Enterprise Service Bus (ESB) Introduction and Use Cases

An ESB (Enterprise Service Bus) is an approach to IT architecture

Complexity can often run rampant in enterprise IT. But whether something is complex or not isn’t necessarily a standalone catalyst for change; what matters is whether or not systems run the way that they should. An enterprise service bus (ESB) appears to be very complicated, but the fact remains that it can be very effective and perform several key functions that assist the developer in application integration.

What is ESB (Enterprise Service Bus)?

At its core, an ESB is an approach to IT architecture. An ESB is designed to integrate various applications together over what is a “bus-like” infrastructure. An enterprise service bus usually is located somewhere between the framework and a suite as another way to perform application integration. An ESB is a middleware tool that distributes tasks among different connected components that make up an application.

It lays down the fundamental infrastructure to do a number of tasks, such as:

  • Implement routing
  • Translation
  • Provide a blanket way to move tasks
  • Offer an application the ability to connect to the “bus”
  • Subscribe to messages sent that are based on structural and business policy rules
  • Other integration capabilities

How ESBs Work

Although businesses may not always find success, ESBs are built to simplify the mess that can arise when different formats, from services and applications to mainframes, want to integrate with each other. The question, however, is how exactly does an ESB work?

  1. An enterprise service bus is a set of switches that sends a direct message on a specific route between either the application and/or components.
  2. Each enterprise has a specific business policy in place that determines which path the ESB will take these messages.

Whether it is a client or a business process, anything that is connected to an ESB do not communicate directly with one another because they communicate via the ESB itself. Essentially, the enterprise service bus exposes the same service interface to potential clients that the connected services then expose to the ESB.

A primary benefit of an enterprise service bus revolves around the ESB being a single point of access. By connecting clients and services via an ESB, a company only needs to look for services in one, single location, the ESB. Even if a business process switches servers, all that needs to be done is to reconfigure the ESB, and the company can still access the service via the ESB.

The ESB also works as a transaction manager, meaning it coordinates distributed transactions that multiple services are involved with. When many different business processes and services need to work together in a transaction, usually a configuration is needed to coordinate the transaction. Through an ESB, however, that is no longer necessary. The company can access the ESB to handle the transaction smoothly.

An enterprise service bus also works as a security manager and centralizes processes such as authentication and authorization. Regardless of whether a business process in an application has authentication or authorization, the ESB can adjust its settings to require this in the service interface that it exposes to clients that use it.

Another way that ESBs work is as a service proxy, by functioning as a gateway for applications that aren’t exposed to a standardized service interface. As an example, if an application exposes a Java RMI service, but the rest of the network runs on .NET, so it cannot call the RMI service directly. By utilizing an ESB, a company can easily implement a service proxy in Java which can call an RMI service. Then the service proxy exposes a web service interface, such as SOAP and WSDL via the ESB to the .NET applications.

What are Some Practical Uses for an ESB?

Now that we’ve discussed just how an enterprise service bus works, it’s time to look deeper at how an enterprise can take advantage of an ESB to perform different tasks within their company. ESBs can be a valuable tool if they are used correctly.

There are some core functionalities that are under the hood of an ESB. These functions combine to make up the ESB architecture. They include:

  • Decoupling

A very valuable capability of an ESB revolves around the decoupling of clients from service providers.

  • Transport Protocol Conversion

The use of ESB also allows the ability to accept one input protocol and communicate with a different service provider, even if the service provider is on a separate protocol.

  • Message Enhancement

Through an ESB, a user can isolate a client while making some general changes to the message as well.

  • Message Transformation

Additionally, through an ESB, a user can transform any potential incoming messages into outgoing formats and structures.

In addition to these key ingredients of an enterprise service bus, additional capabilities include added security to protect any unauthorized access, routing abilities to redirect a request to a different service provider, and transaction management. Some other ways that an enterprise can best take advantage of an ESB include:

  • Run-time resolution of destinations, services, and resources
  • Location transparency
  • Any-to-any connectivity, as well as maximum connection density
  • Designed for redundancy, horizontal scalability, failover
  • Policy, access control, rules externalized
  • Logical messaging network layer implement on top of the physical messaging network layer
  • Common namespace

Proprietary or Open Source? 

