Tutorials SOA Web ServicesThe previous pattern (Self-Service) provided an interaction between the consumer and the service. In the extended enterprise business pattern, the interaction between the two partner businesses is explored. The collaborative businesses expose their functionality as services.
A business can access the service exposed by its partner through a programmatic interface. A business may act as a service consumer, a service provider, or both. The architecture for this pattern is illustrated in the following figure.
This pattern essentially is a manifestation of application integration pattern. However, due to SOA implementation based on open standards, such integration is loosely coupled. The loose coupling also facilitates the integration of disparate technologies. In the case of application integration, the coupling may not be always possible and is usually tightly coupled. The application of SOA also mandates meeting additional QoS (Quality of Service) requirements such as security, performance, and availability.
Consider the case of the automobile industry. An automobile manufacturing company depends on several other manufacturers for its spare parts. The company maintains its inventory of spare parts and when it runs low on stocks, a new order is placed with the supplier. A few years ago, the access to the entire inventory was closely guarded and the suppliers had to wait for a physical intimation from the company. A part of the inventory may now be exposed directly to the supplier. The supplier can monitor the inventory levels and supply the goods to the company when a threshold low is reached. Rather than exposing the application interface to the inventory management system, this may be implemented as SOA.
The desired service is defined and coded to expose the relevant inventory status to individual suppliers. The Direct Connection pattern for the Extended Enterprise fits perfectly in this scenario. It involves the interaction between the two cooperating (partner) businesses. To expose the inventory to the associated business partners may require a tight implementation of security. Creating secured web services is discussed later in this book.
