The RPC and UI updates are contained in a UIDL request (user interface definition language). The server runs the appropriate event handlers and returns the resulting UI updates, such as to show a notification. When a user interacts with a Vaadin application, such as when clicking a button, an RPC is generally made to the server. The primary handler is the UidlRequestHandler. The last handler to be invoked is the BootstrapHandler, which is responsible for creating a new UI instance when no other handler can handle the request. This in turn offers the request to each of its request handlers one by one, until a handler is found that can handle the request. When the VaadinServlet receives a request, the request is forwarded to a VaadinService instance. The boostrapping for TypeScript-based projects works a bit differently. Note: This article was written around Vaadin 14.8.0 using Java views only. Because of this, it is good to be aware of the UI’s lifecycle, so that UI instances do not hang around for longer than necessary. It also stores the PushConnection when push is used, any pending JavaScript invocations, the current theme, and more. Through the UIInternals class, a UI instance stores all attached server-side components in a StateTree. As there can only be one body element per HTML document, and there is generally one document per browser tab, a UI can also be seen as corresponding to a browser tab. We can interact with the underlying element through the Element API, for example UI.getCurrent().getElement().setAttribute("foo", "bar"). It is a Component whose underlying HTML element is the body element. The UI is one of the most central classes of a Vaadin app.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |