The central management of consolidated operations is primary to organizational functions. Enterprise requirements for centralized coordination extend into the coordinated operations of information systems. One prominent advantage to the central management of business communications is the client-server system of accelerated communication.
The strategic speed of deployment is one cost-effective means to achieve ROI. Delivering software to customers within the window of consumer interest assuredly enhances the marketability of software products. Another path towards increased ROI is client-server architecture. Allowing for accelerated information deployment, client-server systems are the preferred approach to strategic enterprise information environments.
Client-server computing allows IT departments to cost-effectively administer and monitor communication from one central location. Client-server configurations smoothly process computing interactions with less down time and facilitated troubleshooting. Services are centralized for ease of detection and access.
As computing designed to integrate multiple workstations with the prioritization of client-centered systems, client-server system development acknowledges that users within enterprise organizations are the center of business. In a client-server system, computers are clients to a central server processor for rapid, distributed, and interactive communication among users.
The latest advances in client-server computing extends services to the internet as network-centric computing. With network-centric computing, remote servers and clients cooperatively communicate over the internet to expand communication and improve production.
Client server system (Source: David Vignoni)
What Characterizes Client-Server Environments?
Network-centric computing emerges out of the original client-server model, bringing to the cutting edge of computing new technology in externalities, distributed ease, and media capacity.
The client-server model contributes multiple processing communication through the input of multiple workstations into a single server over which complete business transactions are delivered.
Network-centric computing adds functionalities to these contributions using an evolved internet model that:
- Contains a browser to provide universal client communication, allowing personal workstations to access the Internet as a server.
- Allows users to independently launch a number of different applications residing on diverse operating systems.
- Supports complex document design, data format standardization, and audio or video formats.
- Performs application versioning and dynamically updates data input.
External computing bases and enabled business points are connected to the internet through concentric networks, expediting expanded possibilities in reaching audiences external to the organization’s internal realm. Computing and communication relationships are direct.
Client and Centric System Architecture
All systems are architectural. Both client-server and network-centric systems are designed in tiered architectures. Both software design and software architectures adhere to the client system tiered structural build of both client-server and network-centric systems.
Three-tiered client-server architecture contains logical processions, data access, data storage and user interfaces on independent modules located on separate computing structures. Three-tiered client-server systems contain both abstract and physical strata. Abstractly the layers are viewed as presentation, process, and database. Physically tiered layers are set as server, client, and network software.
Network-centric systems are two-tiered in design. This client-centered model utilizes a method in which both input and processing occurs on the client end. The client is able to directly access the data rather than appealing to a network for processing. All data activity is implemented on the client with the server acting as system support. Since layers in the two-tiered model are less distinct, containing less defined partitioning of application logic, the design has limits in scalability and can be somewhat difficult to maintain.
Testing Within Client Environments
Difficulties are characteristic of software QA testing. In addition to traditional testing challenges, testers within the client environment encounter an additional and distinct set of difficulties. Multi-tiered interfaces must be tested both individually and as interactive components.
Rather than linear, testing must be stacked and three-dimensional from a distributed perspective. Since data is dispersed across various server platform levels, testing must address a number of multi-layered processing issues, including:
- API and GUI interfacing
- Diversity of platforms
- Distributed processing
- Replicated data
- Multi-level relationships
- Configuration testing
- Data compatibility
- Multi-level interface compatibility
- Diverse and distributed databases
- Diversity of targeted environments and systems
The less complex the software design the smoother the design is to test. Therefore, the two-tiered network centric system is less of a testing challenge than Client Server implementations. Verification of the two-tiered database is a smoother process with most errors and deficiencies being external to procedures. However, deficiencies that are detected often require reinstallation of the software at each workstation.
Example of a 3-tiered client server (Source: Bartledan)
Building a Client Test Environment
The tiered structure of the client processing environment, therefore, eludes many traditional integrated testing formats. Linear testing, even when automated, is narrow in addressing the dimensions of client centric processing. The testing initiative must begin with a comprehensive multi-dimensional testing plan.
Client environment testing must be comprehensively built around data access, data storage, and independent user interfaces. The abstractions of presentation, process, and database must subsequently be included in module design, as must the physically tiered layers of server, client, and network functionality.
The client test build must, therefore, begin with the consideration of the diverse software and hardware platforms that make up client tiered systems. The build must next take into account client connections to diverse network and the performances therein.
