Exam 2

Describe how rollback is different from compensation and how each is used by the WS-TX specifications

(?) compensation doesn't roll back changes.. assuming it does different things depending on what fails

Describe the delivery assurances provided via WS-ReliableMessaging

ACKs and NAKs; they can also be delivered prior to a sequence being complete; AtMostOnce: promises delivery of one or zero messages; AtLeastOnce: Allows a message to be delivered once or several times; ExactlyOnce: guarantees that a message will only be delivered once; InOrder: guarantee that messages are delivered in order

What's the difference between active and passive intermediary's?

Active modifies the message and passive does not

___ provides a means of equipping SOAP messages with self governing, routing related meta information

Addressing

delivery assurances, ReliableMessaging

AtMostOnce, AtLeastOnce, and ExactlyOnce are examples of ____ associated with the ___ industry standard

What is ACID

Atomic (all changes succeed or none succeed), Consistent(data changes cant violate data model), Isolated (multiple transactions can't interfere with each other), Durable (after success, changes can survive failures)

Define the orchestrated task service model

BPEL process definitions encapsulated and exposed via web services; aka process service model

WS-BPEL

Business Process Execution Language; industry spec that standardizes orchestration

WS-CDL

Choreography Description Language; attempts to organize information exchange across multiple orgs

Compare component and service aggregation

Components and web services are self contained units of logic capable of being aggregated, developed using proprietary tech, and underlying logic may or may not be component based; (web services communicate with non-proprietary tech)

Compare how service contracts exist within components and web based services

Components are physically coupled to logic, web services are physically decoupled from logic

Describe proprietary techs that components and services can use

Components rely on Remote Procedure Call (RPC); RPC protocols enable component comms via proxy stubs

3 common implementation mediums for building services

Components, web services (SOAP), or rest services

___ provides a framework for managing context information across services

Coordination

Describe an XML schema that is entity centric and how it relates to business entity models

Data sets that represent specific business models; used together with entity service model

Scaling out

Distributing load across multiple programs

Prior to popularization of XML schema, what was the commonly used technology

Document Type Definitions (DTD)

An ___ is considered middleware that establishes an intermediate layer of processing through a variety of message processing features

ESB

Describe XML schemas including simple, complex types, and attributes

Elements that contain child elements are complex; elements that contain only values are simple; attributes only contain values (simple) which refer to built in (primitive) data types; complex types are constructs that contain hierarchies

Explain how a message is carried in a SOAP envelope

Envelope document holds an optional header and a required body section (the message payload)

XML Namespaces

Establishes means of creating unique IDs; exists in every XML language; can figure out language/process elements when they are mixed together in the same document

Policy Alternative

Groups of policy assertions that gives requestor choices

Describe each of the roles a service is capable of dynamically assuming within a runtime context

Initiator, relayer, recipient, service provider, service consumer

Describe how service activities relate to MEPs

MEPs are design-time patterns while service activities are runtime execution scenarios; service activity can be considered an instance of MEP

___ are an important part of XML based languages that essentially establish a means of creating unique identifiers. Every XML language (including XML Schema, WSDL, and SOAP) has a pre-defined ___ associated with it

Namespaces, Namespace

___ abstracts and centralizes bussiness process logic

Orchestration

Expand the acronym BPEL and describe how WS-BPEL helps express complex service composition logic

Orchestration service like Access/Bloom service; BPEL: Business Process Execution Language; hub and spoke architecture; expresses business process logic in an industry-standard manner; its a web service composition language;

___ originally provided by WSDL 1.1. were intended to provide callback functionality, but they are not recommended by the WS-I and they are not supported by WSDL 2.0

Outbound MEPs

6 REST architectural goals

Performance, scalability, simplicity, modifiability, visibility, reliability

Describe the content of a WS-Policy definition document, including the policy definition, policy assertions and policy alternatives

Policy Definition: presented individually by required or optional policy assertions; Policy Assertion: can be industry standard (ReliableMessaging, Addressing, SecurityPolicy) or custom defined; allows addition of policy assertions that won't break service contracts; Policy Alternatives: groups of policy assertions; represents one acceptable combination of policy assertions; enables service consumer a choice of policies

Characterize XML Schema Language

Predefined and related elements is a vocabulary; vocabs can be business documents

Describe what is meant by a primitive and complex MEP

Primitive: govern simple message exchanges; Complex: comprised of multiple primitive MEPs

