DISTRIBUTED SYSTEMS CHAPTER 2 ARCHITECTURES
EXAM QUESTIONS AND ANSWERS
Software architecture - ANSWER tell us how the software components are
organized and how they interact
How can we separate applications from the underlying platforms? - ANSWER
- use a middleware layer which provides distribution transparency
System architecture - ANSWER - the final instantiation of a software
architecture where it goes on real machines
- this can include centralized or decentralized architecture
component - ANSWER a modular unit with well-defined interfaces and are
replaceable, while the system continues to operate
4 architectural styles - ANSWER - layered architecture (components are
organized in a heirarchy making calls down the layers)
- Object-based architecture
- resource-centered architecture
- Event-based architecture
communication protocol stacks - ANSWER each layer implements a
communication service with the layer offering an interface for functions that
can be called and allowing data to be sent to one or several targets
- communication protocol describes the rules that parties must follow to
exchange info
Transmission Control Protocol (TCP) - ANSWER - provides reliable, ordered,
and error-checked delivery of a stream of packets on the internet
- AF_NET and SOCK_STREAM are used to specify that the TCP protocol
should be used to communicate between two parties
Three logical levels in Application layering - ANSWER * application-
interface level
* processing level
, * data level (data is persistent and responsible for keeping data consistent across
apps)
Object-based and Service-oriented Architectures - ANSWER - each object is a
component and components are connected through procedure calls
- benefits: encapsulate data (called an objects state) and the operations (or
methods) into a single entity
- when a client binds to a distributed object the implementation of the object's
interface, called a proxy, is loaded into the client's address space
proxy - ANSWER - the implementation of an object interface
- it mashal's method invocations into messages and unmarshals reply messages
to return the result of the method invocation to the client
- incoming invocations from the client are passed to a server stub called a
skeleton, which unmarshals the request to make method invocations at the
object interface
remote objects - ANSWER - a distributed object where the state is not
distributed (its on a single machine)
- only the interfaces implemented by the object are available on other machines
In service-oriented architecture (SOA) a distributed app is a composition of
many _______ - ANSWER - different services that may not all belong to the
same administrative org
- thus SOA is based on service composition
One of the problems with service composition - ANSWER - connecting
different components can turn into an integration nightmare
An alternative to service composition that helps deal with integration hassles -
ANSWER - resource based architectures
- the distributed system is a huge collection of resources managed by
components where resources can be added or removed
Representational State Transfer (REST) architecture - ANSWER 1. Resources
are identified through a single name scheme
2. All services offer the same interface consisting of four operations at most
(PUT, GET, DELETE, POST)
EXAM QUESTIONS AND ANSWERS
Software architecture - ANSWER tell us how the software components are
organized and how they interact
How can we separate applications from the underlying platforms? - ANSWER
- use a middleware layer which provides distribution transparency
System architecture - ANSWER - the final instantiation of a software
architecture where it goes on real machines
- this can include centralized or decentralized architecture
component - ANSWER a modular unit with well-defined interfaces and are
replaceable, while the system continues to operate
4 architectural styles - ANSWER - layered architecture (components are
organized in a heirarchy making calls down the layers)
- Object-based architecture
- resource-centered architecture
- Event-based architecture
communication protocol stacks - ANSWER each layer implements a
communication service with the layer offering an interface for functions that
can be called and allowing data to be sent to one or several targets
- communication protocol describes the rules that parties must follow to
exchange info
Transmission Control Protocol (TCP) - ANSWER - provides reliable, ordered,
and error-checked delivery of a stream of packets on the internet
- AF_NET and SOCK_STREAM are used to specify that the TCP protocol
should be used to communicate between two parties
Three logical levels in Application layering - ANSWER * application-
interface level
* processing level
, * data level (data is persistent and responsible for keeping data consistent across
apps)
Object-based and Service-oriented Architectures - ANSWER - each object is a
component and components are connected through procedure calls
- benefits: encapsulate data (called an objects state) and the operations (or
methods) into a single entity
- when a client binds to a distributed object the implementation of the object's
interface, called a proxy, is loaded into the client's address space
proxy - ANSWER - the implementation of an object interface
- it mashal's method invocations into messages and unmarshals reply messages
to return the result of the method invocation to the client
- incoming invocations from the client are passed to a server stub called a
skeleton, which unmarshals the request to make method invocations at the
object interface
remote objects - ANSWER - a distributed object where the state is not
distributed (its on a single machine)
- only the interfaces implemented by the object are available on other machines
In service-oriented architecture (SOA) a distributed app is a composition of
many _______ - ANSWER - different services that may not all belong to the
same administrative org
- thus SOA is based on service composition
One of the problems with service composition - ANSWER - connecting
different components can turn into an integration nightmare
An alternative to service composition that helps deal with integration hassles -
ANSWER - resource based architectures
- the distributed system is a huge collection of resources managed by
components where resources can be added or removed
Representational State Transfer (REST) architecture - ANSWER 1. Resources
are identified through a single name scheme
2. All services offer the same interface consisting of four operations at most
(PUT, GET, DELETE, POST)
