place holder for the old user guide page

About Tuscany User Guide

It is assumed that by now you have browsed through the introduction to SCA
section or are familiar with SCA. This user guide helps you learn more about SCA through Tuscany. It starts with building a simple application and progresses into more advanced features through references to samples that reside in Tuscany.

Before we start, let's emphasise that it is Tuscany's goal to provide an implementaiton that avoids imposing rules and requirements on how you write your applications. In fact the goal is to let you write application code without being concerned about the technology you choose or the environment in which it will be used. You focus on your business logic and Tuscany infrastructure will handle the rest.

Create Your First Application

This simple exercise provides you with a hands-on experience for creating an SCA calculator application. Although this is a simple application, it will cover the following items:

• Creating SCA POJO-based components
• Composing an application
• Deploying the application
• Modifying the application to use a different binding

Give create a calculator application a try.

Create a Store Application

Now that you have created a simple calculator application, let's move on to a more interesting application called store. This application is developed in Eclipse enviromment and uses more advanced features that are offered in Tuscany. You will notice that it is as simple to create this application as it was to create the calculator application.

Getting Started with Tuscany using a Tuscany Distribution In Eclipse
This is a quick getting started guide that go trough the steps of building the store scenario using the Tuscany SCA distribution manually installed into Eclipse

Getting Started with Tuscany using the Tuscany Eclipse Plugin
This is a quick getting started guide that go trough the steps of building the store scenario using the Tuscany Eclipse plugin.

First Steps - Building your first web services using Tuscany
This is a quick guide that go through the steps of exposing your pojo component as web services.

Create a Distributed Application

A Tuscany application can be run in a single or multi-node environment. Here we introduce SCA node and walk you through an example that demonstrates how the calculator example can be distributed. This exercise will cover the following:

• What is a node?
• How to create and configure a node?
  Give distributed calculator a try.
  note the following sections need to go into a tutorial for distributed sample

Tuscany SCA Node

In order to run an SCA application Tuscany SCA Java provides a runtime that is wrapped up in a Node. The runtime itself is made up of many of the modules that are present in the modules directory of the Tuscany SCA Java distribution. As you might expect there are functions that read XML, create an in memory mode model of the SCA assembly, create the components and wire them together ready to process incoming messages. All of these functions are wrapped up in a Node. A node is configured using SCA contributions and will run a single composite. When running standalone the node also defines the scope of component services that references can target by name. SCA defines the term Domain to describe this scope.
A node runs within a single JVM. A JVM can run many Nodes.

host embedded

For a long time in Tuscany we have had a modules called host.embedded that contains the code required to get the runtime up and running in standalone configuration. This was developed before the distributed domain support was added but the main interface here is called an SCADomain. It's just a very small domain with only one node inside it. You can't see the node and you configure and access it via the SCADomain interface. The majority of samples and tests use this today. However the new SCA Node implementation can work in both standalone and distributed configuration so may be more appropriate in situations other than the simple Tuscany samples and tests. We will convert more samples ant tests to this approach over time to show the benefit of using the node implementation.

Tuscany SCA Node Implementation

Available from release 1.2 there is a new domain/node implementation. The node part of this can be run either stand alone or as part of a distributed domain. Most of the sample and test code has not started using this implementation yet and there may be more changes to the API.

Creating and Configuring Node

Creating a node in code is straightforward. For example,

SCANode2 node = SCANode2Factory.newInstance().createSCANodeFromClassLoader("calculator.composite", null);

The node uses current classes classloader to located the named composite file. The location of the composite file is assumed to be the location if the SCA contribution. The assumption here is that only one contribution is required.

If more contributions must be loaded by the node the following interface can be used.

SCANode2  node = SCANode2Factory.newInstance().createSCANode("file:/C:/CalculatorContribution1/Calculator.composite",
        		                               new SCAContribution("CalculatorContribution1",
        		                                                               "file:/C:/CalculatorContribution1"),
                                                       new SCAContribution("CalculatorContribution2",
        		                                                               "file:/C:/CalculatorContribution2"));

Where

"file:/C:/CalculatorContribution1/Calculator.composite"

Is the explicit location of the composite file to be run and

new SCAContribution("CalculatorContribution1",
        		        "file:/C:/CalculatorContribution1")

Shows how to provide contribution details. Multiple contributions can be specified. You might have multiple contributions if, for example, you have chosen to separate common artifacts from those specific to this composite. The contribution containing common artifacts can then be used in other SCA applications without change.

Starting a Node

Once the node is created it is configured and ready for use. It can be started as follows.

node.start();

Locating Services

A local service reference can be retrieved in the following way.

calculatorService = ((SCAClient)node).getService(CalculatorService.class, "CalculatorServiceComponent");

Stopping a Node

If you are done with the node or need to stop is processing messages use the following.

node.stop();

You can run SCA applications in many different ways but the same underlying runtime is used but packaged in slightly different ways as follows

Command Line

Most of the samples that are shipped with the Tuscany SCA Java distribution run from the command line by driving the Node API or old SCADomain API programmatically.

