Default Behavior:
Before customization, a framework behaves in a manner specific to the user's action.
Inversion of Control:
Unlike other libraries, the global flow of control within a framework is employed by the framework rather than the caller.
Extensibility:
A user can extend the framework by selectively replacing default code with user code.
Non-modifiable Framework Code:
A user can extend the framework but not modify the code. The purpose of software framework is to simplify the development environment, allowing developers to dedicate their efforts to the project requirements, rather than dealing with the framework's mundane(ordinary and not interesting or exciting), repetitive functions and libraries.
Software frameworks consist of frozen spots and hot spots.
Frozen spots define the overall architecture of a software system, that is to say its basic components and the relationships between them.These remain unchanged(frozen) in any instantiation of the application framework.
Hot spots represent those parts where the programmers using the framerwork add their own code to add the functionality specific to their own project.
Creational Patterns
Abstract factory: Provide an interface for creating families of related or dependent objects without specifying
their concrete classes.
Builder: Separate the construction of a complex object from its representation allowing the same construction
process to create various representations.
Factory method: Define an interface for creating an object, but let subclasses decide which class to instantiate.
Factory Method lets a class defer instantiation to subclasses.
Lazy initialization: Tactic of delaying the creation of an object, the calculation of a value, or some other expensive
process until the first time it is needed.
Multiton: Ensure a class has only named instances, and provide global point of access to them.
Object pool: Avoid expensive acquisition and release of resources by recycling objects that are no longer in
use. Can be considered a generalization of connection pool and thread pool patterns.
Prototype: Specify the kinds of objects to create using a prototypical instance, and create new objects by
copying this prototype.
Resource acquisition is initialization: Ensure that resources are properly released by tying them to the lifespan
of suitable objects.
Singleton: Ensure a class has only one instance, and provide a global point of access to it.
Structural Patterns
Adapter or Wrapper: Convert the interface of a class into another interface clients expect. Adapter lets classes
work together that could not otherwise because of incompatible interfaces.
Bridge: Decouple an abstraction from its implementation allowing the two to vary independently.
Composite: Compose objects into tree structures to represent part-whole hierarchies. Composite lets clients
treat individual objects and compositions of objects uniformly.
Decorator: Attach additional responsibilities to an object dynamically keeping the same interface. Decorators
provide a flexible alternative to subclassing for extending functionality.
Facade: Provide a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface
that makes the subsystem easier to use.
Front Controller: Provide a unified interface to a set of interfaces in a subsystem. Front Controller defines a
higher-level interface that makes the subsystem easier to use.
Flyweight: Use sharing to support large numbers of fine-grained objects efficiently.
Proxy: Provide a surrogate or placeholder for another object to control access to it.
Behavioral Patterns
Blackboard: Generalized observer, which allows multiple readers and writers. Communicates information
system-wide.
Chain of responsibility: Avoid coupling the sender of a request to its receiver by giving more than one object
a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object
handles it.
Command: Encapsulate a request as an object, thereby letting you parameterize clients with different requests,
queue or log requests, and support undoable operations.
Interpreter: Given a language, define a representation for its grammar along with an interpreter that uses the
representation to interpret sentences in the language.
Iterator: Provide a way to access the elements of an aggregate object sequentially without exposing its underlying
representation.
Mediator: Define an object that encapsulates how a set of objects interact. Mediator promotes loose coupling
by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently.
Memento: Without violating encapsulation, capture and externalize an object’s internal state allowing theobject to be restored to this state later.
Null object: Avoid null references by providing a default object.
Observer or Publish/subscribe: Define a one-to-many dependency between objects where a state change in
one object results with all its dependents being notified and updated automatically.
Servant: Define common functionality for a group of classes.
Specification: Recombinable business logic in a Boolean fashion.
State: Allow an object to alter its behavior when its internal state changes. The object will appear to change
its class.
Strategy: Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets
the algorithm vary independently from clients that use it.
Template method: Define the skeleton of an algorithm in an operation, deferring some steps to subclasses.
Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithm’s
structure.
Visitor: Represent an operation to be performed on the elements of an object structure. Visitor lets you define
a new operation without changing the classes of the elements on which it operates.
Concurrency Patterns
Reduce the overhead of acquiring a lock by first testing the locking criterion (the
“lock hint”) in an unsafe manner; only if that succeeds does the actual lock proceed. Can be unsafe when implemented
in some language/hardware combinations. It can therefore sometimes be considered an anti-pattern.
Event-based asynchronous: Addresses problems with the Asynchronous pattern that occur in multithreaded
programs.
Guarded suspension: Manages operations that require both a lock to be acquired and a precondition to be
satisfied before the operation can be executed.
Lock: One thread puts a “lock” on a resource, preventing other threads from accessing or modifying it.
Monitor object: An object whose methods are subject to mutual exclusion, thus preventing multiple objects
from erroneously trying to use it at the same time.
Reactor: A reactor object provides an asynchronous interface to resources that must be handled synchronously.
Read-write lock: Allows concurrent read access to an object but requires exclusive access for write operations.
Scheduler: Explicitly control when threads may execute single-threaded code.
Thread pool: A number of threads are created to perform a number of tasks, which are usually organized in a
queue. Typically, there are many more tasks than threads. Can be considered a special case of the object pool
pattern.
Thread-specific storage: Static or “global” memory local to a thread.
Data Access Patterns
Another interesting area where patterns have a wide application is the area of data access patterns.
ORM Patterns: Domain Object Factory, Object/Relational Map, Update Factory.
Resource Management Patterns: Resource Pool, Resource Timer, Retryer, Paging Iterator.
Cache Patterns: Cache Accessor, Demand Cache, Primed Cache, Cache Collector, Cache Replicator.
Concurrency Patterns: Transaction, Optimistic Lock, Pessimistic Lock.
Enterprise Patterns
If you deal with J2EE or with .Net Enterprise applications, the problems that occur and the solutions to them are
similar. These solutions are the Enterprise patterns.
Presentation Tier Patterns: Intercepting Filter, Front Controller, View Helper, Composite View, Service to
Worker, Dispatcher View.
Business Tier Patterns: Business Delegate, Value Object, Session Facade, Composite Entity, Value Object
Assembler, Value List Handler, Service Locator.
Integration Tier Patterns: Data Access Object, Service Activator.
Real-Time Patterns
Architecture Patterns: Layered Pattern, Channel Architecture Pattern, Component-Based Architecture, Recursive
Containment Pattern and Hierarchical Control Pattern, Microkernel Architecture Pattern, Virtual
Machine Pattern.
Concurrency Patterns: Message Queuing Pattern, Interrupt Pattern, Guarded Call Pattern, Rendezvous Pattern,
Cyclic Executive Pattern, Round Robin Pattern.
Memory Patterns: Static Allocation Pattern, Pool Allocation Pattern, Fixed Sized Buffer Pattern, Smart
Pointer Pattern, Garbage Collection Pattern, Garbage Compactor Pattern.
Resource Patterns: Critical Section Pattern, Priority Inheritance Pattern, Priority Ceiling Pattern, Simultaneous
Locking Pattern, Ordered Locking Pattern.
Distribution Patterns: Shared Memory Pattern, Remote Method Call Pattern, Observer Pattern, Data Bus
Pattern, Proxy Pattern, Broker Pattern.
Safety and Reliability Patterns: Monitor-Actuator Pattern, Sanity Check Pattern, Watchdog Pattern, Safety
Executive Pattern, Protected Single Channel Pattern, Homogeneous Redundancy Pattern, Triple Modular
Redundancy Pattern, Heterogeneous Redundancy Pattern.