1. Dependency Inversion
Dependency inversion principle: Rely on abstraction, not on concreteness.Programming for interfaces, not for implementations.The level of abstraction includes the business logic of the application system and strategic decisions that are important to the whole system. It is the embodiment of inevitability and is relatively stable.While the specific level contains some minor implementation-related algorithms and logic, as well as tactical decisions, with considerable chance choices.Specific levels of code are subject to frequent changes.
ajax Basic Concepts To understand this concept, one must first know synchronous interaction and asynchronous interaction.
synchronous interaction: the client browser sends a request to the server, and the server returns a page. the returned page will overwrite the previous page. we call this interaction synchronous interaction asynchronous interaction: that is, the browser can be broken to send a request to the server, the server returns data, and the returned data will not overwrite the previous page.
In the development test, cross-domain operations will inevitably be carried out under different domains. For security reasons, the same origin policy in the browser prevents scripts loaded from one domain from obtaining or operating.
Document attributes under another domain, which need to be solved in a cross-domain way, such as using JSON with Padding, iFrame, etc.
just saw a post on a BBS (XX community → introduction of new software), feel the same way and reprint it.
Title: At present, the degree of hooliganism in rogue software is outrageous
Similar to www.58.com and www.byair.com, they jumped out of my maxthon every day and set it as an advertisement to filter. It was useless. Later, on the recommendation of Kanban friends, they used Huangshan to kill him.
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From: http://www.hollischuang.com/archives/1716 At present, almost many large websites and applications are deployed in a distributed way. The problem of data consistency in distributed scenarios has always been an important topic.The distributed CAP theory tells us that "no distributed system can satisfy Consistency, Availability and Partition tolerance at the same time, at most it can satisfy two at the same time."Therefore, many systems have to choose between the three at the
Firewall Series (II)-Main Technologies of Firewall Essential Knowledge: TCP/IP Basis
Packet Filtering work object–> packetFirewall processes packets before they enter the systemThe Firewall module that implements Packet Filtering should be located at the network layer of the operating system protocol stack.
Filter Objects filtering for IP View the packet header of each IP packet, compare the packet header data with the rule set, forward the packets allowed by the rule set, and reject the packets not allowed by the rule set
Firewall Series (III)-Main Technologies of Firewall Proxy Technology Proxy Technology Overview The Firewall of proxy technology runs between the internal network and the external network in the form of a proxy server, realizes the security control function at the application layer, and plays the role of transferring application services between the internal network and the external network. 1. Agent Execution Process (Two Cases) 1. The proxy server monitors the request
Firewall Technology (I)
At present, effective measures to ensure network security mainly include: Firewall, identity authentication, encryption, digital signature and content check, etc.
Firewall refers to the combination of a series of components arranged between different networks or network security domains.It is the only entrance and exit of information between different networks or network security domains. It can control (allow, deny and monitor) the flow of information into and out of the network according to the enterprise's security policies and has strong anti-attack capability.