DISTRIBUTED SYSTEMS CH.2
ARCHITECTURES QUESTIONS
WITH 100%VERIFIED ANSWERS
Three logical levels in Application layering - ✔✔* application-interface level
* processing level
* data level (data is persistent and responsible for keeping data consistent across apps)
Object-based and Service-oriented Architectures - ✔✔- 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 - ✔✔- 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 - ✔✔- 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 _______ -
✔✔- 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 - ✔✔- connecting different components
can turn into an integration nightmare
, An alternative to service composition that helps deal with integration hassles - ✔✔-
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 - ✔✔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)
3. Messages sent to or from a service are fully self-described
4. After executing an operation at a service, that component forgets everything about the caller
(stateless execution)
S3 is an example of what architecture - ✔✔RESTful architecture
- GET request to a URI of a bucket to get a list of objects
- PUT request with the URI of the bucket and object
Disadvantage of RESTful architecture - ✔✔- it can prohibit easy solutions to
intricate communication schemes
- for example if distributed transactions are needed then services need to keep track of the state
of execution
Publish-subscribe architectures - ✔✔- dependencies between process are loosely
coupled - strong separation between processing and coordination
Cabri taxonomy of coordination models and coupling - ✔✔- direct = temporally coupled
and referentially coupled
- mailbox = temporally DEcoupled and referentialy coupled
- event-based = temporally coupled and referentially DEcoupled
ARCHITECTURES QUESTIONS
WITH 100%VERIFIED ANSWERS
Three logical levels in Application layering - ✔✔* application-interface level
* processing level
* data level (data is persistent and responsible for keeping data consistent across apps)
Object-based and Service-oriented Architectures - ✔✔- 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 - ✔✔- 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 - ✔✔- 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 _______ -
✔✔- 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 - ✔✔- connecting different components
can turn into an integration nightmare
, An alternative to service composition that helps deal with integration hassles - ✔✔-
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 - ✔✔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)
3. Messages sent to or from a service are fully self-described
4. After executing an operation at a service, that component forgets everything about the caller
(stateless execution)
S3 is an example of what architecture - ✔✔RESTful architecture
- GET request to a URI of a bucket to get a list of objects
- PUT request with the URI of the bucket and object
Disadvantage of RESTful architecture - ✔✔- it can prohibit easy solutions to
intricate communication schemes
- for example if distributed transactions are needed then services need to keep track of the state
of execution
Publish-subscribe architectures - ✔✔- dependencies between process are loosely
coupled - strong separation between processing and coordination
Cabri taxonomy of coordination models and coupling - ✔✔- direct = temporally coupled
and referentially coupled
- mailbox = temporally DEcoupled and referentialy coupled
- event-based = temporally coupled and referentially DEcoupled
