected libraries.

    * the library is simply broken or it expects certain parameters in
      its environment (applet parameter or system property or property file).

    * the library may only work within a J2EE environment from a
      certain vendor, for example the WebSphere Application server or
      the Sun Java Application server.

------------------------------------
  PHP issues
  ------------

  All PHP versions between 4.4.1 and 5.0.3 crash when the dl()
  function is used.

  If you use one of these versions, please add an entry to the
  php.ini, see install instructions above.

---------------------------------------------
  GCJ/GNU Java issues
  -------------------
  
  Running the PHP/Java Bridge under GCJ ("GNU Java") is supported on Linux
  and Solaris only.  If you run FreeBSD 5.3, please use Sun, Blackdown
  or IBM java instead.

---------------------------------------------
  FreeBSD issues
  --------------
  
  FreeBSD and some other BSD variants contain an incorrect
  implementation of Nagle's algorithm. Because of this 10 subsequent
  HTTP GET requests on the local interface cost ~1 second, which makes
  pure Java unusable on this operating system.

  Either modify PHP so that it sets the socket option NDELAY, or switch
  off the delay for local TCP sockets in the FreeBSD kernel or use unix
  domain sockets to communicate with the Java VM:

  * Compile a java.so and natcJavaBridge.so and start the Java VM as
    follows:

    export LD_LIBRARY_PATH=/path/to/dir/containing/natcJavaBridge.so
    java -jar JavaBridge.jar LOCAL:/tmp/javabridge.socket
   
  * Add the following to your php.ini:

    extension=java.so
    [java]
    java.socketname=/tmp/javabridge.socket

------------------------------------
  UTF-8
  -----
  
  Since PHP does not support Unicode, the PHP/Java Bridge uses UTF-8 to
  convert characters into the host representation. All strings are
  created with new String(..., "UTF-8") and all internal String->byte[]
  conversions use getBytes("UTF-8").
  
  If you have old PHP files which are not UTF-8 encoded, you can
  change the default encoding with java_set_file_encoding().  For
  example:

    java_set_file_encoding("ISO-8859-1");

  For a list of available encodings please see the documentation of
  the JVM's file.encoding system property.

  The java_set_file_encoding() primitive only affects java.lang.String
  creation and internal conversions, it does not alter the JVM's
  file.encoding system property nor does it change the behaviour of
  methods which use the file.encoding property, getBytes() for
  example.  If you use:
  
    $str=new Java ("java.lang.String", "Cze????! -- ???????? -- Gr");
    echo $str->getBytes();

  the output conversion depends on the file.encoding system property
  which in turn depends on the process' LANG environment variable. You
  can check the file.encoding with the test.php script, see above.

  To be portable please do not use conversions which depend on the
  JVM's file.encoding. They are easy to avoid, the above example
  should be written as:

    $str=new Java ("java.lang.String", "Cze????! -- ???????? -- Gr");
    echo (string)$str;  // in PHP5 or higher
    echo $str->toString(); // in PHP4

------------------------------------
  Creating thread dumps in Java 6
  -------------------------------

  * Become "super user" or "admin user" and start the program jconsole
    located in the JDK 1.6 bin directory, for example with the following
    command:

      su -c "/opt/jdk1.6/bin/jconsole"

    On Windows make sure you have admin privileges before starting
    jconsole.
     
  * In the "Create new connection" dialog select "local process" and
    click on the "JavaBridge" entry. -- If the JavaBridge doesn't appear
    there, check if the JavaBridge is running within a Java 1.6 VM and if
    the jconsole has been started with sufficient permissions.

  * Click "connect".

  * Open the "Threads" tab and click on the thread you're interested in.

------------------------------------
  Creating thread dumps in Java < 6
  ---------------------------------

  Older Java VM must be started with the following options:
  
  -Xdebug -Xrunjdwp:transport=dt_socket,address=9147,server=y,suspend=n
  
  The following description assume that Java is running as a sub
  component of Apache or IIS:

  * On Windows set the "java.java" php .ini option (in the global php.ini
    file) to:
  
    extension=php_java.dll
    [java]
    java.java="javaw -Xdebug -Xrunjdwp:transport=dt_socket,address=9147,server=y,suspend=n"
  
  * On Unix add the "java.wrapper" php .ini option (in the global php.ini
    file or in /etc/php.d/java.ini):
  
    extension = java.so
    [java]
    java.wrapper = /tmp/java.wrapper
  
    Create the file /tmp/java.wrapper with the following content:
  
    #!/bin/sh
    set -x
    java=$1; shift
    exec $java "-Xdebug -Xrunjdwp:transport=dt_socket,address=9147,server=y,suspend=n" "$@"
  
    Add the required permissions; in a command window type (as super user):
    
    chmod +x /tmp/java.wrapper
    /usr/sbin/setenforce 0     # Security Enhanced Linux only
  
  * On Windows or Unix: restart the web server, for example with:

    apachectl restart
  
  * Open a command window and type the following commands:
  
    jdb -attach 127.0.0.1:9147
    suspend
    where all
    resume


------------------------------------
  Performance tuning
  ------------------

  The PHP/Java Bridge protocol is very sensitive to network
  latency. If the Java server and PHP client do not run on the same
  computer, the objective is to minimize the number of network
  round-trips; java_values() can be used to obtain a Java array, Map
  or Collection in one round-trip and java_begin_document(),
  java_end_document() can be used to execute PHP code on the server.
  
  The call java_values($obj) evaluates $obj on the server-side and, if
  it is a Java array, Map or Collection, retrieves its values in one
  call.

  The java_begin_document()/java_end_document() pair encapsulates PHP
  code, sends an image of it (as a streamed XML document) to the server
  and executes it there. This works for all PHP statements. But the
  following primitives are not allowed while in stream mode:
  java_session(), java_begin_document(), java_end_document(),
  java_values(), __toString(), and the PHP iterator cannot be used to
  iterate values of Java objects.

  Example:

    $iter = $hits->iterator();                       // 1 round trip
    $resultList = new Java("java.util.LinkedList");  // 1 round trip
    $n = $hits->length()                             // 1 round trip

    java_begin_document();                           // 1 round trip
    while($n--) {
      $next = $iter->next();
      $resultList->add($next->get("name"));
    }
    java_end_document();                             // 1 round trip
    $ar = java_values($resultList);                  // 1 round trip

  Assuming that a ping to the back-end reveils an average round-trip
  time of 6ms, the above code costs 6*6ms = 36ms (ignoring CPU and
  network bandwidth contraints).

  The more intuitive approach:

    $n = $hits->length();                            // $n = 30000
    while($iter->hasNext()) {                        // $n * 6ms
      $next = $iter->next();                         // $n * 6ms
      $a[$i++]=$next->get("name");                   // $n * 6ms
    }
 
  costs 30000*18ms + 6 ms = 9 min. It is 15000 times slower, 
  assuming that the client CPU can generate and send the XML document
  within 6ms and that the server CPU can generate/send the values of the
  resultList within 6ms, which usually isn't the case.

------------------------------------
  Mailing List
  ------------

  Please report bugs/problems to the mailing list:

    php-java-bridge-users@lists.sourceforge.net

