This is a gateway user manual providing information on running and using the UNICORE 6 gateway. Please note also the following places for getting more information:

UNICORE Website:

Developer’s list:

1. Introduction

The Gateway is the entry point into a UNICORE site. It is installed in front of any networking firewall. It authenticates incoming messages and forwards them to their intended destination. The gateway receives the reply and sends it back to the client.

In effect, traffic to a “virtual” URL, e.g. “https://mygateway:8088/Alpha” is forwarded to the real URL, e.g. “https://host1:7777”. In this way, only a single open port in a site’s firewall has to be configured. (Technical note: this process only works for “most” HTTP requests (i.e. POST, GET and PUT), and is not a complete HTTP reverse proxy implementation).

The mappings of virtual URL to real URL for the available sites are listed in a configuration file “”. Additionally, the gateway supports dynamic registration of sites.

The second functionality of the gateway is authentication of incoming requests. Connections to the gateway are made using client-authenticated SSL, so the gateway will check whether the caller presents a certificate issued by a trusted authority.


UNICORE Gateway is distributed either as a platform independent and portable bundle (as a part of the UNICORE core server package) or as an installable, platform dependent package such as RPM.

Depending on the installation package used paths to various Gateway files are different. If installing using distribution-specific package the following paths are used:


If installing using portable bundle all Gateway files are installed under a single directory. Path prefixes used then are as follows, where INST is a directory where Gateway was installed:


The above variables (CONF, BIN and LOG) are used throughout the rest of this manual.

2. Installation

UNICORE Gateway is distributed in the following formats:

  1. As a part of platform independent installation bundle called UNICORE core server bundle. The UNICORE core server bundle is provided in two forms: one with a graphical installer and one with a command line installer.

  2. As an RPM available for Linux platforms. This RPM is tested on Scientific Linux 5, but should work without any problems with recent version of Centos (e.g. Centos 5.5), Fedora (e.g. Fedora 13, 14) and other Red Hat derivatives.

2.1. Installation from the core server bundle

Download the core server bundle from the UNICORE project website.

If you use the graphical installer follow the on-screen instructions and do not forget to check click the Gateway checkbox when prompted.

If you use the console installer then for generic installation instruction review the README file available after extracting the bundle. You don’t have to change any defaults as the Gateway is installed by default.

2.2. Installation from the RPM package (RedHat distributions)

Download RPM package from UNICORE download site and install it using rpm command as root user:

$> rpm -i unicore-gateway-VERSION.noarch.rpm

You can also (what is suggested) use yum to install and subsequently update the Gateway.

The yum installation may be performed as follows (note that first command is needed only if you have not yet installed the EMI yum repository):

$> wget --no-check-certificate \ \
   -O /etc/yum.repos.d/emi-1.repo
$> yum install unicore-gateway

3. Configuration

The gateway is configured using a set of configuration files, which usually reside in the CONF subdirectory.


This file contains settings related to the Java VM, such as the Java command to use, memory settings, library paths etc.


This is a simple list connecting the names of sites and their physical addresses. An example is:

DEMO-SITE = https://localhost:7777
REGISTRY = https://localhost:7778

If this file is modified, the gateway will re-read it at runtime, so there is no need to restart the gateway in order to add or remove sites.

Additionally sites may register dynamically at runtime.


Use the “hostname” property to configure the network interface and port the gateway will listen on, and to select between https (recommended!) and http.

hostname = https://localhost:8080
If you set the host to “”, the gateway will listen on all network interfaces of the host machine, else it will listen only on the specified one.

If the scheme of the hostname URL is set to https, the Gateway uses the configuration data from to configure the HTTPS listener.



The gateway supports the usual JKS (.jks) and PKCS12 (.p12) keystore / truststore types. These are determined automatically using the file extension.

As truststore types, you may also use “file” or “directory” by explicitely setting the “truststoretype” parameter. In case of “file”, the “truststore” parameter is assumed to denote a single file containing trusted certificates in PEM format. In case of “directory”, the truststore setting is assumed to denote a directory. This directory will be scanned for files in PEM format (having the file extension “.pem” or “.cert”), which will be loaded as trusted certs. For example, to load all the pem files in /etc/security/trusted, you can set


CRL checking

The gateway supports CRL checking if the CRLs are available as local files or on the network. To enable CRL checking, you need to ensure that the gateway start script sets the following system property:

OPTS=$OPTS”<path to properties file>”

The start script is found in BIN directory after installation and is named" (in case of installation from Java bundle) or (in case of installation from distribution-specific package).

Windows note: you can set system properties in the wrapper.conf file.

The properties file contains the following settings:

#crl checking mode: STRICT, LAX or NONE
crlcheck.mode = LAX

#update interval in seconds
crlcheck.interval = 86400

# list of URLs to CRLs
1.crl.url =
2.crl.url = file:///path/to/local/CRLFile

In LAX mode, CRLs are checked but it is not an error if for a given CA no CRL has been loaded. In STRICT mode, a CRL must be checked for each certificate authority. Finally, NONE means no CRL checking. The update interval is given in seconds. The CRL location is given as a URL. Local files, HTTP servers, anonymous FTP etc can be used for CRL distribution.

currently HTTPS connections will use the usual Java security, so it might be necessary to add the CRL server certificate to the Java truststore (i.e. the Gateway truststore is not used for this purpose).

