Angular Architecture

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Prasad Kharkar is a java enthusiast and always keen to explore and learn java technologies. He is SCJP,OCPWCD, OCEJPAD and aspires to be java architect.

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We saw how to get started with Angular 4 and created a simple hello world app. In this article we will get a short overview of angular architecture and how all parts of app hold together in angular architecture.

Angular Architecture:

Diagram below shows basic parts of an angular app. We will go through them one by one.

Angular Architecture
Angular Architecture

 

  • Templates:
    • Just like plain HTML, we can create angular templates which understand how to communicate with backing components.
    • We can use plain html tags and component tags.
    • These templates ultimately create DOM structure on web browser. Data in templates is held by backing components.
  • Components:
    • Components are  the ones which hold data from view which is created because of templates.
    • A Component and a Template collectively create a view.
    • Components and corresponding templates communicate through property bindings and event bindings.
  • Data Binding:
    • Data binding happens between template and component. It can be either one way or two way binding.
    • value binding is unidirectional and it is bound from component to template.
    • Property binding is unidirectional and it is bound from component to template.
    • Event binding is unidirectional and it is bound from template to component. When any event happens on DOM, then Component it notified.
    • Two way data binding is bidirectional and combines property binding and event binding.
  • Metadata:
    • Metadata provides all angular functionality to typescript classes. Without metadata, there is nothing angular about classes.
    • Templates and components can communicate with the help of metadata.
  • Services:
    • Services are not a separate angular component. Anything can be service.
    • Usually services include all the business logic and component merely consume it.
    • It is good practice to have service layer in any application which is not dependent on view part.
    • Usually services are injected in component where there are required using dependency injection mechanism.
  • Dependency Injection:
    • Angular manages a pool of all service instances and stores them in a location.
    • Whenever a component asks for a specific services, angular looks for that service in the pool.
    • If service is found then it is given to component so that it can use it.
    • If service is not found, a new instance is given to component and placed in pool so that other component can also be given.
  • Directives:
    • Directives are classes marked with @Directive decoration. They can make structural or behavioural changes in angular apps.
  • Modules:
    • Angular apps are modular.They are called NgModules.
    • Angular apps have one angular class rootModule.
    • @NgModule is a decorator function which takes a metadata object.
    • We can define providers, imports, exports and declarations in @NgModule

I hope this article helped understand angular architecture in short. In next article, we will see it running with a simple app.

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Prasad Kharkar

Prasad Kharkar is a java enthusiast and always keen to explore and learn java technologies. He is SCJP,OCPWCD, OCEJPAD and aspires to be java architect.

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