Saturday 23 April 2022

Software Development: Iterative and Evolutionary Development

Iterative and Evolutionary Development

Involves early programming and testing of a partial system, in repeating cycles.
Relies on short quick development steps (or iterations), feedback and adaptation to clarify the requirements and design so successively enlarging and refining a system.
Normally assumes that the development starts before all requirements are defined in detail, feedback is used to clarify and improve the evolving specifications.
Each iteration will include requirements, analysis, design, implementation, and test.
Iterative feedback and evolution leads towards the desired system. The requirements and design instability lowers over time.

Current research demonstrates that iterative methods are associated with higher success and productivity rates, and lower defect levels.

Timeboxing

A key idea is that iterations are timeboxed, or fixed in length.

Most iterative methods recommend in iteration length between 2 – 6 weeks.
If it seems that it will be difficult to meet the deadline, the recommended response is to de-scope

De-scoping: removing tasks or requirements from the iteration, and including them in a future iteration, rather than slipping the completion date.

Iterative and Evolutionary Development (also known as iterative and inceremental development; spiral development and evolutionary development)

Build-Feedback-Adapt Cycles

In complex changing systems, feedback and adaptation are key ingredients for success:

Feedback from early development, programmers trying to read specifications, and client demos: to refine the requirements.
Feedback from tests and developers : to refine the design and models.
Feedback from the progress of the team tackling early features : to refine the schedule and estimates.

Benefits of Iterative development

Less project failure, better productivity, and lower defect rates
Early rather than late mitigation of high risks
Early visible progress
Early feedback, user engagement, and adaptation
Managed complexity: the team is not overwhelmed by “analysis paralysis” or very long and complex steps
The learning within an iteration can be methodically used to improve the development process itself, iteration by iteration.

The Unified Process is a popular iterative software development process.

Why a new methodology?

Process-oriented methods:

Requirements of a project are completely frozen before the design and development process commences.
Not always feasible
Need for flexible, adaptable and agile methods, which allow the developers to make late changes in specifications.

Waterfall (Sequential) Lifecycle

Promotes big up-front “speculative” requirements and design steps before programming.
Historically promoted due to belief or hearsay rather than statistically significant evidence.
Success/failure studies show that the waterfall has high failure rates.

Why the waterfall lifecycle fails?

The key false assumption:

The specifications are predictable and stable and can be correctly defined at the start, with low change rates.
But change is a constant on software projects.
A typical software project experienced a 25% change.

Friday 22 April 2022

Add dynamic rows in html table with Add, Edit, Delete feature in PHP and MySQLi

dynamic-table.php

<!DOCTYPE html>

<head>

<title> Dynamic Table in PhP</title>

</head>

<body>

$(document).ready(function(){

$("#fromdate").datepicker({

changeMonth: true,

changeYear: true,

dateFormat: 'dd/mm/yy'

});

$("#todate").datepicker({

changeMonth: true,

changeYear: true,

dateFormat: 'dd/mm/yy'

});

var employeeData = $('#employeeList').DataTable({

"processing":true,

"serverSide":true,

"bFilter":false,

"bSort" : false ,

"bPaginate": false,

"bInfo" : false,

"order":[],

"ajax":{

url:"action.php",

type:"POST",

data:{action:'listEmployee'},

dataType:"json"

}

});

$('#addEmployee').click(function(){

$('#employeeModal').modal('show');

$('#employeeForm')[0].reset();

$('.modal-title').html("<i class='fa fa-plus'></i> Add Employment Details");

$('#action').val('addEmployee');

$('#save').val('Add');

});

$("#employeeList").on('click', '.update', function(){

var empId = $(this).attr("id");

var action = 'getEmployee';

$.ajax({

url:'action.php',

method:"POST",

data:{empId:empId, action:action},

dataType:"json",

success:function(data){

$('#employeeModal').modal('show');

$('#empId').val(data.id);

$('#post').val(data.post);

$('#company').val(data.company);

$('#type').val(data.type);

$('#fromdate').val(data.fromdate);

$('#todate').val(data.todate);

$('#scale').val(data.scale);

$('#gross').val(data.gross);

$('.modal-title').html("<i class='fa fa-plus'></i> Edit Employee");

$('#action').val('updateEmployee');

$('#save').val('Save');

}

})

});

$("#employeeModal").on('submit','#employeeForm', function(event){

event.preventDefault();

