Soa And Web Services

Front 1

What is SOA?

Back 1

Service Oriented Architecture is an architecture for building loosely coupled, blackbox, and modular, black box services that can be orchestrated in tandom to achieve a specific function.

Front 2

Do we need to build SOA from scratch?

Back 2

No, we can wrap systems to loosely couple our system and provide a generic way for external applications and services to use the system as a service.

Front 3

Are Web-Services SOA?

Back 3

To be SOA, they need to be:

-Loosely coupled

-be Described (WSDL)

-Be Discoverable (UDDI)

Front 4

What is a reusable service?

Back 4

A reuseable service is a reusable, loosely coupled, granular, autonomous and stateless.

It needs to be able to be described.

its constraints can be defined by multiple runtime contracts.

Its lifecycle should be goverened at the enterprise level from design time through runtime.

Front 5

How can you achieve loose coupling in a SOA

Back 5

You can provide a service interface like WSDL for a SOAP web service to make it loosely coupled, hiding the implementation from the user.

Front 6

What is ESB

Back 6

ESB is the Enterprise Service bus, which provides an infrastructure to implement a Service Oriented Architecture.

The Enterprise Service bus facilitates standards based integration. It also provides mechanisms for security, Service Level Agreements, Transformation, Routing, Registry, and Transformation capabilities.

Front 7

What are the common pitfalls of SOA?

Back 7

Developers who focus on building an SOA solution, rather than addressing a specific business problem are more likely to create unnecessarily complex interconnections between resources, or may attempt to solve too many problems at once in one service.

Front 8

What is a Web Service?

Back 8

A Web Service is a service accessible over the web with a standardized messaging system like XML.

Front 9

Why are Web Services Needed?

Back 9

Web Services provide interoperability between platforms. They are reusable, can be used independent of the client's platform, and can use http protocol.

Front 10

What are the types of web services?

Back 10

SOAP (Simple Object Access Protocol) - Its a description of an xml messaging protocol(?)

REST (Representation State Transfer) - its a description of an architecture for distributed hypermedia systems(?)

Front 11

What is the difference between SOAP and REST?

Back 11

Soap Has a WSDL Contract

Provides Web Services Security, Reliable messaging, and Transactions. But it requires tools to implement the web service, uses more bandwidth due to the SOAP headers, and the message is contained within the soap envelope.

Rest has no contract, only provides SSL over http for security. But it doesn't require tools, uses less bandiwdth, and transports raw XML or JSON over http.

Front 12

When should you use SOAP or Rest?

Back 12

You should use SOAP when you need some sort of encryption, if connectivity is an issue, or need to enforce atomic transactions.

Rest can be used for simple data manipulation using common http methods. Get Put Post Delete

Front 13

What is the goal of Web services?

Back 13

The goal of web services is to achieve service oriented architecture within an organization.

Front 14

What are the two approaches to create a SOAP based web service.

Back 14

Top-Down/Contract First and Bottom Up/Contract Last

Front 15

What is the web service protocol stack.

Back 15

The Web Service protocol stack is a set of protocols that allow for a service to be described, discovered, and implemented.

There are 4 layers to the stack.

Xml Messaging

Service Transport

Service Description

Service Discovery

Front 16

Is SOAP Stateful or Stateless.

Back 16

Stateless. Http!

Front 17

What is an XML schema. How does it differ from a Document Type Definition?

Back 17

A schema describes an XML markup language, by defining elements and attributes and how they're used, ordered, nested, and their type.

XML allows for much stronger typing than a Document Type Definition, and using the schema, can provide validation and compound documents using multiple markup languages.

Front 18

What is the difference between complex types and simple types in XML schemas?

Back 18

Complex types describe how elements are organized and nested, whereas simple types represent primitive types. Complex types and simple types can represent objects with properties and primitives types in java respectively.

Front 19

What is an XML namespace?

Back 19

XML namespaces provide a similar utility as packages, where they help organize elements, provide access control, and prevent naming conflicts.

Front 20

What is SOAP?

Back 20

Simple Object Access Protocol is a distributed protocol. 1.1 is the standard messaging protocol used by J2EE Web Services. Its purpose is to provide a generic way of interaction between applications over a network using XML.

Front 21

What is the basic Structure of soap?

Back 21

A soap message's root is the soap:envelope element, with and optional soap:header contained inside it. The header has infrastructure data like security tokens, transaction ids, and routing information.

inside the envelope there is a soap:body which actually carrys the application specific message data to be exchanged.

Front 22

What are the different SOAP messaging modes?

Back 22

Soap supports Document/Literal and RPC/Encoded messaging modes. There are also RPC/Literal and Document/Encoded messaging modes.

maybe be fuzzy on whats supported.

web sources say document/literal and rpc/literal

Front 23

What is the Document/Literal messaging mode?

Back 23

The body of a soap message can be validated against an xml schema.

Front 24

What is RPC/Literal?

Back 24

Document-style message that formats its body according to a schema. This schema is included in the WSDL.

a well formed xml element that contains arbitrary application data and belongs to an xml schema and namespace is located in the soap body.

Front 25

What is RPC/Literal?

Back 25

RPC-style message that formats its body according to a schema that reflects the rules defined in the SOAP standard. This schema is included in the WSDL. This can model calls to produres or method calls with parameters and return values.

Front 26

What are the different Messing Exchange Patterns in SOAP?

Back 26

One-Way and Request-Response

Front 27

How are SOAP messages delivered. What is their protocol?

Back 27

HTTP primarily, though other protocols are possible.

Front 28

Are SOAP messages delivered using post or get?

Back 28

POST, get can't store enough information to carry the SOAP message.

Front 29

What is WSDL?

Back 29

WSDL is an XML markup language used to describe a web service and specify the exact message format, internet protocol, and address that a client must use to communicate with a particular web service.

Front 30

Can you explain the structure of a WSDL? What is the structure of a WSDL?

Back 30

Its an XML document that adheres to the WSDL XML schema. It contains important elements inside definitions:

types

import,

message

portType,

operations,

binding,

service

Front 31

What is UDDI?

Back 31

Universal Description, Discovery and Integration.

Its a tool used to create a registry of web services within an organization.

You can access data in a UDDI using SOAP, making the UDDI a web service.

Front 32

What is SAAJ?

Back 32

SOAP with Attachments API for Java is SAAJ. Its used for creating, reading and modifying SOAP messages using Java.

Its based on the abstract factory pattern. Message Handlers in JAX RPC use SOAP with Attachments API for Java to represent a SOAP java message.

Front 33

Which API is used to implement web services?

Back 33

JAX-WS The Java API for XML Web Services - Centerpiece of the API stack for web services called the integrated stack which includes JAX-WS, JAX-B, and SAAJ.

JAX-RPC Java API for XML-based RPC - for building web applications and web services that incorporate xml-based rpc functionality according to the SOAP 1.1 specification.

JAX-RS Java API for XML Restful Services - creating a web service according to the Representational State Transfer architectural style,

Front 34

What is JAX-B

Back 34

Java API for XML Binding allows develops to bind an XML schema to a representation in java code, allowing for the use of XML without necessarily needing to know much about xml itself.

Front 35

JAX-RPC

Back 35

Java API for Remote procedure Calls is Java RMI over soap, which connects a remote service to a local object using xml messages.

Front 36

What are the ways of accessing a web service?

Back 36

Synchronously and Asynchronously.