Soap

Prabhat Gangwar
SOAPSOAP
Overview

AgendaAgenda
► Introduction
• Software as a service
• Starting with the service
► What is SOAP?
• SOAP how it is
• SOAP messaging framework
• Extensibility
• SOAP processing model
• Protocol binding
► Why SOAP?
► Web Services Solution
• What is the Web Service?
• Stack of layers
• Demo example

SOAP -> Introduction -> Software as a service
““Software as a service”Software as a service”
What is it?
• providing unified software, which every customer will
able to use
• building IT-systems ultimately utility like electricity and gas to
provide ability for everyone plug into it
• deliver the SOA (Service Oriented Architecture) in the more
natural way ‘cause widespread acceptance of the Internet

SOAP -> Introduction -> Software as a service
Private IT “generating” stationsPrivate IT “generating” stations
EJB
EJB
EJB
EJB
Today organizations build their
own home-grown, large and
complex IT “generating” stations
using existed technologies like
J2EE, CORBA, DCOM and others.
CORBA Broker
CORBA Broker
CORBA Broker
CORBA Broker
DCOM
DCOM DCOM

SOAP -> Introduction -> Starting with the service
Service oriented architecture (SOA)Service oriented architecture (SOA)
• Previously
The way a service was created and delivered to the
customer was dictated by the available technology
• Our goal
To start with the service we want to provide and then work
backwards into the technology

Delivering SOADelivering SOA
Natural way to provide SOA is to reverse above trend
Choosing the
technology
Providing
Service
Working under
Service we want
to provide
Backwards into
the technology

Delivering SOA (2)Delivering SOA (2)
The quote from IBM:
”So it (SOA) basically boils down to distributed computing with
standards that tell us how to invoke different applications as
services in a secure and reliable way and then how we can link
the different services together using choreography to create
business processes. And then finally so that we can manage
these services so that ultimately we can manage and monitor
our business performance.”
Resume: while this is technologically valid, it is missing the point
of SOA – we are focused on the technology that enables SOA
and not on SOA itself.

SOAP -> What Is SOAP? -> SOAP how it is
SOAP philosophySOAP philosophy
• SOAP is stands by Simple Object Access Protocol
• SOAP is a simple and flexible messaging framework for
transferring information specified in the form of an XML infoset
between an initial SOAP sender and ultimate SOAP receiver
• SOAP does not define any application semantics but defines
the mechanism to express application messaging semantics

SOAP philosophy (2)SOAP philosophy (2)
More formal SOAP definition:
SOAP is a lightweight protocol intended for exchanging structured
information in a decentralized, distributed environment. SOAP
uses XML technologies to define an extensible messaging
framework, which provides a message construct that can be
exchanged over a variety of underlying protocols. The
framework has been designed to be independent of any
particular programming model and other implementation
specific semantics.

SOAP terminologySOAP terminology
• Node: Enforcing the rules that govern the exchange of SOAP messages. It accesses
the services provided by the underlying protocols through one or more SOAP
bindings
• Role: A SOAP node’s expected function in message processing
• Binding: Formal set of rules for carrying a SOAP message within or on the top of
another protocol (underlying protocol) for the purpose of exchange
• SOAP Application: Software entity that produces, consumes or otherwise acts upon
SOAP message in a manner conforming to the SOAP processing model
• Message path: Set of SOAP nodes through which a single SOAP message passes

SOAP -> What Is SOAP? -> SOAP messaging framework
SOAP messagesSOAP messages
Standard SOAP message:
<?xml version=“1.0”?>
<soap:Envelope
xmlns:soap="http://schemas.xmlsoap.org/soap/
envelope/>
<soap:Header> 

</soap:Header>
<soap:Body>

</soap:Body>
</soap:Envelope>
Envelope
Header: Contains
requirements
specific to message
optional
Body: Information
used by application
(object data, error
messages, return
values)
required

SOAP requestSOAP request
Example of the SOAP message that represents a request to transfer
funds between bank accounts:
<?xml version=“1.0”?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<x:TransferFunds xmlns:x="urn:examples-org:banking">
<from>22-342439</from>
<to>98-283843</to>
<amount>100.00</amount>
</x:TransferFunds>
</soap:Body>
</soap:Envelope>