Describe the static and dynamic approaches to web service discovery

Public service registry (service providers can register their services with these); Private service registry (within an enterprise)

Individual service contracts do not need to be published for ___ because the use a uniform contract instead, However, each ___ is not required to support all available HTTP ____

REST Services, REST service, methods

Describe the uniform contract and list the HTTP methods associated with the uniform contract

REST does not have service contracts but share a uniform contract like the HTTP protocol; communicate via HTTP methods (GET POST DELETE PUT HEAD OPTIONS)

REST stands for:

Representational State Transfer

Describe REST service and the technologies it uses for communication

Representational State Transfer introduces architectural style dfiend by goals and constraints (SOAP is based on combined usage of specific tech and industry standards); the goals represent the properties that need to exist for it to be considered RESTful and constraints are the design decisions that need to be applied in order to realize these goals

Characterize the web services framework with respect to standards and vendor independence

SOAP intended to unify RPC comms through XML and HTTP which lead to industry standard, vendor neutral, web based communication framework

Whereas SOAP-based web services primarily rely on the use of ___ headers to exchange message metadata, REST services primarily rely on the use of ___ headers to exchange message metadata

SOAP, HTTP

Decoupling

Separating the consumption of finite resources

The scope of a ___ is limited to interaction with and between services only

Service Activity

Describe intermediary types and the function of intermediate routing and processing

Service Agents are lightweight event driven programs that automatically intercept and process messages; and Intermediary Services are services that transition through the roles of service provider and service consumers

Compare point-to-point communication to chaining services into service compositions

Services can be point-to-* (chaining multiple service calls together)

How is the SOAP industry standard used for web service messaging

Simple Object Access Protocol established standardized format for XML messages and HTTP

What makes a web service service oriented

Solution logic is exposed via standardized service contracts

Explain how components can also be service oriented

The components are shaped to the 8 service oriented design principles to whatever extent possible

Why are SOAP service and web service synonymous?

They are complementary and share the same basic infrastructure

UDDI

Universal Description, Discovery, and Integration is a registry model standard; originally positioned as core web service technology but not anymore; are XML docs that contain discoverable meta information about services

List 3 major standards organizations that have influenced the web services framework

W3C World Wide Web Consortium (XML, XML Schema, XQuery, XML Encryption, XML Signature, XPath, XSLT, WSDL, SOAP, WS-CDL, WS-Addressing), OASIS Organization for the Advancement of Structured Information Standards (WS-BPEL, WS-Security, UDDI, ebXML, SAML) , WS-I Web Services Interoperability Organization (Basic Profile 1.2/2.0, Reliable Security Profile 1.0; also closed in 2010 and became part of OASIS)

Describe the relationship between WS-* and the first generation web service communication framework

WS-* are extensions of the core web service framework and very vendor-driven although remain vendor neutral

___ provides industry standard message routing features via set of pre-defined SOAP headers

WS-Addressing

When using ____ services participating in a transaction vote on the outcome so as to communicate whether the transactions should be rolled back or committed

WS-AtomicTransaction

___ provides the industry standard protocols that emulate ACID transaction functionality across web services

WS-AtomicTransaction

The WS-Coordination industry standard establishes a base coordination framework for which the ___ and ___ industry standards provide additional protocols and rules

WS-AtomicTransaction, WS-BusinessActivity

Describe WS-BusinessActivity and its role in supporting long running, complex service activities

WS-BA supplies protocols to support long running complex activities (based on WS-Coordination framework); BA's can span minutes, hours, or days and involve manual steps; failed transactions aren't rolled back and invoke a separate compensation process

___ establishes a framework that provides an industry standard means of communication if a message failed to arrive, succeeded in arriving and whether a series of messages arrived int he intended sequence

WS-ReliableMessaging

3 industry standrads most commonly associated with the first gen SOAP based web services framework

WSDL SOAP UDDI

Explain how a WSDL definition supports a service contract and provides both abstract and concrete descriptions

WSDL definition is an XML document service description form a service contract; abstract: {portType, operation, message}; concrete: binding, port, service

Describe the industry standard for web services

WSDL for SOAP and HTTP for REST

How are WSDL, SOAP, and UDDI integral to the overall web services framework

WSDL standardized messaging format, SOAP for message structure, Universal Description, Discovery, and Integration (UDDI) allows orgs to discover web services published by others

Whats WSDL

Web Service Description Language expresses messaging based technical interface via XML

Describe the concept of web service messaging compared to component data exchange using binary RPC style communication

Web service messaging is Entity centric xml schemas based on the entity service model and normally standardized separately from web service contracts so they can establish an independent data architecture; they rely solely on messages for communication; this is the difference between web services and RPC communication

Rest Service

Web service that relies on uniform contract provided by HTTP

SOAP based web service

Web service that utilizes the WSDL language to express service contracts

XML relates to data and metadata...

