Home > Articles > Networking > Wireless/High Speed/Optical

Introduction to Mobile Application Architectures

As mobile devices become more common, it becomes imperative to understand how this environment poses unique application architecture challenges. This chapter will help you understand the issues involved in developing applications for mobile devices.
This chapter is from the book

Where there is no vision, the people perish.

Proverbs 29:18

In this chapter, we discuss mobile application architectures. We start by describing some of the general concepts and terms behind client-server architectures and follow this by describing clients and servers and the connectivity between them. We then present several interesting architectural patterns and describe why they are useful as general mobile application architecture solutions. Finally, we discuss some of the tenets behind good architectural design and the considerations you need to be aware of when designing mobile applications.

3.1 Client-Server

Application architectures are often modeled to highlight or illustrate the overall layout of the software (e.g., application code and platform) and hardware (e.g., client, server, and network devices). While there are many possible combinations of software and hardware, application architectures often fall into a series of recognizable patterns.

Application architectures are commonly modeled in terms of a client-server architecture wherein one or more client devices requests information from a server device. The server typically responds with the requested information (see Figure 3-1).

03fig01.gifFigure 3-1 Client-server architecture

We can further consider client-server architectures using layers and tiers and the communication between the layers and tiers. Each of these is described in greater detail in the following sections.

3.1.1 Layers

Application code functionality is not necessarily uniform throughout an application. Certain sections of application code are better suited for handling the user interface, while other sections are developed to manage the business logic or communicate with the database or back-end systems.

Layering describes the division of labor within the application code on a single machine. Layers are often no more than code modules placed in different folders or directories on the client or server.

With client-side code, there are generally zero to three layers of application code. With server-side code, there are generally one to three layers of application code. This is partly a matter of good software design that helps code re-usability, partly a matter of security, and partly a matter of convenience.

A client with zero code layers essentially has no custom application code. This type of client is commonly referred to as a thin client and is possible in client-server architecture if the server holds all the custom application code. A client with one to three layers of application code is commonly referred to as a fat client.

A server can also have one to three layers of custom application code. However, you cannot have zero code layers on a server by definition.

The code layer that interacts most closely with the user is often referred to as the Presentation Layer. The second layer is often referred to as the Business Layer, as it typically handles the business logic of the code. The third layer is often referred to as the Data Access Layer. It typically handles communication with the database or data source (see Figure 3-2).

03fig02.gifFigure 3-2 Layers

It is possible to have more than three layers on either the client or server but too many layers can become unwieldy and difficult to manage. As a result, this is not frequently encountered.

3.1.2 Tiers

While breaking up application code functionality into layers helps code re-usability, it does not automatically make the architecture scalable. In order to do so, it is important to distribute the code over multiple machines.

Tiers describes the division of labor of application code on multiple machines. Tiering generally involves placing code modules on different machines in a distributed server environment. If the application code is already in layers, this makes tiering a much simpler process.

The code that interacts most closely with the user is often placed in the Presentation Tier. A second tier, which holds the application business logic and data access logic, is often referred to as the Application Tier. The third tier often houses the database or data source itself and is often referred to as the Database Tier (see Figure 3-3). This is an example of a three-tiered architecture.

03fig03.gifFigure 3-3 Tiers

The servers that make up each tier may differ both in capability and number. For example, in a large-scale distributed web application environment, there may be a large number of inexpensive web servers in the Presentation Tier, a smaller number of application servers in the Application Tier, and two expensive clustered database servers in the Database Tier. The ability to add more servers is often referred to as horizontal scaling or scaling out. The ability to add more powerful servers is often referred to as vertical scaling or scaling up. Tiering the application code in such a fashion greatly facilitates the ability to scale applications.

In large-scale distributed web applications, tiers are often bounded by firewalls. For example, a firewall may be placed in front of the Presentation Tier while a second firewall may be placed in front of the Application Tier. The Presentation Tier is thus sandwiched between firewalls in what is termed the Demilitarized Zone (DMZ), while the Application and Database Tier servers are shielded behind the second firewall in what is termed the Intranet Zone. Tiering therefore also facilitates security and allows large enterprises to shield precious internal systems from traffic originating from untrusted zones such as the Internet and DMZ. Without tiering, it becomes very difficult to secure internal systems.

Tiers generally describe server architectures, and we do not typically count client devices as a tier. While it is possible to do so, this is not a usual convention.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020