Access Policy Consolidation for Event Processing Systems

SUMMARYRecently, event processing (EP) has gained considerable attention as an individual discipline in computer science. From a software engineering perspective, EP systems still lack the maturity of well‐established software architectures. For the development of industrial EP systems, generally accepted software architectures based on proven design patterns and principles are still missing. In this article, we introduce a catalog of design patterns that supports the development of event‐driven architectures (EDAs) and complex EP systems. The design principles originate from experiences reported in publications as well as from our own experiences in building EP systems with industrial and academic partners. We present several patterns on different layers of abstractions that define the overall structure as well as the building blocks for EP systems. Architectural patterns that determine the top‐level structure of an EDA can be distinguished from design patterns that specify the basic mechanisms of EP. The practical application of the catalog of patterns is described by the pattern‐based design of a sample EDA for a sensor‐based energy control system. Finally, we propose a coherent and general reference architecture for EP derived from the proposed patterns.Copyright © 2013 John Wiley & Sons, Ltd.

Complex Event Processing (CEP) is a powerful technology used in complex and real-time environments. CEP is an Event Driven Architecture (EDA) style consists of processing different events within the distributed enterprise system attempting to discover interesting information from multiple streams of events in timely manner. In real world, the streams of events are uncertain, which means that is not guaranteed that an event has actually occurred, this uncertainty is due mainly to imprecise content from the event sources (Sensors, RFID,...). As a result, probabilistic CEP has become an important issue in complex environments that require a real-time reaction given streams of probabilistic events.

Event processing (EP) is a data processing technology that conducts online processing of event information. In this survey, we summarize the latest cutting-edge work done on EP from both industrial and academic research community viewpoints. We divide the entire field of EP into three subareas: EP system architectures, EP use cases, and EP open research topics. Then we deep dive into the details of each subsection. We investigate the system architecture characteristics of novel EP platforms, such as Apache Storm, Apache Spark, and Apache Flink. We found significant advancements made on novel application areas, such as the Internet of Things; streaming machine learning (ML); and processing of complex data types such as text, video data streams, and graphs. Furthermore, there has been significant body of contributions made on event ordering, system scalability, development of EP languages and exploration of use of heterogeneous devices for EP, which we investigate in the latter half of this article. Through our study, we found key areas that require significant attention from the EP community, such as Streaming ML, EP system benchmarking, and graph stream processing.

The use of Complex Event Processing (CEP) and Stream Processing (SP) systems to process high-volume, high-velocity Big Data has renewed interest in procedures for managing these systems. In particular, self-management and adaptation of runtime platforms have been common research themes, as most of these systems run under dynamic conditions. Nevertheless, the research landscape in this area is still young and fragmented. Most research is performed in the context of specific systems, and it is difficult to generalize the results obtained to other contexts. To enable generic and reusable CEP/SP system management procedures and self-management policies, this research introduces the Attributed Graph Rewriting for Complex Event Processing Management ( AGeCEP ) formalism. AGeCEP represents queries in a language- and technology-agnostic fashion using attributed graphs. Query reconfiguration capabilities are expressed through standardized attributes, which are defined based on a novel classification of CEP query operators. By leveraging this representation, AGeCEP also proposes graph rewriting rules to define consistent reconfigurations of queries. To demonstrate AGeCEP feasibility, this research has used it to design an autonomic manager and to define a selected set of self-management policies. Finally, experiments demonstrate that AGeCEP can indeed be used to develop algorithms that can be integrated into diverse CEP systems.

SPARQL was originally developed as a derivative of SQL to process queries over finite-length datasets encoded as RDF graphs. Processing of infinite data streams with SPARQL has been approached by using pre-processors dividing streams into finite-length windows based on either time or the number of incoming triples. Recent extensions to SPARQL can support interconnections of queries, enabling event processing applications to be constructed out of multiple incrementally processed collaborating SPARQL update rules. With more elaborate networks of queries it is possible to perform event processing on heterogeneous event formats without strict restrictions on the number of triples per event. Heterogeneous event support combined with the capability to synthesize new events enables the creation of layered event processing systems. In this paper we review the different types of complex event processing building blocks presented in literature and show their translations to SPARQL update rules through examples, supporting a modular and layered approach. The interconnected examples demonstrate the creation of an elaborate network of SPARQL update rules for solving event processing tasks.

