Architecture of the Software

c/S structure, that is, client/server (client/server) structure, is well-known software system architecture, through the rational allocation of tasks to the client side and server side, reduce the communication overhead of the system, can make full use of the advantages of both ends of the hardware environment. Early software systems used this as the preferred design standard.

b/s structure, that is, Browser/server (browser/server) structure, with the rise of internet technology, a change of C/s structure or improved structure. In this structure, the user interface is implemented entirely through the WWW browser, some transaction logic is implemented in the front end (presentation layer), but the main transaction logic is implemented on the server side, forming the so-called 3-tier structure (presentation layer, business logic layer, data access layer).

We collectively refer to all the server software in the middle tier (business logic layer) of the three-tier architecture as middleware, whose main task is to respond to client requests, perform complex enterprise logic operations, access the enterprise's backend data resources, generate results that meet customer needs, and return to the customer. As a result, the customer's direct access to the data source is replaced by requests for the application, where the client accesses the application and the application queries and accesses the data, ensuring that the data is not illegally used and tampered with.

Peer to peer structure, compared to C/S, weakening or even canceling the traditional server, so that the various nodes in the Distributed system logical equivalence. The topology of the peer:

• Centralized topology: Napster is essentially not a purely peer-to-peer system that stores information about the index and location of music files uploaded by all Napster users through a central server. When a user needs a music file, it is connected to the Napster server, retrieved on the server, and the server returns the user information that holds the file, and the requestor connects directly to the file owner for the file transfer.
• No-center unstructured topology: Gnutella is a peer file sharing system, the biggest difference between it and Napster is that Gnutena is a purely peer-to-peer system with no index server, which uses flood (ffooding) discovery and random forwarding based on a completely random graph ( RANDOMW giant Iker) mechanism. In order to control the transmission of the search message, the TTL (TimeToLive) is implemented by reducing the value.
• Structured topology: Distributed hash list DHT (Distributed hash table)
• Hybrid topology: Select nodes with high performance (processing, storage, bandwidth, etc.) as super nodes (Supernode), store the information of other parts of the system on each super node, discover that the algorithm only forwards between the super nodes, and the Super node forwards the query request to the appropriate normal node.

Architecture of the Software