Welcome!

Microservices Expo Authors: Zakia Bouachraoui, Liz McMillan, Jason Bloomberg, Elizabeth White, Pat Romanski

Related Topics: Microservices Expo

Microservices Expo: Article

Building SOA with Tuscany SCA

A simple service-oriented infrastructure

Many articles have already been written about service-oriented architecture (SOA) and Service Component Architecture (SCA), for example, see references [1] and [2]. In this article we'll focus on a freely available, open source implementation of the Service Component Architecture that provides a simple way to implement SOA solutions. This SCA implementation is being developed in the Apache Tuscany Incubator project. The project started in 2006 and is being used by many who are looking for a simple SOA infrastructure. The recent Tuscany SCA version 1.0, which was released in September 2007, supports the Service Component Architecture specifications 1.0. In addition to implementing the SCA specifications, Tuscany is also a nursery for new ideas. Some of these ideas will find their way into the specifications and some will be regarded as extensions available in Apache Tuscany Incubator. For example, support for Ruby, JavaScript, XQuery, data binding and Web 2.0 are currently extensions beyond the specification.

This article will walk you through what is available in Apache Tuscany Incubator and therefore highlight the benefits of SCA.

Using Tuscany SCA
A Common Approach to Application Construction and Deployment

Enterprise software development is increasingly influenced by technology choices, regulations, competition and expectations for responsiveness to change. Enterprises need the flexibility to adopt new business practices (like outsourcing of mortgage handling by a bank), enforce new regulations, and extend or down-size without much cost (mergers and acquisitions). In addition, as the complexity of the enterprise grows, a common management paradigm becomes a necessity for managing business applications. Service Component Architecture provides a simple programming model to address these challenges. SCA's simple language maps easily to the business. Let's consider we are building a banking application that handles account inquiries. Table 1 maps business-level questions to SCA.

SCA provides a consistent model of distributed applications and of the components from which they are constructed. This model explicitly separates business logic (Component/Services/References) from the details of how a running application is assembled (Composite/Wire) and deployed. This promotes a common terminology and supports a common understanding of the capability of applications and the way those applications work together. This common model also provides the hooks for tooling, governance, monitoring, and management in the service-oriented world.

When it comes to building a solution for real, one of the most important questions is likely to be "how can existing IT infrastructure and skills be used?" Tuscany SCA does not invent new technologies for component implementations (Implementation) and message exchange (Binding). It neither requires you to learn a new programming language nor communications protocols. You are free to leverage your existing investment in applications, technology, and skills as long as suitable support exists in Tuscany SCA. This is not much of a hurdle; Tuscany SCA has a straightforward extensibility model so new or proprietary technologies can easily be included.

The following sections describe Tuscany SCA in the context of three familiar scenarios. It should be noted that Tuscany SCA is not restricted to these scenarios. The sample code and configuration used here can be found in the Tuscany SCA Java distribution [3] and is available under the Apache License [4].

Enterprise Applications
In a typical enterprise, business functions are implemented using various technologies, business data is represented in different formats, and business applications communicate using heterogeneous protocols. It is almost impossible to converge all applications onto one technology stack such as Web services and so it remains difficult and costly to integrate different applications in an enterprise. Enterprises face many challenges including the following.

•  Business applications are tightly coupled with the IT infrastructure and early design decisions have to be made before real deployment.
•  Application developers are forced to learn and understand many technologies beyond business domain knowledge
•  Business logic is polluted and coupled to various technology-specific API calls imposed by the IT infrastructure. It's not easy to write and not easy to change.

SCA separates business services from the concerns related to specific hardware, software and network protocols by providing a unified programming model that allows the SCA runtime to handle these issues transparently. Let's look at a simple business scenario to see how Tuscany SCA can help enterprise application integration. The scenario here is the BigBank demo from the Tuscany SCA distribution [5]. As illustrated in Figure 1, the application comprises a number of assembled components and ultimately returns a total account balance in response to account inquires.

The use of the SCA programming model allows the BigBank developer to decouple the process of designing and creating the scenario from infrastructure concerns. In the BigBank composite, basic units of business logic are modelled as SCA components called AccountComponent, StockQuoteComponent, etc. Their business logic is implemented using Java and various scripting languages. Components are assembled by wiring references to services. Once all business logic is implemented, appropriate bindings are applied to references and services to indicate how the components should communicate.

The XML-based SCA configuration language describes all of the information about loosely coupled enterprise services and the bindings to be used. Since binding information can be changed in the SCA configuration without changing the business logic, the implementation code is not polluted with protocol handling information and, furthermore, bindings can be changed during deployment without impacting the application.

The following SCA configuration shows the AccountService exposed using JSONRPC (binding.jsonrpc) and Web services (binding.ws). The service can easily be made accessible over RMI by simply adding binding.rmi.