In such areas as transport, healthcare, business process management, financial services, complex event processing (CEP) systems are becoming in demand. Large volumes of streams of events are generated and collected by these systems. Real-time processing of event stream data is essential. Based on current and past events, a decision is made, and forecasting future events is an alternative goal. For the fastest reaction to non-standard behavior, it is necessary to process data streams in real time, it means, as quickly as possible. That's why it is important to find new technologies which can speed up data processing. In this article expensive queries in CEP is identified, effective optimizations to improve their performance significantly is proposed. It is developed and implemented algorithm, which should decrease processing time. The results are compared with state-of-the-art CEP system.

In recent years there is a huge increase in real-time data, which cannot be processed efficiently. Complex event processing has become a very important method to get meaningful information. However, supporting complex event detection in multiple sources environments is a challenging problem. To allow for inferring high level information from vast amounts of continuous arriving data. In this paper, we present a complex event processing system based on a novel distributed computing platform Storm, which goes further than distributing queries and achieves better scalability by parallelizing event detection, and also higher efficiency through the use of some optimizations. The experimental shows that the event processing system is effective and better scalability.

This study presents a novel method to develop kleene operators on a Binary Tree-Based Directed Graph (BTDG) to improve expressibility and performance of our developed complex event processing system. Complex Event Processing (CEP) systems are widely employed to notify opportunities and threats, which many of these situations are discovered through detection of multiple occurrences of the similar set of events. Many of CEP systems proposed kleene operators to detect these situations. The high expressibility of our implemented CEP system achieved by developing algorithms on kleene operator. These algorithms are designed on a BTDG as a unified basis to arrange input data and joining this input according to a given query. The performance is improved through directing events instantly to join with other events, dynamically switching to an optimal plan and late applying combination for kleene with specified size. The experiments shows kleene operator on BTDG brings rather high degree of expressiblity and performance in compare to its counterparts.

Knowledge-infused and consistent Complex Event Processing over real-time and persistent streams

Complex event processing is a key technology for analyzing event patterns in real-time data streams. It has been widely applied in IoT monitoring, financial risk control, smart manufacturing and other time-sensitive fields. Query patterns serve as the core matching mechanism in complex event processing systems. These patterns are primarily defined through selection policies, predicate constraints and timestamps to establish complex event detection rules. The selection policy is particularly important as it determines the sequential relationships between events. This directly affects the system's event matching efficiency and accuracy. However, in practical applications, due to different business requirements for event sampling frequencies, event streams often contain numerous consecutive events of the same type representing identical states. While all these events participate in complex event matching, traditional processing methods generate large numbers of semantically redundant partial matches. Analysis shows that only a very small proportion of these intermediate results eventually form complete matches, creating serious computational redundancy issues. This redundancy not only significantly increases system resource consumption but also reduces overall processing efficiency due to ineffective computations. To address this critical problem, this paper innovatively proposes a cache-based optimized selection policy. The core concept of this policy is to effectively reduce redundant matching results by extracting representative events from continuous event sequences. Experimental results show that this policy can significantly decrease the redundant matching rate while alleviating system load, providing new insights for optimizing complex event processing systems.

Complex event processing (CEP) over event streams has become increasingly important for real-time applications ranging from health care, supply chain management to business intelligence. These monitoring applications submit complex event queries to track sequences of events that match a given pattern. As these systems mature the need for increasingly complex nested sequence query support arises, while the state-of-art CEP systems mostly support the execution of only flat sequence queries. In this paper, we introduce our nested CEP query language NEEL for expressing nested queries composed of sequence, negation, AND and OR operators. Thereafter, we also define its formal semantics. Subtle issues with negation and predicates within the nested sequence context are discussed. An E-Analytics system for processing nested CEP queries expressed in the NEEL language has been developed. Lastly, we demonstrate the utility of this technology by describing a case study of applying this technology to a real-world application in health care.

