Before the emergence of service-oriented architecture (SOA), the term middleware would often be equated with an application server. However, today with the degree of progress on service-oriented architecture the term middleware will often be equated with Enterprise Service Bus (ESB). This is because if the application server is the foundation for middleware then ESB represents the largest and most important part of middleware in Service Oriented Architecture.
Enterprise Service Bus (ESB) is a term used to describe a wide variety of products whose primary goal is to extend the simple messaging capabilities of an application server to allow the inclusion of enterprise functionality needed to support SOA. It has also been observed that a major difference between ESB and middleware is the fact that ESB is Service-Oriented whereas middleware has functions that are applicable outside the realm of services in a distributed system.
The ESB can accomplish business communication by implementing one of many communication models. An SOA enterprise may need to send a single message to many recipients who may be operating on various systems. Given that confidentiality and security are essential when sending data over a public channel the sender may require confirmation of delivery even under the most extreme conditions. Businesses have begun to combine application servers such as CORBA to integrate web applications to existing systems for greater productivity in e-commerce. Common Object request broker architecture or CORBA acts as an application server with the main objective being to support communication between distributed objects. The CORBA interface takes things a step further is step to make distributed systems integrate and operate. The CORBA interface performs this task by abstracting network communication and programming languages that are useful for an object to object interaction. The CORBA system has become fairly well recognized when industries such as telecommunications started to rely on the system as the integration glue for distributed systems.
In addition to the above use of an advanced application server that can allow for communication between distributed systems another useful part of ESB is the use of various advanced database resources. The system has been described in a manner that indicates the use of a Microsoft SQL server for storing information on products and sales. One major advantage that comes with the use of advanced database products is the access to some stored procedures. These are useful in that they can be used to encapsulate and enforce business rules in stored data. This is especially useful because once created these procedures can be stored and used to reproduce a data at any time thus reducing the time taken to synthesize data and provide useful results.
Further advantages that the system can find accessible via SOAP-based back-end interface include improved security. With this interface in place, none of the standard methods for security will be used. Instead a SOAP message is used to transfer the required set of credentials with each message. This log-in information can be placed either in the message header or in the message body. These credentials will then be analyzed using the back-end system. Each SOAP-based message includes two transactions namely a request and a response. This suggests that when this messaging mechanism is used the two systems can maintain a certain degree of security due to the constant authentication required. This constant authentication between the requesting computer and the back-end server is useful in ensuring information is submitted to a trusted destination. This procedure effectively integrates requested information as well as requested parameters and values for the secure transfer of information between two points.
Another strong point of the current system is the use of CSV format to transfer spreadsheet data from one computer to the next. CSV or comma-separated value format is one of the few available cross-platform formats. The simplicity of the CSV format can ensure that the organization will be able to share its data across platforms. The CSV files are also readable by most database software which commonly uses proprietary file formats. Another valuable improvement could be the use of platform-independent formats for archives. As it has been observed that the current system has reasonably good security and good cross-platform database mechanisms, a suitable cross-platform archiving system may be useful in ensuring large amounts of data can be transferred between machines operating on different platforms. It should be noted that whereas these platform-independent approaches involve some loss in functionality the transfer of the data is more crucial than the losses. This approach can allow for a normal spreadsheet with formulas to prepare the automatic bonus reports and send them to many locations.
Due to the increased demand for suitable middleware products for the service-oriented architecture IBM has released a product known as WebSphere. The product message broker supports such services standards as SOAP and WSDL. It also provides messaging services such as Biztalk and Java message service (SOA 14). In the more recent versions of the product, the message broker provides advanced ESB capability such as universal connectivity and data transformation.
Among the ESB products available Cape Clear is among the options that could provide a suitable solution to the enterprise. This product has been rated as one of the ESB middleware products that are capable of steering towards more flexible and affordable service-oriented solutions. The current release includes features such as a process orchestration language that provides enterprises with the capacity to weave multiple services into workflows with partners. In addition to this, the product also offers an integration server, facilities for data transformation and support for data created by long-running processes. However, in selecting an appropriate ESB solution for this set of problems the most appropriate solution would be IBM’s WebSphere. This is because one shortcoming of Cape Clear is it does not provide a messaging backbone although it provides support for messaging using other vendors’ products.
Due to an increase in pressure to integrate among enterprises using disparate systems several companies have begun to develop various ESB products. One such solution is known as Sonic ESB 5.0 which is based on standards such as XML and SOAP. Traditional software was connected via point to point links whereas ESB’s propose connections based on various SOA standards. This position allows or enhances interoperability between distributed and different platforms. This is because it allows for systems that provide essential operations to be incrementally added to the ESB.
Another good ESB product is the system known as WASP produced by Systinet. This is a development framework that revolves around web services. The product is favorable because despite it being a commercial product it is also available to no charge thus providing small enterprises an opportunity to access the product. The system is developed for use within the Sun Forte integrated development environment. The WASP software allows the creation of a web service using three components; its interface, which is embodied by the WSDL file for the service, the actual implementation of the service (e.g. the logic behind the application) and deployment information; specifying the deployment portion of the WSDL description of the service. A finished application is made up of a group of web services that make up a complete deployment package. Systinet provides a series of products that make up the WASP package. These include WASP developer, WASP server, WASP UDDI and WASP security. The WASP software is recommended because web services are fast becoming a very crucial component of a distributed system. It is for this reason that any software such as WASP which can quickly and reliably produce services is considered essential for the future.