Use Cases

Introduction

The Examples provide coding level details for implementing particular aspects of ServiceMix. This document extends the coding examples into their business use.

Business Use Case for the Basic Example

ServiceMix is an Enterprise Service Bus (ESB) that is based on the Java Business Integration (JBI) standard JSR 208. The JBI-based design specifies a standards-based pluggable architecture with a JVM-based runtime component called the Normalized Message Router (NMR). The Basic example demonstrates how applications communicate via the ServiceMix ESB, and the role that the NMR can play in that communication. Similar techniques could be used to plug any external ¹ application or service into ServiceMix (e.g. SAP, Peoplesoft, spreadsheets, POJOs, Webservices and EJBs) and allow it to communicate with other external applications or components using ServiceMix itself.

A hypothetical business scenario, which extends the Basic Example, is that of a department store distributor. This distributor sells products from multiple wholesalers (suppliers) to various retailers (customers). The distributor presents a common interface for product ordering to each of its department store customers. However, the distributor must work with a different ordering interface for each wholesale suppliers for the products they are buying.

Using an ESB, the distributor has developed a number of components to receive department store orders and then dynamically route and transform these orders to the appropriate wholesaler. The order processing flow is described as follows:

1. Using the distributor's web interface, a department store customer submits an order for multiple products. An HTTP request is sent to the OrderReceiver, an HTTP binding component (BC). ³
2. The OrderReceiver sends the message to an OrderRouter service engine (SE) ⁴ component. This SE is responsible for parsing the order and deciding, based on the message content, which OrderTransformer should receive which part of the message (i.e., an order for a product).
3. The OrderRouter publishes the orders to the appropriate message topics based on the message content. Specifically, the OrderRouter publishes the messages based on which wholesaler sells the item.
4. The OrderTransformer is a service engine component, which modifies the message and puts it in a format which is readable by the wholesaler interface that will fulfill the order.
5. Each OrderTransformer sends the modified message to the OrderProcessor.
6. The OrderProcessor is a binding component that has two functions:
   a. It places an order to the appropriate wholesaler through the wholesaler's Webservice or proprietary interface.
   b. It also publishes a message about the order on a topic.
7. The message on the topic is subsequently picked up by the BusinessMonitor component via the jmsTrace component.
8. The BusinessMonitor component monitors the orders for quality assurance and business analytics, such as data mining.

The following diagram illustrates this:

1. External means the application is outside of the ESB.
2. Resource Adapter: a resource adapter provides connectivity between a specific external application and the ESB. In the Basic example the jencks container provides a JMS resource adapater.
3. Binding Component (BC): a BC provides connectivity to applications that are external to the ESB.
4. Service Engine (SE): a service engine provides business logic and transformation services to other components within the enterprise service bus.

Business Use Case for the File Binding Example

The file binding example shows how components of ServiceMix can interact with the file system. This is important because many applications write files out to a directory on disk and other applications may need access to. This application gives a simple example of how a ServiceMix component can read a file from the disk, process it into a normalized message, then send it via the NMR, to another ServiceMix component. The receiving component can then look at the message (which contains the file) and process it and write it out to another location on disk.

A hypothetical business scenario: An online wholesale distributor of books, CDs and books on tape, receives a nightly order from a retail store. The nightly order is transmitted to the distributor as a file and placed in a particular directory on disk. There is a ServiceMix component that continually scans that directory looking for order files. When it sees a file, it reads it in and processes it. It divides the order into separate orders for its suppliers, e.g., one order will be placed with the distributor's book supplier, one order will go to the CD supplier, etc. At some later point, the suppliers will log in and retrieve their files. This is not shown in this example.

The following diagram illustrates this: