Application state management is the process of maintaining knowledge of an application's inputs across multiple related data flows that form a complete business transaction -- or a session -- to understand the condition of the app at any given moment. In computer science, an input is information put into the program by the user and state refers to the condition of an application according to its stored inputs -- saved as variables or constants. State can also be described as the collection of preserved information that forms a complete session.
Core business applications process sensitive information like orders, payments, invoices and bills of material. This processing depends on the state of the application and results in changes to the balance of inventories, accounts and financial ledgers. State management allows developers to determine the state of the application to ensure the changes made appropriately reflect the real-world context and business processes.
How State Management Works
Overall, state management makes the state of an app visible in the form of a data structure, improving developers' ability to work with the app. State management libraries provide developers with the tools needed to create the data structures and change them when new actions occur.
There are two accepted models for state management: the front-end -- or client-side -- and back-end -- or server/application-side models.
In front-end state management, the user's own app or browser maintains the program's state, often by having certain buttons or user interface features enabled or disabled and sending the state along with the message. The user interface connection ensures the user and the application are in harmony throughout the session.
In back-end state management, an application component will use an external data structure or database to record the final state when it's done processing activities. Processing the next message will start with retrieving the previous state from the database. The state variable in the data structure can also synchronize the user interface -- and through it the user -- with the state of the session.
Cloud computing techniques forbid in-program storage of data between data flows in a given session since scaled or replaced instances lose the state data needed for session processing. Microservice principles allow for either front-end or back-end state management. However, serverless computing based on functional programming principles requires that the output of any function be the same as long as the input is the same, which means only front-end state control would be appropriate.
State Management Libraries
Any implementation of state management is likely to be supported by a set of development tools collected in a state management library. These libraries ensure the implementations of front-end or back-end state management work together to successfully obtain and provide understanding and control of the application.
State management libraries speed the development of application state and make the state management code easier to maintain by enforcing common practices across multiple stateful applications. It's critical to pick front-end and back-end techniques that work for the application, as well as the best tool library to implement these techniques.
State management libraries are explicit to development techniques such as the development language or the front- or back-end nature of state control. It's important for development teams to research their options and make the best choice for both current and likely future needs.
State Management in Application Development
Early applications controlled the user dialog, so the individual steps within a session were dictated by the process itself; write data to the user, accept changes, confirm them and commit them. With the advent of web applications based on the stateless vision of HTML, it became necessary to more clearly define state management practices.
When a session message -- such as an HTML page -- is received, it is interpreted based on the state, which is recorded as a variable or constant that every process can access. The record ensures that receiving, for example, a "confirmation" message while in the "waiting for confirmation" state is handled differently than it would be in the "waited too long for user response state." That, in turn, ensures that application systems that update databases and produce durable business records are always synchronized with the real world where users live.
Advantages of State Management
State management is essential in aligning and integrating core business applications and the cloud. Without some form of state management, business activities as routine as the purchase of something or a request for information would have to be structured as a single request or response exchange. This could put a significant burden on the user and would almost certainly reduce the effectiveness of the application. In some cases, such as the processing of an order, a stateless exchange could hide critical information like current stock levels, resulting in what could be a significant business impact on the seller and a major inconvenience to the buyer.
State management tools are typically offered in the form of state management libraries, designed for developers who want to build state awareness into their applications. Most of these tools are used to implement front-end state management because that mechanism is easiest to execute and offers the tightest integration with the application's user base. Front-end state control is also ideal for state management when the goal of development is to add a cloud front-end to a business process.