This page provides important information for users of the Ice RPMs on Linux platforms. You can obtain these RPMs at the ZeroC web site.

On this page:

Overview of the Ice RPMs

Ice for Linux is distributed in several RPM packages:

ZeroC also supplies RPMs for the following third-party packages:

The db48-devel and the mcpp-devel RPMs are only necessary for building Ice from source.

Setting up your Linux environment to use Ice

After installing Ice, read the relevant language-specific sections below to learn how to configure your environment and start programming with Ice.

C++

No special compiler or linker options are required for an RPM installation of the Ice for C++ development kit (ice-c++-devel).

Java

To use Ice for Java, you must add Ice.jar to your CLASSPATH, as shown below:

$ export CLASSPATH=/usr/share/java/Ice.jar:$CLASSPATH

If you intend to use Freeze for Java, you must include Freeze.jar in your CLASSPATH along with Ice.jar:

$ export CLASSPATH=/usr/share/java/Freeze.jar:$CLASSPATH

Note that Freeze requires Berkeley DB. Freeze.jar contains a manifest that automatically loads the Berkeley DB classes (db-4.8.30.jar), which means you do not need to include this file in your CLASSPATH when executing a Freeze application. However the JVM does require that the directory containing Berkeley DB's native libraries be listed in java.library.path, therefore you must add this directory to your LD_LIBRARY_PATH. Assuming you are using the RPM installation of Berkeley DB, the bash command is shown below:

$ export LD_LIBRARY_PATH=/usr/lib:$LD_LIBRARY_PATH

On an x86_64 system with a 64-bit JVM, the 64-bit Berkeley DB libraries are installed in /usr/lib64, so use this setting instead:

$ export LD_LIBRARY_PATH=/usr/lib64:$LD_LIBRARY_PATH

When building a Java application that uses Freeze, you will need to add the Berkeley DB JAR file to your CLASSPATH:

$ export CLASSPATH=/usr/share/java/db-4.8.30.jar:$CLASSPATH

Ice for Java supports protocol compression using the bzip2 classes included with ant. Compression is automatically enabled if these classes are present in your CLASSPATH. You can either add ant.jar to your CLASSPATH, or download only the bzip2 classes from

http://www.kohsuke.org/bzip2/

Note that these classes are a pure Java implementation of the bzip2 algorithm and therefore add significant latency to Ice requests.

When using the Ice for Java SSL plugin (IceSSL), you may experience occasional hangs. The most likely reason is that your system's entropy pool is empty. If you have sufficient system privileges, you can solve this issue by editing the file

<java.home>/jre/lib/security/java.security

and changing it to use /dev/urandom instead of /dev/random. If you do not have permission to modify the security file, you can also use the
command-line option shown below:

$ java -Djava.security.egd=file:/dev/urandom MyClass ...

On Linux systems with IPv6 enabled, you may experience occasional hangs the first time an Ice object adapter is activated within a JVM. A work-around is to disable IPv6 support by setting the Java property java.net.preferIPv4Stack to true. For example:

$ java -Djava.net.preferIPv4Stack=true MyClass ...

For more information on this issue, refer to the relevant Java bug.

Eclipse Development

ZeroC has created a Slice2Java plug-in for Eclipse that automates the translation of your Slice files. If you use Eclipse, we strongly recommend using this plug-in for your own development.

For installation instructions, please refer to the ZeroC web site. The manual provides more information about configuring the plug-in and using it in your projects.

Android

Ice requires Android 2.1 or later. Aside from that, there are no other special requirements for using Ice in an Android application. We strongly recommend installing our Slice2Java plug-in for Eclipse to automate the compilation of your Slice definitions.

Python

The Ice for Python run-time RPM (ice-python) installs the Ice extension and its associated Python files into the site-packages directory. The RPM also installs a .pth file that enables you to import the various Ice modules without requiring any additional configuration.

Mono

The RPM installation adds the .NET run-time libraries to the global assembly cache (GAC), so that no changes to your environment are necessary to locate the assemblies.