$('#save').attr('disabled','disabled');

var formData = $(this).serialize();

$.ajax({

url:"action.php",

method:"POST",

data:formData,

success:function(data){

$('#employeeForm')[0].reset();

$('#employeeModal').modal('hide');

$('#save').attr('disabled', false);

employeeData.ajax.reload();

}

})

});

$("#employeeList").on('click', '.delete', function(){

var empId = $(this).attr("id");

var action = "empDelete";

if(confirm("Are you sure you want to delete this employee?")) {

$.ajax({

url:"action.php",

method:"POST",

data:{empId:empId, action:action},

success:function(data) {

employeeData.ajax.reload();

}

})

} else {

return false;

}

});

</script>

</div>

</div>

<thead>

<tr>

<th>Department/ Institute/ Company</th>

<th>Permanent/ Temporary/ Contract</th>

<th>Scale of pay</th>

<th>Gross Amount</th>

</tr>

</table>

</div>

<h4 class="modal-title"><i class="fa fa-plus"></i> Edit Employment Details</h4>

</div>

<div class="form-group"

</div>

<label for="company" class="control-label">Department/ Institute/ Company</label>

</div>

<label for="type" class="control-label">Permanent/ Temporary/ Contract</label>

</div>

</div>

</div>

<label for="scale" class="control-label">Scale of pay</label>

</div>

<label for="gross" class="control-label">Gross Amount</label>

</div>

<button type="button" class="btn btn-default" data-dismiss="modal">Close</button>

</div>

</form>

</div>

</div>

</div>

</div>

action.php

<?php

include('Employee.php');

$emp = new Employee();

if(!empty($_POST['action']) && $_POST['action'] == 'listEmployee') {

$emp->employeeList();

}

if(!empty($_POST['action']) && $_POST['action'] == 'addEmployee') {

$emp->addEmployee();

}

if(!empty($_POST['action']) && $_POST['action'] == 'getEmployee') {

$emp->getEmployee();

}

if(!empty($_POST['action']) && $_POST['action'] == 'updateEmployee') {

$emp->updateEmployee();

}

if(!empty($_POST['action']) && $_POST['action'] == 'empDelete') {

$emp->deleteEmployee();

}

Config.php

<?php
class dbConfig {
protected $serverName;
protected $userName;
protected $password;
protected $dbName;
function dbConfig() {
$this -> serverName = 'localhost';
$this -> userName = 'root';
$this -> password = "";
$this -> dbName = "employee";
}
}
?>

Employee.php

<?php require('config.php'); class Employee extends Dbconfig { protected $hostName; protected $userName; protected $password; protected $dbName; private $empTable = 'employment'; private $dbConnect = false; public function __construct(){ if(!$this->dbConnect){ $database = new dbConfig(); $this -> hostName = $database -> serverName; $this -> userName = $database -> userName; $this -> password = $database ->password; $this -> dbName = $database -> dbName; $conn = new mysqli($this->hostName, $this->userName, $this->password, $this->dbName); if($conn->connect_error){ die("Error failed to connect to MySQL: " . $conn->connect_error); } else{ $this->dbConnect = $conn; } } } public function employeeList(){ $sqlQuery = "SELECT * FROM ".$this->empTable." "; $result = mysqli_query($this->dbConnect, $sqlQuery); $employeeData = array(); while( $employee = mysqli_fetch_assoc($result) ) { $empRows = array(); $empRows[] = $employee['post']; $empRows[] = $employee['company']; $empRows[] = $employee['type']; $empRows[] = $employee['fromdate']; $empRows[] = $employee['todate']; $empRows[] = $employee['scale']; $empRows[] = $employee['gross']; $empRows[] = '<button type="button" name="update" id="'.$employee["id"].'" class="btn btn-warning btn-xs update">Update</button>'; $empRows[] = '<button type="button" name="delete" id="'.$employee["id"].'" class="btn btn-danger btn-xs delete" >Delete</button>'; $employeeData[] = $empRows; } $output = array( "draw" => intval($_POST["draw"]), "data" => $employeeData ); echo json_encode($output); } public function getEmployee(){ if($_POST["empId"]) { $sqlQuery = " SELECT * FROM ".$this->empTable." WHERE id = '".$_POST["empId"]."'"; $result = mysqli_query($this->dbConnect, $sqlQuery); $row = mysqli_fetch_array($result, MYSQLI_ASSOC); echo json_encode($row); } } public function updateEmployee(){ if($_POST['empId']) { $updateQuery = "UPDATE ".$this->empTable." SET userid = '".$_POST["userid"]."', post = '".$_POST["post"]."', company = '".$_POST["company"]."', type = '".$_POST["type"]."', fromdate = '".$_POST["fromdate"]."' , todate = '".$_POST["todate"]."' , scale = '".$_POST["scale"]."', gross = '".$_POST["gross"]."' WHERE id ='".$_POST["empId"]."'"; $isUpdated = mysqli_query($this->dbConnect, $updateQuery); } } public function addEmployee(){ $insertQuery = "INSERT INTO ".$this->empTable." (userid, post, company, type, fromdate, todate,scale, gross) VALUES ('".$_POST["userid"]."','".$_POST["post"]."', '".$_POST["company"]."', '".$_POST["type"]."', '".$_POST["fromdate"]."', '".$_POST["todate"]."', '".$_POST["scale"]."', '".$_POST["gross"]."')"; $isUpdated = mysqli_query($this->dbConnect, $insertQuery); } public function deleteEmployee(){ if($_POST["empId"]) { $sqlDelete = " DELETE FROM ".$this->empTable." WHERE id = '".$_POST["empId"]."'"; mysqli_query($this->dbConnect, $sqlDelete); } } } ?>

