With businesses using so many different software programs to fill their needs, sometimes it's necessary that the different programs work together to get the end results they are looking for. In those situations, middleware is required.
Middleware is considered by many to be a rather vague term in that it is specially designed software that can link two separate applications together. Since this can be used in such a wide variety of ways, it is better understood by discussing some specific examples in how it can be used. One popular example is the middleware that is used to connect a database system with a web server.
This allows a user to request data from a database using forms displayed on a Web browser, according to Webopedia, while also allowing for the Web server to return Web pages based on the user's request.
"The term middleware is used to describe separate products that serve as the glue between two applications, Webopedia writes on its website. "Middleware is sometimes called plumbing because it connects two sides of an application and passes data between them."
Middleware provider MulseSoft says middleware software is a layer between two systems that makes it easy for the two to communicate and is considered the glue that holds together applications, making seamless connectivity possible without requiring the two applications to communicate directly.
"In a highly distributed environment in which businesses need to connect with legacy systems, cloud and SaaS applications, and business management software such as SAP and Salesforce, the role of a middleware technology is critical," the company writes on its website.
Examples of middleware
Middleware is applied in all aspects of a business's network. In his book Data Warehousing for Dummies, 2nd Edition (For Dummies 2009), author Thomas Hammergren writes that middleware is computer software that connects software components. Among some ways he says middleware service can be used, include
- Security: Authenticates a particular client program to some system component to verify, for example, that the client program and its user are really who they say they are.
- Transaction management: Ensures that a system or database don't get corrupted if problems occur.
- Message queues: Enables loosely coupled systems to pass messages back and forth to each other. Those messages can trigger actions or transactions to occur.
- Application server: A server that hosts an application programming interface (API), which exposes business logic and business processes so that other applications can use the shared logic and processes.
- Web server: A computer program that's responsible for accepting requests from Web browsers, as well as sending responses and content to those browsers — usually Web pages, such as HTML documents, and linked objects, such as images.
- Directory: Enables a client program to find other services or servers located in a distributed enterprise.
There are a variety of other ways middleware can be used to connect two pieces of software or applications. According to PC Mag, the include distributed processing, which are different from messaging middleware in that they cause actions to occur in real time, rather than sending data back and forth and network logon middleware, which includes a common approach for identifying users and setting up standardized directory plans.
When building web applications, special middleware is often used. Examples include when using the web framework Django or the Ruby programming language.
Django is a high-level Python Web framework that encourages rapid development and clean, pragmatic design. It lets users build high-performing, elegant Web applications quickly. Middleware used in Django is a framework of hooks into the request/response processing.
Each Django middleware component is responsible for doing some specific function. For example, Django includes a middleware component, TransactionMiddleware, which wraps the processing of each HTTP request in a database transaction.
Django has a variety of middleware components. They include:
- Cache middleware: If these are enabled, each Django-powered page will be cached for as long as the CACHE_MIDDLEWARE_SECONDS setting defines.
- GZip middleware: Compresses content for browsers that understand GZip compression, which is sued on all modern web browsers.
- Local middleware: This customizes the content for each user by enabling language selection based on data from the request.
- Message middleware: Enables cookie- and session-based message support.
- CSRF protection middleware: Adds protection against Cross Site Request Forgeries by adding hidden form fields to POST forms and checking requests for the correct value.
One of the other more popular customized middleware is used in Racks, which is part of the Ruby programming language. Ruby is a dynamic, open source programming language with a focus on simplicity and productivity.
Rack middleware is a way to filter a request and response coming into an application. According to application design firm Intridea, Rack middleware are used to implement a pipelined development process for web applications.
"They can do anything from managing user sessions to caching, authentication, or just about anything else," the Intridea writes on its blog.
Among some of the more popular Rack middleware, according to RubyForge, a collaborative software development management system dedicated to projects related to the Ruby programming language, are:
- Rack::URLMap: This is used to route to multiple applications inside the same process.
- Rack::CommonLogger: This is used when creating Apache-style logfiles.
- Rack::ShowException: This is used for catching unhandled exceptions and presenting them in a nice and helpful way with clickable backtrace.
- Rack::File: Developers use this when for serving static files.