【正文】 ns and works of cooperation between other example, in P2P file sharing applications, when the work bandwidth utilization reaches a certain threshold, still predatory on the node using the work resources to applications and works in harmony with other applications, P2P applications is the development of longterm solution. 《 Journal of Harbin Institute of Technology》 8 Paper2 Object landscapes and lifetimes Technically, OOP is just about abstract data typing, inheritance, and polymorphism, but other issues can be at least as important. The remainder of this section will cover these issues. One of the most important factors is the way objects are created and destroyed. Where is the data for an object and how is the lifetime of the object controlled? There are different philosophies at work here. C++ takes the approach that control of efficiency is the most important issue, so it gives the programmer a choice. For maximum runtime speed, the storage and lifetime can be determined while the program is being written, by placing the objects on the stack (these are sometimes called automatic or scoped variables) or in the static storage area. This places a priority on the speed of storage allocation and release, and control of these can be very valuable in some situations. However, you sacrifice flexibility because you must know the exact quantity, lifetime, and type of objects while you39。s credibility, and credibility of information providers do not establish direct this type of trust model, the nodes determine the reliability of the information, and gives a positive or negative feedback rating, and further calculate the trust example, in filesharing application Kazaa, only consider the positive feedback to the data signature way to build credibility, that is, if the user accepted the authenticity of the information, then the signature, the information obtained more signatures, the authenticity of the as resources, limited trust model to establish the credibility of information sharing applications, does not have broad the node for the transaction to establish the credibility of the trust model are explained. (1) global trust model Trust model of such a work analysis and feedback of all transactions for each node to establish a unique credibility. The world39。s system resources, as well as the rapid increase in work bandwidth, the traditional Client / Server Network Application Mode server performance bottlenecks and single point of failure issue is not only limited the full use of end system resources,also increasingly unable to meet the new distributed P2P works to work together, distributed information sharing, largescale parallel puting such as showing the unique advantages of the new development to make it hot. P2P works are willing to share resources on the node the basic assumption that each node share its own resources and from other nodes where the resources for their own , such individuals to provide resources for the public, and node behavior result in unconstrained mode of P2P work there are three problems. (1) ride (FreeRiding) problem FreeRriding consumption of other nodes that node only contribution to the resources without sharing their own Gnutella P2P file sharing system, for example, 70% of the nodes is the latest monitoring also shows that in the eDonkey filesharing work, about 80% of the nodes is the FreeRider. (2) Public Goods and sorrow (the Tragedy of the Commons) problem Public Goods and sorrow means the work resources as a nonexclusive public resources are most uncontrolled use of P2P nodes, according to statistics, P2P traffic accounted for 60% of Inter Zong traffic flow, and the user is not the total number of significant growthcases, P2P traffic is still growing fact, P2P work users of its fundamental purpose is rational to maximize their utility, but does not consider the work39。re writing the program. If you are trying to solve a more general problem such as puteraided design, warehouse management, or airtraffic control, this is too restrictive. The second approach is to create objects dynamically in a pool of memory called the heap. In this approach, you don39。s trustworthiness and product description, munication with the buyer, delivery time, delivery and related practical applications, the nodes will affect the credibility of all the factors that quantify the confidence and credibility of integrated reached node is not , under normal circumstances, the trust model in P2P works, according to the node between satisfaction with the transaction to determine credibility. credibility, trust and mutually beneficial relationship Shown in Figure 1, if node A has a reciprocal behavior of other nodes, then A will have a good reputation, so node A will be other nodes in the trust, and transaction reciprocal behavior by other plan involves a trusted work of reciprocity, or you can call it incentive the social field, only when the behavior of the past affect the future (for sociology as the future of the shadow (Shadow of Future) phenomenon), people have incentive to build mutual , the trust model and the incentive mechanism of interaction between the good, P2P works can effectively promote the cooperation between nodes. Figure 1 credit, trust and mutually beneficial relationship between a simple model Trust Model classification In P2P work, there are all kinds of attack models, including: fraud, counterfeiting, defamation, fraud bined with a frontend node (headend node generally provide reliable service, the cooperative nodes give a fair evaluation. However, these frontend nodetrying to give a high internal malicious nodes to disguise malicious node positive behavior) of the joint fraud, change the ID to reenter the work node and the nodes intermittently to provide credible information and servic