10 - Web Services

Question 1

what does API stand for?

Answer 1

application programming interface

Question 2

set of clearly defined methods of communication between various components

Answer 2

API

Question 3

a published document that defines how these methods of communication can be used

Answer 3

API

Question 4

refers to the actual implementation of an interface

Answer 4

API

Question 5

used informally to refer to the document that describes the usage of this interface

Answer 5

API

Question 6

APIs that are designed to support interoperable machine-to-machine interaction over a network

Answer 6

web services

Question 7

types of web service implementations (2)

Answer 7

1. simple object access protocol (SOAP)
2. representational state transfer (REST)

Question 8

_____ usage revolves around the exchange of XML messages

Answer 8

SOAP Web Services

Question 9

true/false

SOAP is transport specific meaning messages can only be exchanged using HTTP/HTTPS

Answer 9

false, SOAP is transport agnostic and messages can be exchanges using any network protocol

Question 10

in SOAP web services, the format of the request/response messages are formally defined in the _____

Answer 10

Web Service Definition files

Question 11

Web Service Definitions are written in Web Service Definition Language (WSDL) which has an _____ structure

Answer 11

XML-like

Question 12

___ is the API/interface definition for SOAP

Answer 12

Web service definition

Question 13

what is the relationship between discovery service, service consumer, and web service

Answer 13

web services publish WSDs to the discovery service which can be downloaded by service consumers from the discover service

service consumers can access services from web services

Question 14

discovery services use the ____ framework for sharing and finding WSDs

Answer 14

universal description, discovery, and integration (UDDI)

Question 15

what does REST stand for?

Answer 15

representational state transfer

Question 16

REST was introduced and defined by _____ in ____ for their PhD dissertation

Answer 16

Roy Fielding, 2000

Question 17

design principles (3)

Answer 17

1. transport
2. data formats
3. stateless

Question 18

REST uses ____ for message transport

Answer 18

HTTP/HTTPS

Question 19

true/false

request/response payloads for RESTful web services can use any data format

Answer 19

true

Question 20

RESTful web services are stateless, each exchange between service and client is _____

Answer 20

self-contained

Question 21

RESTful web services use ___ and ___ urls

Answer 21

HTTP and HTTPS

Question 22

RESTful web service urls are usually designed in a ____, ____ pattern

Answer 22

self-descriptive, directory-like

Question 23

why should we stick to the REST API constraints?

Answer 23

the system will more easily be able to achieve desired performance, scalability, and other architectural goals

Question 24

6 constraints of REST

Answer 24

1. Client-Server
2. Stateless
3. Cache
4. Uniform Contract
5. Layered System
6. Code-on-Demand (optional)

Question 25

solution logic is separated into ___ and ____

Answer 25

consumer and service logic

Question 26

how do consumers invoke services?

Answer 26

using a published technical contract

Question 27

true/false being stateless means that each request depends on the context from an earlier message

Answer 27

false, requests don't depend on context from an earlier message

Question 28

what is one benefit of being stateless that relates to server storage?

Answer 28

statelessness frees up server storage space and processing power that would otherwise be used to store and read earlier messages

Question 29

true/false response messages are explicitly labeled as cacheable or non-cacheable for potential reuse

Answer 29

true

Question 30

services to implement cache-control (2)

Answer 30

1. ways to tell if request messages are equivalent or not 2. ways to label if a response is cacheable or not, by whom, and for how long

Question 31

cache improves runtime efficiency by eliminating ____

Answer 31

the need to send duplicate responses

Question 32

___ and ___ share a common, general technical contract

Answer 32

service consumers, service providers

Question 33

clients of a RESTful web service need to know (3)

Answer 33

1. url and http method for a particular operation 2. required inputs 3. returned outputs

Question 34

a common general contract standardizes the interaction between different entities, making ___ possible

Answer 34

interoperability

Question 35

true/false it is in the interest of both parties that the uniform contract changes as much as possible to avoid security risks

Answer 35

false, it should change as little as possible

Question 36

true/false each layer in a layered system can see past the next layer

Answer 36

false, it can't see past the next layer

Question 37

true/false each service is only concerned about interacting with the adjacent layers

Answer 37

false, they are only concerned about interacting with the next layer

Question 38

true/false each layer's logic cannot evolve independently unless a change in the API is made

Answer 38

false, each layer's logic can evolve independently of the others as long as the API between them remains the same

Question 39

service consumers can support the execution of deferred service logic

Answer 39

code-on-demand

Question 40

disadvantage of code-on-demand

Answer 40

consumers need an execution environment for the deferred process (requires additional features on the consumer's part)

Question 41

REST Architectural Goals (7)

Answer 41

1. Performance 2. Scalability 3. Simplicity 4. Modifiability 5. Visibility 6. Portability 7. Reliability

Question 42

areas of consideration for developing a RESTful sevice

Answer 42

REST architectural goals

Question 43

factors to consider in terms of performance (2)

Answer 43

1. throughput & latency of request and responses 2. resource utilization in the server

Question 44

addresses an architecture's need to support a varying number of concurrent connections

Answer 44

scalability

Question 45

true/false services must be easy to scale-up but does not necessarily mean that it should also be easy to scale down

Answer 45

false, it should be both easy to scale up and scale down

Question 46

reduce the complexity of the app by separating functionalities into modules wherein each unit is distinct

Answer 46

simplicity

Question 47

benefit/s of simplicity

Answer 47

easier debugging/refactoring

Question 48

required for an app that will change over time

Answer 48

modifiability

Question 49

self monitoring and regulating parts of the architecture, with the goal of optimizing performance

Answer 49

visibility

Question 50

refers to the ease of moving applications from deployed location to another

Answer 50

portability

Question 51

degree of the service's susceptibility to failure

Answer 51

reliability

Question 52

how can downtimes be addressed?

Answer 52

by using redundant servers