The local case and data can be loaded into memory within the Runnable. Later, after retrieval has placed the data on disk, the situation will be The disk then the task can simply read it and cache it right away. (Aĭisk access is necessary to determine whether the data exists locally.) Objects that load data therefore follow theĬonvention of first checking the memory cache for the desired data, and if it's not there create a Runnable to determine in a separate thread where the data must be drawn from, disk or network. One consequence of the disk-access restriction is that determining whether needed data is on disk and canīe loaded directly, or is not local and therefore must be retrieved, must not be done in the rendering thread. Tasks it runs typically read the data from disk and add it to the global memory cache Therefore loading the data from disk is dispatched toĪnother thread pool, the ThreadedTaskService. One of the WorldWind conventions is that no code mayĪccess the computer's disk in any way during rendering. Thread as the retriever, which is neither the event-dispatching (UI) thread nor the rendering thread, but the oneĬreated by the retrieval service for that retriever.ĭata that has been previously retrieved or is otherwise local (on disk) is brought into memory in a thread separateįrom the event-dispatching thread or the rendering thread. BasicElevationModel just persists the raw data. TiledImageLayer,įor instance, can convert non-DDS formats to DDS, or simply store the data as-is in the file cache. Persistence and any processing prior to it is object specific. RetrievalPostProcessor is passed the data immediately upon download and determines how to persist it. When a retriever's data arrives, the retrieval service calls the retriever's RetrievalPostProcessor, which was specified to the retriever's constructor. Access to the retrieval service is through WorldWind, which holds a singleton The service runs each retriever in an individual Objects retrieveĭata by passing the retrieval service a Retriever. RetrievalService manages a thread pool for retrieval tasks. The data the layer displays, and by an ElevationModel to retrieve elevation data. Retrievers are typically created by a Layer to retrieve The most commonly used concrete Retriever is HTTPRetriever, which Retriever encapsulates a single network retrieval request. Implement retrieval are Retriever and RetrievalService. Retrieval and local caching of that data is therefore a primary feature of WorldWind. WorldWind works with enormous quantities of data and information, all of which exist primarily on remote data Implementations and easily integrate them into WorldWind. This allows application developers to create their own Most of WorldWind's components are defined by interfaces. Implementations of Model, SceneController and View. Wind provides several Globe objects representing Earth, Mars and the Earth's moon, and provides basic Objects implementing a particular interface may be used wherever that interface is called for. The objects implementing the above interfaces may be those provided by WorldWind or those created by applicationĭevelopers. The scene controller subsequently manages the display of the globe and its layers inĬonjunction with an interactive View that defines the user's view of the planet. Model They then pass that model to a SceneController that displays the globe and its layers in a In typical usage, applications associate a Globe and several Layers with a View - interactively controls the user's view of the model. SceneController - controls the rendering of a Model.Model - aggregates a Globe and the Layers to apply to.Layer - applies imagery or information to a Globe.Globe - represents a planet's shape and terrain.In addition to WorldWindow, there are five major WorldWind interfaces. Swing/AWT and, in the future, SWT-Eclipse. Toolkit-specific implementations of the interface are provided for The API is defined primarily by interfaces, soĬomponents can be selectively replaced by alternative components. Applications use WorldWind by placing one or more WorldWindow components WorldWind is a collection of components that interactively display 3D geographic information within JavaĪpplications.
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