This document discusses design patterns at the medium scale level between architectural patterns and programming language idioms. It provides an overview of different categories of design patterns including structural decomposition, organization of work, access control, management, and communication. It then focuses on explaining the whole-part pattern for structural decomposition and the master-slave pattern for organizing work. It describes the context, problem, solution, structure, dynamics, implementation, variants, examples, and consequences of these two patterns.
Improved stability of products or packages, forming a unit load
More efficient handling and storage of unit loads
Some degree of dust and moisture protection
Some degree of tamper resistance and resistance to package
pilferage
The document discusses OGSI (Open Grid Services Infrastructure), which defines mechanisms for creating, managing, and exchanging information among grid services. OGSI builds on web services standards like SOAP, XML, and WS-Security to provide a common way to access grid services. The Open Grid Services Architecture (OGSA) defines the overall structure and services provided in grid environments. OGSI further specifies the behaviors and interfaces that define how clients interact with grid capabilities. Standards are important for making grid computing practical by enabling interoperability, application portability, and efficient resource sharing across systems.
Type constructor concepts where the examples are clearly described and points are easy to understand. Every point is clearly connected once we go through ppts.
Client Server Architecture in Software engineeringpruthvi2898
What is client?
A client is a single-user workstation ...
What is server?
A server is one or more multi-user processors ..
What is client server architecture?
Client-server architecture is a network architecture ...
Types of client server architecture.
2 types
1) 2-tier
2) 3-tier
Transactions and Concurrency Control in distributed systems. Transaction properties, classification, and transaction implementation. Flat, Nested, and Distributed transactions. Inconsistent Retrievals, Lost Update, Dirty Read, and Premature Writes Problem
The document describes an architecture framework for ecommerce applications consisting of 6 layers: 1) Application services with consumer, business, and intra-organization applications, 2) Brokerage and data management for service integration, 3) Interface layer providing catalogs and directories, 4) Secure messaging for communicating data, 5) Middleware services for interaction between systems, and 6) Network infrastructure including the World Wide Web as an architecture with protocols like HTTP, IP, and TCP. Communication between layers is enabled by protocols such as FTP, HTTP, SMTP, and SSL to securely transfer files and messages.
The document describes the seven layers of the Open Systems Interconnection (OSI) model from the physical layer to the application layer. It provides details on the responsibilities of each layer, including moving bits at the physical layer, packaging data into frames at the data link layer, routing packets at the network layer, managing flows at the transport layer, maintaining sessions at the session layer, and providing access to applications at the application layer. The presentation layer is responsible for translation, compression, and encryption between the application and network layers.
Query Decomposition and data localization Hafiz faiz
This document discusses query processing in distributed databases. It describes query decomposition, which transforms a high-level query into an equivalent lower-level algebraic query. The main steps in query decomposition are normalization, analysis, redundancy elimination, and rewriting the query in relational algebra. Data localization then translates the algebraic query on global relations into a query on physical database fragments using fragmentation rules.
Improved stability of products or packages, forming a unit load
More efficient handling and storage of unit loads
Some degree of dust and moisture protection
Some degree of tamper resistance and resistance to package
pilferage
The document discusses OGSI (Open Grid Services Infrastructure), which defines mechanisms for creating, managing, and exchanging information among grid services. OGSI builds on web services standards like SOAP, XML, and WS-Security to provide a common way to access grid services. The Open Grid Services Architecture (OGSA) defines the overall structure and services provided in grid environments. OGSI further specifies the behaviors and interfaces that define how clients interact with grid capabilities. Standards are important for making grid computing practical by enabling interoperability, application portability, and efficient resource sharing across systems.
Type constructor concepts where the examples are clearly described and points are easy to understand. Every point is clearly connected once we go through ppts.
Client Server Architecture in Software engineeringpruthvi2898
What is client?
A client is a single-user workstation ...
What is server?
A server is one or more multi-user processors ..
What is client server architecture?
Client-server architecture is a network architecture ...
Types of client server architecture.
2 types
1) 2-tier
2) 3-tier
Transactions and Concurrency Control in distributed systems. Transaction properties, classification, and transaction implementation. Flat, Nested, and Distributed transactions. Inconsistent Retrievals, Lost Update, Dirty Read, and Premature Writes Problem
The document describes an architecture framework for ecommerce applications consisting of 6 layers: 1) Application services with consumer, business, and intra-organization applications, 2) Brokerage and data management for service integration, 3) Interface layer providing catalogs and directories, 4) Secure messaging for communicating data, 5) Middleware services for interaction between systems, and 6) Network infrastructure including the World Wide Web as an architecture with protocols like HTTP, IP, and TCP. Communication between layers is enabled by protocols such as FTP, HTTP, SMTP, and SSL to securely transfer files and messages.
The document describes the seven layers of the Open Systems Interconnection (OSI) model from the physical layer to the application layer. It provides details on the responsibilities of each layer, including moving bits at the physical layer, packaging data into frames at the data link layer, routing packets at the network layer, managing flows at the transport layer, maintaining sessions at the session layer, and providing access to applications at the application layer. The presentation layer is responsible for translation, compression, and encryption between the application and network layers.
Query Decomposition and data localization Hafiz faiz
This document discusses query processing in distributed databases. It describes query decomposition, which transforms a high-level query into an equivalent lower-level algebraic query. The main steps in query decomposition are normalization, analysis, redundancy elimination, and rewriting the query in relational algebra. Data localization then translates the algebraic query on global relations into a query on physical database fragments using fragmentation rules.
This document provides an overview of relational algebra operations. There are five basic relational algebra operators: select, project, union, intersection, and cartesian product. The select and project operators are unary operators that operate on a single relation. Select filters rows based on a predicate, while project extracts specified column values. Union and intersection are binary operators that combine two relations, union returning all rows and intersection returning matching rows. Cartesian product returns all possible combinations of rows from two relations. Relational algebra provides a way to formulate queries using these relational operators.
J2EE is a Java platform for developing distributed, transactional, multi-tier enterprise applications. It includes technologies like servlets, JSPs, EJBs, and services like JMS, JTA, and JNDI. The purpose of J2EE is to support developing applications that are distributed, transactional, and secure across multiple tiers. Common architectures include 2-tier client-server, 3-tier with separation of presentation, business and data layers, and n-tier with additional logical separations. MVC is a common design pattern that separates the application into model, view and controller components.
CORBA allows software components written in different languages and running on different machines to communicate. It defines IDL for language-neutral interfaces and an ORB that handles remote requests between clients and servers transparently. The presentation discusses CORBA concepts and architecture, including components like IDL, ORB, object adapters, and the interface repository that enable communication across heterogeneous systems.
This document discusses resource management techniques in distributed systems. It covers three main scheduling techniques: task assignment approach, load balancing approach, and load sharing approach. It also outlines desirable features of good global scheduling algorithms such as having no a priori knowledge about processes, being dynamic in nature, having quick decision-making capability, balancing system performance and scheduling overhead, stability, scalability, fault tolerance, and fairness of service. Finally, it discusses policies for load estimation, process transfer, state information exchange, location, priority assignment, and migration limiting that distributed load balancing algorithms employ.
1. The Common Object Request Broker Architecture (CORBA) enables software components written in different languages and running on different computers to communicate.
2. An Object Request Broker (ORB) is the core of any CORBA distributed system and is responsible for enabling communication between objects and clients while hiding issues related to distribution and heterogeneity.
3. CORBA uses an object-oriented model where object implementations reside on servers and are specified using the CORBA Interface Definition Language (IDL). The ORB handles object invocations between clients and servers.