Under the umbrella of an enterprise service bus, there are a few different approaches when it comes time for a company to decide what kind of ESB they want. There are numerous factors that go into this decision, from costs and scalability to software vendors and license partners. A primary question companies must ask themselves is whether they want to go with a proprietary or open-source ESB.

There are benefits to both, but also a few drawbacks as well.

  • Proprietary

Proprietary ESBs make a lot of sense for companies that want simpler usability, product stability, and ownership. Some of the features of a proprietary ESB include:

- Functionality

Proprietary ESBs provide a vast range of integration features as well as an extensive list of tools such as BAM,   EDA, and CEP.

- Maintenance

Administration and monitoring tools that are available for a proprietary ESB offer a level of stability and functionality that are beyond comparison.

  • Open Source

Now on the other hand, open-source ESBs also provide a great deal of benefits and features that businesses can spin into some major advantages. From the ease of installation to the open source community, the biggest advantages to an open source ESB are:

- Cost

An open source ESB can cost exponentially less than that of a proprietary solution.

- Vendor-Agnostic

Because an open-source ESB is vendor-agnostic, companies have greater flexibility to work across different platforms.

So while proprietary and open-source ESBs each have their strengths, there are also a few drawbacks as well. Proprietary ESBs can be costly, much more so than an ESB, and are also more difficult to install. Open-source ESBs, meanwhile, can be tricky to integrate across different providers in a mix-and-match scenario, and also require more employee skill and time to test, manage, and maintain the offering.

What to Look for in an ESB Platform 

As noted above, there are many important things that an ESB does, and it is critical to ensure that the enterprise service bus performs all of the processes that you need. An ESB must have some form of the following:

  • Routing – channel a request to a particular service provider.
  • Message transformation – convert the structure and format of the incoming business service request to the structure and format expected by the service provider.
  • Message enhancement – add or modify information within the message as required by the service provider.
  • Protocol transformation – accept one form of protocol from the consumer as input and communicate it to the service provider via a different protocol.
  • Service mapping – translate a business service into a corresponding service implementation.
  • Message processing – manage state and perform request management by accepting an input request and ensure delivery back to the client.
  • Process choreography – manage complex business processes that require the coordination of multiple business services to fulfill one single business service request.
  • Service orchestration – manage the coordination of different implementation services.
  • Transaction management – provide a single unit of work for a business service request by providing a framework for the coordination of multiple services across different disparate services.
  • Security – protect enterprises from unauthorized access.

For an ESB to run efficiently, it is integral that it has all of these capabilities. When a company decides to go with an enterprise service bus, it must take the proper steps to ensure that it has all the functionality that it requires.

Connect Enterprise Service Bus Architecture Painlessly

Can business processes and application integration get pretty complex? Of course. That’s why you need a solution that makes ecosystem and application integration simple. Remove the complexity of application-to-application or system-to-application integration with internal resource planning, ESB, legacy EDI, and cloud solutions, while also supporting connectivity to your external communities via Cleo’s application integration technology.

Further, Cleo allows you to extend the functionality of your ESB with deep protocol flexibility, providing more reliable and robust data movement capabilities between enterprise applications and the ESB.

Cleo simplifies the onboarding and integration of new connectors by utilizing a host of adapters, APIs, and wizards to seamlessly build and manage end-to-end integrations between internal and partner systems. In this way, Cleo helps shield your business from some of the inherent complexity it takes when integrating to an ESB, adding a painless way to conduct application integration, and helping your business clear complex integration hurdles.


An enterprise service bus can appear complex and tough to navigate, but it does remain a very useful tool within an enterprise. It is difficult to synthesize down a truly concise definition of what an ESB does in a few sentences, as it is a wide-ranging tool that provides multiple benefits. ESBs however, remain common and despite certain drawbacks, have proven very useful to facilitate service location transparency, sharing of services and processes across an enterprise, and separating business service from the service implementation. Ultimately, companies that elect for an ESB must be sure that it checks off all of their necessary goals or risk losing the flexibility that an ESB promises.

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