Cross-cutting concern - AbsoluteAstronomy.com

Computer science

Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...

, cross-cutting concerns are aspects of a program

Computer program

A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...

which affect other concerns

Concern (computer science)

In computer science, a concern is a particular set of behaviors needed by a computer program, the conceptual sections. A concern can be as general as database interaction or as specific as performing a calculation, depending on the level of conversation between developers and the program being...

.
These concerns often cannot be cleanly decomposed

Modularity (programming)

Modular programming is a software design technique that increases the extent to which software is composed of separate, interchangeable components called modules by breaking down program functions into modules, each of which accomplishes one function and contains everything necessary to accomplish...

from the rest of the system in both the design and implementation, and can result in either scattering (code

Source code

In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...

duplication), tangling (significant dependencies between systems), or both.

For instance, if writing an application

Application software

Application software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with...

for handling medical records, the bookkeeping and indexing of such records is a core concern

Core concern

In computer science, a core concern is one of the main concerns a program is written for. The main coding of the application is to satisfy the core concerns, such as doing the tasks as visualized...

, while logging a history of changes to the record database or user database, or an authentication system, would be cross-cutting concerns since they touch more parts of the program.

Background

Cross-cutting concerns are parts of a program which rely on or must affect many other parts of the system. They form the basis for the development of aspects

Aspect (computer science)

In computer science, an aspect of a program is a feature linked to many other parts of the program, but which is not related to the program's primary function. An aspect crosscuts the program's core concerns, therefore violating its separation of concerns that tries to encapsulate unrelated functions...

. Such cross-cutting concerns do not fit cleanly into object-oriented programming

Object-oriented programming

Object-oriented programming is a programming paradigm using "objects" – data structures consisting of data fields and methods together with their interactions – to design applications and computer programs. Programming techniques may include features such as data abstraction,...

or procedural programming

Procedural programming

Procedural programming can sometimes be used as a synonym for imperative programming , but can also refer to a programming paradigm, derived from structured programming, based upon the concept of the procedure call...

.

Cross-cutting concerns can be directly responsible for tangling, or system inter-dependencies, within a program

Computer program

. Because procedural and functional language constructs consist entirely of procedure calling, there is no semantic through which two goals (the capability to be implemented and the related cross-cutting concern) can be addressed simultaneously. As a result, the code addressing the cross-cutting concern must be scattered, or duplicated, across the various related locations, resulting in a loss of modularity

Modularity (programming)

.

Aspect-oriented programming

Aspect-oriented programming

In computing, aspect-oriented programming is a programming paradigm which aims to increase modularity by allowing the separation of cross-cutting concerns...

aims to encapsulate cross-cutting concerns into aspects

Aspect (computer science)

to retain modularity. This allows for the clean isolation and reuse of code addressing the cross-cutting concern. By basing designs on cross-cutting concerns, software engineering

Software engineering

Software Engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software, and the study of these approaches; that is, the application of engineering to software...

benefits are affected, including modularity and simplified maintenance.

Examples

Examples of concerns that tend to be crosscutting include:

Synchronization
Synchronization (computer science)
In computer science, synchronization refers to one of two distinct but related concepts: synchronization of processes, and synchronization of data. Process synchronization refers to the idea that multiple processes are to join up or handshake at a certain point, so as to reach an agreement or...
Real-time constraints
Real-time computing
In computer science, real-time computing , or reactive computing, is the study of hardware and software systems that are subject to a "real-time constraint"— e.g. operational deadlines from event to system response. Real-time programs must guarantee response within strict time constraints...
Error detection and correction
Error detection and correction
In information theory and coding theory with applications in computer science and telecommunication, error detection and correction or error control are techniques that enable reliable delivery of digital data over unreliable communication channels...
Product features
Feature interaction problem
Feature interaction is a software engineering concept. It occurs when the integration of two features would modify the behavior of one or both features....
Memory management
Memory management
Memory management is the act of managing computer memory. The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and freeing it for reuse when no longer needed. This is critical to the computer system.Several...
Data validation
Data validation
In computer science, data validation is the process of ensuring that a program operates on clean, correct and useful data. It uses routines, often called "validation rules" or "check routines", that check for correctness, meaningfulness, and security of data that are input to the system...
Persistence
Persistence (computer science)
Persistence in computer science refers to the characteristic of state that outlives the process that created it. Without this capability, state would only exist in RAM, and would be lost when this RAM loses power, such as a computer shutdown....
Transaction processing
Transaction processing
In computer science, transaction processing is information processing that is divided into individual, indivisible operations, called transactions. Each transaction must succeed or fail as a complete unit; it cannot remain in an intermediate state...
Internationalization and localization
Internationalization and localization
In computing, internationalization and localization are means of adapting computer software to different languages, regional differences and technical requirements of a target market...

which includes Language localisation
Language localisation
Language localisationThe spelling "localization", a variant of "localisation", is the preferred spelling in the US and Canada. is the second phase of a larger process of product translation and cultural adaptation to account for...
Information security
Information security
Information security means protecting information and information systems from unauthorized access, use, disclosure, disruption, modification, perusal, inspection, recording or destruction....
Caching
Cache
In computer engineering, a cache is a component that transparently stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere...
Logging
Monitoring
Observer pattern
The observer pattern is a software design pattern in which an object, called the subject, maintains a list of its dependents, called observers, and notifies them automatically of any state changes, usually by calling one of their methods...
Business rule
Business rule
A Business rule is a statement that defines or constrains some aspect of the business and always resolves to either true or false. Business rules are intended to assert business structure or to control or influence the behavior of the business. Business rules describe the operations, definitions...

s
Code mobility
Mobile code
In computer science, mobile code is software transferred between systems, e.g. transferred across a network or via a USB flash drive, and executed on a local system without explicit installation or execution by the recipient...
Domain-specific optimizations
Optimization (computer science)
In computer science, program optimization or software optimization is the process of modifying a software system to make some aspect of it work more efficiently or use fewer resources...

External links

AOSD.net's glossary of aspect oriented
Aspect-oriented programming
In computing, aspect-oriented programming is a programming paradigm which aims to increase modularity by allowing the separation of cross-cutting concerns...

terms.
AspectJ
AspectJ
AspectJ is an aspect-oriented extension created at PARC for the Java programming language. It is available in Eclipse Foundation open-source projects, both stand-alone and integrated into Eclipse. AspectJ has become the widely-used de-facto standard for AOP by emphasizing simplicity and usability...

http://eclipse.org/aspectj/, an Aspect-Oriented extension to the Java programming language
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
Bergmans, L., M. Aksit (2001): Composing Multiple Concerns Using Composition Filters, http://trese.cs.utwente.nl/ (24 July 2004)
Berg, K. van den, Conejero, J. and Chitchyan, R. (2005). AOSD Ontology 1.0 ‐ Public Ontology of Aspect‐Orientation. AOSD Europe Network of Excellence, retrieved May 2005, from http://www.aosd-europe.net/deliverables/d9.pdf
Here is an example of handling a cross-cutting concern: http://blogs.captechconsulting.com/blog/balaji-muthuvarathan/persistence-pattern-using-threadlocal-and-ejb-interceptors

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

Background

Examples

See also

Further reading

External links