Chapter 8 Aspect-Oriented Software Engineering
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
A Brief Introduction to Aspect-Oriented Programming
R R R A Brief Introduction to Aspect-Oriented Programming" R R Historical View Of Languages" R •# Procedural language" •# Functional language" •# Object-Oriented language" 1 R R Acknowledgements" R •# Zhenxiao Yang" •# Gregor Kiczales" •# Eclipse website for AspectJ (www.eclipse.org/aspectj) " R R Procedural Language" R •# Also termed imperative language" •# Describe" –#An explicit sequence of steps to follow to produce a result" •# Examples: Basic, Pascal, C, Fortran" 2 R R Functional Language" R •# Describe everything as a function (e.g., data, operations)" •# (+ 3 4); (add (prod 4 5) 3)" •# Examples" –# LISP, Scheme, ML, Haskell" R R Logical Language" R •# Also termed declarative language" •# Establish causal relationships between terms" –#Conclusion :- Conditions" –#Read as: If Conditions then Conclusion" •# Examples: Prolog, Parlog" 3 R R Object-Oriented Programming" R •# Describe " –#A set of user-defined objects " –#And communications among them to produce a (user-defined) result" •# Basic features" –#Encapsulation" –#Inheritance" –#Polymorphism " R R OOP (cont$d)" R •# Example languages" –#First OOP language: SIMULA-67 (1970)" –#Smalltalk, C++, Java" –#Many other:" •# Ada, Object Pascal, Objective C, DRAGOON, BETA, Emerald, POOL, Eiffel, Self, Oblog, ESP, POLKA, Loops, Perl, VB" •# Are OOP languages procedural? " 4 R R We Need More" R •# Major advantage of OOP" –# Modular structure" •# Potential problems with OOP" –# Issues distributed in different modules result in tangled code." –# Example: error logging, failure handling, performance -
An Aggregate Computing Approach to Self-Stabilizing Leader Election
An Aggregate Computing Approach to Self-Stabilizing Leader Election Yuanqiu Mo Jacob Beal Soura Dasgupta University of Iowa Raytheon BBN Technologies University of Iowa⇤ Iowa City, Iowa 52242 Cambridge, MA, USA 02138 Iowa City, Iowa 52242 Email: [email protected] Email: [email protected] Email: [email protected] Abstract—Leader election is one of the core coordination 4" problems of distributed systems, and has been addressed in 3" 1" many different ways suitable for different classes of systems. It is unclear, however, whether existing methods will be effective 7" 1" for resilient device coordination in open, complex, networked 3" distributed systems like smart cities, tactical networks, personal 3" 0" networks and the Internet of Things (IoT). Aggregate computing 2" provides a layered approach to developing such systems, in which resilience is provided by a layer comprising a set of (a) G block (b) C block (c) T block adaptive algorithms whose compositions have been shown to cover a large class of coordination activities. In this paper, Fig. 1. Illustration of three basis block operators: (a) information-spreading (G), (b) information aggregation (C), and (c) temporary state (T) we show how a feedback interconnection of these basis set algorithms can perform distributed leader election resilient to device topology and position changes. We also characterize a key design parameter that defines some important performance a separation of concerns into multiple abstraction layers, much attributes: Too large a value impairs resilience to loss of existing like the OSI model for communication [2], factoring the leaders, while too small a value leads to multiple leaders. -
A Theory of Fault Recovery for Component-Based Models⋆
A Theory of Fault Recovery for Component-based Models? Borzoo Bonakdarpour1, Marius Bozga2, and Gregor G¨ossler3 1 School of Computer Science, University of Waterloo Email: [email protected] 2 VERIMAG/CNRS, Gieres, France Email: [email protected] 3 INRIA-Grenoble, Montbonnot, France Email: [email protected] Abstract. This paper introduces a theory of fault recovery for component- based models. We specify a model in terms of a set of atomic components incrementally composed and synchronized by a set of glue operators. We define what it means for such models to provide a recovery mechanism, so that the model converges to its normal behavior in the presence of faults (e.g., in self-stabilizing systems). We present a sufficient condition for in- crementally composing components to obtain models that provide fault recovery. We identify corrector components whose presence in a model is essential to guarantee recovery after the occurrence of faults. We also for- malize component-based models that effectively separate recovery from functional concerns. We also show that any model that provides fault recovery can be transformed into an equivalent model, where functional and recovery tasks are modularized in different components. Keywords: Fault-tolerance; Transformation; Separation of concerns; BIP 1 Introduction Fault-tolerance has always been an active line of research in design and imple- mentation of dependable systems. Intuitively, tolerating faults involves providing a system with the means to handle unexpected defects, so that the system meets its specification even in the presence of faults. In this context, the notion of spec- ification may vary depending upon the guarantees that the system must deliver in the presence of faults. -
Continuation Join Points