3.5. Dynamic registration of Vsites

Dynamic registration is controlled by three properties in CONF/ file:


If set to true, the gateway will accept dynamic registrations which are made by sending a HTTP POST request to the URL /VSITE_REGISTRATION_REQUEST

Filters can be set to forbid access of certain hosts, or to require certain strings in the Vsite addresses. For example

will deny registration if the remote hostname contains “” or “”. Conversely,

will only accept registrations if the remote address contains “”. These two (deny and allow) can be combined.

3.6. Disabling the detailed Vsite listing (monkey page)

To disable the Vsite details page, set

#disable details display on the web page

3.7. Server parameters

To fine-tune the operational parameters of the embedded Jetty server, you can set some properties. These are the defaults:

#minimum number of threads
#maximum number of threads
#time after which an idle connection will be terminated
#same, but under low resource conditions
#low resource threshold

You can use the non-blocking IO connector offered by Jetty:

due to a known issue (see the NIO connector has been reported to not work properly for large messages (e.g. when transfering files using BFT). Therefore we currently discourage the use of the NIO connector until this issue is resolved.

To enable the use of the NIO connector, set

#use NIO connector

This will scale up to higher numbers of concurrent connections than the default connector.

3.8. Scalability settings

The gateway acts as a https client for the VSites behind it. The number of concurrent calls is limited, and controlled by two parameters

# maximum total number of concurrent calls to Vsites
# total number of concurrent calls per site

You can also control the limit on the maximum SOAP header size which is allowed by the gateway. Typically you don’t have to touch this parameter. However if your clients do produce very big SOAP headers and gateway blocks them you can increase the limit. Note that such a giant SOAP header usually means that the client is not behaving in a sane way, e.g. is trying to perform a DoS attack.

# maximum size of an accepted SOAP header, in bytes

Note that gateway may consume this amount of memory (plus some extra amount for other data) for each opened connection. Therefore, this value multiplied by the number of maximum allowed connections, should be significantly lower, then the total memory available for the gateway.

3.9. Proxy certificate support

UNICORE optionally supports proxy certificates as used by other Grid middleware systems. In general, we think proxies are a bad idea, but for interoperability purposes, proxies are supported as an extension. To enable the proxy certificate support,

#enable proxy authentication
#optional validator class name (default: eu.unicore.proxy.RFC3820ProxyValidator)
proxyValidator=<class name>

You need to install the necessary extension libraries into the gateway lib directory. The proxy extension is available separately from Sourceforge, if in doubt, ask on the UNICORE support or development mailing lists.

3.10. AJP Connector for using Apache httpd as a frontend

If you wish to use the Apache webserver (httpd) as a frontent for the gateway (e.g. for security or fault-tolerance reasons), you can enable the AJP connector instead of the usual one.


  • Apache httpd

  • mod_jk for Apache httpd

Enabling AJP13 Gateway with Jetty and mod_jk

Enable "mod_ssl" module in httpd configuration files, for instance "ssl.conf":

 LoadModule ssl_module modules/
 Listen 443

Enable "mod_jk" module in httpd configuration files, for instance "jk.conf":

 LoadModule jk_module modules/
 JkWorkersFile "conf.d/"

Define a "mod_jk" worker, to dialog with Gateway’s AJP connector, in "" configuration file as referred in the above "jk.conf":


Configure a httpd virtual SSL host, dedicated to act as Gateway’s frontend, in the httpd configuration files, for instance "unicore.conf". This virtual host lets the "mod_jk" worker defined above in "", manage all the requests received and forwards the full client’s certificate chain:

 # Apache VirtualHost configuration to serve as frontend
 # for an "AJP connector enabled" UNICORE6 Gateway
 <VirtualHost {{frontend_ip}}:{{frontend_port}}>
     # Pass every request on this VirtualHost to the jetty worker
     # defined in mod_jk's worker properties file.
     JkMount /* jetty
     # Pass SSL_CLIENT_CERT environment variable to the AJP connector
     JkOptions +ForwardSSLCertChain

     # Log
     ErrorLog "logs/unicore_error_log"
     TransferLog "logs/unicore_access_log"
     JkLogFile "logs/unicore_mod_jk.log"

     # Enable SSL
     SSLEngine on

     # Export SSL-related environment variables, especially SSL_CLIENT_CERT
     # which contains client's PEM-encoded certificate
     SSLOptions +StdEnvVars +ExportCertData

     # Client have to present a valid certificate
     SSLVerifyClient require

     # Server certificate
     SSLCertificateFile "{{/path/to/httpd_cert.pem}}"
     SSLCertificateKeyFile "{{/path/to/httpd_key.pem}}"

     # Trusted CAs
     SSLCACertificateFile "{{/path/to/cacert.pem}}"

On the Gateway, enable Jetty AJP connector instead of its HTTP connector in Gateway configuration file CONF/

 #enable AJP connector

External references

3.11. Gateway plugins

The gateway supports tunneling other protocols through its socket. This is still experimental, so use at your own risk. To establish the tunnel, a special HTTP message is sent to the gateway:


the method must be “HEAD”, and the message must contain the “Upgrade” header. The gateway replies:

HTTP/1.1 101 Switching protocols

After this the gateway’s socket connection is passed to a custom handler, which can read data from the client and write replies. The handler can be configured in CONF/


The handler class must implement the eu.unicore.gateway.util.ProtocolPluginHandler interface. For more details please refer to the sourcecode of the plugin interface class.


