Infs1200 Assignment Help

UQAttic.net [Chat]  INFS1200 2011 midsem notes Module 1: Database Systems What is a database? A database is a collection of related facts.  What is a DBMS? ● ● DBMS – Data Base Management System   The DBMS facilitates:  o o o Defining the database: Specifying types, structure and constraints for the data  Constructing a database: Storing the data on a storage medium  Manipulating a database: Querying and updating the database   What is a database system?     Components ● ● ● ● The stored database: A collection of related facts  The DBMS: The software that defines, constructs and manipulates a database  The applications: The programs that manipulate the database  The users: The people who use the database through the DBMS or applications  Why use a database system? ● ● ● It is not internal and specific to an application program  One database can be manipulated and shared among many users  Allows the application programmer to focus on programming the application  INFS1200 2011 midsem notes ● UQAttic.net [Chat]  Allows you to change the data without affecting the application   The DBMS software   Typical functions Controlling redundancy ● ● Redundancy occurs when one fact is stored in more than once place  Can cause problems such as:  o o o ● Duplication of effort  Wastage of storage space  Inconsistent data  Redundancy can sometimes also enhance performance provided it is controlled  Restricting unauthorized access ● ● ● Different user groups may have different privileges (create, update, delete, etc.)  Controlled by the DBMS through the use of accounts and passwords  Usually contains at least the following roles:  o o o Casual user: May be able to access some data but usually not confidential data  Parametric users: May be given update access but generally can’t change the  structure of the data  Database administrators: Highest privileges, create user accounts and modify  structure  Providing multi-user interfaces ● ● Query languages for casual end users   Programming language interfaces for application programmers  INFS1200 2011 midsem notes ● UQAttic.net [Chat]  Forms and commands for parametric users  Complex relationships DBMS has the ability to represent complex relationships among the data.  Enforcing integrity constraints The DBMS has the capability to define and enforce integrity constraints which are restrictions  placed on the data, based on the meaning of the data, for example:  ● ● ● ● Every subject must have a unique code  A student cannot have 2 different grades for the same subject   A student cannot enrol in more than one four 12-credit subjects in a semester   Student number must be a 9 digit integer  Providing backup and recovery The DBMS provides facilities to recover from hardware and software failures through backup  and recovery systems, for example:  ● ● ●   An update action is being executed  The computer system fails mid-update  The DBMS restores the data to a state prior to the update and restarts the update program    INFS1200 2011 midsem notes UQAttic.net [Chat]  Module 2: Requirements engineering Phases of system development lifecycle 1. 2. 3. 4. 5. Planning  Analysis  Design  Implementation  Maintenence  System development life cycle (SDLC) 1. Project identification and selection  ● Part of cooperate systems planning process  2. Project initiation and planning  ● Project justification, scope study, feasibility, resource allocations, etc.  3. Analysis  ● Identify problems and opportunities based on description of current system; how to fix,  enhance or replace the current system  ● Process modelling, logic modelling, conceptual data modelling  4. Logical design  ● Functional, detailed system specification  ● Forms, reports, interfaces and logical data modelling  5. Implementation  ● Code, documentation, training and support  6. Maintenance  ● New versions, updates  Role of a systems analyst ● Study the problems and needs of an organisation and determine how people, methods and  information technology can be combined to improve the situation  ● ● Help system users and other business managers define their requirements  Act as an agent of change and innovation  System design methodolegies ● Structured design  o o ● Parallel Development  Rapid application development (RAD)  o o o o ● Waterfall model  Phased methodology  Spiral model  Prototyping  Throwaway prototyping  Agile development  INFS1200 2011 midsem notes o UQAttic.net [Chat]  Extreme programming (XP)   Prototyping 1. Planning  a. Analysis  b. Design  c. Code  2. System prototype  3. Code  4. System  Advantages ● ● ● ● Interacting with users allowing dynamic changes  Supports incremental development  Allows you to assess feasibility early  Allows you to explore performance issues early  Problems ● ● ● Users treat prototype as a solution  May not be scalable  Lacks formal methodologies and proof of correctness  Why requirements engineering ● The late correction of requirement errors could cost up to 200 times if not corrected during  requirements engineering.  ● Most problems with software come down to problems with the requirements  What is requirements engineering? Identification of the:  ● ● ● Goals to be achieved by the system  The application of goals in services and constraints  The assignment of responsibilities of the requirements to humans, devices or software  A transformation process from goals to tasks:  ● ● ● A language, model or tool  Automatic support to ensure the quality such as completeness, traceability, verifiability and  reusability   Supporting requirement evolution, viewpoints and inconsistency management  How to do requirement engineering ● ● Domain analysis  Drawing conclusions about domain  INFS1200 2011 midsem notes ● ● ● ● ● UQAttic.net [Chat]  Negotiation and agreement  Specification  Verification and validation of specification  Documentation  Evolution  Dangers of modelling ● A model is never perfect   o o Phenomena in the model may not be present in the application domain  Phenomena in the application domain may not be present in the model  So what should we do? ISO 100% Principle:  “All relevant general static and dynamic aspects, I.e. all rules, laws, etc. of the Universe of  Discourse should be described in the conceptual schema. The information system cannot  be held responsible for not meeting those described elsewhere, including in particular those  in application programs.”  