SOAP responseSOAP response
Response :
<soap:Body>
<x:TransferFundsResponse xmlns:x="urn:examples-org:banking">
<balances>
<account>
<id>22-342439</id>
<balance>33.45</balance>
</account>
<account>
<id>98-283843</id>
<balance>932.73</balance>
</account> </balances>
</x:TransferFundsResponse>
</soap:Body> </soap:Envelope>

SOAP fault codesSOAP fault codes
Name Meaning
VersionMismatch The processing party found an invalid namespace for the SOAP
Envelope element
MustUnderstand An immediate child element of the SOAP Header element that was
either not understood or not obeyed by the processing party contained
a SOAP mustUnderstand attribute with a value of ”1”
Client The Client class of errors indicates that the message was incorrectly
formed or didn’t contain the appropriate information in order to
succeed. It is generally an indication that the message should not be
resent without change
Server The Server class of errors indicates that the message could not be
processed for reasons not directly attributable to the contents of the
message, but rather to the processing of the message. For example,
processing could include communicating with an upstream processor,
which didn’t respond. The message may succeed if re-sent at a later
point in time

SOAP fault exampleSOAP fault example
The following sample SOAP message contains Fault element that indicates an
“Insufficient Funds” error occurred while processing the previous request:
<soap:Body>
<soap:Fault>
<faultcode>soap:Server</faultcode>
<faultstring>Insufficient funds</faultstring>
<detail>
<x:TransferError xmlns:x="urn:examples-org:banking">
<sourceAccount>22-342439</sourceAccount>
<transferAmount>100.00</transferAmount>
<currentBalance>89.23</currentBalance>
</x:TransferError>
</detail> </soap:Fault>
</soap:Body> </soap:Envelope>

SOAP -> What Is SOAP? -> Extensibility
SOAP HeaderSOAP Header
• Header element, like the Body element, is a generic container
for control information
• Elements placed in the Header are referred to as header blocks
• Header should contain information that influences payload
processing
• Header is the right place to put some credential information that
helps control access to the operation

SOAP -> What Is SOAP? -> Extensibility
SOAP Header (example)SOAP Header (example)
This example related to our previous example dedicated to bank accounts:
<soap:Header>

<s:credentials xmlns:s="urn:examples-org:security“ mustUnderstand=“1”>
<username>dave</username>
<password>evad</password>
</s:credentials>
</soap:Header>
<soap:Body>
<x:TransferFunds xmlns:x="urn:examples-org:banking">
<from>22-342439</from>
<to>98-283843</to>
<amount>100.00</amount>
</x:TransferFunds>
</soap:Body>
</soap:Envelope>

SOAP -> What Is SOAP? -> Processing Model
Simple messaging scenarioSimple messaging scenario
• SOAP defines a processing model that outlines rules for
processing a SOAP message as it travels from SOAP sender
to a SOAP receiver

Sophisticated SOAP messagingSophisticated SOAP messaging
• However, SOAP processing model allows for more interesting
architectures, which contains multiple intermediary nodes

Intermediaries nodesIntermediaries nodes
• while processing a message, a SOAP node assumes one or more roles
that influence how SOAP header is processed
• roles are given unique names (in the form of URIs), so they can be
identified during processing
<soap:Envelope
xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Header>
<wsrp:path xmlns:wsrp="http://schemas.xmlsoap.org/rp"
soap:actor="http://schemas.xmlsoap.org/soap/actor/next"
soap:mustUnderstand="1"
>
...

SOAP 1.2 RolesSOAP 1.2 Roles
Remark: SOAP 1.1 defines only one role next. Every node must acts as next role
SOAP role name Description
http://www.w3.org/2002/06/soap-
envelope/role/next
Each SOAP intermediary and the ultimate SOAP
receiver MUST act in this role and MAY
additionally assume zero or more other SOAP
roles
envelope/role/none
SOAP nodes MUST NOT act in this role
envelope/role/ultimateReceiver
To establish itself as an ultimate SOAP receiver,
a SOAP node MUST act in this role. SOAP
intermediaries MUST NOT act in this role