The Gateway uses Log4j for logging, configured using a properties file (CONF/ Edit this file if you need to change the granularity of the logging, or where the logs are written to. By default, the logs are written to files in the logs folder, and files are rolled over daily. Since the 6.2.0 release, you change the log levels at runtime by editing and saving the configuration file (CONF/ by default). The following logger names exist:


General gateway logging


Log IPs of clients, and the DN after the SSL handshake


HTTP processing, Jetty server

Certificate details and other security

The recent versions of the Gateway uses the so called MDC (Mapped Diagnostic Context) to provide additional information on the client which is served. In the MDC the client’s IP address and client’s Distinguished Name is stored. You can control whether to attach MDC to each

Here is an example file

# Set root logger level to INFO and its only appender to A1.
log4j.rootLogger=INFO, A1

# A1 is set to be a file appender with date rollover

# configure daily rollover: once per day the log will be copied
# to a file named e.g. gateway.log.2008-12-24

# A1 uses the PatternLayout
log4j.appender.A1.layout.ConversionPattern=%d [%t] [%X{clientIP} %X{clientName}] %-5p %c{1} - %m%n

# log levels

# also configure JDK (java.util.logging) logging
# Default global logging level.
# Loggers and Handlers may override this level

More details on Log4j configuration file format can be found here:

Detailed list of variables of the PatternLayout’s pattern are listed here:

4. Web interface ("monkey page")

For testing and simple monitoring purposes, the gateway displays a website showing detailed site information (the details view can be disabled). Once the Gateway is running, open up a browser and navigate to https://<gateway_host>:8080 (or whichever URL the gateway is running on). As the gateway usually runs using SSL, you will need to import a suitable client certificate into your web browser.

A HTML form for testing the dynamic registration is available as well, by clicking the link in the footer of the main gateway page.

5. Using the Gateway for failover and/or loadbalancing of UNICORE sites

The Gateway can be used as a simple failover solution and/or loadbalancer to achieve high availability and/or higher scalability of UNICORE/X sites without additional tools.

A site definition (in CONF/ can be extended, so that multiple physical servers are used for a single virtual site.

An example for such a so-called multi-site declaration in the file looks as follows:

#declare a multisite with two physical servers

MYSITE=multisite:vsites=https://localhost:7788 https://localhost:7789

This will tell the gateway that the virtual site "MYSITE" is indeed a multi-site with the two given physical sites.

5.1. Configuration

Configuration options for the multi-site can be passed in two ways. On the one hand they can go into the file, by putting them in the multi-site definition, separated by ";" characters:

#declare a multisite with parameters


The following general parameters exist


List of physical sites


Class name of the site selection strategy to use (see below)


Name of a file containing additional parameters

Using the "config" option, all the parameters can be placed in a separate file for enhanced readability. For example you could define in

#declare a multisite with parameters read from a separate file


and give the details in the file "conf/":

#example multisite configuration
vsites=https://localhost:7788 https://localhost:7789

#check site health at most every 5 seconds

5.2. Available Strategies

A selection strategy is used to decide where a client request will be routed. By default, the strategy is "Primary with fallback", i.e. the request will go to the first site if it is available, otherwise it will go to the second site.

Primary with fallback

This strategy is suitable for a high-availability scenario, where a secondary site takes over the work in case the primary one goes down for maintenance or due to a problem. This is the default strategy, so nothing needs to be configured to enable it. If you want to explicitely enable it anyway, set


The strategy will select from the first two defined physical sites. The first, primary one will be used if it is available, else the second one. Health check is done on each request, but not more frequently as specified by the "strategy.healthcheck.interval" parameter. By default, this parameter is set to 5000 milliseconds.

Changes to the site health will be logged at "INFO" level, so you can see when the sites go up or down.

Round robin

This strategy is suitable for a load-balancing scenario, where a random site will be chosen from the available ones. To enable it, set


Changes to the site health will be logged at "INFO" level, so you can see when the sites go up or down.

Custom strategy

You can implement and use your own failover strategy, in this case, use the name of the Java class as strategy name:


6. Building the Gateway from source

To checkout the latest version of the Gateway source code, do

svn co gateway

You will need to install Maven from Compile using

mvn install

Compiles the code and runs the tests.

mvn assembly:assembly

builds distribution archives in zip and tar.gz format in the target/ directory