Continuation Join Points Yusuke Endoh, Hidehiko Masuhara, Akinori Yonezawa (University of Tokyo) 1 Background: Aspects are reusable in AspectJ (1) Example: A generic logging aspect can log user inputs in a CUI program by defining a pointcut Login Generic Logging id = readLine(); Aspect Main CUI Aspect cmd = readLine(); pointcut input(): call(readLine()) logging return value 2 Background: Aspects are reusable in AspectJ (2) Example: A generic logging aspect can also log environment variable by also defining a pointcut Q. Now, if we want to log environment variable (getEnv) …? Generic Logging Aspect A. Merely concretize an aspect additionally Env Aspect CUI Aspect pointcut input(): pointcut input(): Aspect reusability call(getEnv()) call(readLine()) 3 Problem: Aspects are not as reusable as expected Example: A generic logging aspect can NOT log inputs in a GUI program by defining a pointcut Login Generic Logging void onSubmit(id) Aspect { … } Main void onSubmit(cmd) GUI Aspect { … } pointcut Input(): call(onSubmit(Str)) logging arguments 4 Why can’t we reuse the aspect? Timing of advice execution depends on both advice modifiers and pointcuts Logging Aspect (inner) Generic Logging abstract pointcut: input(); Aspect after() returning(String s) : input() { Log.add(s); } unable to change to before 5 Workaround in AspectJ is awkward: overview Required changes for more reusable aspect: generic aspect (e.g., logging) two abstract pointcuts, two advice decls. and an auxiliary method concrete aspects two concrete pointcuts even if they are not needed 6 Workaround in AspectJ is awkward: how to define generic aspect Simple Logging Aspect 1. define two pointcuts abstract pointcut: inputAfter(); for before and after abstract pointcut: inputBefore(); after() returning(String s) : inputAfter() { log(s); } 2. -
Towards an Expressive and Scalable Framework for Expressing Join Point Models
Towards an Expressive and Scalable Framework for expressing Join Point Models Pascal Durr, Lodewijk Bergmans, Gurcan Gulesir, Istvan Nagy University of Twente {durr,bergmans,ggulesir,nagyist}@ewi.utwente.nl ABSTRACT a more fine-grained join point model is required. Moreover, Join point models are one of the key features in aspect- these models are mostly rooted in control flow and call graph oriented programming languages and tools. They provide information, but sometimes a pointcut expression based on software engineers means to pinpoint the exact locations in data flow or data dependence is more suitable. programs (join points) to weave in advices. Our experi- ence in modularizing concerns in a large embedded system This paper proposes an expressive and scalable fine-grained showed that existing join point models and their underlying framework to define join point models that incorporate both program representations are not expressive enough. This data and control flow analysis. One can subsequently specify prevents the selection of some join points of our interest. In a pointcut language which implements (part of) this join this paper, we motivate the need for more fine-grained join point model. Allowing different implementation strategies point models within more expressive source code represen- and language independence is the strength of this model. tations. We propose a new program representation called a program graph, over which more fine-grained join point The paper is structured as follows: First, we will motivate models can be defined. In addition, we present a simple lan- this research with two example concerns we encountered in guage to manipulate program graphs to perform source code our IDEALS[6] project with ASML[2]. -
Flowr: Aspect Oriented Programming for Information Flow Control in Ruby
FlowR: Aspect Oriented Programming for Information Flow Control in Ruby Thomas F. J.-M. Pasquier Jean Bacon Brian Shand University of Cambridge Public Health England fthomas.pasquier, [email protected] [email protected] Abstract Track, a taint-tracking system for Ruby, developed by the SafeWeb This paper reports on our experience with providing Information project [17]. Flow Control (IFC) as a library. Our aim was to support the use However, we came to realise certain limitations of the mech- of an unmodified Platform as a Service (PaaS) cloud infrastructure anisms we had deployed. For example, to enforce the required by IFC-aware web applications. We discuss how Aspect Oriented IFC policy, we manually inserted IFC checks at selected applica- Programming (AOP) overcomes the limitations of RubyTrack, our tion component boundaries. In practice, objects and classes are the first approach. Although use of AOP has been mentioned as a natural representation of application components within an object possibility in past IFC literature we believe this paper to be the oriented language and it seems natural to relate security concerns first illustration of how such an implementation can be attempted. with those objects. We should therefore associate the primitives and We discuss how we built FlowR (Information Flow Control for mechanisms to enforce IFC with selected objects. Furthermore, we Ruby), a library extending Ruby to provide IFC primitives using wish to be able to assign boundary checks on any class or object AOP via the Aquarium open source library. Previous attempts at without further development overhead. We also wish to be able providing IFC as a language extension required either modification to exploit the inheritance property to define rules that apply to of an interpreter or significant code rewriting. -
