software architecture slide 2
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33 what are cohension levels from bad to good?
coincidental
logical
temporal
procedural
communicational
sequential
functional
32 what are coupling levels from bad to good?
content
common
external
control
stamp
data
message
no coupling
31 what is cohesion and coupling
cohesion: measure of how strongly a module's responsibilities are related, its 'unity of purpose'
coupling: measure of responsibility overlap beween modules, the probability that modifying one module requires modifying the other.
30 what are catogories of tactics for modifiability?
reduce size of a module
increase cohesion
reduce coupling
defer binding
29 what questions should an architect has to consider to plan for modifiability?
what can change
what is the likelihood of the change
when is the change made and who makes it
what is the cost of change
28 what is modifiablility
modifiability is about change and our interest in
it is the coust and risk of making changes
27 what are catogries of tactics for security?
Detect ATtacks
Resist attacks
React to attacks
recover from attacks
26 what are other characteristics that support CIA?
Authentication
Nonrepudiation
Authorization
25 what are CIA characteristics of security
Confidentiality
Integrity
Availability
24 what is attack
attack is action against system with the intention of doing harm
unauthorized attempt to access servides
attempt to deny services to legitimate users
23 what is security?
security is a measure of the system's ability to protect data and information form unauthorized access while still providing access to people and systems taht are authorized
23 what catogories for performance tactics?
control resource demand
Manage resource
22 what is performance?
Performance is about time and the software system's ability to meet timing requirements.
21 what is orchestrate?
Use a control mechanism to coordinate, manage and sequence the invocation of services
20 what are the proxy design pattern?
19 what catogories for interoperability tactics?
Locate
service discovery
manage interface
tailor interface
18 what is interoperability
Interoperability is about the degree to which two ore more systems can usefully exchage meaningful information via interfaces in a particular context.
17 what are catagories of availability tactics?
Detect Faults
Recover from Faults
preparation and repair
reintroduction
Prevent Faults
16 what do availability tactics do?
Availability tactics enable a system to endure faults so that services remain compliant with their specifications
The tactics keep faults from becoming failures or at least bound the effects of the fault and make repair possible.
15 what is fault or combination of faults
A fault has the potantial to cause a failure.
A failure occurs when the system no longer delivers a service conssitent with its specification
such a failure is observable by the system's actors
14 what is availability?
Availability refers to the ability of a system to mask or repair faults such that the cumulative service outage period does not exceed a required value over a specific time interval.
13 what are the categories of design decisions to make?
Allocation of responsibilities
Coordination model
Data model
Management of resources
Mapping among architectural elements
Choice of techonology
Binding time decisions
12 what is the difference between tactics and architectural/design patterns?
A tactic provedes a solution for one quality attribute
A pattern provides a bundled solution for multiple attributes
11 what are tactics
tactics are design decision influencing the achievement of a quality attribute responce
tactics, like architectural/design patterns, are techniques that architects have been using for years.
Not invented, but captured from parctice.
10 how to achieve quality attribute
architects can use architectural tactics to achieve the required quality attributes
9 how to specify quality attribute requirement?
using six-part quality attribute scenario's
source of stimulus
stimulus
environment
artifact
resonse
response measure
8 what is the solution of conflicts between quality attributes
trade-off of architectural decisions.
7 are there conflicts between quality attributes.
Yes
withicn complex systems, quality attributes can never be achieved in isolation. The achievement of any one will have an effect, sometimes positive and somtimes negative, on the achievement of others.
6how many cantegories for quality arrtributes
there are two categories of quality attributes
those that describe some property of the system at runtime
such as availability, performance or usability
those that describe some property of the development of the system
such as modifiability or testability
5 what is architect's interest in functionality?
the architect's interest in functionality isin how it interacts with and constrains the system's qualities.
4 why responsibilites can not be allocated arbitrarily to any modules?
Although responsibilites can be allocated arbitrarily to any modules, soft ware architecture constrains this allocation when quality attributes are important.
3 where does the most basic of architectural structures come from?
functionality is achieved by assigning responsibilities to architectural elemetns, resulting in one of the most basic of architectural structures.
2 what is the relationship between functionality and architecture?
Functionality does not determinde architecture
Given a set of required functionalities, there is no end to the architectures you could create to satisfy that functionality.
if functionality were theonly thing that mattered, you wouldn't have to divide the system into pieces at all.
1 what is functionality?
functionality is the ability of the system to do the work for which it was intended.
