Methods of Application Architecture & Delivery Models | CompTIA IT Fundamentals FC0-U61 | 3.4

In this video you will learn various methods of application architecture and delivery models.

Application Delivery Methods

Application delivery refers to the pool of services that combine to provide application functionality, usually web-based software applications, from the data centers or cloud environments where the required data processing and computing is executed to the application clients or end-users over the internet. Applications can be delivered in a variety of ways and may require different levels of access to the internet or other resources before they can be used.

Locally Installed

A local install is a software installation that is performed on your local computer. It is by far the most common way to install software. The installation files might come from a local storage device such as a CD or DVD optical disc or a downloadable file, but after the installation is complete, the application is ready to run.  The characteristics of a locally installed app include the following:

  • Network Not Required:  After initial installation, the application does not need network access.  Many apps prefer network access to validate a product key or license key.
  • Application Exists Locally:  The application files are stored on a drive that is connected to the computer.  Typically, applications are stored on the system drive — the hard drive or solid-state drive (SSD) that is built into the computer.  In Windows, this is referred to as the C: drive.
  • Files Saved Locally:  The application is designed to save files to local storage.  Most locally installed applications can also save files to network storage as an option.

Typically locally installed apps include office suites, photo-editing and video-editing apps, and games.

Local Network Hosted

A local network hosted application is one that is installed on a local network (LAN).  It includes the following:

  • Network Required:  If a network connection is not available, the application cannot run.
  • Internet Access Not Required:  Although the application needs a network connection, it does not need internet access.

Windows applications that are installed on a server and accessed by clients running Remote Desktop Services are examples of local network hosted applications.

Cloud Hosted

A cloud hosted application is a software as a service (SaaS) that enables users to open and use a software application that is hosted in the cloud on a subscription basis. Cloud hosted applications are hosted on a cloud infrastructure that users can access through the internet from anywhere in the world. Some key features of a cloud hosted application are:

  • Internet Access Required:  Because the app is on the internet, your device must have internet access to run.
  • Service Required:  You must have a subscription to the cloud hosted service to use it.  The service might be free or cost money, but without a subscription to the service, it’s not available to you.
  • Files Saved in the Cloud:  Cloud hosted services save files to the cloud.  With many apps, you can also download your files, but the default location for the files is the cloud.

Examples of cloud hosted applications include Google Docs & Microsoft Office web apps (Word, Excel, & PowerPoint).

Two other types of hosted services are:

  • Platform as a Service (PaaS): A category of cloud computing services that provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app.
  • Infrastructure as a Service (IaaS): A service model that delivers computer infrastructure on an outsourced basis to support enterprise operations. Typically, IaaS provides hardware, storage, servers and data center space or network components; it may also include software.

Application Architecture Models

An applications architecture describes the behavior of applications used in business, focused on how they interact with each other and with users. It is focused on the data consumed and produced by applications rather than their internal structure. The essential parts of any application are as follows:

  • Presentation:  The application’s user interface (menus, look & feel).
  • Logic (Programming):  The portion of the application that takes input from the presentation layer and uses it to create or manage data.
  • Data:  Information created or used by the application.

Depending on the application, additional parts (layers) may also be introduced between the programming and data layers.  The terms one-tier, two-tier, three-tier, and n-tier for applications refer to how the different layers are organized and stored on a computer or network.


One-tier architecture involves putting all of the required components for a software application or technology on a single server or platform.  One-tier architecture has presentation, logic, and data layers all stored in the same location. A locally installed application is an example of a one-tier app.


A two-tier architecture is a software architecture in which a presentation layer or interface runs on a client, and a data layer or data structure gets stored on a server.  Separating these two components into different locations represents a two-tier architecture.


A three-tier architecture is a client-server architecture in which the functional process logic, data access, computer data storage & user interface are developed and maintained as independent modules on separate platforms.  Three-tier architecture is a software design pattern and a well-established software architecture. Three-tier architecture uses three layers that are typically hosted on different devices, such as a computer and two servers.  For example, a cloud hosted app uses the following tiers (layers):

  • The presentation tier is run on a computer, tablet, or smartphone.  This can also be referred to as the client layer.
  • The programming (logic) tier is run on an application server in the cloud.
  • The data tier is stored on a file server in the cloud.
Three-Tier Architecture

Cloud hosted apps such as Google Docs use three-tier application architecture:

  • Tier-one is the Google Docs web page, as presented on a computer or mobile device.
  • Tier-two is the Google Docs application running on a Google Docs application server.
  • Tier-three is Google Drive cloud storage for Google Docs files.


N-tier architecture is a client-server architecture concept in software engineering where the presentation, processing and data management functions are both logically and physically separated.  These functions are each running on a separate machine or separate clusters so that each is able to provide the services at top capacity since there is no resource sharing. This separation makes managing each easier since doing work on one does not affect the others; easier isolating any problems that might occur.  An n-tier architecture uses more than three layers and is frequently used for database applications. For example, an n-tier architecture used for a database app might have the following layers:

  • Tier-One:  The presentation layer running on a computer or mobile device.
  • Tier-Two:  The logic (programming) layer running on a server.
  • Tier-Three:  The data access layer running on another server.
  • Tier-Four:  The database layer running on a database server.

N-tier application architecture also works well in environments where the use of virtualized or physical servers can improve performance.