Aspect] is a simple and practical aspect-oriented extension to Java With just a few new constructs, AspectJ provides support for modular implementation of a range of crosscutting concerns. In AspectJ's dynamic join point model, join points are well-defined points in the execution of the program; pointcuts are collections of join points; advice are special method-like constructs that can be attached to pointcuts; and aspects are modular units of crosscutting implementation, comprising pointcuts, advice, and ordinary Java member declarations. AspectJ code is compiled into standard Java bytecode. Simple extensions to existing Java development environments make it possible to browse the crosscutting structure of aspects in the same kind of way as one browses the inheritance structure of classes. Several examples show that AspectJ is powerful, and that programs written using it are easy to understand.

An overview of AspectJ

Distribution-related concerns, such as data replication, often crosscut the business code of a distributed application. Currently such crosscutting concerns are frequently realized on top of distributed frameworks, such as EJBs, and initial AO support for the modularization of such crosscutting concerns, e.g., JBoss AOP and Spring AOP, has been proposed.Based on an investigation of the implementation of replicated caches using JBoss Cache, we motivate that crosscutting concerns of distributed applications benefit from an aspect language for explicit distributed programming. We propose AWED, a new aspect language with explicit distributed programming mechanisms, which provides three contributions. First, remote pointcut constructors which are more general than those of previous related approaches, in particular, supporting remote sequences. Second, a notion of distributed advice with support for asynchronous and synchronous execution. Third, a notion of distributed aspects including models for the deployment, instantiation and state sharing of aspects. We show several concrete examples how AWED can be used to modularly implement and extend replicated cache implementations. Finally, we present a prototype implementation of AWED, which we have realized by extending JAsCo, a system providing dynamic aspects for Java.

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Explicitly distributed AOP using AWED

Our work is along the line of the work of B. Smith and P. Maes. We first discuss our notion of reflection in object-oriented concurrent computation and then present a reflective object-oriented concurrent language ABCL/R. We give several illustrative examples of reflective programming such as (1) dynamic concurrent acquisition of “methods” from other objects, (2) monitoring the behavior of concurrently running objects, and (3) augmentation of the time warp mechanism to a concurrent system. Also the definition of a meta-circular interpreter of this language is given as the definition of a meta-object. The language ABCL/R has been implemented. All the examples given in this paper are running on our ABCL/R system.

Reflection in an Object-Oriented Concurrent Language.

Silicon (Si) is not classified as an essential element for plants, but numerous studies have demonstrated its beneficial effects in a variety of species and environmental conditions, including low nutrient availability. Application of Si shows the potential to increase nutrient availability in the rhizosphere and root uptake through complex mechanisms, which still remain unclear. Silicon-mediated transcriptional regulation of element transporters for both root acquisition and tissue homeostasis has recently been suggested as an important strategy, varying in detail depending on plant species and nutritional status. Here, we summarize evidence of Si-mediated acquisition, uptake and translocation of nutrients: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), boron (B), chlorine (Cl), and nickel (Ni) under both deficiency and excess conditions. In addition, we discuss interactions of Si-with beneficial elements: aluminum (Al), sodium (Na), and selenium (Se). This review also highlights further research needed to improve understanding of Si-mediated acquisition and utilization of nutrients and vice versa nutrient status-mediated Si acquisition and transport, both processes which are of high importance for agronomic practice (e.g., reduced use of fertilizers and pesticides).

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Interactions of Silicon With Essential and Beneficial Elements in Plants.

http://www.hirschfeld.org/writings/media/LinckeAppeltauerSteinertHirschfeld_2010_AnOpenImplementationForContextOrientedLayerCompositionInContextJS_AuthorsVersionElsevier.pdf

An open implementation for context-oriented layer composition in ContextJS

JavaScript is widely used to build increasingly complex Web applications. Unsurprisingly, these applications need to address cross-cutting concerns. Therefore support for aspect-oriented programming is crucial to preserve proper modularity. However, there is no aspect-oriented extension of JavaScript that fully embraces the characterizing features of that language: dynamic prototype-based programming with higher-order functions. In this paper, we present AspectScript, a full-fledged AOP extension of JavaScript that adopts higher-order programming and dynamicity as its core design principles. In AspectScript, pointcuts and advices are standard JavaScript functions, bringing the benefits of higher-order programming patterns to define aspects. In addition, AspectScript integrates a number of state-of-the-art AOP features like dynamic aspect deployment with scoping strategies, and user-defined quantified events. We illustrate AspectScript in action with several practical examples from the realm of client Web applications, and report on its current implementation. AspectScript is a practical extension that provides better modularity support to build Web applications, and that will eventually make it possible to empirically validate the benefits brought by advanced aspect language mechanisms in an evergrowing application domain.