employee.sql

CREATE TABLE `employment` (

`id` int(10) NOT NULL,

`userid` int(10) DEFAULT NULL,

`post` varchar(100) DEFAULT NULL,

`company` varchar(100) DEFAULT NULL,

`type` varchar(25) DEFAULT NULL,

`fromdate` varchar(25) DEFAULT NULL,

`todate` varchar(25) DEFAULT NULL,

`scale` varchar(50) DEFAULT NULL,

`gross` varchar(50) DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

Thursday 21 April 2022

Unified Process (UP) Best Practices

Get high risk and high value requirements first
Constant user feedback and engagement
Early cohesive core architecture
Test early, often, and realistically
Apply use cases where needed
Do some visual modeling with UML
Manage requirements and scope creep
Manage change requests and configuration

How to persist the selected value of the select box after form submit?

<?php
if ($_POST['submit']) {
if ($_POST['srf'] != "") {
$srf = $_POST['srf'];
} else {
$srfErr = "This field is required.";
}
}
?>
<form method="post">
<select name="srf" id="srf" class="form-control">
<option value="">Select</option>
<option <?php if (isset($srf) && $srf=="1") echo "selected";?>>1</option>
<option <?php if (isset($srf) && $srf=="2") echo "selected";?>>2</option>
<option <?php if (isset($srf) && $srf=="3") echo "selected";?>>3</option>
</select> <?php if($srfErr!= ""){ ?>
<p><b><?php echo $srfErr; ?></b></p>
</div>
<?php }?>
<input type="submit" name="submit" value="submit" />
</form>

Unified Process Phases

Inception

Inception is not a requirements phase; rather a feasibility phase, where just enough investigation is done to support a decision to continue or stop. –
The life-cycle objectives of the project are stated, so that the needs of every stakeholder are considered. Scope and boundary conditions, acceptance criteria and some requirements are established.
Approximate vision, business case, scope, vague estimates.

Inception - Activities

Formulate the scope of the project: Needs of every stakeholder, scope, boundary conditions and acceptance criteria established.
Plan and prepare the business case: Define risk mitigation strategy, develop an initial project plan and identify known cost, schedule, and profitability trade-offs.
Synthesize candidate architecture: Candidate architecture is picked from various potential architectures
Prepare the project environment

Inception - Exit criteria

An initial business case containing at least a clear formulation of the product vision - the core requirements - in terms of functionality, scope, performance, capacity, technology base.
Success criteria (example: revenue projection).
An initial risk assessment.
An estimate of the resources required to complete the elaboration phase.

Elaboration

An analysis is done to determine the risks, stability of vision of what the product is to become, stability of architecture and expenditure of resources.
Refined vision, iterative implementation of core architecture, resolution of high risks, identification of most requirements and scope, more realistic estimates

Elaboration - Entry criteria

The products and artifacts described in the exit criteria of the previous phase.
The plan approved by the project management, and funding authority, and the resources required for the elaboration phase have been allocated

Elaboration - Activities

Define the architecture: Project plan is defined. The process, infrastructure and development environment are described.
Validate the architecture.
Baseline the architecture: To provide a stable basis for the bulk of the design and implementation effort in the construction phase.