Cs8603-Distributed Systems Syllabus Unit 3 Distributed Mutex & Deadlock Distributed Mutual Exclusion Algorithms: Introducti
CS8603-DISTRIBUTED SYSTEMS SYLLABUS UNIT 3 DISTRIBUTED MUTEX & DEADLOCK Distributed mutual exclusion algorithms: Introduction – Preliminaries – Lamport‘s algorithm –Ricart-Agrawala algorithm – Maekawa‘s algorithm – Suzuki–Kasami‘s broadcast algorithm. Deadlock detection in distributed systems: Introduction – System model – Preliminaries –Models of deadlocks – Knapp‘s classification – Algorithms for the single resource model, the AND model and the OR Model DISTRIBUTED MUTUAL EXCLUSION ALGORITHMS: INTRODUCTION INTRODUCTION MUTUAL EXCLUSION : Mutual exclusion is a fundamental problem in distributed computing systems. Mutual exclusion ensures that concurrent access of processes to a shared resource or data is serialized, that is, executed in a mutually exclusive manner. Mutual exclusion in a distributed system states that only one process is allowed to execute the critical section (CS) at any given time. In a distributed system, shared variables (semaphores) or a local kernel cannot be used to implement mutual exclusion. There are three basic approaches for implementing distributed mutual exclusion: 1. Token-based approach. 2. Non-token-based approach. 3. Quorum-based approach. In the token-based approach, a unique token (also known as the PRIVILEGE message) is shared among the sites. A site is allowed to enter its CS if it possesses the token and it continues to hold the token until the execution of the CS is over. Mutual exclusion is ensured because the token is unique. In the non-token-based approach, two or more successive rounds of messages are exchanged among the sites to determine which site will enter the CS next. Mutual exclusion is enforced because the assertion becomes true only at one site at any given time. -
Separation of Concerns in Multi-Language Specifications
INFORMATICA, 2002, Vol. 13, No. 3, 255–274 255 2002 Institute of Mathematics and Informatics, Vilnius Separation of Concerns in Multi-language Specifications Robertas DAMAŠEVICIUS,ˇ Vytautas ŠTUIKYS Software Engineering Department, Kaunas University of Technology Student¸u 50, 3031 Kaunas, Lithuania e-mail: [email protected], [email protected] Received: April 2002 Abstract. We present an analysis of the separation of concerns in multi-language design and multi- language specifications. The basis for our analysis is the paradigm of the multi-dimensional sepa- ration of concerns, which claims that multiple dimensions of concerns in a design should be imple- mented independently. Multi-language specifications are specifications where different concerns of a design are implemented using separate languages as follows. (1) Target language(s) implement domain functionality. (2) External (or scripting, meta-) language(s) implement generalisation of the repetitive design features, introduce variations, and integrate components into a design. We present case studies and experimental results for the application of the multi-language specifications in hardware design. Key words: multi-language design, separation of concerns, meta-programming, scripting, hardwa- re design. 1. Introduction Today the high-level design of a hardware (HW) system is usually based either on the usage of the pure HW description language (HDL) (e.g., VHDL, Verilog), or the algo- rithmic one (e.g., C++, SystemC), or both. The emerging problems are similar for both, the HW and software (SW) domains. For example, the increasing complexity of SW and HW designs urges the designers and researchers to seek for the new design methodolo- gies. -
Multi-Dimensional Concerns in Parallel Program Design
Multi-Dimensional Concerns in Parallel Program Design Parallel programming is difficult, thus design patterns. Despite rapid advances in parallel hardware performance, the full potential of processing power is not being exploited in the community for one clear reason: difficulty of designing parallel software. Identifying tasks, designing parallel algorithm, and managing the balanced load among the processing units has been a daunting task for novice programmers, and even the experienced programmers are often trapped with design decisions that underachieve in potential peak performance. Over the last decade there have been several approaches in identifying common patterns that are repeatedly used in parallel software design process. Documentation of these “design patterns” helps the programmers by providing definition, solution and guidelines for common parallelization problems. Such patterns can take the form of templates in software tools, written paragraphs with detailed description, or even charts, diagrams and examples. The current parallel patterns prove to be ineffective. In practice, however, the parallel design patterns identified thus far [over the last two decades!] contribute little—if none at all—to development of non-trivial parallel software. In short, the parallel design patterns are too trivial and fail to give detailed guidelines for specific parameters that can affect the performance of wide range of complex problem requirements. By experience in the community, it is coming to a consensus that there are only limited number of patterns; namely pipeline, master & slave, divide & conquer, geometric, replicable, repository, and not many more. So far the community efforts were focused on discovering more design patterns, but new patterns vary a little and fall into range that is not far from one of the patterns mentioned above. -