The instructions for running the demos assume that you have configured your kernel to automatically execute the Mono interpreter. Visit the Mono Project for a description of how to configure your kernel to register Mono's .exe files as non-native binaries. If you don't want to configure your kernel, you will need to run executables with mono. For example,

$ mono server.exe

Managed code

The main Ice for .NET assembly (Ice.dll) included in the RPM uses unmanaged code. If you require only managed code then you can download the Ice source distribution and build Ice for Mono in a purely managed version. Note that the managed version of Ice for Mono omits support for protocol compression.

You can download the source distribution at the ZeroC web site.

Ruby

The Ice for Ruby run-time RPM (ice-ruby) installs the Ice extension and its associated Ruby files into the site_ruby directory. No additional configuration is necessary to use Ice in your Ruby programs.

PHP

The Ice extension for PHP is loaded automatically when the interpreter loads the contents of the file /etc/php.d/ice.ini (on Red Hat Enterprise Linux) or /etc/php5/conf.d/ice.ini (on SuSE Linux Enterprise Server). This file contains the line shown below:

extension=IcePHP.so

You can modify this file to include additional configuration directives.

At run time, the PHP interpreter requires the Ice shared libraries.

You can verify that the Ice extension is installed properly by examining the output of the php -m command, or by calling the phpinfo() function from a script.

Your application will also need to include at least some of the Ice for PHP run-time source files (installed in /usr/share/php on RHEL and /usr/share/php5 on SLES11). This installation directory is included in PHP's default include path, which you can verify by executing the following command:

% php -i | grep include_path

If the installation directory is listed, no further action is necessary to make the run-time source files available to your application. Otherwise, you can modify the include_path setting in php.ini to add the installation directory:

include_path = /usr/share/php:...

Another option is to modify the include path from within your script prior to including any Ice run-time file:

ini_set('include_path', ini_get('include_path') . PATH_SEPARATOR . '/usr/share/php');
require 'Ice.php'; // Load the core Ice run time definitions.

SELinux Notes (for Red Hat Enterprise Linux users)

SELinux augments the traditional Unix permissions with a number of new features. In particular, SELinux can prevent the httpd daemon from opening network connections and reading files without the proper SELinux types.

If you suspect that your PHP application does not work due to SELinux restrictions, we recommend that you first try it with SELinux disabled. As root, run:

# setenforce 0

to disable SELinux until the next reboot of your computer.

If you want to run httpd with the Ice extension and SELinux enabled, you must do the following:

1. Allow httpd to open network connections:

   # setsebool httpd_can_network_connect=1
   

   You can add the -P option to make this setting persistent across reboots.

1. Make sure any .ice file used by your PHP scripts can be read by httpd. The enclosing directory also needs to be accessible. For example:

   # chcon -R -t httpd_sys_content_t /opt/MyApp/slice
   

For more information on SELinux in Red Hat Enterprise Linux, refer to this Red Hat document.

Using the sample programs on Linux

Sample programs are provided in a separate archive, which can be downloaded from the ZeroC web site.

Please refer to the README.DEMOS file included in that package for more information.

Startup scripts for IceGrid and Glacier2 services

The ice-servers RPM includes the following sample /etc/init.d scripts and associated configuration files:

• /etc/init.d/icegridregistry and /etc/icegridregistry.conf
• /etc/init.d/icegridnode and /etc/icegridnode.conf
• /etc/init.d/glacier2router and /etc/glacier2router.conf

The installation of this RPM also creates a user account and group for running these services (account ice and group ice), and data directories for icegridregistry and icegridnode (/var/lib/ice/icegrid/registry and /var/lib/ice/icegrid/node1).

By default, all these services are off at all runlevels. You need to manually switch on one or more runlevels, for example:

#
# On a Red Hat Enterprise Linux system, configure the icegridregistry
# to start at runlevel 3 and 5:
#
chkconfig --level 35 icegridregistry on

#
# On a SuSE Linux Enterprise Server system, configure the
# icegridregistry to start at runlevel 3 and 5:
#
chkconfig icegridregistry 35

Before doing so, please review the script itself and its associated configuration file.

Starting the IceGrid Administrative Console on Linux

A Java-based graphical tool for administering IceGrid applications is included in this distribution. The Java archive file is installed as

/usr/share/java/IceGridGUI.jar

With a suitable Java environment, you can execute the application using the following command:

$ icegridgui

or

$ java -jar IceGridGUI.jar