Elaboration - Exit criteria

A detailed software development plan, with an updated risk assessment, a management plan, a staffing plan, a phase plan showing the number and contents of the iteration , an iteration plan, and a test plan
The development environment and other tools
A baseline vision, in the form of a set of evaluation criteria for the final product.
A domain analysis model, sufficient to be able to call the corresponding architecture ‘complete’.
An executable architecture baseline.

Construction

The Construction phase is a manufacturing process. It emphasizes managing resources and controlling operations to optimize costs, schedules and quality. This phase is broken into several iterations.
Iterative implementation of the remaining lower risk and easier elements, and preparation for deployment.

Construction - Entry criteria

The product and artifacts of the previous iteration. The iteration plan must state the iteration specific goals
Risks being mitigated during this iteration.
Defects being fixed during the iteration.

Construction - Activities

Develop and test components: Components required satisfying the use cases, scenarios, and other functionality for the iteration are built. Unit and integration tests are done on Components.
Manage resources and control process.
Assess the iteration: Satisfaction of the goal of iteration is determined.

Construction - Exit Criteria

The same products and artifacts, updated, plus
A release description document, which captures the results of an iteration
Test cases and results of the tests conducted on the products
An iteration plan, detailing the next iteration
Objective measurable evaluation criteria for assessing the results of the next iteration(s).

Transition

The transition phase is the phase where the product is put in the hands of its end users. It involves issues of marketing, packaging, installing, configuring, supporting the user. community, making corrections, etc.
Beta tests, deployment.

Transition - Entry criteria

The product and artifacts of the previous iteration, and in particular a software product sufficiently mature to be put into the hands of its users.

Transition - Activities

Test the product deliverable in a customer environment.
Fine tune the product based upon customer feedback
Deliver the final product to the end user
Finalize end-user support material.

Transition - Exit criteria

An update of some of the previous documents, as necessary, the plan being replaced by a “post-mortem” analysis of the performance of the project relative to its original and revised success criteria;
A brief inventory of the organization’s new assets as a result this cycle.

Wednesday 20 April 2022

ER [Entity–relationship] Model

ER Model is a popular high-level (conceptual) data model. It is an approach to designing Semantic Conceptual schema of a Database. ER model allows us to describe the data involved in a real-world environment in terms of objects and their relationships, which are widely used in design of database. ER model provides preliminary concepts or idea about the data representation which is later modified to achieve final detailed design.

Important concepts/notions used in ER modeling are-

Entity

It is an object in real-world or some idea or concept which can be distinguished from other objects.

Ex.: person, school, class, department, weather, salary, temperature etc.

Entity has independent existence.

Entity type

Each entity belongs to an Entity type that defines the structure.

Entity Set

It is a Collection of similar objects.

Attribute

Reflects a property of an object or entity. We have following types of attributes.

> Simple attribute

> Composite attribute

> Single valued attribute

> Multi-valued attribute

> Derived attribute

> Stored attribute

Key

Is an Attribute of an entity type whose value can uniquely identify an entity in a set.

Relationship

The association between entities is known as relationship.

Domain of an attribute

The set of possible values is known as domain of an attribute

Degree of a Relationship

Degree is the number of entity type participate in a relationship.

If there are two entity types involved it is a binary relationship type

eg: Manager manages employee

If there are three entity types involved it is a ternary relationship type

Cardinality of a relationship

Relationships are rarely one-to-one.

For example, a manager usually manages more than one employee. This is described by the cardinality of the relationship, for which there are four possible categories.

The Agile Principles

1. Satisfy the customer through early and continuous delivery of valuable software.

2. Welcome changing requirements, even late in development.

3. Deliver working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter time scale.

4. Business people and developers must work together daily throughout the project.

5. Build projects around motivated individuals.

6. The most efficient and effective method of conveying info.

7. Working software is the primary measure of progress.

8. Agile processes promote sustainable development.

9. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.

10. Continuous attention to technical excellence and good design enhances agility.

11. Simplicity – the art of maximizing the amount of work NOT done is essential.

12. The best architectures, requirements, and designs emerge from self- organizing teams.

13. At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly.