Modeling and Verifying the Ballooning in Xen with CSP

Apache Kafka is an open source distributed messaging system based on the publish-subscribe model, which achieves low latency, high throughput and good load balancing. As a popular messaging system, the transmission of messages between applications is one of the core functions of Kafka. Therefore, the reliability and security of data in the process of message transmission in Kafka have become the focus of attention. The formal methods can analyze whether a model is highly credible. Therefore, it is significant to analyze Kafka messaging mechanism which describes the communication process and rules between each module entity in Kafka from the perspective of formal methods. In this paper, we apply the process algebra CSP (Communicating Sequential Processes) and the model checking tool PAT (Process Analysis Toolkit) to analyze Kafka messaging mechanism. The results of verification show that the model caters for its specification and guarantees the reliability of messages in the normal communication process. Moreover, in order to further analyze the security of Kafka messaging mechanism, we add the intruder model and the authentication protocol Kerberos model and compare the verification results of Kafka messaging mechanism with or without the secure protocol Kerberos. The results show that the Kerberos protocol has improved the security of Kafka messaging mechanism in some aspects, but there are still some security loopholes.

With the rapid expansion of Internet of Things (IoT), Constrained Application Protocol (CoAP) is developed to enable those devices with small memory, constrained computing power and limited ability to communicate with other nodes in the network. Meanwhile, group communication is very useful for managing and controlling a set of homogeneous devices in many IoT scenarios. Thus, many scholars are devoted to expanding CoAP to enable group communication. Furthermore, because CoAP is widely applicated in transportation, health care, industrial and many other areas, the security and consistency of data is of great importance. In this paper, we adopt Communicating Sequential Processes (CSP) to model group communication CoAP, and we use model checker Process Analysis Toolkit (PAT) to verify six properties of our model, including deadlock freedom, divergence freedom, data reachability, data leakage, client faking and entity manager faking. The verification results show that the original architecture has the security risk of data leakage. So we enhance it by adding message authentication code in the process. In the light of the new verification results, it can be found that we succeed in eliminating the possibility of data leakage.KeywordsGroup communicationCoAPCSPModelingVerification

As a leading architecture of Information-Centric Networking (ICN), Named Data Networking (NDN) plays an important role in the future network construction. NDN retrieves and identifies a data packet according to the packet's name instead of its IP address. Conventional protocols of TCP/IP Internet are unsuitable for NDN. Therefore, Named-data Link State Routing protocol (NLSR) is proposed as an intra-domain routing protocol for NDN. Although NLSR applies a five-layer trust model to guarantee its data security, there are still a lot of security issues in its data access mechanism, such as the fake and leakage of data. In this paper, we apply Communicating Sequential Processes (CSP) to formalize this mechanism. Using Process Analysis Toolkit (PAT), we verify four properties, including deadlock freedom, data availability, data security and data decryption. According to the verification results, the trust model cannot protect the data from fake and leakage once intruders appear. We adopt a method similar to digital signature in the first improved model. However, the process of obtaining keys still needs to be executed multiple times during the verification of a data packet. To further accelerate the key fetching and verification process, all the keys, needed to validate a data packet, are packaged in a special packet of the second improvement.

Variable length codes (VLC) have found widespread use for efficient encoding of symbols with unequal probabilities in many practical situations. However, bit errors can cause a loss of decoder synchronism that often leads to error propagation. Recent advances in the development of VLC that limit the effect of error propagation, such as reversible VLC and self-synchronising VLC, contribute further to their popularity. However, it is still important to model the performance of various VLC code sets so that comparisons can be made between different coding schemes and for different applications. Communicating sequential processes (CSP) is a well-established formal description technique that allows one to analyse the behaviour of concurrently evolving processes. It has been successfully applied to industrial-scale problems. The paper describes how CSP can be applied to the modelling of the resync process of VLC. This approach offers three main advantages. First, a complete model comprises processes and events as basic building blocks, making this approach highly scalable. Second, different semantic models provide different level of abstraction. Third, tools are available for automatic generation of sync sequences, which also provide a measure of sync performance. This facilitates comparisons of different VLC schemes in addition to code sets obtained using a given coding scheme.

Formal description of network behavior is the important part in network management. But some problems have not yet to be adequately addressed are the semantic and behavioral aspects of composition in this domain. Therefore a formal description method was presented to network behavior. The method includes a simple formal language, and its semantic was described by CSP. The formal language has graphical syntax with topology style. And it also has some characters that are suitable for the formal research and analysis about some problems in network management. Consequently, the method can be used to provide precise formal description and analysis about network behavior. And a reliable mathematical foundation is also provided for the correctness and validity of software system design.

With the process of non-functional properties research on real-time systems, resource estimation and analysis of realtime systems become a hotspot. Process Algebra is a formal method fit for analyzing the functional properties of real-time systems, but it can not analyze the resource properties. Resource Communicating Sequential Process (RCSP) proposed in this paper can handle it efficiently by extending resource semantics on Communicating Sequential Process (CSP). In this paper, the resource consumption of real-time instructions is mapped into the resource of RCSP, then the resource consumption of realtime systems can be modeled and optimized by using RCSP; the resource optimal checking algorithms are proposed to check the resource satisfiability of instructions and calculate the minimum resource and accumulated resource of real-time systems. This formal method improves the accuracy and efficiency of resource calculation, the calculation results can be used to quantitatively analyze and optimize the resource consumption of real-time systems.

