Cloud computing services are becoming ubiquitous, and are becoming the primary source of computing power for both enterprises and personal computing applications. One of the fundamental issues in this environment is related to task scheduling. The scheduler should do the scheduling process efficiently in order to utilize the available resources. In this paper a cloud task scheduling policy based on artificial bee colony algorithm compared with different scheduling algorithms has been proposed. The main goal of the proposed algorithm is minimizing the makespan of a given tasks set. Artificial bee colony algorithm models the behavior of honey bees and can be used to find solutions for difficult or impossible combinatorial problems. Algorithms have been simulated using Cloudsim toolkit package. Experimental results showed that the artificial bee colony algorithm outperformed ACO, FPLTF and FCFS algorithms.

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Today computer and the internet play an important role in our daily life. We have shown highly remarkable of automated behavior that is criminal in violation of terms of services such as auto sharing or send friend request. SO, CAPTCHA is used for protecting webpages against automated programs which are called bots. It is providing challenge response tests that determine whether or not the users are human or bot. It contains various contorted letters that are difficult for attacker's bots, but easy for humans. Since there are a lot of services on the internet, for example (email, social network, search engine) which allow users to register, during registration, some attackers write malicious programs that make website resources damaged by making automated software which is called (Bots). Many research developed more techniques to prevent accessing web resources by spammers. This paper introduces a new mechanism of CAPTCHA approach using extended finite automata (XFA) for securing web pages and online social networks against a new breed of bots. The XFA CAPTCHA is a CAPTCHA based on image which generates its tests using the automata Graph technique. The result of our research evidence that the mechanism of XFA CAPTCHA is effective in terms of security and usability respectively. As a result of that, it improved the rate of efficiency by 97.8%, the time for solving is around 20 seconds, and the value the probability of success rate for speculation attack is decreased to 1.03% in average. When compared to other CAPTCHAs, the XFA CAPTCHA is a strong competitor in terms of security and usability function.