The document discusses web security for e-commerce and describes various threats such as insecure transmission and unauthorized access. It explains methods for protecting online businesses including cryptographic techniques, transport and application layer security, and firewalls. Specific topics covered include client/server applications, communication channels, OSI and TCP/IP models, security threats, cryptography services, digital signatures, envelopes, certificates, and secure channels.
The document discusses database management systems and data independence. It defines data independence as the ability to change the database schema at one level without requiring changes at other levels. There are two types of data independence: logical data independence, which allows changing the conceptual schema without changing the external schema; and physical data independence, which allows changing the internal schema without changing the conceptual schema. The document provides examples of each type of data independence and explains the importance of data independence for database maintenance and flexibility.
Hey friends, here is my "query tree" assignment. :-) I have searched a lot to get this master piece :p and I can guarantee you that this one gonna help you In Sha ALLAH more than any else document on the subject. Have a good day :-)
This document contains teaching material on distributed systems operating systems from the book "Distributed Systems: Concepts and Design". It discusses key concepts around processes, threads, communication, and operating system architecture to support distributed applications and middleware. The material is made available for teaching purposes and cannot be used without permission.
The document describes different types of database system users and components. It discusses naive users, application programmers, sophisticated users, and database administrators. It then explains the roles of the query processor, DML compiler, DDL interpreter, compiler and linker, and query evaluation engine. The document also outlines the functions of the storage manager, authorization manager, integrity manager, transaction manager, file manager, and buffer manager. It concludes by comparing the two-tier and three-tier client-server architectures.
Halftoning is the process of converting a greyscale image to a binary image made up of black and white dots. In newspapers, halftoning simulates greyscale using patterns of black dots of varying sizes on a white background. Traditionally, halftoning was done photographically by projecting an image through a halftone screen with an etched grid onto film. Different screen frequencies control dot size. Digital halftoning techniques include patterning, which replaces each pixel with a pattern from a binary font, and dithering, which thresholds the image against a dither matrix to determine black and white pixels.
The document summarizes key concepts in distributed database systems including:
1) Distributed database architectures have external, conceptual, and internal views of data. Common architectures include client-server and peer-to-peer.
2) Distributed databases can be designed top-down using a global schema or bottom-up without a global schema.
3) Fragmentation and allocation distribute data across sites for performance and availability. Correct fragmentation follows completeness, reconstruction, and disjointness rules.
This document discusses distributed databases and distributed database management systems (DDBMS). It defines a distributed database as a logically interrelated collection of shared data physically distributed over a computer network. A DDBMS is software that manages the distributed database and makes the distribution transparent to users. The document outlines key concepts of distributed databases including data fragmentation, allocation, and replication across multiple database sites connected by a network. It also discusses reference architectures, components, design considerations, and types of transparency provided by DDBMS.
The document discusses distributed query processing and optimization in distributed database systems. It covers topics like query decomposition, distributed query optimization techniques including cost models, statistics collection and use, and algorithms for query optimization. Specifically, it describes the process of optimizing queries distributed across multiple database fragments or sites including generating the search space of possible query execution plans, using cost functions and statistics to pick the best plan, and examples of deterministic and randomized search strategies used.
A network switch is a telecommunications device that receives messages and sends them to their intended destinations. It connects network segments or devices and forwards data to one or multiple targets that need to receive it. Switches operate at the data link layer to process and forward data, unlike hubs but similar to routers. They improve network performance by reducing broadcast domains and using hardware to map ports to device addresses.
This document discusses various learning theories relevant to nursing education. It describes behavioral learning theories which focus on observable behaviors and stimuli-response models. Cognitive learning theories consider thoughts and mental processes. Adult learning theory proposes adults are self-directed learners who need to understand why they are learning something. Bandura's social learning theory emphasizes modeling behaviors and developing self-efficacy. The document also covers Piaget's stages of cognitive development and Gagne's categories of learning outcomes.
The document discusses 2D arrays, including their definition as an array of arrays, implementation methods of row-major and column-major ordering, and formulas for calculating element addresses based on storage method. It also covers basic arithmetic operations on 2D arrays like addition, subtraction, and multiplication. Examples of problems involving 2D arrays and their solutions are provided.
This document provides an overview of relational algebra operations. There are five basic relational algebra operators: select, project, union, intersection, and cartesian product. The select and project operators are unary operators that operate on a single relation. Select filters rows based on a predicate, while project extracts specified column values. Union and intersection are binary operators that combine two relations, union returning all rows and intersection returning matching rows. Cartesian product returns all possible combinations of rows from two relations. Relational algebra provides a way to formulate queries using these relational operators.
J2EE is a Java platform for developing distributed, transactional, multi-tier enterprise applications. It includes technologies like servlets, JSPs, EJBs, and services like JMS, JTA, and JNDI. The purpose of J2EE is to support developing applications that are distributed, transactional, and secure across multiple tiers. Common architectures include 2-tier client-server, 3-tier with separation of presentation, business and data layers, and n-tier with additional logical separations. MVC is a common design pattern that separates the application into model, view and controller components.
CORBA allows software components written in different languages and running on different machines to communicate. It defines IDL for language-neutral interfaces and an ORB that handles remote requests between clients and servers transparently. The presentation discusses CORBA concepts and architecture, including components like IDL, ORB, object adapters, and the interface repository that enable communication across heterogeneous systems.
This document discusses resource management techniques in distributed systems. It covers three main scheduling techniques: task assignment approach, load balancing approach, and load sharing approach. It also outlines desirable features of good global scheduling algorithms such as having no a priori knowledge about processes, being dynamic in nature, having quick decision-making capability, balancing system performance and scheduling overhead, stability, scalability, fault tolerance, and fairness of service. Finally, it discusses policies for load estimation, process transfer, state information exchange, location, priority assignment, and migration limiting that distributed load balancing algorithms employ.
1. The Common Object Request Broker Architecture (CORBA) enables software components written in different languages and running on different computers to communicate.
2. An Object Request Broker (ORB) is the core of any CORBA distributed system and is responsible for enabling communication between objects and clients while hiding issues related to distribution and heterogeneity.
3. CORBA uses an object-oriented model where object implementations reside on servers and are specified using the CORBA Interface Definition Language (IDL). The ORB handles object invocations between clients and servers.
The document discusses web security for e-commerce and describes various threats such as insecure transmission and unauthorized access. It explains methods for protecting online businesses including cryptographic techniques, transport and application layer security, and firewalls. Specific topics covered include client/server applications, communication channels, OSI and TCP/IP models, security threats, cryptography services, digital signatures, envelopes, certificates, and secure channels.
The document discusses database management systems and data independence. It defines data independence as the ability to change the database schema at one level without requiring changes at other levels. There are two types of data independence: logical data independence, which allows changing the conceptual schema without changing the external schema; and physical data independence, which allows changing the internal schema without changing the conceptual schema. The document provides examples of each type of data independence and explains the importance of data independence for database maintenance and flexibility.
Hey friends, here is my "query tree" assignment. :-) I have searched a lot to get this master piece :p and I can guarantee you that this one gonna help you In Sha ALLAH more than any else document on the subject. Have a good day :-)
This document contains teaching material on distributed systems operating systems from the book "Distributed Systems: Concepts and Design". It discusses key concepts around processes, threads, communication, and operating system architecture to support distributed applications and middleware. The material is made available for teaching purposes and cannot be used without permission.
The document describes different types of database system users and components. It discusses naive users, application programmers, sophisticated users, and database administrators. It then explains the roles of the query processor, DML compiler, DDL interpreter, compiler and linker, and query evaluation engine. The document also outlines the functions of the storage manager, authorization manager, integrity manager, transaction manager, file manager, and buffer manager. It concludes by comparing the two-tier and three-tier client-server architectures.
