261_review Flashcards
Concept of database and database management systems
DB=an integrated collection of stored data that is centrally mannaged and controlled. Mgm-system software that manages and controls access tdb
What is a relational database system (RDBMS)?
a db mgm system that stores data in tables
Schema
a description of the structure-content-and access controls of a physical data store or database
Table
2D data structure containing rows and columns alscalled a relation
Row
portion of table containing data that describes one entity-relationship or object-alscalled tuple or record
Column/field
a column of a relational database table alscalled an attribute
Primary key
a key used tuniquely identify a row of a relation db table
Foreign key
a field value stored in one relational db table that alsexists as a primary key value in another table
Representing relationship
are represented within a relatikon db by foreign keys
Enforcing referential integrity
a consistent relational db state in which every foreign key value alsexists as a primary key value
Normalization
a technique that ensures relational db schema quality by minimizing data redundancy
Functional dependency
a 1-1 correspondence between 2 field values
1NF
a relational db table structure that has nrepeating fields or groups of fields
2NF
a relational db table structure in which every non-key field is functionally dependent on the primary key
3NF
a relational db table structure in which nnon-key field is functionally dependent on any other non-key field
Distributed Databases Architecture
organizations typically store data in many different databases-often under the control of many different dmbss
Single database server
Clients on one or more LANS share a single database locatedn a single computer system
Replicated database server
Each server stores a separate copy of the needed data. Clients interact with the db server on their own LAN
Partitioned database server
minimize need for db synchronization by partitioning db contents among multiple db servers
Federated database server
is commonly used taccess data stored in dbs with incompatible storage models or dbmss.
What is UML? What type of modeling is it used for?
uml is the accepted standard Omodeling language of the industry.
Use case model
A collection of models that can be used tcapture system requirements based on use cases with the object-oriented approach
The objective of an use case model
is tidentify and define all of the elementary business processes that the system must support.
Use cases
a diagram tshow the various user roles and how these roles use the system
Actor
stick figure that represents a user outside the system
Automation boundary
the boundary seperating the user/actor from the system
<> relationship
adiditional use case that other use cases may need tuse tperform their function-i.e. validate customer
Activity Diagram
is an easily understood diagram tdocument the workflows of the business processes (swimlanes)
Use activity diagram tdescribe use cases
stick-figure-ovals-lines connecting
Understand the notation of an activity diagram
black circle starts flow-oval boxes-black bar indicates repitition-double circle indicates end-swimlane for system-clerkactor-sometimescustomer
Know how tconstruct an activity diagram
swimlanes-oval boxes-etc.
System Sequence Diagram (SSD)
Contains an actor-the system and twparallel dashed lines below
The purpose of a SSD
is used tdescribe the flow of information intand out of the automated sytem.
Understand the notation of SSD
input message on solid line inquireOnitem(catalogID-prodID-size)-return value on dashed line -item information
Know how tconstruct a SSD
rectangle for loops OR *[another item] description-price-extendedprice on top line. := additem(itemID-quantity)-under the line
State Machine Diagram
used tallow analysts tidentify and document which domain objects require status checking
The purpose of a state machine diagram
sometimes it is important tknow the status of a problem domain objects-i.e. state of an order
Understand the terminologies of state machine diagram
state-transition-pseudostate-destination state-origin state-message event-guard condition-path
State
A condition during an object’s life when it satisifies some criterion-performs some action-or waits for an event
Transition
the movement of an object from one state tanother state
Pseudostate
the starting point of a state machine diagram indicated by a black dot
Destination sate
for a particular transition-the state twhich an object moves after the completion of the transition
Origin sate
for a particular transition-the original state of an object from which the transition occurs
Message event
the trigger for a transition which causes the object tleave the origin state
Guard-condition
a true/false test tsee whether a transition can fire
Path
a sequential set of connected states and transitions
What are the composite states?
a state containing other states and transitions (that is a path)
Know how tconstruct a state machine diagram
psuedostate black dot starts-oval/square state-arrow path with message fill()-lowMsg().
How does an Oprogram work?
consists of a set of program objects that cooperate taccompliswh a result
List the models used in the Odesign
component diagram-deployment diagram-design class diagram-interaction diagram-design state machine diagram-package diagrams
Oarchitectural design
first step in system design
Enterprise-level system
a system that has shared resources among multiple people or groups in an organization
Client/server network-based systems
connection is permanent tthe system and values in variables can be passed back and forth and can be remembered by each component in the system. View layer has direct access tfields in system.
Internet-based systems
npermenant connection client and server dnot know the state of each other
Component Diagram
a type of implementation diagram that shows the overall system architecture and the logical components within it (ports/sockets square diagram)
Notation
sockets-ports-conponents-
API
application program interface - the set of public methods that is available tthe outside world
Two-Layer architecture design
web page code i.e. php and the sub program taccess the data i.e. mysql
Three-Layer architecture design
for systrem s that require more complex business logic it is better tadd a layer sthat separate classes exist for botht he domain logic and the data access process.
What are web services?
computer programs that provide services tother systems via the internet and are posted in a directory sthat other systems can find and use them.
