{"id":163,"date":"2023-05-14T15:02:03","date_gmt":"2023-05-14T15:02:03","guid":{"rendered":"https:\/\/itnotes.apjsoftwares.com\/?p=163"},"modified":"2023-05-14T15:02:03","modified_gmt":"2023-05-14T15:02:03","slug":"data-flow-diagrams-dfd-or-bubble-chart","status":"publish","type":"post","link":"https:\/\/itnotes.apjsoftwares.in\/index.php\/2023\/05\/14\/data-flow-diagrams-dfd-or-bubble-chart\/","title":{"rendered":"Data Flow Diagrams (DFD) or Bubble Chart"},"content":{"rendered":"\n<p>It is a technique developed by Larry Constantine to express the requirements of a system in a graphical form.<\/p>\n\n\n\n<ul>\n<li>It shows the flow of data between various functions of the system and specifies how the current system is implemented.<\/li>\n\n\n\n<li>It is an initial design phase that functionally divides the requirement specifications down to the lowest level of detail.<\/li>\n\n\n\n<li>Its graphical nature makes it a good communication tool between user and analyst or analyst and system designer.<\/li>\n\n\n\n<li>It gives an overview of what data a system processes, what transformations are performed, what data are stored, what results are produced and where they flow.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Basic Elements of DFD<\/strong><\/h3>\n\n\n\n<p>DFD is easy to understand and quite effective when the required design is not clear and the user wants a notational language for communication. However, it requires a large number of iterations for obtaining the most accurate and complete solution.<\/p>\n\n\n\n<p>The following table shows the symbols used in designing a DFD and their significance \u2212<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td>Symbol Name<\/td><td>Symbol<\/td><td>Meaning<\/td><\/tr><tr><td>Square<\/td><td><img decoding=\"async\" loading=\"lazy\" alt=\"Square\" src=\"blob:https:\/\/itnotes.apjsoftwares.com\/5394ca44-1c25-445c-8ed8-629dcdfb57f3\" width=\"35\" height=\"35\"><\/td><td>Source or Destination of Data<\/td><\/tr><tr><td>Arrow<\/td><td><img decoding=\"async\" loading=\"lazy\" alt=\"Arrow\" src=\"blob:https:\/\/itnotes.apjsoftwares.com\/d83350a1-6d3f-471d-b6c8-c5c3d3f1c4ea\" width=\"129\" height=\"34\"><\/td><td>Data flow<\/td><\/tr><tr><td>Circle<\/td><td><img decoding=\"async\" loading=\"lazy\" alt=\"Circle\" src=\"blob:https:\/\/itnotes.apjsoftwares.com\/6dc22807-c41f-4087-8626-76836aa23954\" width=\"53\" height=\"35\"><\/td><td>Process transforming data flow<\/td><\/tr><tr><td>Open Rectangle<\/td><td><img decoding=\"async\" loading=\"lazy\" alt=\"Rectangle\" src=\"blob:https:\/\/itnotes.apjsoftwares.com\/53c95d04-37f1-4776-8257-fa6a4cc23f49\" width=\"103\" height=\"48\"><\/td><td>Data Store<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Types of DFD<\/strong><\/h3>\n\n\n\n<p>DFDs are of two types: Physical DFD and Logical DFD. The following table lists the points that differentiate a physical DFD from a logical DFD.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td>Physical DFD<\/td><td>Logical DFD<\/td><\/tr><tr><td>It is implementation dependent. It shows which functions are performed.<\/td><td>It is implementation independent. It focuses only on the flow of data between processes.<\/td><\/tr><tr><td>It provides low level details of hardware, software, files, and people.<\/td><td>It explains events of systems and data required by each event.<\/td><\/tr><tr><td>It depicts how the current system operates and how a system will be implemented.<\/td><td>It shows how business operates; not how the system can be implemented.<\/td><\/tr><\/tbody><\/table><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>It is a technique developed by Larry Constantine to express the requirements of a system&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[7],"tags":[],"_links":{"self":[{"href":"https:\/\/itnotes.apjsoftwares.in\/index.php\/wp-json\/wp\/v2\/posts\/163"}],"collection":[{"href":"https:\/\/itnotes.apjsoftwares.in\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itnotes.apjsoftwares.in\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itnotes.apjsoftwares.in\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/itnotes.apjsoftwares.in\/index.php\/wp-json\/wp\/v2\/comments?post=163"}],"version-history":[{"count":1,"href":"https:\/\/itnotes.apjsoftwares.in\/index.php\/wp-json\/wp\/v2\/posts\/163\/revisions"}],"predecessor-version":[{"id":164,"href":"https:\/\/itnotes.apjsoftwares.in\/index.php\/wp-json\/wp\/v2\/posts\/163\/revisions\/164"}],"wp:attachment":[{"href":"https:\/\/itnotes.apjsoftwares.in\/index.php\/wp-json\/wp\/v2\/media?parent=163"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itnotes.apjsoftwares.in\/index.php\/wp-json\/wp\/v2\/categories?post=163"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itnotes.apjsoftwares.in\/index.php\/wp-json\/wp\/v2\/tags?post=163"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}