Use Cases for a Generic Information Sharing System

Use Cases for a Generic Information Sharing System Walt Scacchi, Ph. D. Systems Analysis and Design for ECommerce and EBusiness GSM 271/FEMBA 271 Fall 2001 10/23/2021 1

Use Case Review A Use Case tells a story of reaching a goal, or a set of stories about reaching or failing. 10/23/2021 2

Use Case Review • A UC story captures: – a relation (activity designated by a verb/verb phrase) – the role/community/actor who performs the activity – normal, exceptional and error scenarios • Scenarios are narratives that describes a sequence of steps, actions or other activities • Scenarios identify objects that the actor manipulates through the relation • Objects have attributes which may be manipulated by steps in the relation 10/23/2021 3

A Use Case Example • UC 4: “Place an order” • (Normal Scenario): • “ 1. The clerk identifies the customer, each item and quantity. • 2. System accepts and queues the order. ” • (Exception Scenarios): • “ 1 a. Low credit: Clerk takes prepayment” • “ 2 a. Low on stock: Customer accepts reduced. . . ” 10/23/2021 4

Use Case Example in detail • “Place an order” -- the relation as a verb phrase • “Clerk”, “Customer” and “System” are the actors • “Order” (as in purchase_order) is an object manipulated by the clerk and system – Order has attributes: “customer-identifier”, “item”, “quantity”, “credit-status”, etc. 10/23/2021 5

Format for Capturing a Use Case • UC Identifier (a verb phrase identifying the relation) • Scenarios • (Optional) Use Case Diagram – Items specific to the relation extracted from the Rich Picture – UML has a modeling/diagramming construct called a “Use Case Diagram”, which is a more primitive subset of a Rich Picture. – Search for details Use Case Diagram on the Web 10/23/2021 6

Reusable Use Cases for an Information Sharing System: Global File Sharing System or Enterprise Portal 10/23/2021 7

Relations in <! -- an ISS> • Create/edit & upload content • • – note: “content” is an abstract • object type that has many • enumerated sub-types • Download content • • Edit/upload content • Upload messages/personal content 10/23/2021 Do Messaging Do Email Access other Web content Manage <! -- an ISS> content Develop & Test <! -- an ISS> 8

Create/edit & upload content • • • <! -- Authors> create (insert) new content or edit (update) existing content <! -- Authors> can transmit the content they create to <! -- Publishers> for edit&upload into <! -- an ISS>, else <! -- Authors> upload their content into <! -- an ISS> <! -- Authors>/staff can only upload one type of content at a time into <! -- an ISS> – (Exception) <! -- an ISS> will allow existing content to be copied from one content object to another without upload. <! -- Authors> can only edit (update) content they have individually created – (Exception) <! -- Authors> may copy and paste content created by other <! -- Authors> from one part of <! -- an ISS> into their content. User error: <! -- an ISS> cannot verify if content uploaded is correct. User is responsible for correctness of content System error: <! -- an ISS> will not allow content edit/upload if the <! -- an ISS> DBMS is not available 10/23/2021 9

Download content • Users (<! -- Authors> and <! -- End-users>) can search and download course content: – for content <! -- Authors> have created; or – for messages or personal info. entered by <! -- End-users>; or – (Exception) from content designated for sharing by all <! -- Authors> (content and linked materials) • User error: <! -- an ISS> will not allow access to content except as allowed by <! -- Sponsor> policy • System error: <! -- an ISS> will not allow search or download of <! -- an ISS> content if <! -- an ISS> DBMS is unavailable. 10/23/2021 10

Edit/upload content • <! -- Authors> can transmit the content they create to <! -- Publishers> for edit&upload into <! -- an ISS> • <! -- Publishers> can upload one type of content at a time into <! -- an ISS> – (Exception) <! -- an ISS> will allow existing content to be copied from one content object to another without upload. • User error: <! -- an ISS> cannot verify if content uploaded is correct. Users are responsible for correctness of content • System error: <! -- an ISS> will not allow content edit/upload if the <! -- an ISS> DBMS is not available 10/23/2021 11

