WWW/Internet - Portal do Software Público Brasileiro

ISBN: 978-972-8939-25-0 © 2010 IADISuses dynamic HTML and Asynchronous JavaScript + XML (Ajax). Using JavaScript, web pages can accessthird party web services, download data, and update pages independently Therefore, web applications areimplemented to compose multiple external data resources. In other words, recent data resources, e.g.RESTful Web services and Web APIs, must be composable.We return now to a consideration of the tiled display wall. The tiled display wall renders high-resolutioncontents in parallel. That is, web applications on WDiM must be decomposable. WDiM is intended toprovide a method that decomposes high-resolution web applications that are implemented to composedistributed web services and APIs.Let us consider drawing high-resolution images to multiple web browsers on monitors of the WDiMsystem. For example, if the high-resolution image is a 5 MB digital photograph taken by a megapixel digitalcamera, then six Full HD monitors are necessary to display every pixel of the image. In this case, at least sixPlayers send HTTP request and fetch the same 5 MB file. Consequently, 30 MB data are sent for visualizinga 5 MB image, which is plainly not efficient.Although multicasting or broadcasting modes that are not supported by web browser might solve thisproblem, our challenge in this research is drawing a high-resolution web application based only on webbrowsers. Therefore, the Players must each draw a fragment of the high-resolution image on a web browser.Such a technique is well known. It is a web mapping service application. For example, Google Mapsdraws a fragment of the huge satellite image on a web browser. In this case, it is apparent that the imageshown on the web browser consists of many small images (256 pixels×256 pixels). Therefore, Google Mapsneed not request images that are outside the bounds of the desired image. Actually, WDiM uses such a tilingmethod to draw raster images.A question that remains is whether each Player can draw correct bounds of a big image. TheCoordinator and WDiM middleware help WDiM application developers to resolve this issue. Put simply,WDiM middleware manages messaging between application logic on the Coordinator and web browsers onall Players. The WDiM middleware and messaging are described in section 5.Next, distributed character strings are not supported in this version of WDiM. If a developer does notdeclare a bounding box, then strings are sent to all Players whether it draws the string on the monitor or not.Lastly, drawing a vector image is a subject for future work. We tackle distributed rendering using AdobeFlash. In this way, distributed rendering on multiple monitors is realized using a combination of existingtechnologies.4. HIGH-RESOLUTION WEB APPLICATIONS ON WDIMTo sum up the salient characteristics, The WDiM system consists of a Coordinator(httpd), multiplePlayers(Nettop computer), and Conductor(Nintendo Wii). A Coordinator is responsible for the messagingand application logic, Players draw high-resolution web application to monitors, and the Conductor receiveuser interaction. Therefore, the WDiM is logically a kind of Model-View-Controller (MVC) architecture(Figure 4).Before describing WDiM middleware, we present two high-resolution web applications of WDiM in thissection to provide an overview of decomposable web application as a mashup of composable web services.4.1 PhotoMosaic: Using Flickr APIPhotomosaic (Silvers R. and Hawley M., 1997 and Finkelstein A. and Range M., 1998) is a technique whichtransforms an input image into a rectangular grid of thumbnail images. WDiM PhotoMosaic applicationcreates Photomosaic images using the large image set of Flickr, the public image hosting service. Aphotographic mosaic is a photograph that has been divided into small sections, each of which is replaced withanother photograph having the appropriate average color of the section. While viewing a photographicmosaic from a distance, it appears as a large photograph, but small photographs can be observed if oneapproaches the photographic mosaic. This application aims to demonstrate WDiM, which is not merely alarge display, but also a high-resolution display.154