This chapter and its sections describe the development concepts of SAPUI5, such as the Model View Controller, data binding, and components. Use this section as a reference.
The top-level structural unit is called a library. Libraries are the master artifacts in the extensibility concept. They bundle a set of controls and related types and make them consumable by Web applications. There are predefined and standard libraries, like sap.m, with many commonly used controls. At the same time, it treats custom UI libraries as first-class citizens, making it easy for you to write and use your own controls alongside the predefined ones.
A UI element is the basic building block of our user interfaces; it is a reusable entity with properties, events, methods, and relations. The most important relations are aggregations to other UI elements, and in this way a tree structure of elements can be created.
From a developer's point of view, a control (e.g. Button, Label, TextField, or Table) is the most important artifact. It is an object which controls the appearance and user interaction of a rectangular screen region. It is a special kind of user interface element which can be used as the root of such a tree structure. In this way, it serves as an entry point, especially for rendering. Besides controls, there are also other non-control elements, which cannot be used as the root of such a tree structure, but only as a dependent part within it (e.g. TableRow, TableCell).
A property has a name and an associated data type. It has a well-defined default value expressed as a literal of that data type. Properties are accessible to application code via the element's API as getters and setters, but are also used by a control's renderer in a read-only way.
Data types are first-class entities in the meta model. This allows reuse of types across libraries and extensibility of the type system. The core library (technically, this is the sap.ui.core library) already defines a core set of types that can be used in other libraries.
An aggregation is a special relation between two UI element types. It is used to define the parent-child relationship within the above mentioned tree structure. The parent end of the aggregation has cardinality 0..1, while the child end may have 0..1 or 0..*. The element's API offers convenient and consistent methods to deal with aggregations (e.g. to get, set, or remove target elements). Examples are table rows and cells, or the content of a table cell.
An association is another type of relation between two UI element types which is independent of the parent-child relationship within the above mentioned tree structure. Directed outgoing associations to a target of cardinality 0..1 are supported. They represent a loose coupling only and are thus implemented by storing the target element instance's ID. The most prominent example is the association between a label and its field.
An event has a name as well as any number of parameters. The element's API offers support to manage event subscriptions.
Apps developed with SAPUI5 run in a browser on any device (mobile, tablet or desktop PC).
When users access an SAPUI5 app, a request is sent to the respective server to load the application into the browser. The view accesses the relevant libraries. Usually the model is also instantiated and business data is fetched from the database.
Depending on the environment in which SAPUI5 is used, the libraries or your applications can be stored, for example, on an SAP NetWeaver Application Server or an SAP HANA Cloud Platform, and business data can be accessed, for example, using the OData model through a SAP Gateway.