Halftoning is the process of converting a greyscale image to a binary image made up of black and white dots. In newspapers, halftoning simulates greyscale using patterns of black dots of varying sizes on a white background. Traditionally, halftoning was done photographically by projecting an image through a halftone screen with an etched grid onto film. Different screen frequencies control dot size. Digital halftoning techniques include patterning, which replaces each pixel with a pattern from a binary font, and dithering, which thresholds the image against a dither matrix to determine black and white pixels.
The document summarizes key concepts in distributed database systems including:
1) Distributed database architectures have external, conceptual, and internal views of data. Common architectures include client-server and peer-to-peer.
2) Distributed databases can be designed top-down using a global schema or bottom-up without a global schema.
3) Fragmentation and allocation distribute data across sites for performance and availability. Correct fragmentation follows completeness, reconstruction, and disjointness rules.
This document discusses distributed databases and distributed database management systems (DDBMS). It defines a distributed database as a logically interrelated collection of shared data physically distributed over a computer network. A DDBMS is software that manages the distributed database and makes the distribution transparent to users. The document outlines key concepts of distributed databases including data fragmentation, allocation, and replication across multiple database sites connected by a network. It also discusses reference architectures, components, design considerations, and types of transparency provided by DDBMS.
The document discusses distributed query processing and optimization in distributed database systems. It covers topics like query decomposition, distributed query optimization techniques including cost models, statistics collection and use, and algorithms for query optimization. Specifically, it describes the process of optimizing queries distributed across multiple database fragments or sites including generating the search space of possible query execution plans, using cost functions and statistics to pick the best plan, and examples of deterministic and randomized search strategies used.
A network switch is a telecommunications device that receives messages and sends them to their intended destinations. It connects network segments or devices and forwards data to one or multiple targets that need to receive it. Switches operate at the data link layer to process and forward data, unlike hubs but similar to routers. They improve network performance by reducing broadcast domains and using hardware to map ports to device addresses.
This document discusses various learning theories relevant to nursing education. It describes behavioral learning theories which focus on observable behaviors and stimuli-response models. Cognitive learning theories consider thoughts and mental processes. Adult learning theory proposes adults are self-directed learners who need to understand why they are learning something. Bandura's social learning theory emphasizes modeling behaviors and developing self-efficacy. The document also covers Piaget's stages of cognitive development and Gagne's categories of learning outcomes.
The document discusses 2D arrays, including their definition as an array of arrays, implementation methods of row-major and column-major ordering, and formulas for calculating element addresses based on storage method. It also covers basic arithmetic operations on 2D arrays like addition, subtraction, and multiplication. Examples of problems involving 2D arrays and their solutions are provided.
Two dimensional arrays in C can be declared and initialized similarly to one dimensional arrays, with the first subscript specifying the row and second subscript specifying the column. Elements are stored in contiguous memory locations in row-major order. The document then presents a sample problem of reading a 2D array of integers from a file, finding the largest element, and printing it out. It also discusses using typedef to define custom data types like matrices and strings.
The document provides an overview of the publish-subscribe model from the perspective of a database. It discusses key aspects of the publish-subscribe model including decoupling of publishers and subscribers, subscription models, and quality measures. It also examines applying publish-subscribe concepts in databases through expressions, continuous queries, and using XML with XFilters and SQL queries.
The document summarizes key concepts about arrays including:
1) Arrays can store homogeneous elements and are stored in consecutive memory locations. Common array types include one-dimensional, two-dimensional, and multi-dimensional arrays.
2) Operations on arrays include insertion, deletion, merging, traversing, and sorting elements. Common sorting algorithms discussed include selection sort and bubble sort.
3) Linear arrays have limitations such as the need to pre-determine the number of elements and static memory allocation.
The document discusses several design patterns including Observer, State, Template Method, Memento, Command, Chain of Responsibility, Interpreter, Mediator, Iterator, Strategy, Visitor, Flyweight, and Singleton patterns. For each pattern, it provides the definition, participants, structure, intent, caveats, and examples.
The document provides an introduction and overview of design patterns. It defines design patterns as common solutions to recurring problems in software design. The document discusses the origin of design patterns in architecture, describes the four essential parts of a design pattern (name, problem, solution, consequences), and categorizes patterns into creational, structural, and behavioral types. Examples of commonly used patterns like Singleton and State patterns are also presented.
The document discusses arrays in C language. It defines an array as a data structure that stores a collection of similar data types. An array is declared by specifying the data type, array name, and size/number of elements. Once declared, an array's size cannot be changed. Elements can be accessed via their index. Multidimensional arrays store elements in multiple dimensions and are accessed using two or more indices.
Two-dimensional arrays in C++ allow the creation of arrays with multiple rows and columns. A 2D array is initialized and accessed using two indices, one for the row and one for the column. 2D arrays can be processed using nested for loops, with the outer loop iterating through each row and the inner loop iterating through each column. Functions can accept 2D arrays as parameters, but the number of columns must be specified since arrays are stored in row-major order.
This document discusses arrays in three sentences:
Arrays are collections of homogeneous data that can be one-dimensional, two-dimensional, or multi-dimensional. One-dimensional arrays store data in a single subscript, while two-dimensional arrays arrange data into rows and columns. Array elements are accessed via an index and each dimension of a multi-dimensional array is identified by a subscript.
This document provides information about arrays in C programming. It defines an array as a linear list of homogeneous elements stored in consecutive memory locations. It notes that arrays always start at index 0 and end at size-1. It describes one-dimensional and multi-dimensional arrays. For one-dimensional arrays, it provides examples of declaration, definition, accessing elements, and several programs for operations like input, output, finding the largest element, and linear search. For multi-dimensional arrays, it describes how they are represented and defined with multiple subscript variables. It also includes a program to add two matrices as an example of a two-dimensional array.
The document discusses multi-dimensional arrays, specifically two-dimensional arrays. It defines two-dimensional arrays as rows and columns that can represent tables, vectors, or matrices. It provides examples of declaring, initializing, inputting, outputting, and storing two-dimensional arrays in C code. It includes code examples for adding, transposing, and multiplying matrices using two-dimensional arrays.
The document discusses software architecture, including definitions, principles, patterns, and modeling techniques. It defines architecture as the structure of a system comprising software elements and relationships. Some key principles discussed are single responsibility, open/closed, and dependency inversion. Common patterns like MVC, layered, and multitier architectures are explained. The document also introduces Unified Modeling Language (UML) for modeling systems using diagrams like class, component, and package diagrams.
The document describes key components of software design including data design, architectural design, interface design, and procedural design. It discusses the goals of the design process which are to implement requirements, create an understandable guide for code generation and testing, and address implementation from data, functional, and behavioral perspectives. The document also covers concepts like abstraction, refinement, modularity, program structure, data structures, software procedures, information hiding, and cohesion and coupling.
This document discusses component, deployment, persistent and UI models in object oriented design. It provides details on component diagrams, describing how they represent high-level reusable parts of a system and their inter-relationships. Deployment diagrams depict the physical resources in a system including nodes, components, and connections. Persistent modeling involves mapping object-oriented class diagrams to relational database schemas. User interface design should match user skills/experience and consider human factors like memory, preferences and preventing errors.
This document discusses software design patterns, which provide reusable solutions to common problems in software design. It covers creational patterns like singleton and abstract factory, structural patterns like adapter and bridge, and behavioral patterns like iterator and observer. Patterns help developers solve recurring problems in an elegant and reusable way by providing tried-and-tested solutions to common design problems. The document also discusses categories of patterns, their elements, and when to use different patterns.
