The feasibility of adopting new technology in the computing world is governed in large part, as it is in other paradigms, by the cost-benefit-risk equation. In the world of electronic computing, whenever a cost-benefit analysis is done, the benefit/risk of adopting open source solutions almost always comes up for discussion. Open source solutions offer very feasible cost-effective alternatives to commercial vendor products for realizing an SOA.

Consider a typical SOA stack. Although SOA is not a totally new concept, a service-oriented architecture leveraging the current technology landscape is usually comprised of a service repository/registry, a service discovery service, and a transportation protocol. Some components of the infrastructure to support these dimensions of SOA include a messaging bus for supporting reliable messaging, an Enterprise Service Bus for service orchestration and transformation, and an underlying application server, which provides the foundation for building service components and hosting the services for applications to consume. At the bottom of the stack is, of course, the operating system.

The open source community offers capabilities that address all the layers of the stack. When adopting an SOA strategy, organizations should evaluate the offerings from open source software (OSS) as well as commercial products. All the prominent vendors in the SOA arena, such as IBM, BEA, Sun, Oracle, and Microsoft, as well as newer players such as Cape Clear and Fiorano, have offerings for SOA enablement. Open source offers the advantages of low-cost, vendor-neutral, standards-based solutions.

Recently the open source community has announced several products that address the needs for implementing an SOA. At the bottom of the stack, Linux offers a commercial grade operating system. JBoss, JonAS, and the Apache server offer the core application server capabilities and have been in the industry long enough to provide mature, reliable alternatives to commercial app servers. On the messaging front, ActiveMQ, JORAM, and JBossMQ are some of the products that provide asynchronous messaging capability. Recently the open source community also released products that address the ESM space such as Mule, celtix, and open-esb. Axis, Synapse, and Sandesha are some of the other products that focus on Web service enablement in an SOA. There are several other products that are either in the process of being released or are being designed to help implement service-oriented architectures. Optaros has an interesting white paper (www.optaros.com/wp/wp_2_soa_oss.shtml) that provides some possible scenarios for leveraging OSS in SOA stacks.

The open source community is not completely divorced from commercial vendors. In fact, most of the open source projects are based on heavy contributions from traditional vendors such as IBM, BEA, and Oracle. IBM has invested heavily in Linux, Eclipse, Apache, etc. For example, late last year, IBM launched the Community Edition of its WebSphere Application server, which is an open source, license-free version. This project was in the works for a while and is the result of the GlueCode acquisition by IBM. WebSphere CE is the new incarnation of GlueCode's Geronimo app server. Similarly, BEA has invested heavily in the Apache Beehive projects, which leverage open source application servers.

While the products offered from the open source community for facilitating service orientation are definitely gaining ground, large organization are still wary of betting the farm on open source alternatives. However, the open source community definitely has a larger presence in service enablement than previous initiatives. This is due to several factors. The tools to support SOA are fairly new and, therefore, open source alternatives are as viable as commercial offerings. At the same time, the pressures on business to cut costs are forcing organizations to look for more cost-effective options. Meanwhile, the open source community has gained substantial trust in the industry through proven technologies and products, as well as due to the backing of vendors who have based large components of their commercial offerings on open source products.