Exploratory Testing - Introduction and Overview

Exploratory testing is an interactive process of concurrent product exploration, test design and test execution. This testing is defined as simultaneous test design, test execution and bug reporting. In this approach, the tester explores the system without having any prior test cases or test scripts. It is also called as ad hoc testing, gorilla testing or intuitive testing. In operational terms, exploratory testing is an interactive process of concurrent product exploration, test design, and test execution. The outcome of an exploratory testing session is a set of notes about the product, failures found, and a concise record of how the product was tested. When practiced by trained testers, it yields consistently valuable and audit-able results. Every tester performs this type of testing at one point or the other. This testing totally depends on the skill and creativity of the tester. Different testers can explore the system in different ways depending on their skills. Thus, the tester has a very vital role to play in exploratory testing.

A systematic approach of exploratory testing can also be used where there is a plan to attack the system under test. This systematic approach of exploring the system is termed as formalized exploratory testing. It is a powerful approach but it has not got recognition and is often misunderstood and not gained the respect it needs. In many situations, it can be more productive than the scripted testing.
This testing believes in concurrent phases of product exploration, test design and test execution. It is categorized under black box testing. It is basically a free-style testing approach where you do not begin with the usual procedures of elaborate test plans and test steps. The test plan and strategy is very well in the tester's mind. The tester asks the right question and judges the outcome. During this phase, the tester is actually learning the product as he tests it. It is interactive and creative. A conscious plan by the tester gives good results.

How to support a reliable communication in transport layer ?

At the Transport layer, each particular set of pieces flowing between a source application and a destination application is known as a conversation.To identify each segment of data, the Transport layer adds to the piece a header containing binary data. This header contains fields of bits. It is the values in these fields that enable different Transport layer protocols to perform different functions.

Reliability means ensuring that each piece of data that the source sends arrives at the destination. At the Transport layer the three basic operations of reliability are:
- tracking transmitted data.
- acknowledging received data.
- retransmitting any unacknowledged data.

This requires the processes of Transport layer of the source to keep track of all the data pieces of each conversation and the retransmit any of data that did were not acknowledged by the destination. The Transport layer of the receiving host must also track the data as it is received and acknowledge the receipt of the data. These reliability processes place additional overhead on the network resources due to the acknowledgement, tracking, and retransmission. To support these reliability operations, more control data is exchanged between the sending and receiving hosts. This control information is contained in the Layer 4 header.

Determining the Need for Reliability
Applications, such as databases, web pages, and e-mail, require that all of the sent data arrive at the destination in its original condition, in order for the data to be useful. Any missing data could cause a corrupt communication that is either incomplete or unreadable. Therefore, these applications are designed to use a Transport layer protocol that implements reliability.