Design patterns are optimized, reusable solutions to the programming problems that we encounter every day. A design pattern is not a class or a library that we can simply plug into our system; it's much more than that. It is a template that has to be implemented in the correct situation. It's not language-specific either. A good design pattern should be implementable in most—if not all—languages, depending on the capabilities of the language. Most importantly, any design pattern can be a double-edged sword— if implemented in the wrong place, it can be disastrous and create many problems for you. However, implemented in the right place, at the right time, it can be your savior.
Design patterns are optimized, reusable solutions to the programming problems that we encounter every day. A design pattern is not a class or a library that we can simply plug into our system; it's much more than that. It is a template that has to be implemented in the correct situation. It's not language-specific either. A good design pattern should be implementable in most—if not all—languages, depending on the capabilities of the language. Most importantly, any design pattern can be a double-edged sword— if implemented in the wrong place, it can be disastrous and create many problems for you. However, implemented in the right place, at the right time, it can be your savior.
The document discusses object-oriented design and analysis. It covers key aspects of the design phase including identifying classes, class responsibilities, and relationships between classes. The purposes of the design phase are to gather information for implementation, reduce implementation time and cost, and be the most time-consuming phase. Results of design include text descriptions and diagrams depicting relationships, usage scenarios, and state changes. The document also discusses translating analysis concepts into design, including understanding quality attributes, constraints, and requirements.
Design Pattern in Software Engineering Bilal Hassan
1. Design patterns are general reusable solutions to common problems in software design. There are creational, structural, and behavioral patterns.
2. Creational patterns deal with object creation mechanisms and include abstract factory, builder, factory method, prototype, and singleton patterns.
3. Structural patterns concern class and object composition, using inheritance to compose interfaces and objects. Examples include adapter, bridge, composite, decorator, facade, flyweight, and proxy patterns.
The document discusses object-oriented design using UML. It describes the design process, including refining the analysis model into a design model with more implementation details. Key artifacts of design include interfaces, subsystems, and classes. Maintaining both analysis and design models is recommended for large, complex systems. Design axioms aim to maximize independence between components and minimize complexity. Corollaries provide guidelines for loosely coupled, single-purpose classes with strong mappings between analysis and design models.
The document discusses component-level design which occurs after architectural design. It aims to create a design model from analysis and architectural models. Component-level design can be represented using graphical, tabular, or text-based notations. The key aspects covered include:
- Defining a software component as a modular building block with interfaces and collaboration
- Designing class-based components following principles like open-closed and dependency inversion
- Guidelines for high cohesion and low coupling in components
- Designing conventional components using notations like sequence, if-then-else, and tabular representations
Open Framework for the Dynamic Reconfiguration of Component-Based SoftwareMadjid KETFI
Open Framework for the Dynamic Reconfiguration of Component-Based Software
M. Ketfi and N. Belkhatir
Proceedings of the International Conference on Software Engineering Research and Practice, SERP 2004, June 21-24, 2004, Las Vegas, Nevada, USA, Volume 2. CSREA Press 2004, ISBN 1-932415-29-7 (pages 948-951).
This document discusses component-based modeling and technology. It covers several topics:
1) It describes different modeling activities and representation techniques used in software development, including diagrams, descriptions, and both graphical and textual representations.
2) It discusses different ways to represent system composition and structure using components, as well as dynamic collaboration using events and actions.
3) It proposes a layered architecture model for applications with four layers - a user interface layer, application layer, access layer, and domain layer.
4) It outlines various modeling process activities including domain investigation, conceptual modeling, user interface modeling, and data modeling.
Software Engineering Tools and Practices.pdfMeagGhn
This document discusses software engineering practices and tools, including the software crisis and issues like increasing complexity, poor quality, high costs and delays. It introduces Unified Modeling Language (UML) as a standard way to visually model software systems using diagrams. It describes different types of UML models including structural, behavioral and architectural modeling. It also discusses concepts like the software development life cycle, configuration management, revision control systems and how to create UML diagrams like use case diagrams and sequence diagrams.
The document outlines structural design patterns including Adapter, Facade, Decorator, Composite, and Proxy patterns. It provides definitions and examples of how each pattern allows objects to be combined into larger structures. The key purpose of structural patterns is that they involve connections between objects and define how components should be structured to work together flexibly in a system.
The document discusses various aspects of component-based modeling and technologies. It begins by introducing component-based models and their importance. It then discusses in detail several component technologies including:
- The ACME architectural description language which uses components, ports, connectors, roles, systems and attachments.
- The Java Bean component model which defines components using methods, properties, events and listeners for interfaces and allows various implementations and assembly approaches.
- COM/DCOM/MTS which uses interfaces as virtual classes and components as binary code with a simple runtime.
- CORBA's component model which uses facets, receptacles, events for interfaces and a container approach for the runtime.
- .NET which uses
The document discusses component-level design which occurs after architectural design. It aims to create a detailed design model from previous models. Key points:
- A software component is a modular building block with well-defined interfaces and collaboration. Components can be viewed as classes, modules, or reusable processes.
- Effective design follows principles like open-closed and dependency inversion. Components have well-defined dependencies and inheritance relationships.
- Class-based components are designed for high cohesion and low coupling. Conventional components are derived from analysis models and decompose problems into logical modules.
Design patterns are known as best practices that the programmer can use to solve common problems when designing an application or system.
Singelton Design Pattern
Factory Design Pattern
Builder Design Pattern
Strategy Design Pattern
Iterator Design Pattern
Observer Design Pattern
Prototype Design Pattern
Command Design Pattern
Decorator Pattern
Proxy Pattern
Adapter Pattern
The document discusses various microbiology techniques for culturing microbes including inoculation, isolation, incubation, inspection, and identification. It describes how to produce pure cultures through methods like streak plating and describes different types of culture media including solid, liquid, enriched, selective, and differential media. The goals are to transfer microbes to produce isolated colonies, grow them under proper conditions, observe characteristics, and identify organisms through comparing data.
The document provides instructions for creating a research poster, including reviewing sample posters and an article on best practices. It discusses font size, logo placement, poster size, image and graphic quality, and elements that make a poster engaging. A sample student research poster is also included, with sections on the problem, methodology, results, conclusions, and references. The poster summarizes a study on the occupations of school-aged children who have siblings with cognitive or behavioral disabilities.
The document provides instructions for creating an effective research poster. It discusses reviewing sample posters to understand best practices like font size, logo placement, size of the poster, and quality of images. It also recommends considering what makes sample posters visually engaging and how one's own poster could be improved.
Position Your Body for Learning implements evidence-based measurements to assess optimal positioning for learning. The document describes three simple assessments - "roll", "rattle", and "rumble" - to determine if desk height matches elbow rest height and chair height matches popliteal height. It explains that proper ergonomic positioning through adjustments can improve students' attention, fine motor skills, and performance on standardized tests. The document provides a form called "Measuring for Optimal Positioning" to document student measurements and identify furniture adjustments needed.
The agenda outlines a thesis dissemination meeting that will include welcome and introductions, a syllabus review, project summaries from students, breaks, a presentation on APA style and thesis document preparation from the writing center, library resources overview, and discussion of thesis resources and dismissal. The document also lists various thesis course, poster, article, and conference resources that will be made available to students.
This document discusses program evaluation, outlining key concepts and approaches. It describes the purposes of program evaluation as determining if objectives are met and improving decision making. Formative and summative evaluations are explained, with formative used for ongoing improvement and summative to determine effects. Both quantitative and qualitative methods are appropriate, including experimental, quasi-experimental and non-experimental designs. Stakeholder involvement, utilization of results, and addressing ethical considerations are important aspects of program evaluation.
