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aduy/SucBenVatLieu_K2009/chuong 4.pdfÆ-nnh 4.6 Ung suat tt€n mãt cát nghiêng. Cát phân tô...
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Product Summary Universal Service Processor USP OpenVMS systems e-business solutions USP Concepts Architecture USP implements a hub-and-spoke architecture where all applications are connected to a central process, called a m e s s a g e b r o k e r . The message broker handles all communication among the connected applications, traditionally called clients and servers. The message broker is responsible for routing messages correctly, authenticating and authorizing user access, and guaranteeing the delivery of the messages. Each application can either be a sender of messages, a recipient, or both. USP middleware C S W S / A p a c h e W e b S e r v e r U S P S e r v i c e s C o n f i g u r a t i o n C l i e n t U S P i n t e r f a c e C l i e n t U S P i n t e r f a c e C l i e n t U S P i n t e r f a c e S e r v e r U S P i n t e r f a c e S e r v e r U S P i n t e r f a c e S e r v e r U S P i n t e r f a c e XML messaging USP Message Broker Server System Client System Benefits of using this architecture include: • • • • • • • Reduced number of network connections Each application only needs to connect to a message broker in order to send information to all other applications. Flexible deployment As the message broker handles all routing, senders and receivers are unaware of one another, so they can be moved around with minimal disruption to the system. Minimal software requirements on the application Because most of the messaging logic is contained within the message broker, smaller software components are required in the application in order to establish connections. Service model Services The business functionality of the client and of the server is application-specific and fully under the control of the developer. USP handles simultaneous requests for different service types: Session Services Application Services Request Services Broadcast Services Session Service A session service is a synchronous stateful service that is active for a long time regardless of the client’s connection. USP allocates a free server instance upon the client’s demand. A virtual channel is established between the client and the server instance for the duration of the session. As soon as the client disconnects, the service is freed but the server instance does not exit. It awaits a connection from another client. A typical example of a session service is a transactional server, for example a database server. Application Service An application service behaves like a session service with only one difference. An application service executes the server code in the context of an authenticated user. The server starts when the client connects to the service and exits as soon as the client disconnects. Request Service A request service is a synchronous, stateless service that behaves like a session service with a session duration of a single request only. A typical example for a request service is a transactional database server ti i l
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