Thirdly, the test build must consider data integrity across network servers with an initial focus on data replications.
Regression testing build emphasizes two points of development, transitions that link process phases and post-process executions. Each new software release test is anchored at three component nodes:
- The stability of previously correct functions.
- Correction of previously reported errors.
- Multi-tiered errors within the newly created functionality.
The most effective functionality tests are scenarios that demonstrate behaviors of business users in organizational conditions. It is imperative to finitely identify the business circumstance when initiating the initial test plan.
Ensuing operational tests must emphasize performance through a concentrated focus on API or GUI interfaces. The cross-tiered quality of client environments creates complexity in assessing interface operations. Interface assessments must remain consistent across tiers and in connection with diverse hardware and system structures. The event-driven dynamics of API or GUI interfaces significantly increase the number of potential logical paths anticipated user actions can take.
Through multi-tiered platforms, operational test builds must in addition center on supporting data which sustains text and content and options for users to customize data depictions, commands, and entries, as well as the fundamental operations which actuate processing.
Acceptance and performance testing are to be built as both multi-user and multi-platform modules.
Client Environment Testing Techniques
Testing techniques must focus on deficiencies in logical progressions as well as coding. Verification of multi-tiered functionality and interfaces is primary to stable operations. Black Box input and output analysis effectively validates user-driven dynamics. Dividing data with equivalence partitioning advances the testing of data and platform interfaces. Boundary analysis in effect dissects and examines the range and quality of communication across servers.
In addition to more traditional testing techniques, structured capture and playback tools have proven successful in developing test scripts from input data during manual testing for the formulation of automated test modules. Unlike traditional capture and playback techniques, which record external input and output functions, structured captures and playbacks assess external interactions from an internal perspective, providing analytical resources to automated testing. Load, stress, and performance tests can all benefit from structured capture and playback tools. Tools can in addition advance the efficiency of regression tests.
Multi-tiered platforms place increased demand on system interfaces and capabilities. To assess capabilities, system tests must, therefore, administer two types of evaluations: single user functional tests to assess interface stability and multi-user testing to measure system capacity. Automated simulations of multiple client access to a single server application best assess system tolerance and capabilities.
Client-server systems and evolved network-centric computing is preferred within enterprise strategic goals as cost-effective business information processing systems. Accelerated deployment of client communication in end-user environments assures ease and efficiency in process completion. In short, client communication environments get the job done.
Attributes of Client-Server Environments
Primary client-server attributes provide significant benefits to information system communication.
- Client-server environments utilize one powerful computer to distribute and monitor computing communications. Client workstations contact the server as a data and information provider.
- Centralization is the prime advantage of client-server computing. The entire communication setup, including authorizations and resource allocations, occurs on Servers.
- Consolidated management of communication resources centralizes data storage for ease of access and retrieval.
- Centralized data storage alleviates complexities in data backup, lessening down times and better assuring full recovery.
- One server is required for operation eases change and upgrade processes. Scalable system expansions and add-ons can be more smoothly implemented and installed.
- Access to multiple network platforms increases accessibility and interactive communication.
- Information uploads are centralized, bypassing the need for multiple installations on individual workstations with the accompanying requirement to increase workstation storage capacities.
- Server roles can be revised and data manipulated to accommodate to diverse client needs.
- Security specifications can be centrally defined at the moment of environmental setup.
However, certain testing requirements complicate validation of system operations and performance:
- Multiple requests traveling through the network can cause congestion, adding required builds to network testing for the avoidance of server breakdowns. Unlike peer-to-peer networking of distributed application architecture between peers, limited client-server bandwidth can become gridlocked with user demands.
- Client-server architecture is not as robust as user demands sometimes require, placing added pressure on performance testing. Server failure causes a breakdown in the entire network.
- Client-servers maintenance and technologies require exclusive IT and QA test management.
Client-server computing supports business accessibility and integration. Networking through the client environment allows each client or workstation to connect to the central server. Clients can access software and hardware applications from diverse sources. Accessibility centralized on the server produces such business benefits as cost reduction, increased flexibility of communication, increased productivity, and efficient resource utilization.
Business needs of the 21st century engendered the rise of the Client Server model to reduce information system hierarchies into systems of linear and direct communication which provide greater decision-making alignment to data and processing access. While requiring greater testing complexity and involvement, single process client environment applications provide enduring benefits to the workplace.