The document outlines topics from Chapter 6 of a course, including similarities and differences between intervention planning for individuals and community programs, best practices for developing mission statements and effective teams, and issues related to program sustainability. It also provides examples and activities for developing SMART goals, vision and mission statements, and sustainability plans for a fall prevention program. Resources and considerations are presented for each step of the program development process.
Compliance, motivation, and health behaviors stanbridge
This document provides information about compliance, motivation, and health behaviors as they relate to learners. It introduces several occupational therapy students and their backgrounds. The objectives cover defining key terms and discussing theories of compliance, motivation concepts, and strategies to facilitate motivation. The document then matches vocabulary terms to their definitions and discusses several theories of behavior change, including the health belief model, self-efficacy theory, protection motivation theory, stages of change model, and theory of reasoned action. Motivational strategies and the educator's role in health promotion are also outlined.
Ch 5 developmental stages of the learnerstanbridge
This document provides an overview of developmental stages of the learner from infancy through older adulthood. It begins with introductions of the presenters and learning objectives. Key terms are defined. Development is discussed in terms of physical, cognitive, and psychosocial characteristics at each stage: infancy/toddlerhood, early childhood, middle/late childhood, adolescence, young adulthood, middle-aged adulthood, and older adulthood. Teaching strategies are outlined for each developmental stage. The role of family in patient education is also addressed.
This document summarizes the content covered in Week 2 of a course on community-based occupational therapy practice. Chapter 3 discusses using theories from related disciplines in community practice and identifying strategies for organizing communities to meet health needs. Chapter 4 covers understanding relevant federal legislation, including laws supporting reimbursement and those focused on education, medical rehabilitation, consumer rights, and environmental issues. The document also lists vocabulary terms and guest speakers for the week.
This document outlines the topics and activities to be covered in Week 3 of a course on community health and health promotion program development. It will describe processes of environmental scanning, trend analysis, and the key steps of community health program development. Students will learn about needs assessments, theories in health promotion planning, goals and objectives, and the ecological approach. They will develop implementation strategies at different levels of intervention and learn the purposes of program evaluation. Readings, discussions, and activities are planned, including a scenario analyzing a sheltered workshop using SWOT analysis. Key terms and concepts are defined.
This document outlines the topics that will be covered in the first two chapters of a course on community-based occupational therapy practice. Chapter 1 will discuss the history and roles of OT in community-based practice as well as characteristics of effective community-based OTs. It will also cover paradigm shifts in OT. Chapter 2 will address concepts in community and public health, determinants of health, and strategies for prevention. It will discuss OT's contributions to Healthy People 2020 and its role in health promotion. The schedule includes lectures, small group work, and a guest speaker.
This document discusses how to critically appraise quantitative studies for clinical decision making. It covers evaluating the validity, reliability, and applicability of studies. Key points include assessing for bias, determining if results are statistically and clinically significant, and considering how well study findings can be applied to patients. Study designs like randomized controlled trials, case-control studies, and cohort studies are examined. The importance of systematic reviews and meta-analyses in evidence-based practice is also covered.
This document discusses the importance of clinical judgment in evidence-based nursing practice. It states that research evidence must be considered alongside patient concerns and preferences. Good clinical judgment requires carefully examining the validity of evidence and how it is applied to specific patients. The fit between evidence and each patient's unique situation is rarely perfect. Nurses must understand patients narratively and use judgment over time to determine the most appropriate care based on evidence and the patient's needs. Experiential learning and developing expertise in caring for particular patient populations enhances a nurse's clinical grasp and judgment.
This document discusses qualitative research and its application to clinical decision making. It describes how qualitative evidence can inform understanding of patient experiences and perspectives, which are important components of evidence-based practice. The document outlines different qualitative research traditions like ethnography, grounded theory, and phenomenology. It also discusses techniques for appraising qualitative studies based on their credibility, transferability, dependability, and confirmability. The key point is that qualitative evidence provides insights into human experiences, values, and meanings that can help inform clinical decisions.
This document discusses critically appraising knowledge for clinical decision making. It explains that practice should be based on unbiased, reliable evidence rather than tradition. The three main sources of knowledge for evidence-based practice are valid research evidence, clinical expertise, and patient choices. Clinical practice guidelines are the primary source to guide decisions as they synthesize research evidence. Internal evidence from quality improvement projects applies specifically to the setting where it was collected, unlike external evidence which is more generalizable. Both internal and external evidence should be combined using the PDSA (Plan-Do-Study-Act) cycle for continuous improvement.
This document discusses implementing evidence-based practice (EBP) in clinical settings. It emphasizes that engaging all stakeholders, including clinical staff, administrators, and other disciplines, is key. It also stresses that assessing and addressing barriers like knowledge, attitudes, and resources is important. Finally, it highlights that evaluating outcomes through quantifiable measures can help determine the impact of EBP changes on patient care.
This document discusses clinical practice guidelines (CPGs), including how they are developed based on evidence, how they can standardize care while allowing flexibility, and how to evaluate and implement them. It notes that CPGs systematically develop statements to guide regional diagnosis and treatment based on the best available evidence. While CPGs provide time-effective guidance, the commitment of caregivers is most important for successful implementation.
This document discusses key aspects of writing a successful grant proposal. It explains that grant proposals request funding for research or evidence-based projects by outlining specific aims, background, significance, methodology, budget, and personnel. Successful grant writers are passionate, meticulous planners who can persuade reviewers of a project's importance and address potential barriers. The most important initial question is whether a project meets the funding organization's application criteria. Proposals need compelling abstracts that explain why a project deserves funding and clearly written background and methodology sections. Common weaknesses that can lead to rejection are a lack of significance or novel ideas and inadequate description of study design.
The document discusses ethical considerations for evidence implementation and generation in healthcare. It outlines key ethical principles like beneficence, nonmaleficence, autonomy and justice. These principles form the foundation for core dimensions of healthcare quality according to the Institute of Medicine. The document also differentiates between clinical research, quality improvement initiatives, and evidence-based practice. It notes some controversies around applying different ethical standards to research versus quality improvement. Overall, the document provides an overview of how ethical principles guide evidence-based healthcare practices and quality improvement efforts.
"Scaling RAG Applications to serve millions of users", Kevin GoedeckeFwdays
How we managed to grow and scale a RAG application from zero to thousands of users in 7 months. Lessons from technical challenges around managing high load for LLMs, RAGs and Vector databases.
AppSec PNW: Android and iOS Application Security with MobSFAjin Abraham
Mobile Security Framework - MobSF is a free and open source automated mobile application security testing environment designed to help security engineers, researchers, developers, and penetration testers to identify security vulnerabilities, malicious behaviours and privacy concerns in mobile applications using static and dynamic analysis. It supports all the popular mobile application binaries and source code formats built for Android and iOS devices. In addition to automated security assessment, it also offers an interactive testing environment to build and execute scenario based test/fuzz cases against the application.
This talk covers:
Using MobSF for static analysis of mobile applications.
Interactive dynamic security assessment of Android and iOS applications.
Solving Mobile app CTF challenges.
Reverse engineering and runtime analysis of Mobile malware.
How to shift left and integrate MobSF/mobsfscan SAST and DAST in your build pipeline.
QA or the Highway - Component Testing: Bridging the gap between frontend appl...zjhamm304
These are the slides for the presentation, "Component Testing: Bridging the gap between frontend applications" that was presented at QA or the Highway 2024 in Columbus, OH by Zachary Hamm.
Main news related to the CCS TSI 2023 (2023/1695)Jakub Marek
An English 🇬🇧 translation of a presentation to the speech I gave about the main changes brought by CCS TSI 2023 at the biggest Czech conference on Communications and signalling systems on Railways, which was held in Clarion Hotel Olomouc from 7th to 9th November 2023 (konferenceszt.cz). Attended by around 500 participants and 200 on-line followers.