/pdf/aspectscript-expressive-aspects-for-the-web-ux8o6odqgx.pdf

AspectScript: expressive aspects for the web

The purpose of this study is to evaluate the relationship between Si and NH4+ toxicity in the context of the nutrition, physiology, and production of sugar beet grown using hydroponics. We hypothesized that NH4+ affects the physiology of the plant, accumulation of nutrients, and dry matter, with the possibility for Si to mitigate this toxicity. The experimental design used was completely randomized, in a factorial scheme of 2 × 5, corresponding with the absence and presence of Si (2 mmol L−1) and five concentrations of NH4+ with four replicates. The following series of physiological evaluations were carried out: photosynthesis, stomatal conductance, transpiration, with the use of an infrared gas analyzer (LICOR, Inc., LI-6400), the dry biomass, N and Si accumulation, and Si use efficiency in the roots. Accumulation of N and photosynthesis in the leaves was higher in the presence of Si. An increase of NH4+ increased transpiration, especially in the plants cultivated without the incorporation of Si. Stomatal conductance was lower in the presence of Si. Dry matter was reduced when plants were exposed to higher concentrations of NH4+, showing a greater reduction in the root than in the aerial part. The use of NH4+ equal to or higher than 15 mmol L−1 damaged the photosynthesis. Transpiration and stomatal conductance were less affected in the presence of Si and in the accumulation of N and Si in the roots. Dry matter was reduced when plants were exposed to higher concentrations of NH4+, and this effect was mitigated in the presence of Si.

Silicon Supplementation Alleviates Ammonium Toxicity in Sugar Beet ( Beta vulgaris L.)

Aspect-Oriented Programming (AOP) promotes better separation of concerns in software systems by introducing aspects for the modular implementation of crosscutting concerns As a result, modularity and adaptability of software systems are greatly enhanced To date, very few AOP proposals take distribution into account This paper considers the explicit introduction of distribution in AOP, by proposing support for distributed aspects: all dimensions of aspects are studied in the light of distribution The result of this work is a versatile kernel for distributed AOP in Java: a flexible infrastructure that allows aspects to be defined and applied in a distributed manner, on top of which various distributed aspect languages and frameworks can be defined

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A versatile kernel for distributed AOP

It is inevitable that some concerns crosscut a sizeable application, resulting in code scattering and tangling. This issue is particularly severe for security-related concerns: It is difficult to be confident about the security of an application when the implementation of its security-related concerns is scattered all over the code and tangled with other concerns, making global reasoning about security precarious. In this study, we consider the case of access control in Java, which turns out to be a crosscutting concern with a nonmodular implementation based on runtime stack inspection. We describe the process of modularizing access control in Java by means of Aspect-Oriented Programming (AOP). We first show a solution based on AspectJ, the most popular aspect-oriented extension to Java, that must rely on a separate automata infrastructure. We then put forward a novel solution via dynamic deployment of aspects and scoping strategies. Both solutions, apart from providing a modular specification of access control, make it possible to easily express other useful policies such as the Chinese wall policy. However, relying on expressive scope control results in a compact implementation, which, at the same time, permits the straightforward expression of even more interesting policies. These new modular implementations allowed by AOP alleviate maintenance and evolution issues produced by the crosscutting nature of access control.

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Aspectizing Java Access Control

https://www.dcc.uchile.cl/TR/2006/TR_DCC-2006-018.pdf

Rodolfo Toledo

Papers

AspectScript: expressive aspects for the web

Silicon Supplementation Alleviates Ammonium Toxicity in Sugar Beet ( Beta vulgaris L.)

A versatile kernel for distributed AOP

Aspectizing Java Access Control

Flexible metaprogramming and AOP in Java