Test cases in each environment are required that explore the input range and probe the boundaries. The number of test cases needed grows exponentially. Subtle bugs arise from unexpected interactions of debugged components.
Programming is unforgiving. Things must work perfectly. Perfection is mandatory. The last bugs take more time to fix than the first. The product is usually obsolete upon or before completion.
The challenge is to find real solutions to real problems on actual schedules with available resources. Software projects go awry for lack of calendar time. The assumption that men and months are interchangeable is invalid. Software schedule and budget estimating is notoriously bad. Schedule progress is poorly monitored. The fallacious response to schedule slippage is to add manpower. This just makes matters worse, much worse.
Cost varies as the product of the number of men and the number of months. Progress does not. When a task cannot be partitioned because of sequential constraints, the application of more effort has no effect on the schedule. You cannot get a baby in a month by getting nine women pregnant.
The effects of training and intercommunication time are important. Adding more programmers lengthens the schedule.
Sequential constraints are especially prominent in component debugging and system test. Testing is usually the most mis-scheduled part of programming. Failure to allow enough time for system test is disastrous. The delay comes at the end of the schedule, almost at the delivery date. Allow enough time in the new schedule to do things right. The number of months of a project depends on its sequential constraints. The maximum number of men depends on the number of independent subtasks The brute force approach is costly, slow, inefficient, and produces systems that are not conceptually integrated.
Key Strategies Build the system with as few minds as possible. Recognize there are large individual differences between high and low performers.
Staff the critical functions with high performers. Insist that a system architect design it all, from the top down. The system architect must confine himself scrupulously to architecture.
Conceptual integrity is the most important consideration in system design. Simplicity and straightforwardness proceed from conceptual integrity. The complete and detailed specification of the user interface is especially important.
Architecture tells what happens, implementation tells how it is made to happen. The system architects must maintain continual vigilance throughout the implementation to ensure continued system integrity.
The System Specification Refrain from hiring implementers until the specifications are complete. The specification must be done by one or two people, if the consistency of prose and product is to be maintained. One must define what is not prescribed as carefully as what is.
Define exactly what a module must do when you specify how big it must be. It is essential to create budgets for the modules—e. Avoid suboptimization to meet component targets. Every project needs a notebook of good subroutines or macros to use. Redo the representation of the data to get the lean, spare, fast program. Representation is the essence of programming.
Before any code is developed, the specification has to be handed to an independent group for scrutinization for completeness and clarity. It is crucial to get the product defined fully. The problems tend to come from the aspects that were never quite specified. You have to have policies written down. The need for a pilot plant before scaling up to full size is critical.
There is a need to get experience with real world conditions. Throw Away the First Version Plan in advance to throw the first version away. You will, anyway. Even the best planning is not so omniscient as to get it right the first time. Save my name, email, and website in this browser for the next time I comment.
Confirmation email was sent to. Contents hide. Estimating Software-Intensive Systems. Estimating product size, performance and quality. Estimating project cost and schedule Estimating process capability and performance. No Comments. Leave a Comment Cancel Reply Please be polite. Your email address will not be published and required fields are marked Save my name, email, and website in this browser for the next time I comment. Continuing education is a factor that plays a significant role in the success of any career.
Product management is a sphere that perfectly confirms this fact. Read More. Top Product Manager Courses in for Beginners and Professionals Today everyone understands that education is not limited to grade school and college years. Just because you've relished in your coveted diploma doesn't mean you're done learning. A user story in Agile methodology is a unit of work that should be done in a particular sprint.
According to the popular Agile concept, a set of user stories should be broken into smaller ones, containable into a single sprint duration. Please enter your valid email address.
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