The original Czech 🇨🇿 version of the presentation can be found here: https://www.slideshare.net/slideshow/hlavni-novinky-souvisejici-s-ccs-tsi-2023-2023-1695/269688092 .
The videorecording (in Czech) from the presentation is available here: https://youtu.be/WzjJWm4IyPk?si=SImb06tuXGb30BEH .
LF Energy Webinar: Carbon Data Specifications: Mechanisms to Improve Data Acc...DanBrown980551
This LF Energy webinar took place June 20, 2024. It featured:
-Alex Thornton, LF Energy
-Hallie Cramer, Google
-Daniel Roesler, UtilityAPI
-Henry Richardson, WattTime
In response to the urgency and scale required to effectively address climate change, open source solutions offer significant potential for driving innovation and progress. Currently, there is a growing demand for standardization and interoperability in energy data and modeling. Open source standards and specifications within the energy sector can also alleviate challenges associated with data fragmentation, transparency, and accessibility. At the same time, it is crucial to consider privacy and security concerns throughout the development of open source platforms.
This webinar will delve into the motivations behind establishing LF Energy’s Carbon Data Specification Consortium. It will provide an overview of the draft specifications and the ongoing progress made by the respective working groups.
Three primary specifications will be discussed:
-Discovery and client registration, emphasizing transparent processes and secure and private access
-Customer data, centering around customer tariffs, bills, energy usage, and full consumption disclosure
-Power systems data, focusing on grid data, inclusive of transmission and distribution networks, generation, intergrid power flows, and market settlement data
"NATO Hackathon Winner: AI-Powered Drug Search", Taras KlobaFwdays
This is a session that details how PostgreSQL's features and Azure AI Services can be effectively used to significantly enhance the search functionality in any application.
In this session, we'll share insights on how we used PostgreSQL to facilitate precise searches across multiple fields in our mobile application. The techniques include using LIKE and ILIKE operators and integrating a trigram-based search to handle potential misspellings, thereby increasing the search accuracy.
We'll also discuss how the azure_ai extension on PostgreSQL databases in Azure and Azure AI Services were utilized to create vectors from user input, a feature beneficial when users wish to find specific items based on text prompts. While our application's case study involves a drug search, the techniques and principles shared in this session can be adapted to improve search functionality in a wide range of applications. Join us to learn how PostgreSQL and Azure AI can be harnessed to enhance your application's search capability.
Session 1 - Intro to Robotic Process Automation.pdfUiPathCommunity
👉 Check out our full 'Africa Series - Automation Student Developers (EN)' page to register for the full program:
https://bit.ly/Automation_Student_Kickstart
In this session, we shall introduce you to the world of automation, the UiPath Platform, and guide you on how to install and setup UiPath Studio on your Windows PC.
📕 Detailed agenda:
What is RPA? Benefits of RPA?
RPA Applications
The UiPath End-to-End Automation Platform
UiPath Studio CE Installation and Setup
💻 Extra training through UiPath Academy:
Introduction to Automation
UiPath Business Automation Platform
Explore automation development with UiPath Studio
👉 Register here for our upcoming Session 2 on June 20: Introduction to UiPath Studio Fundamentals: https://community.uipath.com/events/details/uipath-lagos-presents-session-2-introduction-to-uipath-studio-fundamentals/
Essentials of Automations: Exploring Attributes & Automation ParametersSafe Software
Building automations in FME Flow can save time, money, and help businesses scale by eliminating data silos and providing data to stakeholders in real-time. One essential component to orchestrating complex automations is the use of attributes & automation parameters (both formerly known as “keys”). In fact, it’s unlikely you’ll ever build an Automation without using these components, but what exactly are they?
Attributes & automation parameters enable the automation author to pass data values from one automation component to the next. During this webinar, our FME Flow Specialists will cover leveraging the three types of these output attributes & parameters in FME Flow: Event, Custom, and Automation. As a bonus, they’ll also be making use of the Split-Merge Block functionality.
You’ll leave this webinar with a better understanding of how to maximize the potential of automations by making use of attributes & automation parameters, with the ultimate goal of setting your enterprise integration workflows up on autopilot.
How information systems are built or acquired puts information, which is what they should be about, in a secondary place. Our language adapted accordingly, and we no longer talk about information systems but applications. Applications evolved in a way to break data into diverse fragments, tightly coupled with applications and expensive to integrate. The result is technical debt, which is re-paid by taking even bigger "loans", resulting in an ever-increasing technical debt. Software engineering and procurement practices work in sync with market forces to maintain this trend. This talk demonstrates how natural this situation is. The question is: can something be done to reverse the trend?
Must Know Postgres Extension for DBA and Developer during MigrationMydbops
Mydbops Opensource Database Meetup 16
Topic: Must-Know PostgreSQL Extensions for Developers and DBAs During Migration
Speaker: Deepak Mahto, Founder of DataCloudGaze Consulting
Date & Time: 8th June | 10 AM - 1 PM IST
Venue: Bangalore International Centre, Bangalore
Abstract: Discover how PostgreSQL extensions can be your secret weapon! This talk explores how key extensions enhance database capabilities and streamline the migration process for users moving from other relational databases like Oracle.
Key Takeaways:
* Learn about crucial extensions like oracle_fdw, pgtt, and pg_audit that ease migration complexities.
* Gain valuable strategies for implementing these extensions in PostgreSQL to achieve license freedom.
* Discover how these key extensions can empower both developers and DBAs during the migration process.
* Don't miss this chance to gain practical knowledge from an industry expert and stay updated on the latest open-source database trends.
Mydbops Managed Services specializes in taking the pain out of database management while optimizing performance. Since 2015, we have been providing top-notch support and assistance for the top three open-source databases: MySQL, MongoDB, and PostgreSQL.
Our team offers a wide range of services, including assistance, support, consulting, 24/7 operations, and expertise in all relevant technologies. We help organizations improve their database's performance, scalability, efficiency, and availability.
Contact us: info@mydbops.com
Visit: https://www.mydbops.com/
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For more details and updates, please follow up the below links.
Meetup Page : https://www.meetup.com/mydbops-databa...
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Introduction of Cybersecurity with OSS at Code Europe 2024Hiroshi SHIBATA
I develop the Ruby programming language, RubyGems, and Bundler, which are package managers for Ruby. Today, I will introduce how to enhance the security of your application using open-source software (OSS) examples from Ruby and RubyGems.
The first topic is CVE (Common Vulnerabilities and Exposures). I have published CVEs many times. But what exactly is a CVE? I'll provide a basic understanding of CVEs and explain how to detect and handle vulnerabilities in OSS.
Next, let's discuss package managers. Package managers play a critical role in the OSS ecosystem. I'll explain how to manage library dependencies in your application.
I'll share insights into how the Ruby and RubyGems core team works to keep our ecosystem safe. By the end of this talk, you'll have a better understanding of how to safeguard your code.
"Choosing proper type of scaling", Olena SyrotaFwdays
Imagine an IoT processing system that is already quite mature and production-ready and for which client coverage is growing and scaling and performance aspects are life and death questions. The system has Redis, MongoDB, and stream processing based on ksqldb. In this talk, firstly, we will analyze scaling approaches and then select the proper ones for our system.
The Microsoft 365 Migration Tutorial For Beginner.pptxoperationspcvita
This presentation will help you understand the power of Microsoft 365. However, we have mentioned every productivity app included in Office 365. Additionally, we have suggested the migration situation related to Office 365 and how we can help you.
