Introduction

Please feel free to send any questions or comments to Ted Stockwell

ServiceTango is an application server for building, deploying, and managing network-delivered business applications.
ServiceTango is designed to be OSGi (Open Services Gateway Initiative) 1.0 compatible.

ServiceTango's primary goal is to use the Java (TM) programming language's platform independence and dynamic code-loading capability to make development and dynamic deployment of business applications easier.

This goal is met in two ways. First, the OSGi Framework Specification provides a consistent programming model during application development; it supports the development and use of services by decoupling a service's specification (the interface) from its implementation.
Thereby:

 Developers can provide multiple implementations to the same service interface
 Developers who use a service can code against that service's interface without regard to its implementation
This support is critical, because ServiceTango is designed to run on a variety of hardware; different hardware characteristics could affect many aspects of the service implementation, yet a stable service interface ensures the stability of the overall software system.

For example, in one deployment a logging service might store log messages on a hard drive, while in another deployment the log entries may be saved remotely. The developers of the two logging service implementations implement the same interface; the developers of services that use a logging service write code against the logging service interface, without regard to which implementation their service might use.

Second, it provides life-cycle management functionality that permits application developers to partition applications into small self-installable components. These components are called bundles. Bundles can be downloaded on demand and removed when they are no longer needed. When a bundle is installed and activated in ServiceTango it can register any number of services that can be used by other bundles.

This dynamic aspect makes the software extensible on the device after deployment: new bundles can be installed for added features or existing bundles can be updated for bugfixes without bringing down the entire system.

Capabilities

 Standard OSG platform, including web server and log handling

Restrictions

 The OSG device manager interface is not supported.

Requirements
Developing with ServiceTango requires that you have the following:

 Runtime environment that supports Java 2. For instance, Java Development Kit (JDK) v1.2 or better.
 Development environment including a Java compiler and interpreter. For instance, JBuilder Foundation (free!).
 An understanding of Java programming.

Installation

ServiceTango is distributed as a .zip file.
It's easy to expand the ServiceTango download with Java's jar tool.
Set your current directory to the directory in which you would like to create the ServiceTango home directory. On a Windows workstation this would typically be the root directory.
Then type the command:

    jar xvf <file-name>

where <file-name> is the substituted with the name of the ServiceTango distribution file that you downloaded. This command creates a directory named ServiceTango off the current directory and copies the ServiceTango files into the new directory. This directory is referred to as the <ServiceTango-Home> directory.

Execution

To start ServiceTango simple execute the command:

    java -cp <ServiceTango-Home>/lib/servicetango.jar org.servicetango.startup.ServiceTango [options]

where [options] may include the following:

-config <file-name>
where <file-name> is the name of a file that contains configuration properties. This is the server's XML configuration file. If not specified then the server will try to use a file named "servicetango.xml" in the current directory.

See the Configuration section for details.

See the Services section for instructions on using the services that come with ServiceTango.

See the Examples section for instructions on starting the ServiceTango instance included in the distribution.

Configuration

ServiceTango may be configured via an XML formatted configuration file. This configuration file is used by ServiceTango to set general operating aspects of ServiceTango. For instance, where ServiceTango stores downloaded bundles. The configuration file is not used to denote what bundles should be loaded by ServiceTango. Ongoing management of a ServiceTango instance is done via one of ServiceTango's administraion interfaces; the ServiceTango console or the ServiceTango Management Panel.

Here is the current syntax of the ServiceTango configration file:


<servicetango>
<!--
The root directory is where the default ServiceTango storage manager will
persist installed bundles.
If this property is not specified then the root directory will default to
./storage
-->
<root-directory>./storage</root-directory>


<!--
The maximum time, in minutes, that ServiceTango will wait for bundles to change
state (to start up, to shut down, etc).
If this property is not specified then the timeout duration will default to 2
minutes.
-->
<bundle-timeout-minutes>2</bundle-timeout-minutes>


<!--
Used to define a global system property.
Equivalent to defining a system property with the -D argument when starting a Java VM.
Some bundles may look for configuration properties in the system properties, it
is more convenient to be able to define system properties in the configuration file.
-->
<system-property>
    <name>some.property.name</name>
    <value>someURL SomeApp</value>
</system-property>
<system-property>
    <name>another.property.name</name>
    <value>someURL SomeApp</value>
</system-property>


</servicetango>

Components

ServiceTango is built with the following third-party libraries and components (other than what's contained in the Java 2 platform):

 Tomcat
Tomcat is the Reference Implementation for the Java Servlet 2.2 and JavaServer Pages 1.1 Technologies.
Tomcat is the official reference implementation for these complementary technologies.
Tomcat also contains an HTTP 1.0 compliant web server.

Tomcat's license is reproduced below as required...
Copyright (c) 1999 The Apache Software Foundation. All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
3. The end-user documentation included with the redistribution, if any, must include the following acknowlegement: "This product includes software developed by the Apache Software Foundation (http://www.apache.org/)." Alternately, this acknowlegement may appear in the software itself, if and wherever such third-party acknowlegements normally appear.
4. The names "The Jakarta Project", "Tomcat", and "Apache Software Foundation" must not be used to endorse or promote products derived from this software without prior written permission. For written permission, please contact apache@apache.org.
5. Products derived from this software may not be called "Apache" nor may "Apache" appear in their names without prior written permission of the Apache Group.
THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 Java API for XML Parsing 1.0.1
The JAVA API for XML Parsing (JAXP) Optional Package provides basic functionality for reading, manipulating, and generating XML documents through pure Java APIs.

Future Enhancements

 The ServiceTango Management Panel
The ServiceTango Management Panel is an application which is used to get information about the entities running in a ServiceTango instance, and to perform operations on those entities (such as stopping or installing bundles)

 Support for the Java Network Laucher Protocol and API.
Bundles that export JNLP services will provide a higher level API to developers for developing network deployable and automatically updating applications than that provided by the OSGi Framework.

 A mail service.
A bundle that exports mail services for sending and receiving mail messages. Because this service will be available to other applications via the OSGi API any other application installed into the same ServiceTango instance will instantly know the correct way to get and send e-mail.

 An e-mail client application.
A complete, Swing-based, e-mail application that can be automatically updated.