There is a pre-packaed launcher that has a mainline for starting nodes. When run from the command line it expects to be running in the context of the binary distribution where "modules" and "lib" directories are present.

It loads all of the jars from

1) the directory where the launcher class is found.
2) the ../modules directory
3) the ../libs directory

It then repeats the process looking for ../modules and ../lib dirs based on the contents of a TUSCANY_HOME environment variable

With the final list it creates a URLClassLoader with the current classloader as the parent and enforces a parent first classloading strategy.

TODO - how does it find the composite file to run?

WebApp

Some of the samples that are shipped with the Tuscany SCA Java distribution run as web apps
TODO

Tomcat

Running a Tuscany SCA Java enabled webapp in Tomcat is as simple as copying the webapp to the Tomcat webapps directory.

Geronimo

TODO

WebSphere

Please see this blog entry to learn how to do this: http://jsdelfino.blogspot.com/2007/10/how-to-use-apache-tuscany-with.html

WebLogic

Please see this user's blog to learn how to do this: http://davesowerby.blogspot.com/2008/02/using-tuscany-with-weblogic.html

Eclipse

There are two Getting Started documents that discuss this.

Getting Started with Tuscany using a Tuscany Distribution In Eclipse
Getting Started with Tuscany using the Tuscany Eclipse Plugin

SCA has the concept of a domain. Section 10 of the SCA Assembly specification describes an SCA Domain as defining "the boundary of visibility for all SCA mechanisms". SCA wires can be used to connect components within a single SCA Domain.

From the calculator sample you can see that the wires between the component references and services, formed by adding a target component name to a reference, are resolved inside an SCA domain. For example, this section of the calculator composite file shows how the CalcuatorServiceComponent targets the AddServiceComponent.

<component name="CalculatorServiceComponent">
        <implementation.java class="calculator.CalculatorServiceImpl"/>
        <reference name="addService" target="AddServiceComponent" />
        <reference name="subtractService" target="SubtractServiceComponent" />
        <reference name="multiplyService" target="MultiplyServiceComponent" />
        <reference name="divideService" target="DivideServiceComponent" />
    </component>

    <component name="AddServiceComponent">
        <implementation.java class="calculator.AddServiceImpl"/>
    </component>

The target="AddServiceComponent" of the CalculatorServiceComponent's addService reference refers to the AddServiceComponent defined later on in this composite. A domain can consist of more than one composite and wires can run between components defined in the composites. The SCA Domain describes the boundary within which target component services can be located.

To connect to services outside of the SCA Domain (whether they be services provided by SCA or by other means) you configure an explicit binding, for example, lets assume that the AddServiceComponent is a non-sca web service out there on the network somewhere. As this is outside the SCA domain we can use an explicit remote binding to talk to it.

<component name="CalculatorServiceComponent">
		<implementation.java class="calculator.CalculatorServiceImpl"/>
        <reference name="addService" >
           <interface.java interface="calculator.AddService" />
            <binding.ws uri="http://localhost:8080/sample-calculator-ws-webapp/AddServiceComponent"/>
        </reference>
        <reference name="subtractService" target="SubtractServiceComponent"></reference>
        <reference name="multiplyService" target="MultiplyServiceComponent"></reference>
        <reference name="divideService" target="DivideServiceComponent"></reference>
    </component>

Tuscany SCA supports running an SCA Domain in a single Node or spread across multiple Nodes potentially on different machines. We have seen a domain with a single node before.

A domain with multiple nodes allows wires to run between components running in the separate nodes which may be running on different JVMs on different machines.

When reference and service are in different composites the domain manager is used to pre-process each composited prior to the composites being deployed to nodes for running. Contributions (containing the composites) are added to the domain manager. Configuration must be provided which tells the workspace where the nodes are that are going to run the composites and which composites they will run. Based on this information the domain manager makes an atom feed available for each composite that is deployed to a node. The node to which the composite is assigned must read the correct atom feed in order to configure itself by downloading the composite to run and the contributions required provide the artifacts required by the composite. There is a Node API that takes as input the URL of an atom feed exposed by the domain manager as follows.

SCANode2 node = SCANode2Factory.newInstance().createSCANodeFromURL("http://localhost:9990/node-config/NodeA");

The URL http://localhost:9990/node-config/NodeA is the URL of the atom feed that the domain manager provides.

The domain manager processes all the relationships between all composite components and provides a fully configured composite to each node, i.e. all of the binding URIs are filled out correctly so it's basically a pre-processing step. You can simulate the effect by manually adding the full uri to the reference binding.ws if you don't want to run with the domain manager

The calculator-distributed sample is a simple example of the use of the workspace. You can fire up the workspace and play with the gui or look at the 3 xml files in the top directory of that sample which the workspace relies on for configuration.

Starting A Domain

There is a launcher that has a mainline for starting the domain. For example,

    public static void main(String[] args) throws Exception {
        DomainManagerLauncher.main(args);
    }

TODO - how is this run without having to create your own mainline.

