1. PROBLEM,PROCESS & PRODUCT
PROBLEM AND SOLUTION
In the problem & solution, there are 3 important problems are identified. They are
1. What is the s/w practitioner/s biggest problem?
2. How does s/w reliability engineering approach it?
3. What’s been the experience with software reliability engineering?
1 What is the s/w practitioner’s biggest problem?
The users of s/w based systems generally rate on the average measures
*the important quality, characteristics are
1.reliability/availability
2.rapid delivery
3.low cost
*these characteristic are user oriented than developer oriented.
* a large group of software people facing the important software is how to resolve conflicting demand
that customers place on them.
*quantitative measures existed for delivery time and cost.
*profitability is the directly related to objectives for reliability and availability.
*if reliability/ availability is set too high delivery time may be too long.
*competitors will beat you to market and product will face heavy loss.
*if the reliability / availability objectives is set too low, your product may get bad reputation.
(i) sales may suffer
(ii) product will again get heavy loss.
*the characteristic of faster delivery includes as the subset with greater agility means with more
response to changes in user needs or requirement.
Therefore including that s/w researcher and developer have built many tools to support the process.

2. By engineering s/w reliability the product reaches the market at right time and at acceptable cost.
2 How does s/w reliability engineering approach it?
 Primary objective of s/w reliability engineering is to heap the engineer, manager or user of
software.
 Secondary objective Is to make everyone aware of s/w reliability and can save money on project
or life cycle.
DEFINITION FOR S/W RELIABILTY:
 s/w reliability engg, is not to make s/w more reliable and available. But it is achieving
correct balance, based on customer needs among reliability availability, delivery time
and cost.
 s/w reliability engg is efficient because it is based on quantitative information about
customers
PRODUCT CHARACTERISTICS:
The product characteristics are reliability, development time, cost.
 Reliability is user oriented and not developer oriented
 It is related to operation rather than design of the program.
 It is dynamic rather than static.
 s/w reliability engg works by quantitatively and the two characteristics are
(i) expected use and decided major quality.
EXPECTED USE: it increases effective resources and delivers decided functionality for the
product under development , much more efficiently by the expected use of the product.
It focuses on resources that most used or most critical functions. Eg: review time, unit code,
test time, testcases.
Maximize test effectiveness making tests highly representative of the field.
SOFTWARE RELIABILTY ENGINEERING PROCESS:
it is designed for both legally and new products.
It process 6 activities :
 defining the product
 implementing operational profiles
 engineering the “just right” reliability
 prepare for test
 executing the test
 guiding test

3. they are illustrated in below fig. (book 11)
 the first activity is defined the product
this includes who is the supplier , customer, user.
 Second is implementing the operational profile- an operation profile is complete set of
operation of the systems.
It will be applied to increase the efficiency of the development of the all developed s/w
and test of all s/w.
You can use operational profiles to allocate measures to reduce cost.
 The third activity is engineering the “jus right” reliability. The principle activities are
1. Defining failure in project
2. Choosing an common reference unit for all failures.
3. Setting an system failure intensity objectives
4. Finding an developed s/w failure intensity objective(FIO) for any s/w you develop
with lowest development cost.
 Fourth activity is prepare for test which involves new test cases
 Fifth activity is the executing the test
1.determine and alterate test time
2. involve test.
3.identify system failures.
 Final activity is guiding test
Processing failure data gathered in test for various purposes.
ARCHITECTURAL PHASE:
Includes design of fault tolerance features.
DEFINING THE PRODUCT:
To define the product -> first need to establish -> who is the supplier -> who is the customer -> user
Def: customer makes purchase decision for a product and users put it to work.
 The main sub activity in defining a product is to list the associated systems.
 Many product will have variations.
 A variation of the product is the product that performs a same general function as the
base product but that defers in functionality or implementation, such that it is tested
separately from it.
 A different software configuration of the product is variation.