| As an example of how ESB technology is changing the economics of integration in a real deployment scenario, let's take a look at how a building material manufacturer is using an ESB. We will pay special attention to how they are taking advantage of the selective deployment model of the ESB. The manufacturer operates 50 plants in 15 countries. They distribute their products through large building supply retailers, such as Home Depot and Lowe's, as well as through a network of more than 60 independent distributors serving retail and wholesale customers in regional markets across the United States. Twenty-eight of their larger distributors are connected to their headquarters using an EDI VAN. Connecting one supplier with 60 distributors is a simple challenge for an integration infrastructure that is capable of scaling out to thousands of diverse endpoints. However, the point of this case study is not the scale of the deployment, but the traits of the ESB that it utilizes. Its simplicity highlights yet another characteristic of the ESB that it is capable of scaling up to large global integration networks, but is also well suited for small projects. 3.5.1 Building a Real-Time Business To improve operations and optimize the distribution chain, this manufacturing company embarked on building an infrastructure that would enable direct distributor participation in inventory management and ATP as a means of achieving real-time order fulfillment. 3.5.1.1 Inventory management The inventory management application allows the manufacturer to better anticipate the demand of its distributors by tracking each distributor's monthly inventory consumption and creating a recommended monthly order requisition for each distributor. By deploying an ESB, the manufacturer can now analyze its distributors' order and sales histories, thus allowing inventory to be jointly managed. This was accomplished by implementing a message exchange that allows the manufacturer to anticipate a distributor's inventory requirements. In this scenario, distributors periodically send product activity data to the manufacturer, which uses that data to anticipate product consumption activity and determine when the distributors need to replenish the stock. They then generate a shipping schedule message indicating the products and quantities that the distributor should order to replenish its stock. The distributor will use this data to generate a purchase order back to the manufacturer. This process allows the manufacturer to better manage inventory, reducing the quantity of on-hand product needed for the distributors and achieving more predictable production schedules and revenue forecasts. 3.5.1.2 Technical challenges The manufacturer looked to integrate the 60 disparate ERP systems of their distributors with their own SAP R/3 inventory management and order processing systems. One of the challenges they faced was accommodating varying levels of technical sophistication among their broad range of distributors. They already had an EDI infrastructure for about half of the larger distributors, but that was a high-cost solution that would not be viable for the smaller distributors. Some of the larger distributors had the technical capability to communicate with them using SOAP and web services, but some of the smaller distributors didn't have the sophistication or technical know-how to do that. Most distributors had an ERP system locally, with the extent of their IT expertise limited to how to operate it. The manufacturer needed a simple solution that could be installed at each of the distributor sites, and configured and managed remotely by a central IT staff. 3.5.1.3 Availability To Promise (ATP) The manufacturer has also deployed an ATP lookup for nonstock items. ATP is a common business function in supply chains that allows you to accurately predict the delivery of goods between multiple buyers and suppliers. This is particularly important when the immediate supplier does not have the item in on-hand inventory and needs to custom-build it, which could involve another level of special-order items from its own suppliers. Being able to plan and predict the timely delivery of nonstock items can significantly reduce the unnecessary cost overhead of carrying special inventory items to effectively meet the demands of customers and avoid lost business. 3.5.2 Flexible Partner Integration The solution for both the inventory management and ATP issues was to deploy an ESB. For the inventory management function, they needed a remote integration solution that was easy to install, deploy, and integrate with the many disparate ERP systems at each distributor site. For the ATP solution, they decided to expose the ATP function as a service and use a direct web services link with the distributors. The inventory management function is facilitated by an ESB-managed business process that controls the routing between the partners and the inventory management application, which is implemented in SAP. There are no integration brokers or application servers required at the remote sites. Still, the solution provides standards-based connectivity, reliable and secure messaging, and transformation and service orchestration between its own systems and the individual ERP systems utilized by the remote distributors. The "edge" of the ESB network is capable of supporting a variety of connectivity options as new distributors come on board. Even existing links with distributors can change their underlying protocol without affecting the higher-level business processes and XML message exchanges between the manufacturer and the distributors. To manage the link between distributors and headquarters, the manufacturer chose to deploy an ESB service container at the remote distributor sites (Figure 3-5). Figure 3-5. Remote ESB containers at distributor sites allow selective deployment of integration capabilities 
Remote ESB containers located at the distributor sites allow selective deployment of integration capabilities when and where they are needed, with no integration brokers or application servers required. In addition, this approach provides both the manufacturer and their distributors the following advantages: A secure, authenticated channel between the distributor and headquarters Reliable delivery of messages, both synchronous and asynchronous, between the distributor and headquarters Simple integration at the partner site A managed environment, where deployment configuration and management can be handled remotely by the manufacturer's IT staff, without requiring any additional IT expertise at each partner site No need to license and install an integration broker, application server, or "partner server" at each distributor location A link to an EDI VAN, and transformation between EDI messages and XML messages Integration with SAP within the manufacturer's inventory management system
Within the ESB network at the manufacturer, data transformation between comma-separated ASCII (CSV) files, an internal canonical XML format based on Common Business Library (xCBL), and SAP's Intermediate Document (IDOC) format is accomplished as part of several orchestrated business processes facilitated by the ESB. More details on the virtues of a canonical XML format are discussed in Chapter 4. Chapter 8 will explore the more technical details of this deployment. | 