Tools for data modelling ● ● ● ● ● ● ER/EER diagrams  DFD, STD  UML (Object-Oriented approach)  First order Logic  Z Specification Language  Goal Graph   From the universe of discourse to the system ● Verifying the correctness of the system  o o ● Ensure there is no ambiguity or no alternate interpretations   Ensure there is no redundancy or derivable data  Validating the completeness  o o Ensure everything in the UoD is represented  Everything expressed by the model is true to the UoD  Dealing with problems in modelling ● ● ● ● ● Ambiguity: Elicitation and assumptions   Conflicting facts: Negotiation and agreement   Incomplete information: Elicitation and assumptions  Alternative design options: Documentation  Potential structural changes: Schema evolution mechanisms   INFS1200 2011 midsem notes UQAttic.net [Chat]  Modelling processes, dynamics and data ● Understanding the tasks, processes and tools for information systems: Dataflow Diagrams  (DFD)  ● ● Understanding the concepts of system dynamics: State Transition Diagrams (STD)  Understand the kinds of data and its relationships and constraints: Entity Relationship  Diagrams (ERD)  Key components of information systems Data  ● ● Raw facts  Processed data presented in a form suitable for human interpretation  Data flows  ● Groups of data in motion, moving from one place in a system to another  Process logic  ● The steps by which data is transformed or moved and a description of events that trigger  these steps  Perspectives on modelling Process-oriented Approach Concentrates on the flow, use and transformation of data  ● ● Tracks data sources, processing steps and destinations of data  Late additions: Temporary data stores, timing and triggered process steps  Data-Oriented Approach Focusing on the ideal organisation of data rather than where and how that data is used  ● A data model describes the kinds of data needed in the system and relationships among  them  ● ● ● Scheme: syntax  Constraints: semantics  Both data-oriented and process-oriented approaches pre-date object-oriented approach  Seperating database and application ● ● Database: A shared collection of logically related data  Application independence   o o The separation of data from the applications which use that data  Database always designed with some applications in mind (typical queries)  Functional analysis and info flow Modelling of business logic (functions/activities/processes):  INFS1200 2011 midsem notes ● ● ● ● ● UQAttic.net [Chat]  Identifying events: Activities observable in the environment (What has happened?)  Examining information flow: How database is used (what is changed)   Analysing: Determining flow of information between functions and the system I/O (how things  changed?)  Decomposing activities (how to organise changes?)  Defining functions: Decomposing operational part of an enterprise system (how to make  changes)  Data flow diagram (DFD) ● ● A graphical analysis tool to identify processes that transform data when it passes through   Convert physical transformations into a logical model that eliminates the existing physical  constraints  ● Database design not considered in the process (concentrates on how inputs are converted  into required outputs)  ● ● Captures essential features only, usual no a complete representation  Imagines the system will ultimately be implemented using ideal technology which:  o o o o Costs nothing  Takes no time to do a job  Has no size limit  Never makes mistakes  DFD Concepts Terminators ● An existing source of information  o o ● ● ● Either the originator or recipient of information  External to information system  Named with a noun  Must have at least one data flow entering or leaving  Denoted by:    Data flows ● Carries data from one place in a system to another   ● Labelled with a noun, sometimes an objective  o o ● ● ● ● One end must be a process  Avoid generic terms   Doesn’t control flow  Not a flow of materials  Direction of flow is relevant  Denoted by:  INFS1200 2011 midsem notes   Process ● An activity that can occur in the information system  o o ● Can transform, generate, retrieve or delete data  Must have both incoming and outgoing data flows  Labelled with a strong active verb  o ● Don’t use generic verbs  Graphical notation    Data stores ● Information repository  o o o o o ● Connects only to processes  Outgoing line: Usage of information  Incoming line: Change of information  At least one incoming and one outgoing flow  Must be named  o o o ● ● Temporary or permanent records  Nouns (possibly qualified adjective) – no verbs  In and out flows are not named   Avoid generic terms   Normally corresponds to tables  Graphical notation    DFD – Functional analysis model ● Shows flows of data between:  o o o ● ● Processes  Processes and external entities   Data stores and processes  Dependency diagram plus data stores and flows  Components  o o o Process  Data store  Data flow  UQAttic.net [Chat]  INFS1200 2011 midsem notes o UQAttic.net [Chat]  Source-sink (environment/interface  Key things to remember about DFD ● ● ● A data driven approach to analyse the data processing  A top-down refinement process to specify the tasks  A representation of system functions  Types of DFD Context level A DFD with one process only, to document the environment in which the system operates:    ● Terminators are not to be labelled with people’s names  o ● A handler is not a terminator  o ● The person who delivers grade reports is not a terminator  Terminators are outside the system  o ● Use their roles instead  How they interact and communicate is not documented  Every event should create a response  o Every inflow stimulates some activity in the system  Level 0 Diagram A DFD that represents the system’s major processes, data flows and data stores at a high  level of detail:  UQAttic.net [Chat]  INFS1200 2011 midsem notes   Process numbering hierachy Numbered using the following example:  Context: 0  Level 0: 1.0, 2.0, 3.0  Level 1: 1.1, 1.2, 1.3  Level 2: 1.1.1, 1.1.2, 1.1.3  Etc.     

