# Package org.zkoss.zk.ui.sys

- Interface Summary
  Interface | Description
  --- | ---
  AbortingReason | The aborting reason used to abort the current execution.
  ComponentCtrl | An addition interface to `Component` that is used for implementation or tools.
  ContentRenderer | Used with `AbstractComponent.renderProperties(org.zkoss.zk.ui.sys.ContentRenderer)` to generate the component content that will be sent to the client.
  DesktopCache | The cache used to store desktops.
  DesktopCacheProvider | Used to retrieve a desktop cache (`DesktopCache`).
  DesktopCtrl | An addition interface to `Desktop` for implementation.
  DiskFileItemFactory | A factory interface for creating `FileItem` and `Media` instances.
  EventListenerMap | Represents a map of event handlers and listeners.
  EventListenerMapCtrl | An addition interface to `EventListenerMap` that is used for implementation or tools.
  EventProcessingThread | Represents an event processing thread.
  ExecutionCtrl | Additional interface to `Execution` for implementation.
  ExecutionInfo | The information about the event being served by the current execution.
  FailoverManager | Represents a class that is able to handle fail-over in the application specific way.
  IdGenerator | Used to generate UUID of components and pages and ID of desktops.
  PageConfig | Represents the info used to initialize a page.
  PageCtrl | Addition interface to `Page` for implementation purpose.
  PageRenderer | The page render used to render a page.
  PageRenderPatch | A patch that is used to process the rendering result of a page.
  PropertiesRenderer | A renderer used to render custom properties for particular components.
  PropertyAccess<T> | A property access interface to speed up Java reflection performance.
  RequestInfo | The request information used with `UiFactory`.
  RequestQueue | A queue of `AuRequest`.
  Scheduler<T extends Event> | A scheduler that is able to schedule a task to execute asynchronously.
  SEORenderer | A plugin that an application could add to generate application-specific SEO content.
  ServerPush | Represents a server-push controller.
  SessionCache | The cache for storing ZK sessions.
  SessionCtrl | Additional interface of `Session` for implementation.
  SessionResolver | Used with `SessionsCtrl.setCurrent(SessionResolver)` to resolve a session dynamically.
  Storage | A storage interface is used for ZK web application to store application data with a string key and a data type value.
  UiEngine | UI engine is responsible to process requests from the client, sends the response back to the client with the assistance of `ExecutionCtrl`.
  UiFactory | Used to create `Session`, `Desktop`, `Page`, `Component`, `Composer`, and `ServerPush`.
  Visualizer | A part of `Execution` for visualizing the components whose visual parts are modified.
  WebAppCtrl | Additional interface of `WebApp` for implementation.
  WebAppFactory | The factory used to instantiate the instance of `WebApp`.

- Class Summary
  Class | Description
  --- | ---
  Attributes | Attributes or library properties to customize the behaviors of ZK, such as page rending, fileupload and so on.
  BooleanPropertyAccess | A Boolean property access class.
  ComponentRedraws | Utilities to implement `ComponentCtrl.redraw(java.io.Writer)`.
  ComponentsCtrl | Utilities for implementing components.
  ConfigParser | Used to parse WEB-INF/zk.xml, metainfo/zk/zk.xml and metainfo/zk/config.xml into `Configuration`.
  DigestUtilsHelper | A helper class for class DigestUtils for md5 encoding, internal use only.
  ExecutionsCtrl | Additional utilities for `Execution`.
  HtmlPageRenders | Utilities for implementing HTML-based `PageRenderer`.
  HtmlPageRenders.RenderContext | The render context which consists of two writers (`HtmlPageRenders.RenderContext.temp` and `HtmlPageRenders.RenderContext.perm`.
  IntegerPropertyAccess | An Integer property class.
  IntPropertyAccess | An int property class.
  JsContentRenderer | An implementation of `ContentRenderer` that renders the content as a JavaScript property (i.e., name: 'value').
  JSCumulativeContentRenderer | An implementation of `ContentRenderer` that renders the content as a JavaScript property (i.e., name: ['value', 'value1', ..]) cumulatively.
  Names | Utilities about variable's names.
  ObjectPropertyAccess | An Object proeprty type
  SessionsCtrl | An additional utilities for implementation related to `Session`.
  ShadowElementsCtrl | Utilities for implementing components.
  StringPropertyAccess | A String property class.
  StubComponent | A stub component is a 'degenerated' component that does not maintain the states at the server.
  StubsComponent | Represents a tree of `StubComponent` that are merged into a single component.
  WebAppFactoryImpl | A web app factory implementation.
  WebAppsCtrl | An additional utilities for implementation related to `WebApp`.
  XmlContentRenderer | An implementation of `ContentRenderer` that renders the content as a Xml attribute (i.e., name="value").