Thin & Thick Client

Thin Client 

  
    A Thin client is a lightweight computer that is purpose built for remoting into a server (typically desktop virtualization resources). It depends heavily on another computer (its server) to fulfill its computational roles.

   In Thin clients many clients share their computations with a server or server farm. The server-side infrastructure makes use of cloud computing software such as application virtualization, hosted shared desktop (HSD) or desktop virtualization (VDI). This combination forms what is known today as a cloud based system where desktop resources are centralized into one or more data centers. The benefits of centralization are hardware resource optimization, reduced software maintenance, and improved security.

• Example of hardware resource optimization: Cabling, bussing and I/O can be minimized while idle memory and processing power can be applied to users sessions that most need it.

• Example of reduced software maintenance: Software patching, security updates, application/OS updates, and OS migrations can be applied, tested and activated for all users in one instance to accelerate roll-out and improve administrative efficiency.

• Example of improved security: Software assets are centralized and easily fire-walled, monitored and protected. Sensitive data is uncompromised in cases of desktop loss or theft.

   

   Thin client hardware generally consists of a computer terminal which provides I/O for a keyboard, mouse, monitor, jacks for sound peripherals, and open ports for USB devices, e.g. printer, flash drive, web cam, card reader, smartphone, etc. Some thin clients include legacy serial and/or parallel ports to support older devices such as receipt printers, scales, time clocks, etc. 

   Thin client software typically consists of a GUI (graphical user interface), cloud access agents (e.g. RDP, ICA, PCoIP), a local web browser, terminal emulations (in some cases), and a basic set of local utilities.

Characterstics of thin clients 

Architecture: 

    In using cloud based architecture, the server takes on the processing load of several client sessions, acting as a host for each endpoint device. The client software is narrowly purposed and lightweight; therefore, only the host server or server farm needs to be secured, rather than securing software installed on every endpoint device (although thin clients may still require basic security and strong authentication to prevent unauthorized access). One of the trade-offs of using cloud architecture and thin clients is that the host becomes a single point of failure. If the hosting server crashes, for example, all users lose their session unless a fail-over process is predefined. 

  The simplicity of thin client hardware and software results in a very low TCO (total cost of ownership), but some of these initial savings can be offset by the need for a more robust cloud infrastructure required on the server side. NOTE: infrastructure costs can be spread out by choosing a subscription based cloud model known as Desktop as a Service or DaaS. DaaS allows IT organizations to outsource the cloud infrastructure to a third party. 

Simplicity:

   Thin client computing is known to simplify the desktop endpoints by reducing the client-side software footprint. With a lightweight, read-only OS, client-side setup and administration is greatly reduced. Cloud access is the primary role of a thin client which eliminates the need for a large suite of local user applications, data storage and utilities. This architecture shifts the most of software execution burden from the endpoint to the data center. 

Hardware

   While the server must be robust enough to handle several client sessions at once, thin client hardware requirements are minimal to that of a traditional PC desktop. Most thin clients have low energy processors, flash storage, memory, and no moving parts. This reduces the cost and power consumption, making them affordable to own and easy to replace or deploy. Since thin clients consist of fewer hardware components than a traditional desktop PC, they can operate in more hostile environments. And because they typically don't store critical data locally, risk of theft is minimized because there is little or no user data to be compromised.

Limitations

   To achieve such simplicity, thin clients sometimes lag behind desktop PCs in terms of extensibility. For example, if a local software utility or set of device drivers are needed in order to support a locally attached peripheral device (e.g. printer, scanner, biometric security device), the thin client operating system may lack the resources needed to fully integrate the required dependencies (although dependencies can sometimes be added if they can be identified). Modern thin clients address this limitation via port mapping or USB redirection software. However, these methods cannot address all use case scenarios.

 Thick Client

   A fat client (also called heavy, rich or thick client) is a computer (client) in client–server architecture or networks that typically provides rich functionality independent of the central server. Originally known as just a "client" or "thick client".

     A fat client still requires at least periodic connection to a network or central server, but is often characterised by the ability to perform many functions without that connection. In contrast, a thin client generally does as little processing as possible and relies on accessing the server each time input data needs to be processed or validated.

Advantages 

• Lower server requirements. A thick client server does not require as high a level of performance as a thin client server (since the thick clients themselves do much of the application processing). This results in drastically cheaper servers. 
• Working offline. Thick clients have advantages in that a constant connection to the central server is often not required.
• Better multimedia performance. Thick clients have advantages in multimedia-rich applications that would be bandwidth intensive if fully served. For example, thick clients are well suited for video gaming.
• More flexibility. On some operating systems software products are designed for personal computers that have their own local resources. Running this software in a thin client environment can be difficult.
• Using existing infrastructure. As many people now have very fast local PCs, they already have the infrastructure to run thick clients at no extra cost.
• Higher server capacity. The more work that is carried out by the client, the less the server needs to do, increasing the number of users each server can support.

Difference between Thin Client & Thick Client