Migration of a Chosen Architectural Pattern to Service Oriented ...

Chapter 3. Architectural Patterns 54Relationships – Client is a container for logic and Client Broker. Logic ofthe client can invoke the client broker but broker cannot invoke the logic.Supplier is a server proving requires operations. A supplier contains SupplierLogic and Supplier Broker. In opposite to Client, Broker invokes Logicand Logic cannot invoke Broker. The connection between Client and Supplieris bidirectional because an asynchronous connection is assumed. Theconnection can be also unidirectional, what removes connection from Supplierto Client (see figure 3.19).Client SupplierClient Logic Client Broker Supplier Broker Supplier LogicFigure 3.19: Example usage of Explicit Invocation pattern15. Peer —to —PeerOverview– the whole pattern consists of only one type of elements: peer.The pattern creates a network build with peers. The number of peers is notspecified because peers can join and leave the network dynamicallyElementsPeer – the whole network consists of only one type of element–Peer. Peer isa server and a client in the same time. This means that each “peer” requestsand consumes services. To start up each peer has to find at least one otherpeer to create a network. This problem can be solved by introducing fewdedicated public peers that are known to other peers.Relationships – there is no limitations in connections between peers (seefigure 3.20).16. C2Overview – this patter is another possible solution for system interactingwith users.ElementsComponent – contains logic of the systemConnector – forwards messages from one Component to another. Connectionsbetween Components and Connectors are asynchronous. Connectorshave to be aware of all the Components “above” and “below” them.Relationships–All requests are asynchronous so the components have toknow only components above in hierarchy to return the result. All requests