Design Pattern - Chain of Responsibility

Mudasir Qazi - mudasirqazi00@gmail.com 1

Chain of ResponsibilityFrom Definition to Implementation

16-Dec-14

Contents / Agenda

• Definition• Advantages and Usage• UML Diagram• Sequence Diagram• Daily life Examples• Implementation – Scenario UML• Implementation – Steps 1 to 4• Results

16-Dec-14

Definition

1.Avoid coupling the sender of a request to its receiver by giving multiple objects a chance to handle the request.

2.We can say that normally each receiver contains reference of another receiver. If one object cannot handle the request then it passes the same to the next receiver and so on.

3.Chain the receiving objects and pass the request along the chain until an object handles it.

• It comes under the “Behavioral Design Patterns”.

16-Dec-14

Advantages and Usage

• Advantages:1. It reduces the coupling.2. It adds flexibility while assigning the responsibilities to objects.3. It allows a set of classes to act as one, events produced in one

class can be sent to other handler classes with the help of composition.

• Usage:1. When more than one object can handle a request and the

handler is unknown.2. When the group of objects that can handle the request must

be specified in dynamic way.

16-Dec-14

UML Diagram

Client’s Request comes to the (abstract) handler and it decides that which of the (concrete) sub handlers will actually full fil the request.

If request is not completed by first assigned sub handler then it returns it to the base handler and it decides which of the sub handlers is now feasible for task.

16-Dec-14

UML – Sequence Diagram

16-Dec-14

Examples1. Leave Application Example:

Lets say we have an organization where Team members when apply for leave, the request goes to the Team Leader. Team leader can approve all the leave request of less than 10 days. If the leave request is of more than 10 days then the request will be passed on to the Project Leader. Project leader is able to approve leaves of up to 20 days. If the leave is applied for more than 20 days then this requests will be passed to the HR. HR can approve up to 30 days of leave. If the leave is of more than 30 days then the leave application cannot be approved by the system and it needs a manual process for approval.

2. Loan Approval Example:In a bank where the approval route for mortgage applications are from the bank manager to the director then to the vice president, where the approval limits are:Manager – 0 to 100kDirector – 100k to 250kVice President – anything above 250kWe will pass the request to the manager until the application is processed.

16-Dec-14

Implementation – Loan Approval Example• We are going to implement loan approval example like discussed above. Following is its UML Diagram.

Approving Limits:Manager – 0 to 100kDirector – 100k to 250kVice President – anything above 250k

16-Dec-14

Step 1 : Loan Class

Our Loan class contains an integer to hold loan amount, a getter property and a constructor working as a setter method.

16-Dec-14

Step 2 : Main Handler (abstract)

This class is going to act as main request handler, every request form client will be accepted by this and then this will pass request to its subclasses.

16-Dec-14

Step 3 : Concrete Classes

Note: All these classes are inherited form our LoanApprover abstract class. And implements the ApproveLoan method with respect to their expectations.

16-Dec-14

Step 4 : Testing

We created three object to test with different amounts. Then we have to tell the hierarchy by SetNextApprover method.

16-Dec-14

Step 5 : Results

• Here are results as we expected.

16-Dec-14

Design Pattern - Chain of Responsibility

Engineering

Patron de conception Chain of Responsibility

Nhvl chain of responsibility quality assurance safety manage

Chain of responsibility codes & practices - Mike Wood - Latus

Supply Chain Social Responsibility - IBM WWW Page · Supply Chain Social Responsibility Global Procurement . ... We can build a stronger and more responsible supply chain by working

Design Patterns David Talby. This Lecture Re-routing method calls Chain of Responsibility Coding partial algorithms Template Method The Singleton Pattern

Unchaining Value Corporate responsibility through the value chain

Learn the Chain of Responsibility Design Pattern

Factory method, strategy pattern & chain of responsibilities

corporate social responsibility - ERIKS Stoomslangen · Corporate Social Responsibility 5 Supply Chain Definition 7 Social Responsibility 9 Environmental Responsibility 13 Business

Chain of Responsibility Ian Price Dale Willey. We Will Cover What is Chain of Responsibility A few examples The Metsker Challenges

Chain of responsibility

Supply chain responsibility: A smelter’s view

TABLE OF CONTENTS - korg.com...Pattern 3 to a value of 1. The patterns will play in a loop, as shown. 001 Pattern 1 CHAIN TO: 2 CHAIN REPEAT: 2 001 Pattern 1 CHAIN TO: 2 CHAIN REPEAT:

Steven Asnicar - Chain of Responsibility Australia

Supply Chain Social Responsibility - IBM WWW Page · IBM Corporate Responsibility IBM Supply Chain Social Responsibility (SCSR) SCSR is integral to IBM’s Corporate Citizenship activity

Chain of Responsibility Pattern

CLIMATE CHANGE RISKS AND SUPPLY CHAIN RESPONSIBILITY

CORPORATE SOCIAL RESPONSIBILITY IN DE SUPPLY CHAIN

Supply Chain Social Responsibility global supply chain. Vision: A global electronics industry supply chain that consistently operates with social, environmental and economic responsibility

Typical Cosmic Metal Abundance Pattern PROTON-PROTON CHAIN