what is an arch style?
is a description of component and connector types and the pattern of their run time
- constrain arch design decisions
- applicable in a dev’t context
- benefit a system
______________ is a named collection of arch design decisions?
arch styles
what are properties of arch styles?
PAS == V Standard Settings
- vocabulary of design elements
—— filter, server, pipe, object
- set of config rules
—– comp can connect only to 2 other comp
- semantic interpretations
—— design elements have well defined meanings
what are common arch styles?
Common I’LL SDP
- implicit invocation
- layered
- language based
- shared state
- data flow
- peer to peer
describe a language based AS with an example
- influenced by the language that implements it
- low level and flexible
example : - major programs and subroutines
- OO style
describe OO style [ comp-conn ]
components - objects
connectors - method invocations
feature - object abstracts local data
Adv / disadv - abstraction
describe a layered AS with examples?
- is a hierarchical organization of system
- each layer acts as:
server : for UL
client : for LL - connectors are protocols
Example: - OSI, dbs …
- client server arch
describe a client-server ( CS ) arch [ comp-conn ]
components - clients and servers
connectors - RPC protocols
what are layers of a CS arch?
presentation
application
data management
list types of CS arch styles
- 2 tier
— fat client model & thin client model - 3 tier
which CS arch type places heavy load on server and network? how?
thin client model,
- server executes data management and application processing
- client only handles presentation
which 2 tier CS arch types are suitable for legacy and new CS systems respectively?
thin and fat client model
what is a 3 tier CS arch?
- each CS layer has its own tier
describe a data flow AS with examples?
- computations are determined by the availability of data
- pattern of data flow is explicit
Examples: - Batch / sequential
- pipe and filter [ non seq ]
describe a pipe and filter [ comp-conn ]
component - filter [ input data stream to output ds]
connector - pipe
- filters are independent [ no shared states ]
- filter has no knowledge of up or down stream
Examples:
- distributes sys
- parallel programs
describe a shared state AS with examples?
- describes a shared data store that is accessed and modified by various components
- central data store is explicitly defined
- aka repository style
Examples: - Blackboard
- rule-based
describe a blackboard [ comp-conn ]
- has 2 type of comp
—— central ds - blackboard
—— components on the blackboard - system is controlled by the blackboard
Example : compiler
describe an implicit invocation AS with examples?
- event announcements instead of method invocation
- listeners will implicitly invoke methods
- component - interface and methods
- connector - 2 types [ imp or exp methods invoked by the listener ]
Example: - publish-subscribe
what are the comp, connectors, topology and data elements in a publish-subscribe arch?
component - publisher, subscriber, proxy
connector - a network protocol [ client - server ]
data elements - subscriptions, notifications, info
topology - subscriber connects to publisher directly or indirectly through intermediary protocols
describe a peer to peer AS with examples?
- state and behavior is distributed among peers
- peer can be client or server
- robust in terms of failure
- scalable in terms of access to resources
what are the comp, connectors, topology and data elements in a peer to peer AS?
comp - peers
conn - network protocols
data elements - network messages
topology :
- may be arbitrary or dynamic
- may have redundant connections b/n peers