XML contains both data and metadata

Explain how XML schemas can be embedded in XML docs

XML docs can link to same XMLs; One XML doc can link to multiple XMLs; Schemas can be embedded in XML docs

List the core family of XML technologies

XML schema, XML Style Sheet Transformation (XLST), XML Query Language (XQuery), XML path language (XPath)

Whereas the ____ lagnunage is used to establish a customized vocabulary of elements that describe data, the ____ language is used to establish a formal structure and data model for this vocabulary

XML, XML Schema

How is XQuery similar to SQL?

XQuery is to XML docs what SQL is to databases

___ are used to map one schema structure to another in order to enable the runtime transformation of XML documents. XPath expressions can be embedded within ___

XSLT Stylesheets, XSLT stylesheets

extensibility

ability to add functionality to the architecture

configurability

ability to permanently modify parts of an architecture

evolvability

ability to refactor and redeploy a service, consumer, or middleware component without impacting other parts of the architecture

customizability

ability to temporarily modify parts of a solution to perform tasks

Problems that XSLT solves

allows services to overcome data representation disparity; facilitates manipulation, ordering, filtering of doc data

purpose of core service logic

back-end party of a web service that carries out whatever task is associated with the operations expressed in the service contract

3 common layers of SOA

business, application, orchestration

Describe the use of HTTP headers by REST services

carries metadata like authentication tokens, response codes, or error information

6 REST constraints

client-server, stateless, cache, layered system, code-on-demand, interface

purpose of message processing logic

combination of runtime system services, service agents, and service logic related to processing of SOAP message and WSDL definition

Orchestration Service

consists of 1 or more process services that compose business and application services according to business rules and business logic

An initial sender is always also a ___ and an ultimate reciever is always also a ___

consumer, provider

Describe WS-Addressing endpoint references (EPR)

defines further detials pertaining to web service contract (endpoint); common use is to target messages to service instances through special identifiers

Business service

direct implementation of the business service model (entity or task service)

Role and purpose of XSL Transformations (XSLT)

dynamically changes structure of XML doc; The separation of content and structure that XML provides the output structure of an XML doc can be separately controlled

An XML vocabulary is primarily comprised of customizable ___

elements

Smoothing out

evening out interactions over peak and non-peak periods

Describe the purpose of an orchestration engine

executes BPEL process definitions defined by a front-end tool

Characterize XML

gives meaning and context to transmitted data; basis for additional specs; foundation layer upon which service layer is built

Policy

governs assembly and structure of policy description documents

Scaling up

increasing capacity of services

Contrast service roles from service models and why both designations are important

initial sender: service consumer that initiated the message transmission(starting point of message path); ultimate receiver: messages ultimate destination (last service along message path); initial sender is always also a service consumer; ultimate receiver is always also a service provider; intermediary is never an initial sender or an ultimate receiver; (**answer to question**): service roles are temporary classifications based on services runtime utilization; service models are permanent classifications based on nature of logic

Define the term service activity

interaction of a group of services to complete a task

Describe how WS-Coordination provides industry-standard service composition control

introduces generic coordinator service model that controls 3 other system services that manage context data; these services carry out an industry standard means of managing a service activity and are represented by SOAP headers; the activation service provides a coordination context to the application service which shares it with other services. All participants register themselves which provides the address of the coordination service

Explain how XSLT is used for data transformation

it maps one schema structure to another and carries out mapping logic out at runtime

Describe the intent of WS-Coordination and the information types used to coordinate service activities

manages interaction between application and participant services; provide activity-specific runtime information; specific to context of the information (context information); context information includes number of services, duration, number of activity instances, and any rules

Describe how REST uses unique identifiers for media types to communicate to service consumers how to encode message contents

media types define type of encoding (application, audio, image, text, video) and also have unique identifiers (json/xml/png/jpeg/mp4 etc etc)

common processing tasks of a web service

message processing logic; core service logic;