Configuring A Domain Through The Web Interface

One the domain manager is running you can get to the web interface of the default domain point you browser at http://localhost:9990/ui. This provides a number of different pages allowing you to

• Add contributions to the domain
• Add node configurations to the domain
• Configure composites to run on specific nodes
• Start local node instances to test the configuration

Configuring a Domain Through The File System

Behind the domain manager web application there are three files where the configuration information is stored.

workspace.xml - stores the ID and location of each contribution that has been added to the domain.

domain.composite - the virtual domain composite. This is an SCA composite that represents the virtual domain which includes all of the composites that will run in the domain. A URI is provided which indicates which contribution each composite comes from. Ultimately an SCANode2 instance will be started for each composite included in the virtual domain. Each SCANode2 instance can be running on separate/distributed processors. So the virtual domain is a consolidated description of you distributed SCA application

cloud.composite - describes the compute cloud (the set of distributed SCANode2 instances) being used to run the SCA application. Each node is assigned a composite and also has details of the configuration of bindings when they run on that node, for example, the root URI is set. It's possibly slightly confusing that this file is in SCA composite format also but this is a convenience because firstly we didn't have to create a new file format and secondly there may be some benefit in the future of representing this network of nodes as a network of SCA services for management purposes although we don't do that yet.

These files are updated when you make changes to the domain through the domain manager interface but they have a fairly simple XML format and can be edited manually or new utilities could be constructed to edit them automatically.

Tuscany Web-based Domain Manager Tool

This article that is hosted outside of Tuscany provides a step by step instruction for how to use the Tuscany web-based domain manager UI to administer an SCA domain and how to use the domain administrative UI to deploy an SOA solution comprised of SCA components.

TODO

The Tuscany SCA runtime comprises a small set of core software which deals with:

• Managing extesions to the Tuscany SCA Runtime(core)
• Building and in memory assembly model of SCA applications (assembly)
• Processing SCA applcations that are contributed (contribution)
• Supporting databindings (databinding)
• Supporting Tuscany SCA when its embedded in other environments (embedded)
• Supporting Tuscany SCA when its running in a servlet container (http)

The collections of interfaces that describe these features are referred to as the System Programming Interface (SPI). The developer guide discusses them in more detail but from a user perspective the important thing to realize is that the majority of interesting functionality in Tuscany SCA is provided by extensions which build upon this core SPI. These extensions provide Tuscany SCA with its ability to support a wide variety features.

• Implementation types
• Binding types
• Databinding types
• Interface description styles
• Hosting environments

So to understand how to use the Tuscany SCA runtime is to understand how to use its extensions. The available extensions are described in the User Reference

Extensions are loaded into the Tuscany SCA runtime using the Java service loading mechanism. Each extension is packaged as a jar and provides a file;

META-INF/services/org.apache.tuscany.sca.core.ModuleActivator

Using this information the Tuscany SCA runtime will load each extensions present on the the Java CLASSPATH. So if you want to use a particular feature make sure that it's available on your classpath. Conversely if you don't want a particular feature to be active remove it from the classpath.

Writing a new extension is a subject in its own right and is described in the extension guide

We don't provide any IDE project files with our disitributions so you will have to import the sample files into your IDE manually. Here's an example of how it can be done using Eclipse. Here the directory tuscany_sca_install_dir is the directory whch holds the Tuscany SCA Java binary installation after it's been extracted from its archive file, for example, for the 0.90 release this will be tuscany-sca-0.90-incubating.

In a new or existing workspace

• Create a new java project to represent the sample you want to work on, e.g.

  my working dir/calculator
  

• Import all of the sample code and resources into this project, e.g.

  Use the File,Import menu and then select  tuscany_sca_install_dir/samples/calculator from the filesystem
  

• Configure the source path to include

  tuscany_sca_install_dir/samples/calculator/src/main/java
  tuscany_sca_install_dir/samples/calculator/src/main/resources
  

• Configure the output folder to be

  tuscany_sca_install_dir/samples/calculator/target
  

• Configure the build path to include all of the jars provided in

  tuscany_sca_install_dir/lib
  

• If you select calculator.CalculatorClient.java and run as "Java Application" you should see

  3 + 2=5.0
  3 - 2=1.0
  3 * 2=6.0
  3 / 2=1.5
  

The details of how to do this for other development environments will vary but the process will be similar.

If you are a Maven user you can use it to generate all of the IDE project files for you automatically. This works best if you generate IDE projects for all of the Apache Tuscany modules. You can then include the ones you are interested in working with in you IDE.

To build IDE project files for all of the modules in Apache Tuscany SCA;

cd sca

If you are an Eclipse user do the following

mvn -Peclipse eclipse:eclipse

If you are an IDEA user do the following

mvn idea:idea

These commands generate project files for each module in Apache Tuscany SCA. The modules you are interested in can now be included in your IDE, for example, in Eclipse, if you create a new Java project and use the option to "create a new project from existing source" you can specify an SCA module directory, which includes the generated project files, and Eclipse will treat it like any other Java project.