Patterns of Enterprise Application Architecture

Domain Logic Patterns

Transaction Script

• Organises business logic by procedures where each procedure handles a single request from the presentation.
• https://www.martinfowler.com/eaaCatalog/transactionScript.html

Domain Model

• An object model of the domain that incorporates both behaviour and data.
• https://www.martinfowler.com/eaaCatalog/domainModel.html

Table Model

• A single instance that handles the business logic for all rows in a database table or view.
• https://www.martinfowler.com/eaaCatalog/tableModule.html

Service Layer

• Defines an application’s boundary with a layer of services that establishes a set of available operations and coordinates the application’s response in each operation.
• https://www.martinfowler.com/eaaCatalog/serviceLayer.html

Data Source Architectural Patterns

Table Data Gateway

• An object that acts as a Gateway to a database table. One instance handles all the rows in the table.
• https://www.martinfowler.com/eaaCatalog/tableDataGateway.html

Row Data Gateway

• An object that acts as a Gateway to a single record in a data source. There is one instance per row.
• https://www.martinfowler.com/eaaCatalog/rowDataGateway.html

Active Record

• An object that wraps a row in a database table or view, encapsulates the database access, and adds domain logic on that data.
• https://www.martinfowler.com/eaaCatalog/activeRecord.html

Data Mapper

• A layer of Mappers that moves data between objects and a database while keeping them independent of each other and the mapper itself.
• https://www.martinfowler.com/eaaCatalog/dataMapper.html

Object-Relational Behavioural Patterns

Unit of Work

• Maintains a list objects affected by a business transaction and coordinates the writing out of changes and the resolution of concurrency problems.
• https://www.martinfowler.com/eaaCatalog/unitOfWork.html

Identity Map

• Ensures that each object gets loaded only once by keeping every loaded object in a map. Looks up objects using the map when referring to them.
• https://www.martinfowler.com/eaaCatalog/identityMap.html

Lazy Load

• An object that doesn’t contain all of the data you need but knows how to get it.
• https://www.martinfowler.com/eaaCatalog/lazyLoad.html

Object-Relational Structural Patterns

Identity Field

• Saves a database ID field in an object to maintain identity between an in-memory object and a database row.
• https://www.martinfowler.com/eaaCatalog/identityField.html

Foreign Key Mapping

• Maps an association between objects to a foreign key reference between tables.
• https://www.martinfowler.com/eaaCatalog/foreignKeyMapping.html

Association Table Mapping

• Saves an association as a table with foreign keys to the tables that are linked by the association.
• https://www.martinfowler.com/eaaCatalog/associationTableMapping.html

Dependent Mapping

• Has one class performs the database mapping for a child class.
• https://www.martinfowler.com/eaaCatalog/dependentMapping.html

Embedded Value

• Maps an object into separate fields of another object’s table.
• https://www.martinfowler.com/eaaCatalog/embeddedValue.html

Serialised LOB

• Saves a graph of objects by serialising them into a single are object (LOB), which it stores in a database field.
• https://www.martinfowler.com/eaaCatalog/serializedLOB.html

Class Table Inheritance

• Represents an inheritance hierarchy of classes with one table for each class.
• https://www.martinfowler.com/eaaCatalog/classTableInheritance.html

Concrete Table Inheritance

• Represents an inheritance hierarchy of classes with one table per concrete class in the hierarchy.
• https://www.martinfowler.com/eaaCatalog/concreteTableInheritance.html

Inheritance Mappers

• A structure to organise database mappers that handle inheritance hierarchies.
• https://www.martinfowler.com/eaaCatalog/inheritanceMappers.html

Object-Relational Metadata Mapping Patterns

Metadata Mapping

• Holds details of object-relational mapping in metadata.
• https://www.martinfowler.com/eaaCatalog/metadataMapping.html

Query Object

• An object that represents a database query.
• https://www.martinfowler.com/eaaCatalog/queryObject.html

Repository

• Mediates between the domain and data mapping layers using a collection-like interface for accessing domain  objects.
• https://www.martinfowler.com/eaaCatalog/repository.html