Aspectj Intertype Declaration Example
Aspectj Intertype Declaration Example Untangible and suspensive Hagen hobbling her dischargers enforced equally or mithridatise satisfactorily, is Tiebold microcosmical? Yule excorticated ill-advisedly if Euro-American Lazare patronised or dislocate. Creakiest Jean-Christophe sometimes diapers his clipper bluely and revitalized so voicelessly! Here is important to form composite pattern determines what i ended up a crosscutting actions taken into account aspectj intertype declaration example. This structure aspectj intertype declaration example also hold between core library dependencies and clean as well as long. Spring boot and data, specific explanation of oop, it is discussed in aop implementation can make it for more modular. This works by aspectj intertype declaration example declarative aspect! So one in joinpoints where singleton, which is performed aspectj intertype declaration example they were taken. You only the switch aspectj intertype declaration example. That is expressed but still confused, and class methods and straightforward to modular reasoning, although support method is necessary to work being a pointcut designators match join us. Based injection as shown in this, and ui layer and advice, after and after a good to subscribe to a variety of an api. What i do not identical will only this requires an example projects. Which aop aspectj intertype declaration example that stripe represents the join point executes unless an exception has finished, as a teacher from is pretty printer. Additional options aspectj intertype declaration example for full details about it will be maintained. The requirements with references to aspectj intertype declaration example is essential way that? Exactly bud the code runs depends on the kind to advice. -
Aspect-Oriented Programmingprogramming Wes Weimer
Aspect-OrientedAspect-Oriented ProgrammingProgramming Wes Weimer (slides adapted from Dave Matuszek, UPenn) Programming paradigms Procedural (or imperative) programming Executing a set of commands in a given sequence Fortran, C, Cobol Functional programming Evaluating a function defined in terms of other functions Scheme, Lisp, ML, OCaml Logic programming Proving a theorem by finding values for the free variables Prolog Object-oriented programming (OOP) Organizing a set of objects, each with its own set of responsibilities Smalltalk, Java, Ruby, C++ (to some extent) Aspect-oriented programming (AOP) = aka Aspect-Oriented Software Design (AOSD) Executing code whenever a program shows certain behaviors AspectJ (a Java extension), Aspect#, AspectC++, … Does not replace O-O programming, but rather complements it 2 Why Learn Aspect-Oriented Design? Pragmatics – Google stats (Apr '09): “guitar hero” 36.8 million “object-oriented” 11.2 million “cobol” 6.6 million “design patterns” 3.0 million “extreme programming” 1.0 million “functional programming” 0.8 million “aspect-oriented” or “AOSD” 0.3 million But it’s growing Just like OOP was years ago Especially in the Java / Eclipse / JBoss world 3 Motivation By Allegory Imagine that you’re the ruler of a fantasy monarchy 4 Motivation By Allegory (2) You announce Wedding 1.0, but must increase security 5 Motivation By Allegory (3) You must make changes everywhere: close the secret door 6 Motivation By Allegory (4) … form a brute squad … 7 Motivation By Allegory (5) -
Aspectmaps: a Scalable Visualization of Join Point Shadows
AspectMaps: A Scalable Visualization of Join Point Shadows Johan Fabry ∗ Andy Kellens y Simon Denier PLEIAD Laboratory Software Languages Lab Stephane´ Ducasse Computer Science Department (DCC) Vrije Universiteit Brussel RMoD, INRIA Lille - Nord Europe University of Chile Belgium France http://pleiad.cl http://soft.vub.ac.be http://rmod.lille.inria.fr of join points. Second, the specification of the implicit invocations is made through a pointcut that selects at which join points the Abstract aspect executes. The behavior specification of the aspect is called the advice. An aspect may contain various pointcuts and advices, When using Aspect-Oriented Programming, it is sometimes diffi- where each advice is associated with one pointcut. cult to determine at which join point an aspect will execute. Simi- The concepts of pointcuts and advices open up new possibil- larly, when considering one join point, knowing which aspects will ities in terms of modularization, allowing for a clean separation execute there and in what order is non-trivial. This makes it difficult between base code and crosscutting concerns. However this sepa- to understand how the application will behave. A number of visu- ration makes it more difficult for a developer to assess system be- alization tools have been proposed that attempt to provide support havior. In particular, the implicit invocation mechanism introduces for such program understanding. However, they neither scale up to an additional layer of complexity in the construction of a system. large code bases nor scale down to understanding what happens at This can make it harder to understand how base system and aspects a single join point.