What is an ESB (Enterprise Service Bus)? #
An ESB stands for Enterprise Service Bus and is a middleware, software platform that is used to connect diverse applications and services in an enterprise, providing a unified way of transferring data between them.
Enterprise service buses became a prominent integration and data transfer solution for large organisations in the late 90s, especially for integrating on-premises legacy systems and applications in a highly complex service-oriented architecture (SOA); a method of using software components, known as services, to communicate with each other across platforms and languages via service interfaces.
How does an enterprise service bus work? #
Utilising a bus-like infrastructure, an ESB acts as the central communication centre within an application workflow, enabling them to connect to each other, following simple structural and business policy rules. An ESB usually incorporates a messaging engine, data transformation and routing capabilities, web services and analytics capabilities.
As legacy systems tend to use old protocols and proprietary data formats, these needed to be translated to work with SOA network protocols, hence the demand for ESB.
ESB is therefore an essential component of service-oriented architecture, providing applications with the ability to connect to the ESB by using standard network protocols, such as SOAP (Simple Object Access Protocol) or JSON (JavaScript Object Notation), which are open standard data interchange formats that systems use to send requests to read or change data.
The development of ESBs was also a significant step forward in finding a replacement solution for point-to-point integration which required a great deal of development and also became extremely inflexible – limiting the ability to easily customise integrations or to actively manage and monitor data transfers.
Benefits of an ESB #
An enterprise service bus provides a standardised approach to integrating different enterprise applications and services, which promotes interoperability and reduces the complexity of integration. The ability to add or remove services without affecting the other services makes it easy to adapt to changing business needs or to integrate new services as they become available.
An ESB provides a centralised security mechanism that can be used to manage authentication, authorisation and encryption. This ensures that sensitive data is protected and that only authorised users can access it. It also provides a centralised view of all the applications and services that are connected to it. This allows for better monitoring and management of the entire system.
Disadvantages of an ESB #
Although adept at handling an enterprise’s complex on-premises internal systems and architecture, ESBs are now becoming cumbersome and heavyweight, especially compared to the lightweight, flexibility and ease of deploying much newer middleware integration platforms.
ESBs were basically a predecessor to API gateways – exposing services for reuse. However, API technology has evolved and become more prevalent and ESBs are now looked upon as being large, time-consuming investments, which tend to be to slow, require high configuration and maintenance, and lacking the agility and flexibility that cloud computing now demands.
Enterprise service bus vs API #
APIs and ESBs are both important middleware technologies that enable integration between different applications and services within an organisation. However, they serve different purposes and have different strengths and weaknesses.
ESBs provide a more comprehensive approach to integration by providing a centralised messaging system that can connect multiple systems, applications and services within an organisation. As they provide a more heavyweight approach to integration, it allows for more complex transformations, routing and orchestration of messages between systems.
APIs, on the other hand, are generally better suited for enabling external access to specific services or data. APIs provide a more lightweight and flexible approach to integration, allowing developers to build customised interfaces that can be accessed via the web, mobile devices or other channels. APIs are typically designed for a specific purpose and are optimised for performance, security and ease of use.