Deployment Diagram
a type of implementation diagram that shows the physical components across different locations (3d rectangle with :server)
Purpose of the deployment diagram
shows the placement of various physical nodes across different locations
Notation of the deployment diagram
3d rectangle with :server underlined
Differences between the domain class diagram and the design class diagram
elaborated attributes and method signatures ie.e ():string/public private
Standard stereotypes of design class
is simply a way tcategorize a model element as a certain type. Indicated by guillemets <<»
Entity class
a design identifier for a problem domain class
Control class
a class that mediates between boundary classes and entity classes acting as a switchboard between the view layer and domain layer
Boundary class
or view class - a class that exists on a systems automation boundary such as an input layer
Data access class
a class that is used tretrieve data from a database
Design class diagram
standard three cell diagram we used in java
Three compartments
stereotype name/attribute list/method list
Visibility
denotes wheter other objects can directly access the attribute- the + or - sign for private or public
Method signature
a notation that shows all of the infomration needed tinvoke or call the method
Overload method
a method with one name but twor more parameter lists
Class-level method
a method that is associated with a class instead of with objects of the class
Class-level attribute
an attribute that contains the same value for all objects in the system
Overridden method
a method in a subclass with inheritance that overrides the moethd in the parent class
Abstract class
a class that can never be instantiated (nobjects can be created of this type - i.e. parent class
Concrete class
a normal class that can be instantiated (objects can be created)
Navigation visibility
a design principle in which one object has a reference tanother object and thus can interact with it
CRC card
an index card with lines that partition int3 areas-class name-responsibility-and collaboration classes
Purpose of crc card
brainstgorming technique that is quite popular among oodevelopers
Process of applying CRC cards in class design
usually done in a brainstorming session.
Design principles - Encapsulation and information hiding
principal of objects in which both data and program logic are included within a single self-contained unit
Design principles - Coupling
qualitative measure of how closely the classes in a design class diagram are linked
Design principles - Cohesion
a qualitative measure of the consistency of functions within a single class
Design principles - Protection from variations
principle in which parst of a system that are unlikely tchange are segregated from those that will
Design principles - Indirection
principle in which an intermediate class is placed between twclasses tdecouple them but still link them
Design principles - Object responsibility
principle in which objects are responsible for carrying out system processing
What does the term of use case realization mean?
the process of elaborating the detailed design with interaction diagrams of a particular use case
What does the term of design patterns mean? What are the benefits of using design patterns?
standard design techniques and templates that are widely recognized as good practice
What is the purpose of using the controller pattern?
designer often define an intermediary class that acts as a buffer between the user interface and the domain classes - we call these classes use case controllers
Understand three-layer sequence diagram
more complex systems include classes whose sole responsibility is texecute database sql statements-get the results of the query-provide the infomration tthe domain layer.
Components of a sequence diagram
view layer-business layer-data access layer
Activation lifeline
a representation of the period in which a method of an object is alive and executing
First cut sequence diagram
detailed sequence diagram uses all of the elements that an SSD uses.
How does a design sequence diagram differ from a SSD?
difference is that the :System object is replaced by all of the internal objects and messages within the system.
What classes are included in first cut sequence diagram?
all the classes needed taccomplish the use case?
Explain syntax of a message on a sequence diagram.
message name should reflect the requested service.
The assumptions of developing a first cut sequence diagram
perfect technology (not including user login steps)-perfect memory assumption (objects assumed created in memory and available for use case)-perfect solution assumption (assumes nexception conditions)
Multilayer sequence diagram
incluses the prevous stuff plus userinterface classes and data access classes
Design viewer layer
consists of a single user interface window or more complex multiple windows tenter and view the data
Design data layer
keeping the code separate from the viewing layer sthat there is a class acting as 3rd party between view and data
Communication Diagram
are useful for showing a different view of the use case - one that emphasizes coupling - easier tchange and rearrange on the fly
Differences between a sequence diagram and a communication diagram
lifeline and activation lifeline symbols are not used-alsfocuses more on the objects themselves
The notations of a communication diagram
actor-message-objects and a link symbol that sends or receives messages
Package Diagram
is simply a high-level diagram that allows designers tassociate classes of related groups
Purpose
show related components and dependencies
Dependency relationship
a relationship between packages classes or use cases that indicates a change in the independent item will require a corresponding change in the dependant item
view layer
view layer(display forms-reports-data fields-capture clicks-rollovers-key entry-accept input-edit and validate input-forward input tdomain layer-start and shut down system)
domain layer
create problem domain classes (persistent)-process all business rules with appropriate logic-prepare persistent classes for storage tthe db
data access layer
establish and maintain connections tthe db-contain all sql statements-process result sets of sqls intappropriate domain objects-disconnect gracefully from db
Design Patterns
patterns exist at various levels of abstraction-may be a class definition or only an approach tsolving a problem
Classification of GoF design patterns
basic classification scheme for patterns-creational-structional-behavioral
Creational
help assign responsibilities tclasses tinstantiate new objects
Structural
provide solutions tmeet the architectural needs of the system-that is the set of classes and the ways they are related- help solve problems associated with indirection
Behavioral
provide solutions tproblems that are related tthe way internal system processes execute-for example the iterator pattern solves the problem of how tprocess arrays and lists effectively
Adapter
roughly akin ttravel adapters in that it plugs an external class intan existing system
Factory
in oop a solution is thave some classes that are factories-these classes instantiate objects from utility classes
Singleton
one instance
Observer
approach tsolving an important system problem
