What is middleware?

Middleware is a kind of translation layer between an operating system and the applications running on it. This enables the exchange and management of data when the operating system and application aren’t compatible with each other.

What is middleware and what does it do?

Middleware is software that invisibly runs in the background. It’s an application that bridges an operating system with the programs running on it. It can be thought of as a hidden translator, allowing distributed applications to communicate and manage one another. Middleware can link two applications to support the exchange of data and databases. It’s also behind everyday applications like online submit forms or web page results that are tailored to your user profile. Middleware can be thought of as a tool that exchanges two languages.

The development of middleware

From 2000 until 2010, Middleware software was synonymous with an application server. With the growing popularity of cloud computing and the replacement of monolithic systems through microservices, middleware has changed.

Instead of deploying complete applications on middleware servers, developers tend to create smaller microservices-based applications. These microservices are packed with all the information needed to connect to the required backend resources and deployed in a container-based system like Docker.

The Docker container is then deployed in a cloud-based service. Here, the middleware combines the microservice hosted in the container and the cloud computing infrastructure on which the container runs. This means that fewer resources are consumed than with a conventional server or on a virtual machine.


IONOS provides Docker hosting, allowing you to build and run your applications in a secure container-based system.

What does middleware mean?

The word “middleware” can be described as an intermediate application. It’s a service software that sits between user-side input on the frontend and queries and calculations running in the backend. A client will typically run an application in the frontend to interact with the software. Resources like databases, file servers, NoSQL data storages and message queues, on the other hand, often run in the backend. Middleware sits in the middle between these two.

Typical characteristics of middleware

To be considered middleware, the software needs to meet various characteristics and support different functions. Middleware must:

  • Work independently of the existing hardware and the operating system
  • Be independent of the specific design of the network and the protocols used
  • Not be dependent on a programming language
  • Run unnoticed in the background

What types of middleware are there?

There are many kinds of middleware, each developed for different applications in web and cloud services. Middleware can be divided into three different areas:

Middleware for communication

This type of software brings different types of networks onto the same level and enables their communication. You can find this application in web services, where the HTTP protocol makes it possible for two computers to connect online regardless of their operating systems.

Middleware for messaging

This middleware is used when two different applications want to exchange messages. How is determined by the middleware. The applications involved can send and receive information in this way. Web services use this software as well as the popular JSON (JavaScript Object Notation).

Middleware for applications

Middleware can be a programming language or operating system designed to work in a platform-independent manner. You might be familiar with the .NET programming language, which is used to program applications for different operating systems. API middleware provides developers with tools to create, expose and manage applications, giving other developers the possibility to connect to them. RPC middleware lets an application trigger a procedure in another application. This procedure can run on the same computer, another computer or over a network.

How does middleware work?

On the most basic level, middleware enables developers to build applications without having to worry about custom integration every time they connect to application components, data sources, computing resources or devices. It does this by providing services that let you communicate over popular messaging frameworks. Examples of these frameworks include JSON (JavaScript Object Notation), REST (Representational State Transfer), XML (Extensible Markup Language), SOAP (Simple Object Access Protocol) or web services.

As a rule, middleware also provides services that enable communication between components written in different languages, like Java, C++, PHP and Python.

Where is middleware used?

Most people work with middleware every day without even knowing it. Here are some typical examples:

Cross-browser communication

Applications in web browsers are mostly managed by middleware. Filling out contact forms or signing up for a newsletter are examples of this. It doesn’t matter which browser or operating system is used, middleware can translate the request into a universal format and store it in a database.

Access to backends

Middleware manages connectivity to various backend resources. These components can provide fast and efficient access to a backend database. In addition, middleware software can manage connections to cloud-based resources.

User-customized processing

Middleware can take a user request and output data used to customize the request results. For example, the middleware application can detect that a client browser making a particular request has the language header set to English. The queries to the backend are adjusted so that only results in English are returned.

Another example is the geographic location of the requesting client. Using the IP address, the server returns data that best matches the location.

Management of computing resources

Middleware plays an important role in concurrent processing, load balancing and transaction management. It can distribute incoming client requests across multiple servers, virtual machines or availability zones in the cloud.

Middleware software can also manage conflicts that may arise when multiple clients attempt to access or modify a particular piece of information in the backend. As application traffic increases, corporate middleware can be set up to distribute client requests across multiple servers, whether on premises or in the cloud.

Checking access rights

Middleware monitors and secures access to backend resources. It can query the authorization of clients. This requires a secure connection via TLS and authentication, consisting of username and password, or a digital certificate. These security features are then used to check whether the external client can be granted access to the requested data servers. If authorization is granted, the data is sent from the middleware server to the client via a secure and encrypted connection.

How do businesses use middleware?

The goal of middleware is to enable communication between different systems. It can be used for:

  • Management of financial transactions
  • Programs for employee security authorizations
  • Coordination of compute-intensive applications on company servers

The message type used can be determined by the company using the middleware. Such a decision depends on which services are used and what kind of data is to be processed by the middleware.


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