Complex event processing (CEP) systems have gained significant importance in various domains, such as finance, logistics, and security, where the real-time analysis of event streams is crucial. However, as the volume and complexity of event data continue to grow, optimizing the performance of CEP systems becomes a critical challenge. This paper investigates the impact of indexing strategies on the performance of databases handling complex event processing. We propose a novel indexing technique, called Hierarchical Temporal Indexing (HTI), specifically designed for the efficient processing of complex event queries. HTI leverages the temporal nature of event data and employs a multi-level indexing approach to optimize query execution. By combining temporal indexing with spatial- and attribute-based indexing, HTI aims to accelerate the retrieval and processing of relevant events, thereby improving overall query performance. In this study, we evaluate the effectiveness of HTI by implementing complex event queries on various CEP systems with different indexing strategies. We conduct a comprehensive performance analysis, measuring the query execution times and resource utilization (CPU, memory, etc.), and analyzing the execution plans and query optimization techniques employed by each system. Our experimental results demonstrate that the proposed HTI indexing strategy outperforms traditional indexing approaches, particularly for complex event queries involving temporal constraints and multi-dimensional event attributes. We provide insights into the strengths and weaknesses of each indexing strategy, identifying the factors that influence performance, such as data volume, query complexity, and event characteristics. Furthermore, we discuss the implications of our findings for the design and optimization of CEP systems, offering recommendations for indexing strategy selection based on the specific requirements and workload characteristics. Finally, we outline the potential limitations of our study and suggest future research directions in this domain.

In-network computing using programmable networking hardware is a strong trend in networking that promises to reduce latency and consumption of server resources through offloading to network elements (programmable switches and smart NICs). In particular, the data plane programming language P4 together with powerful P4 networking hardware has spawned projects offloading services into the network, e.g., consensus services or caching services. In this paper, we present a novel case for in-network computing, namely, Complex Event Processing (CEP). CEP processes streams of basic events, e.g., stemming from networked sensors, into meaningful complex events. Traditionally, CEP processing has been performed on servers or overlay networks. However, we argue in this paper that CEP is a good candidate for in-network computing along the communication path avoiding detouring streams to distant servers to minimize communication latency while also exploiting processing capabilities of novel networking hardware. We show that it is feasible to express CEP operations in P4 and also present a tool to compile CEP operations, formulated in our P4CEP rule specification language, to P4 code. Moreover, we identify challenges and problems that we have encountered to show future research directions for implementing full-fledged in-network CEP systems.

Event processing systems link event producers and consumers in a flexible manner, by supporting multiple communication patterns and powerful message transformations. Such systems support both loosely coupled communication patterns, such as one-to-one or one-to-many and tightly coupled (request-response) patterns. An important concern in these systems is the allocation of resources used to support event processing. These include traditional constrained resources such as CPU and network, as well as an increasing reliance on storage resources. For instance, transactional and reliable producers require events to be logged to stable storage. In this paper we consider the problem of utility driven allocation of these resources, taking into account resource capacity. In contrast to previous work, we (1) develop a unified utility model to deal with throughput requirements of one-way flows and latency requirements of request-response flows, (2) differentiate between classes of consumers for one-to-many flows and subject these classes to consumer admission control, (3) compute system optimization constraints using both resource bandwidth and latency and (4) develop a control architecture that combines periodic optimization with continuous rate control, both of which are utility aware. We describe an experimental evaluation of our approach on a prototype event processing server.

Complex Event Processing (CEP) systems aim at processing large flows of events to discover situations of interest. In CEP, the processing takes place according to user-defined rules, which specify the (causal) relations between the observed events and the phenomena to be detected. We claim that the complexity of writing such rules is a limiting factor for the diffusion of CEP. In this paper, we tackle this problem by introducing iCEP, a novel framework that learns, from historical traces, the hidden causality between the received events and the situations to detect, and uses them to automatically generate CEP rules. The paper introduces three main contributions. It provides a precise definition for the problem of automated CEP rules generation. It dicusses a general approach to this research challenge that builds on three fundamental pillars: decomposition into subproblems, modularity of solutions, and ad-hoc learning algorithms. It provides a concrete implementation of this approach, the iCEP framework, and evaluates its precision in a broad range of situations, using both synthetic benchmarks and real traces from a traffic monitoring scenario.