You can also read: https://www.systoolsgroup.com/updates/office-365-tenant-to-tenant-migration-step-by-step-complete-guide/
Conversational agents, or chatbots, are increasingly used to access all sorts of services using natural language. While open-domain chatbots - like ChatGPT - can converse on any topic, task-oriented chatbots - the focus of this paper - are designed for specific tasks, like booking a flight, obtaining customer support, or setting an appointment. Like any other software, task-oriented chatbots need to be properly tested, usually by defining and executing test scenarios (i.e., sequences of user-chatbot interactions). However, there is currently a lack of methods to quantify the completeness and strength of such test scenarios, which can lead to low-quality tests, and hence to buggy chatbots.
To fill this gap, we propose adapting mutation testing (MuT) for task-oriented chatbots. To this end, we introduce a set of mutation operators that emulate faults in chatbot designs, an architecture that enables MuT on chatbots built using heterogeneous technologies, and a practical realisation as an Eclipse plugin. Moreover, we evaluate the applicability, effectiveness and efficiency of our approach on open-source chatbots, with promising results.
1. Introduction
Design patterns are medium-scale patterns.
They are smaller in scale than architectural
patterns, but are at a higher level than the
programming language-specific idioms.
Architectural Patterns
Design Patterns
programming language-specific idioms
2. Group Design Patterns
Structural Decomposition
Organization of Work
Access Control
Management
Communication
3. Overview(1)
Structural Decomposition This category includes patterns
that support a suitable decomposition of subsystems and
complex components into cooperating parts. The Whole-
Part pattern is the most general pattern we are aware of
in this category.
Organization of Work. This category comprises patterns
that define how components collaborate together to solve
a complex problem. We describe the Master-Slave
pattern, which helps you to organize the computation of
services for which fault tolerance or computational
accuracy is required.
4. Overview(2)
Access Control. Such patterns guard and control access to
services or components. We describe the Proxy pattern
here.
Management. This category includes patterns for handling
homogenous collections of objects, services and
components in their entirety. We describe two patterns: the
Command Processor pattern addresses the management
and scheduling of user commands, while the View
Handler pattern describes how to manage views in a
software system.
5. Overview(3)
Communication. Patterns in this category help to organize
communication between components. Two patterns address
issues of inter-process communication: the Forwarder-Receiver
pattern deals with peer-to-peer communication, while the
Client Dispatcher-Server pattern describes location-transparent
communication in a Client-Server structure. The Publisher-
Subscriber pattern helps with the task of keeping data
consistent between cooperating components.
*An important property of all design patterns is that they are
independent of a particular application domain.
*Most design patterns are independent of a particular programming
paradigm.
7. Structural Decomposition()
The Whole-Part design pattern helps
with the aggregation of components
that together form a semantic unit.
The Composite pattern organizes
objects into tree structures that
represent part-whole hierarchies.
8. The Whole-part Design Pattern
Example
Context
Problem
Solution
Structure
Dynamics
Implementation
Variants
Example Resolved
Known Uses
See also
11. Whole-part-- Problem
A complex object should either be decomposed
into smaller objects, or composed of existing
objects, to support reusability, changeability and
the recombination of the constituent objects in
other types of aggregate.
Clients should see the aggregate object as an
atomic object that does not allow any direct
access to its constituent parts.
12. Whole-part-- Solution
Introduce a component that encapsulates smaller objects, and
prevents clients from accessing these constituent parts
directly. Define an interface for the aggregate that is the
only means of access to the functionality of the
encapsulated objects. allowing the aggregate to appear as a
semantic unit.
The general principle of the Whole-Part pattern is applicable
to the organization of three types of relationship:
An assembly-parts relationship
A container-contents relationship
The collection-members relationship
17. Whole-part– Implementation(1)
1 Design the public interface of the Whole. Analyze the
functionality the Whole must offer to its clients.
2 Separate the Whole into Parts, or synthesize it from
existing ones. There are two approaches:
The bottom-up approach allows you to compose Wholes
from loosely-coupled Parts that you can later reuse when
implementing other types of Whole.
The top-down approach makes it is possible to cover all
of the Whole's functionality.
18. Whole-part– Implementation(2)
3 If you follow a bottom-up approach, use existing
Parts from component libraries or class libraries
and specify their collaboration.
4 If you follow a top-down approach, partition the
Mirhole's services into smaller collaborating
services and map these collaborating services to
separate Parts.
19. Whole-part– Implementation(3)
5 Specify the services of the W'hole in terms of
services of the Parts.---two possible ways to call a
Part service:
If a client request is forwarded to a Part service, the
Part does not use any knowledge about the execution
context of the Whole, relying on its own
environment instead.
A delegation approach requires the Whole to pass its
own context information to the Part.
20. Whole-part– Implementation(4)
6 Implement the Parts. If the Parts are Whole-Part
structures themselves, design them recursively
starting with step 1. If not, reuse existing Parts
from a library, or just implement them if their
implementation is straightforward and further
decomposition is not necessary.
7 Implement the Whole. Implement the Whole's
services based on the structure you developed
in the preceding steps.
21. Whole-part– Variants(1)
Shared Parts. This variant relaxes the restriction that
each Part must be associated with exactly one
Whole by allowing several Wholes to share the
same Part.
22. Whole-part– Variants(2)
The next three variants describe the implementation of the
Whole-to-Parts relationships we introduced in the Solution
section:
Assembly-Parts In this variant the Whole may be an object
that represents an assembly of smaller objects.
Container-Contents. In this variant a container is
responsible for maintaining differing contents.
The Collection-Members variant is a specialization of
Container-Contents, in that the Part objects all have the
same type.
26. Whole-part– Known Uses
The key abstractions of many object-oriented
applications follow the Whole-Part pattern.
Most object-oriented class libraries provide
collection classes such as lists. sets. and maps.
These classes implement the Collection-Member
and Container-Contents variants.
Graphical user interface toolkits such as Fresco
or ET++ use the Composite variant of the Whole-
Part pattern.
28. Whole-part– See also
the Composite design pattern is applicable when:
You want to represent whole-part hierarchies of objects.
You want clients to be able to ignore the difference
between compositions of objects and individual objects.
Composite is a variant of the Whole-Part design pattern
that you should consider when facing these two
requirements.
The Facade design pattern helps to provide a simple
interface to a complex subsystem.
29. 3.3 Organization of Work(1)
Structural Decomposition
Organization of Work
Access Control
Management
Communication
30. Organization of Work(2)
The implementation of complex services is often solved
by several components in cooperation.
The Master-Slave pattern supports fault computation and
computational accuracy.
Master-Slave applies the 'divide and conquer' principle.
The Master-Slave pattern is widely applied in the areas of
parallel and distributed computing.
The Chain of Responsibility, Command and Mediator
patterns also belong to this category
34. Master-Slave– Problem(1)
Clients should not be aware that the
calculation is based on the “divide and
conquer” principle.
Neither clients nor the processing of sub-
tasks should depend on the algorithms for
partitioning work and assembling the final
result.
35. Master-Slave– Problem(2)
It can be helpful to use different but
semantically-identical implementations for
processing sub-tasks, for example to
increase computational accuracy.
Processing of sub-tasks sometimes needs
coordination, for example in simulation
applications using the finite element method.
36. Master-Slave-- Solution
A master component divides work into equal sub-tasks, delegates
these sub-tasks to several independent but semantically-identical
shve components, and computes a final result from the partial
results the slaves return.
This general principle is found in three application areas:
Fault tolerance
Parallel computing
Computational accuracy
39. Master-Slave—Dynamics(1)
A client requests a service from the master
The master partitions the task into several equal sub-tasks.