Upload messages/personal information content • <! -- End-users> can download, update, then upload personal information for sharing with other users. • <! -- End-users> (end-users) can upload messages for sharing with other <! -- End-users> at any time. – (Exception): <! -- End-users> can send&receive messages from other <! -- End-users> via <! -- an ISS>, without uploading these messages into <! -- an ISS> • User error: <! -- an ISS> cannot verify if content uploaded is correct in any sense. User is responsible for correctness of content • System error: <! -- an ISS> will not allow content edit/upload if the <! -- an ISS> DBMS is not available 10/23/2021 12

Do User Messaging • <! -- Authors> can request <! -- End-users> in their courses to download or upload messages via a <! -- Asynchronous Messaging System>or <! -- Synchronous Messaging System> • <! -- Authors> or <! -- End-users> can download/upload messages for sharing with other <! -- End-users> at any time. – (Exception) <! -- Authors> can remove messages from their <! -- Asynchronous Messaging System> • User error: Messages that are deleted from a <! -- Asynchronous Messaging System> cannot be retrieved • User error: <! -- Synchronous Messaging System> message content is usually not saved by <! -- an ISS> • System error: <! -- Asynchronous Messaging System> message content managed by the <! -- an ISS> may be lost if the <! -- an ISS> Database is not backed-up. 10/23/2021 13

Do Email • Any user can access internal or external email systems via <! -- an ISS> to create, upload, download, update then upload messages for other users at any time. • <! -- an ISS> does not manage email messages or message services – (Exception): Users can create, upload, download, update then upload email messages via <! -- an ISS>, without uploading these messages into <! -- an ISS>. • User error: Users cannot use <! -- an ISS> to manage or keep track of personal/private email messages or message content • System error: An email server may fail to send or receive email messages with or without notifying email users – (Exception) Email servers will notify users if sent mail cannot be delivered 10/23/2021 14

Access other Web content • <! -- Authors> can create content that contains Web hyperlinks • Users can select hyperlinked items – A selected item is downloaded into the User’s client if the Web server can retrieve the item. – (Exception) Users that select hyperlinked content will be disconnected from <! -- an ISS> after a certain elapsed time, unless they return to <! -- an ISS> • User error: <! -- an ISS> will not allow access to its content directly from the Web • System error: <! -- an ISS> may unexpectedly terminate a user session if a user accesses Web items that attempt to upload information into <! -- an ISS>, or launch applications unknown to <! -- an ISS>. 10/23/2021 15

Manage <! -- an ISS> content • <! -- IS System Developers> create the representations, relations, and system components that provide users access to content managed by <! -- an ISS>. • <! -- an ISS> is used to organize, store, query, retrieve or update content that is managed by <! -- an ISS> • <! -- an ISS> uses a (relational) database management system to organize, query, retrieve or update content that is stored in its database – (Exception) <! -- an ISS> stores data that identifies content, and controls access to content, stored as files in a networked file server, or as Web-based content accessed via the Web. • User error: <! -- an ISS> cannot be used to store arbitrary files for endusers. • System error: <! -- an ISS> cannot control updates to external content accessed via the Web. 10/23/2021 16

Develop & Test <! -- an ISS> • <! -- IS System Developers> create the representations that other users utilize to create, insert, update or delete their content. • <! -- IS System Developers> create, insert, update and delete content stored in <! -- an ISS> representations to test its properations – (Exception) <! -- IS System Developers> cannot guarantee that all functions supported by <! -- an ISS> have been tested. – (Exception) <! -- IS System Developers> cannot guarantee that all functions supported by <! -- an ISS> are re-tested every time any <! -- an ISS> function or operation is modified (updated). • User error: <! -- IS System Developers> expect that users will notify them if users encounter anomalies in <! -- an ISS> usage. • System error: <! -- an ISS> system components may fail to operate correctly even though they have been tested. 10/23/2021 17