<component name="AccountServiceComponent">
    <implementation.java class="bigbank.account.AccountServiceImpl" />

    <service name="AccountService">
       <tuscany:binding.jsonrpc uri="/AccountJSONService" />
       <binding.ws
       wsdlElement="http://bigbank#wsdl.port(AccountService/AccountServiceSoap)" />
    </service>

    ...
</component>

The following SCA configuration shows bindings applied to component references. Again these bindings can be changed or augmented without changing the business logic.

<component name="AccountServiceComponent">
    ...
    <reference name="calculatorService">
       <tuscany:binding.rmi host="localhost" port="8099" serviceName="CalculatorRMIService" />
    </reference>

    <reference name="stockQuoteService">
       <binding.ws uri="http://localhost:8081/services/StockQuoteWebService" />
    </reference>
    ...
</component>

More Stories By Haleh Mahbod

Haleh Mahbod is a program director with IBM, managing the team contributing to the Apache Tuscany as well as SOA for PHP open source. She has extensive development experience with database technologies and integration servers.

More Stories By Raymond Feng

Raymond Feng is a senior software engineer with IBM. He is now working on the Service Component Architecture (SCA) runtime implementation in Apache Tuscany project as a committer. Raymond has been developing SOA for more than 4 years and he was a key developer and team lead for WebSphere Process Server products since 2002.

More Stories By Simon Laws

Simon Laws is a member of the IBM Open Source SOA project team working with the open source Apache and PHP communities to build Java, C++, and PHP implementations of the Service Component Architecture (SCA) and Service Data Object (SDO) specifications. Prior to this role he was working in the distributed computing space building service-oriented solutions for customers with a particular interest in grid computing and virtualization.

Comments (2)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


Microservices Articles
Digital Transformation is well underway with many applications already on the cloud utilizing agile and devops methodologies. Unfortunately, application security has been an afterthought and data breaches have become a daily occurrence. Security is not one individual or one's team responsibility. Raphael Reich will introduce you to DevSecOps concepts and outline how to seamlessly interweave security principles across your software development lifecycle and application lifecycle management. With ...
CloudEXPO New York 2018, colocated with DXWorldEXPO New York 2018 will be held November 11-13, 2018, in New York City and will bring together Cloud Computing, FinTech and Blockchain, Digital Transformation, Big Data, Internet of Things, DevOps, AI, Machine Learning and WebRTC to one location.
DevOpsSummit New York 2018, colocated with CloudEXPO | DXWorldEXPO New York 2018 will be held November 11-13, 2018, in New York City. Digital Transformation (DX) is a major focus with the introduction of DXWorldEXPO within the program. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive over the long term.
Two apparently distinct movements are in the process of disrupting the world of enterprise application development: DevOps and Low-Code. DevOps is a cultural and organizational shift that empowers enterprise software teams to deliver better software quicker – in particular, hand-coded software. Low-Code platforms, in contrast, provide a technology platform and visual tooling that empower enterprise software teams to deliver better software quicker -- with little or no hand-coding required. ...
"We do one of the best file systems in the world. We learned how to deal with Big Data many years ago and we implemented this knowledge into our software," explained Jakub Ratajczak, Business Development Manager at MooseFS, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
All zSystem customers have a significant new business opportunity to extend their reach to new customers and markets with new applications and services, and to improve the experience of existing customers. This can be achieved by exposing existing z assets (which have been developed over time) as APIs for accessing Systems of Record, while leveraging mobile and cloud capabilities with new Systems of Engagement applications. In this session, we will explore business drivers with new Node.js apps ...
Using new techniques of information modeling, indexing, and processing, new cloud-based systems can support cloud-based workloads previously not possible for high-throughput insurance, banking, and case-based applications. In his session at 18th Cloud Expo, John Newton, CTO, Founder and Chairman of Alfresco, described how to scale cloud-based content management repositories to store, manage, and retrieve billions of documents and related information with fast and linear scalability. He addres...
While some developers care passionately about how data centers and clouds are architected, for most, it is only the end result that matters. To the majority of companies, technology exists to solve a business problem, and only delivers value when it is solving that problem. 2017 brings the mainstream adoption of containers for production workloads. In his session at 21st Cloud Expo, Ben McCormack, VP of Operations at Evernote, discussed how data centers of the future will be managed, how the p...
Containers and Kubernetes allow for code portability across on-premise VMs, bare metal, or multiple cloud provider environments. Yet, despite this portability promise, developers may include configuration and application definitions that constrain or even eliminate application portability. In this session we'll describe best practices for "configuration as code" in a Kubernetes environment. We will demonstrate how a properly constructed containerized app can be deployed to both Amazon and Azure ...
The now mainstream platform changes stemming from the first Internet boom brought many changes but didn’t really change the basic relationship between servers and the applications running on them. In fact, that was sort of the point. In his session at 18th Cloud Expo, Gordon Haff, senior cloud strategy marketing and evangelism manager at Red Hat, will discuss how today’s workloads require a new model and a new platform for development and execution. The platform must handle a wide range of rec...