The pacemaker challenge proposed by Software Quality Research Laboratory is looking for formal methods to produce precise and reliable systems. Safety critical systems like pacemaker need to guarantee important properties (like deadlock-free, safety, etc.), which concern human lives. Formal methods have been applied in designing safety critical systems with verified desirable properties. In this paper, we propose a formal model of pacemaker, modeling its behaviors and its communication with the external environment, using a real-time formalism. Critical properties, such as deadlock freeness and heart rate limits are then verified using the model checker PAT(Process Analysis Toolkit). This work yields a verified formal model of pacemaker systems, which can serve as specification for real pacemaker implementations.

The software industry has entered a new era. Software defects are still costing the economy billions. The experts' skill lies in the creation of the formal model. Their skill is unlikely to extend into the knowledge required from various domain experts. How do the domain experts and formal-methods experts communicate with one another to provide critical input into the abstract model and the actual system? We have encountered this problem repeatedly when bringing in a formal methods expert to analyse a complex component. A design approach called analytical software design (ASD) tries to address these barriers by combining some elements of the Cleanroom Software Engineering technique pioneered by IBM Federal Systems with the framework based on communicating sequential processes (CSP). Experience has shown that applying ASD results in software with very low defect levels entering integration and system testing.

The cost of problem analysis and programming dominates by far the cost of computer utilization. This dominance will increase in the future as hardware elements become more powerful and economical and problems become more complex and demanding of highly skilled analysis. As this trend continues, the sophisticated user will become increasingly intolerant of a situation which prevents economic transfer of programs and data from one installation or hardware type to another. A standard machine independent environment which provides data management services at several levels to programmers and task programs should be defined. Programs would then interface with a set of virtual machines, or standard program environments, which are independent of the particular hardware configuration of the installation.

We target the problem of managing the power states of the servers in a Cloud Data Center (CDC) to jointly minimize the electricity consumption and the maintenance costs derived from the variation of power (and consequently of temperature) on the servers’ CPU. More in detail, we consider a set of virtual machines (VMs) and their requirements in terms of CPU and memory across a set of Time Slot (TSs). We then model the consumed electricity by taking into account the VMs processing costs on the servers, the costs for transferring data between the VMs, and the costs for migrating the VMs across the servers. In addition, we employ a material-based fatigue model to compute the maintenance costs needed to repair the CPU, as a consequence of the variation over time of the server power states. After detailing the problem formulation, we design an original algorithm, called Maintenance and Electricity Costs Data Center (MECDC), to solve it. Our results, obtained over several scenarios from a real CDC, show that MECDC largely outperforms two reference algorithms, which instead either target the load balancing or the energy consumption of the servers.

Designing a cloud infrastructure for HPC applications requires to correlate design choices for virtualization solutions, resources management strategies, and their implementation on specific hardware platforms. Such investigations can hardly be conducted without accurate simulation tools. This paper introduces VMcSim, the first micro architecture and virtualized many core simulation framework. VMcSim models a x86-based asymmetric many core micro architecture, including a virtualization layer which allows to model a hyper visor, a set of virtual machines with their virtual resources (CPU and memory), their operating system, and their applications. By simulating all the involved hardware and software layers, VMcSim outperforms other simulators. Simulation accuracy is evaluated through several benchmark (SPLASH-2). The simulator is demonstrated with the evaluation of virtual resources placement policies in multicore systems.

The rapid development and wide application of network technology is to lay a solid foundation for the college the virtual internship platform. The literature and logical analysis method was used in this article. The establishment of the virtual internship model is proposed in the transportation professional in the text. The framework structure and main contents of the virtual internship platform for building were discussed in-depth on the basis of analysis of the characteristics and advantages of the virtual internship platform.KeywordsTransportation professionalsThe virtual internshipInternship platformConstruction

Virtualized servers run a diverse set of virtual machines (VMs), ranging from interactive desktops to test and development environments and even batch workloads. Hypervisors are responsible for multiplexing the underlying hardware resources among VMs while providing them the desired degree of isolation using resource management controls. Existing methods provide many knobs for allocating CPU and memory to VMs, but support for control of IO resource allocation has been quite limited. IO resource management in a hypervisor introduces significant new challenges and needs more extensive controls than in commodity operating systems.This paper introduces a novel algorithm for IO resource allocation in a hypervisor. Our algorithm, mClock, supports proportional-share fairness subject to minimum reservations and maximum limits on the IO allocations for VMs. We present the design of mClock and a prototype implementation inside the VMware ESX server hypervisor. Our results indicate that these rich QoS controls are quite effective in isolating VM performance and providing better application latency. We also show an adaptation of mClock (called dmClock) for a distributed storage environment, where storage is jointly provided by multiple nodes.

Cloud computing and big data: Technologies and applications

This paper includes a causal-based modelling of software meas-urement processes in order to clarify the real situations in the em-pirical software engineering field. A first overview about existing causal network approaches shows the problems and possible bene-fits using these formal techniques in the software engineering area. The definition and extension of the causal modelling using causal networks helps to understand the relationships between the differ-ent software process artefacts and their causalities. The causal net-work based process model (CNPM) concept is based on the causal network idea of Pearl. The description of first applications of the CNPM approach for CMMI demonstrates the empirical reasoning of the software improvement processes in an explicit manner.