Java Service for the Web Model

The Electronic Trading System Consists of a number of Multi-Threaded Win32 Applications, running under Ten Windows 2000 Servers each with Eight Processors as well as a number of IBM AIX Unix Processes Shown here is the n-tier architecture of Java Services For The Web The design is based on the importance of Model Objects/Entities and their ability to support multiple IDL protocols Model Entities report changes received from the Distributor as Model Events Those Component Managers/Marshallers listening for those events can: Extract The Entity From The Notification List Ask The Model Entity What The Notification Means in HTML Table Row Terms Ask The Model Entity What The Notification Means in Pseudo-JavaScript that the JavaScript Client Can Exploit The main Unix Process is Central Server (CS) and as part of the Trading System Infastructure three styles of connection are supported Server Remote Service Once the Apache Web Server is started the first loaded object is the Servlet This Servlet performs the following tasks: Instantiates the message Distributor, which exploits Java Just-intime-Compilation by loading the Model Entities Invokes DataBaseLoader, which as a component marshaller, instructs the model entities to load objectdata from the database Instantiates the main Service ServerConnection Invokes the MessageLoader to finalise the population of Model Entities with dynamic data not available in the database (for example who is logged on) Instantiates the Peer Server that controls Server Push via the web page applet. Finally when users connect the persistant jsp:useBean UserSession is invoked on a per user basis. DataBaseLoader and MessageLoader are transient marshaller delegates. The role of MessageLoader is to reject Server Push messages being sent prior to the Client Pull requesting the data ServerConnection, Distributor, Peer Server and UserSession are persistant. Each AppletConnection has UserSession as a member that combined with remote scripting effectively supports dynamic subscriptions to messages passed from Model Entities as Model Events. The point being there is no point pushing a message to the client for a frame page that is not open on that client.