The master delegates the execution of these sub-tasks to
several slave instances, starts their execution and waits for
the results they return
The slaves perform the processing of the sub-tasks and
return the results of their computation back to the master
The master computes a final result for the whole task from
the partial results received from the slaves
The master returns this result to the client
41. Master-Slave– Implementation(1)
The implementation of the Master-Slave pattern follows
five steps:
1.Divide work. Specify how the computation of the task
can be split into a set of equal sub-tasks. Identify the
sub-services that are necessary to process a sub-task.
2.Combine sub-task results. Specify how the final
result of the whole service can be computed with the
help of the results obtained from processing individual
sub-tasks.
42. Master-Slave– Implementation(2)
3. Specify the cooperation between master and
slaves. Define an interface for the sub-service
identified in step 1. It will be implemented by
the slave and used by the master to delegate the
processing of individual sub-tasks.
4.Implement the slave components according to
the specifications developed in the previous step.
5.Implement the master according to the
specifications developed in step 1 to 3.
43. Master-Slave– Variants(1)
Master Slave for fault tolerance. In this variant the
master just delegates the execution of a service to a
fixed number of replicated implementations, each
represented by a slave.
Master-Slave for parallel computation. The master
divides a complex task into a number of identical
sub-tasks, each of which is executed in parallel by a
separate slave. The master builds the final result
from the results obtained from the slaves.
44. Master-Slave– Variants(2)
Master-Slave for computational accuracy. The
execution of a service is delegated to at least three
different implementations, each of which is a
separate slave.
45. Master-Slave– Variants(3)
Further variants exist for implementing slaves:
Slaves as Processes. To handle slaves located in separate
processes, you can extend the original Master-Slave
structure with two additional components
Slaves as Threads. Every slave is implemented within
its own thread of control.
Master Slave with slave coordination. The computation
of a slave may depend on the state of computation of
other slaves
46. Master-Slave– Known Uses
Matrix multiplication. Each row in the product matrix
can be computed by a separate slave.
Transform-coding an image, for example in
computing the discrete cosine transform (DCT) of
every 8 x 8 pixel block in an image. Each block can
be computed by a separate slave.
Computing the cross-correlation of two signals. This
is done by iterating over all samples in the signal,
computing the mean-square distance between the
sample and its correlate, and summing the distances.
48. Master-Slave– See also
The Master-Slave Pattern for Parallel Compute
Services [Bro96] provides additional insights for
implementing a Master-Slave structure.
The book Programming with Threads [KSS96]
describes the Slaves as Threads variant in detail.
Object Group [Maf96] is a pattern for group
communication and support of fault tolerance in
distributed applications. It corresponds to the Master-
Slave for fault tolerance variant and provides additional
details for its implementation.
49. 3.4 Access Control (1)
Structural Decomposition
Organization of Work
Access Control
Management
Communication
50. Access Control(2)
Sometimes a component or even a whole subsystem
cannot or should not be accessible directly by its clients.
The Proxy design pattern makes the clients of a
component communicate with a representative rather than
to the component itself.
The Facade pattern provides a uniform interface to a set of
interfaces in a subsystem.
The Iterator pattern provides a way to access the elements
of an aggregate object sequentially without exposing its
underlying representation.
51. 3.4.1Proxy
Example
Context
Problem
Solution
Structure
Dynamics
Implementation
Variants
Example Resolved
Known Uses
See also
53. Proxy-- Context
Context A client needs access to the services of
another component. Direct access is technically
possible, but may not be the best approach.
54. Proxy– Problem(1)
Accessing the component should be run-time-
efficient, costeffective, and safe for both the
client and the component.
Access to the component should be transparent
and simple for the client. The client should
particularly not have to change its calling
behavior and syntax from that used to call any
other direct-access component.
55. Proxy– Problem(2)
The client should be well aware of possible
performance or financial penalties for
accessing remote clients. Full transparency
can obscure cost differences between
services.
56. Proxy-- Solution
Let the client communicate with a representative rather
than the component itself.
This representative-called a proxy-offers the interface of
the component but performs additional pre- and post-
processing such as access-control checking or making
read-only copies of the original.
57. Proxy—Structure(1)
The original implements a particular service.
The client is responsible for a specific task.
The abstract original provides the interface
implemented by the proxy and the original
60. Proxy—Dynamics(1)
While working on its task the client asks the proxy to carry
out a service.
The proxy receives the incoming service request and pre-
processes it.
If the proxy has to consult the original to fulfill the request,
it forwards the request to the original using the proper
communication protocols and security measures.
The original accepts the request and fulfills it. It sends the
response back to the proxy.
The proxy receives the response.
62. Proxy– Implementation(1)
To implement the Proxy pattern, carry out the following
steps:
1. Identify all responsibilities for dealing with access
control to a component.
2. 2 If possible introduce an abstract base class that
specifies the common parts of the interfaces of both
the proxy and the original. Derive the proxy and the
original from this abstract base.
63. Proxy– Implementation(2)
3. Impkment the proxy's finctions. To this end check
the roles specified in the first step.
4. Free the original and its clients from responsibilities
that have migrated into the proxy.
5. Associate the proxy and the original by giving the
proxy a handle to the original.
6. Remove all direct relationships between the original
and its clients.
64. Proxy– Variants(1)
Remote Proxy. Clients of remote components should
be shielded from network addresses and inter-
process communication protocols.
Protection Proxy. Components must be protected
from unauthorized access.
Cache Proxy. Multiple local clients can share results
from remote components.
Synchronization Proxy. Multiple simultaneous
accesses to a component must be synchronized.
65. Proxy– Variants(2)
Counting Proxy. Accidental deletion of components
must be prevented or usage statistics collected.
Virtual Proxy. Processing or loading a component is
costly, while partial information about the
component may be sufficient.
Firewall Proxy. Local clients should be protected
from the outside world.
66. Proxy– Example Resolved
You may often need to use more than one of the above
Proxy variants Resolved -you may want the proxy to
play several of the above roles and fulfill the
corresponding responsibilities.
You can solve remote data access problems by using
proxies with the properties of both Remote and Cache
Proxy variants. Implementing such a mixed-mode
proxy can be accomplished by using the Whole-Part
pattern
67. Proxy– Known Uses(1)
NeXTSTEP. The Proxy pattern is used in the
NeXTSTEP operating system to provide local stubs
for remote objects.
OMG-CORBA uses the Proxy pattern for two
purposes. Socalled 'client-stubs', or IDL-stubs, guard
clients against the concrete implementation of their
servers and the Object Request Broker.
Orbix, a concrete OMG-CORBA implementation,
uses remote proxies.
68. Proxy– Known Uses(2)
World Wide Web Proxy describes aspects of the
CERN HTTP server that typically runs on a firewall
machine. It gives people inside the firewall concurrent
access to the outside world. Efficiency is increased by
caching recently transferred files.
OLE. In Microsoft OLE servers may be implemented
as libraries dynamically linked to the address space of
the client, or as separate processes. Proxies are used to
hide whether a particular server is local or remote from
a client
69. Proxy– Consequences
Benefits:
Enhanced egiciency and lower cost
Decoupling clients from the location of seruer
components
Separation of housekeeping code from
functionality
liabilities:
Less emiency due to indirection
Overkill via sophisticated strategies
70. Proxy– See also
The Decorator pattern is very similar in structure to
Proxy. Concrete component-the original in the Proxy
pattern-implements some behavior that is invoked via a
decorator-the proxy in the Proxy pattern. Both classes
inherit from a common base. The major difference
between the Decorator and Proxy patterns is one of
intent. The decorator adds functionality or, more
generally, gives options for dynamically choosing
functionality in addition to the core functionality of
Concrete component. The proxy frees the original from
very specific housekeeping code.