The WS-Security framework supports ___ security which enables message contents to be protected during transport and during processing by service intermediaries

message-layer

3 facets of uniform contract

methods, resource identifiers, and media types

ESB

middleware that establishes intermediate layer of processing with a variety of message processing feautres; can help resolve common service composition design problems related to reliability, scalability, compatibility and message routing; are commonly expected to provide: asynchronous queuing intermediate routing, reliable messaging, policy centralization, rules centralization, event-driven messaging, data format transformation, data model transformation, protocol bridging

A WSDL document defines a series of ___, each of which represents a function the web service is capable of performing, Each ___ is defined through a set of ___ and/or ___ messages

operations, operation, input, output

Describe the need for orchestration and the role of orchestration as middleware

overcomes system incompatibilities, abstracts and centralizes business process logic, supports non-agnostic services to be more agnostic;

Rest Design goals

performance, scalability, simplicity, modifiability, visibility, portability, reliability

Correlation

places the association of message exchanges into the hands of the message itself

To enforce rules beyond a WSDL definition, ___ can be used

policies

Policy Attachment

policy expressions are physically bound to policy scopes

Confidentiality

privacy of message has been protected throughout its message path

Explain the purpose of WS-Security

provides extensions to implement message layer security; enables message contents to be protected during transport and during processing by service intermediaries; can provide authentication and authorization controls

How does XPath relate to XSLT and XQuery

provides functions for values/filtering; XPath addresses can be absolute/relative; often are embedded within XSLT stylesheets and XQuery modules

Describe the purpose of the WS-Addressing standard

provides industry standard message routing features via a set of predefined SOAP headers (Endpoint Refernces EPRs; Messaging Information Headers/Message Addressing Properties)

Explain the intent of reliable messaging and the mechanics behind the WS-ReliableMessaging framework

provides industry standard way of communicating; whether the message successfully arrives, fails, or a series of message arrived in their intended sequence; includes ReliableMessaging and Reliability and are competing specifications

Describe how XML Schema can be used to define data models and data types

provides means to express a data model for a vocabulary; provides structure, validation rules, type constraints, and inter-element relationships

Explain the role the WS-Policy framework and how policies can be used

provides set of specs that define assembly and structure of policy description docs; allows a service to express characteristics and preferences beyond its technical interface; alleviates the service from having to implement and enforce policy rules and constraints in a customer manner;

Describe the relationship between REST and the World Wide Web

provides the standards for URLs and URIs and the HTTP standards which the WWW works on

Define the term message exchange pattern (MEP)

represent set of templates that provide already mapped out sequences for the exchange of mesages

With REST services you establish ___ that are represented by unique identifiers, usually in the format of ___ or ___

resources, URIs, URLs

Describe how a service activity represents an abstracted view of actual runtime activity and the benefits of that abstraction

service activities represent service interaction only; solution logic is not mapped as part of the service activity

Define the terms service consumer and service proxy

service consumer makes requests; service proxy enables apps to send and receive messages over a channel as method calls

Policy Assertion

service properties expressed by a policy description (service characteristics, preferences, capabilities, requirements, rules)

An intermediary service is a service that transitions through ___ and ___ roles at runtime

service provider, service consumer

Describe what constitutes a SOAP based web service

solution logic that has a published WSDL definition and exchanges SOAP compliant messages; can be part of larger system or a self contained component; does not have to use WSDL

Describe WS-AtomicTransaction and the ACID-style transaction functionality it provides

supports common complex compositions that propagate a transaction across web service boundaries; provides industry standard protocols that emulate ACID transaction functionality; services registered for a transaction vote on the outcome (to commit or abort [rollback] changes);

To ensure the outcome of a service activity, ___ can be applied

transactions

Describe the message-level security provided by WS-Security and why transport-level security is sometimes insufficient with service compositions

transport layer security isnt sufficient because intermediaries are often involved which cannot guarantee that the message is protected; WS-Security works with XML-Signature and XML-Encryption standards to guarantee message security

An ESB is expected to provide the following types of functions: Data format transformation, data model transformation, protocol bridging

true

WS-Policy allows for the definition of policies that can be ignored by service consumers

true

Application Service

typically represents technology specific logic (like a utility service)

Explain how XML is used to implement a standardized data representation layer

wide range of vendor neutral types; creates federated and standardized data representation layer

Describe a REST service capability as a combination of a uniform contract method and a resources identifier

www.example.com/invoicetotal is an example of a uniform contract method and a resource identifier