Help

If you ever wanted to a course which was easy, well structured and provide a good balance between prac and theory, well INFS1200 is among the ever increasingly rare courses, offered at UQ, which actually meets this criteria. Unlike some of the 1st year courses, INFS1200 is designed to be easy and intuitive, boosting your morale and confidence lost from some of those other painful 1st courses.

For those of you who don't know what information systems is, it essentially entails the design and implementation of databases from start to finish, from the actual paperwork right down to SQL. No programming experience is assumed (SQL isn't actually a proper programming language BTW).

The lectures are actually useful and insightful, with no technical issues associated with lecture recordings (otherwise this would've been an utter embarassment for an IT lecturer) and the lecturer, Professor Shazia Sadiq providing very informative yet consise explanations that are easy for any layperson to understand, despite her accent. Additionally, she does provide real-world examples (not a reference to QUT) relating to databases and encourages class participation, making the course meaningful. The only minor upset was when Shazia mysterious vanished, only to have Professor Xue Li to fill her role for an 8am lecture. He may be a knowledge man with strong words, but the strength of his words is comparable with the strength of his accent, making it extremely difficult to understand functional dependencies, which was in fact the most difficult component of the course.

As for the content, some may complain that the terminology is bit over the top for such intuitive concepts. I would say that it isn't, and doing well in the exam is matter of memorising a few bits and pieces here and there, practicing some SQL as well as completing some past exams. The exam itself poses no surprises and is a direct reflection of all the past exams, so you can be sure of an easy 7.

Another thing, don't bother with the textbook, unless you plan on taking later year courses in info system. The textbook will overwhelm you with complicated terminology that could be easy explained by a high school student or quick google search for that matter.

The only real complaint that I can make is that it simply isn't challenging enough. Other courses bombard you content, encourage critical thinking or force you to think creatively, INFS1200 doesn't really do either of these and you could get a 7 simply by attending all the tutorials and revising everything the hour before the exam (though I don't encourage it).

Overall, if you're ever in need of an easy breezy course to complement that nasty, painful 1st/2nd year couse such as ENGG1100 or PHYS1002 (just to name a few), then INFS1200 is worth considering even if your not planning to undertake a computer science, software engineering or any IT major.

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