Web Presentation Patterns

Model View Controller

• Splits user interface interaction into three distinct roles.
• https://www.martinfowler.com/eaaCatalog/modelViewController.html

Page Controller

• An object that handles a request for a specific page or action on a Web site.
• https://www.martinfowler.com/eaaCatalog/pageController.html

Front Controller

• A controller that handles all requests for a Web site.
• https://www.martinfowler.com/eaaCatalog/frontController.html

Template View

• Renders information into HTML by embedding markers in an HTML page.
• https://www.martinfowler.com/eaaCatalog/templateView.html

Transform View

• A view that processes domain data element by element and transforms it into HMTL.
• https://www.martinfowler.com/eaaCatalog/transformView.html

Two Step View

• Turns domain data into HTML in two steps: first by forming some kind of logical page, then rendering the logical page into HTML.
• https://www.martinfowler.com/eaaCatalog/twoStepView.html

Application Controller

• A centralised point for handling screen navigation and the few of an application.
• https://www.martinfowler.com/eaaCatalog/applicationController.html

Distribution Patterns

Remote Facade

• Provides a coarse-grained facade on fine-grained objects to improve efficiency over a network.
• https://www.martinfowler.com/eaaCatalog/remoteFacade.html

Data Transfer Object

• An object that carries data between processes in order to reduce the number of method calls.
• https://www.martinfowler.com/eaaCatalog/dataTransferObject.html

Offline Concurrency Patterns

Optimistic Offline Lock

• Prevents conflicts between concurrent business transactions by detecting a conflict and rolling back the transaction.
• https://www.martinfowler.com/eaaCatalog/optimisticOfflineLock.html

Pessimistic Offline Lock

• Prevents conflicts between concurrent business transactions by by allowing only one business transaction at a time to access data.
• https://www.martinfowler.com/eaaCatalog/pessimisticOfflineLock.html

Coarse-Grained Lock

• Locks a set of related objects with a single lock.
• https://www.martinfowler.com/eaaCatalog/coarseGrainedLock.html

Implicit Lock

• Allows framework or layer supertype code to acquire offline locks.
• https://www.martinfowler.com/eaaCatalog/implicitLock.html

Session State Patterns

Client Session State

• Stores session state on the client.
• https://www.martinfowler.com/eaaCatalog/clientSessionState.html

Server Session State

• Keeps the session state on a server system in a serialised form.
• https://www.martinfowler.com/eaaCatalog/serverSessionState.html

Database Session State

• Stores session data as committed data in the database.
• https://www.martinfowler.com/eaaCatalog/databaseSessionState.html

Base Patterns

Gateway

• An object that encapsulates access to an external system or resource.
• https://www.martinfowler.com/eaaCatalog/gateway.html

Mapper

• An object that sets up a communication between two independent objects.
• https://www.martinfowler.com/eaaCatalog/mapper.html

Layer Supertype

• A type that acts a supertype for all types in its layer.
• https://www.martinfowler.com/eaaCatalog/layerSupertype.html

Separated Interface

• Defines an interface in a separate package from its implementation.
• https://www.martinfowler.com/eaaCatalog/separatedInterface.html

Registry

• A well-known object that other objects can use to find common objects and services.
• https://www.martinfowler.com/eaaCatalog/registry.html

Value Object

• A small simple object, like money or a date range, whose equality isn’t based on identity.
• https://www.martinfowler.com/eaaCatalog/valueObject.html

Money

• Represents a monetary value.
• https://www.martinfowler.com/eaaCatalog/money.html

Special Case

• A subclass that provides special behaviour from particular cases.
• https://www.martinfowler.com/eaaCatalog/specialCase.html

Plugin

• Links classes during configuration rather than compilation.
• https://www.martinfowler.com/eaaCatalog/plugin.html

Service Stub

• Removes dependence upon problematic services during testing.
• https://www.martinfowler.com/eaaCatalog/serviceStub.html

Record Set

• An in-memory representation of tabular data.
• https://www.martinfowler.com/eaaCatalog/recordSet.html

Useful Links

• Enterprise Integration Patterns

• Enterprise Integration Patterns: Designing, Building, and Deploying Messaging Solutions (Amazon)