SOAP -> What Is SOAP? -> Protocol Bindings
Protocol BindingsProtocol Bindings
• each intermediary could choose to use different communication
protocol without affecting the SOAP message
• standard protocol binding is required to ensure high level of
interoperability across SOAP applications and infrastructure
• a concrete protocol binding defines exactly how SOAP message
should be transmitted with given protocol
• it defines the details of how SOAP fits within the scope of another
protocol, which probably has its own messaging framework with
a variety of headers

SOAP -> What Is SOAP? -> Protocol Bindings
SOAP HTTP BindingsSOAP HTTP Bindings
SOAP 1.1 specification only codifies a protocol binding for HTTP, due to its wide use
Remark: the context type header for both HTTP request and response messages must be set
to txt/xml (application/soap+xml in SOAP 1.2)

SOAP -> Why SOAP?
Industry acceptance for SOAPIndustry acceptance for SOAP
• developers have been able to download and use the technology, rather
than just read specifications and industry analysis
• SOAP changes both the way software will be developed and the way
industry rivals and cooperating
• many of the key industry software leaders have announced their support for
SOAP, including, HP, SAP, Software AG, Sun Microsystems, and
Oracle
• Microsoft and IBM have lead to the release of Web Services platform, with
SOAP services being the core technology in the initial releases
• emergence of Web Services Definition Language (WSDL) and Universal
Description, Discovery and Integration (UDDI)

SOAP -> Why SOAP?
SOAP transportSOAP transport
Most of SOAP servers currently use HTTP as the transport protocol for the XML
payload in SOAP message ‘cause HTTP satisfies a number of requirements:
• Ubiquity
• Firewall friendliness
• Simplicity
• Scalability
• Readily capable of being secure
There are a number of SOAP implementations that support other transport layers,
such as
• HTTPS – using SSL provides security
• SMTP – enables asynchronous SOAP requests / SOAP report
It can be expected that other transport protocols, such as MSMQ or FTP, will be
supported eventually. IBM has an interesting for HTTPR to provide a reliable
transport layer for SOAP messages

SOAP -> Why SOAP?
SOAP extensibilitySOAP extensibility
SOAP defines a communication framework that allows for such features
to be added down the road as layered extensions. Microsoft, IBM and
other software vendors working out a common suite of SOAP extensions
that will add many of these features that most developers expect. SOAP
extensibility is key.

SOAP -> Why SOAP?
Enterprise Application IntegrationEnterprise Application Integration
(EAI)(EAI)
• There has been considerable speculation that current Enterprise Application
Integration (EAI) products will be made redundant by SOAP.
• But, there is still a role for heavy-duty, enterprise-grade EAI products that integrate
with more obscure legacy systems or provide unusually high qualities of service.
• Significant: SOAP will encourage and enable a whole new generation of EAI
projects that were not previously possible due to technical and cost constraints.

SOAP -> Why SOAP?
SOAP: advantages and disadvantagesSOAP: advantages and disadvantages
Advantages
• Human readable XML
• Easy to debug
• SOAP runs over HTTP
• Firewalls not affected
• Services can be written in any language,
platform or operating system
Disadvantages
• S-L-O………………..-W
• XML produces a lot of overhead for small messages
• Web Services speed relies on Internet traffic conditions
• Not strictly-typed XML

SOAP -> Web Services Solution -> What Is the Web Service?
What about definition?What about definition?
Each software vendor defines Web Service in a slightly different way:
Gartner: “WS is loosely coupled software components that interact with
one another dynamically via standard Internet technology.”
Forrest Research: “WS is a formatted connection between people,
systems and applications, that expose elements of business
functionality as a software service and create new business
value.”
Common feature: WS is components that you can use, re-use, mix, and
match to enhance Internet and Intranet applications.

SOAP -> Web Services Solution -> What Is the Web Service?
At the basic levelAt the basic level
Web Service is:
• universal client/server architecture that allows disparate systems
to communicate with each other without using proprietary client
libraries
• architecture that simplifies the development process typically
associated with client/server applications by effectively eliminating
code dependencies between client and server
• architecture where server interface information is disclosed to the
client via a configuration file encoded in a standard format (WSDL).
Doing so allows the server to publish a single file for all target client
platforms

SOAP -> Web Services Solution -> Stack of Layers
What’s from WebServices.org?What’s from WebServices.org?
Layer Example
Service Negotiation Treading partner agreement
Workflow, discovery and
Register
UDDI (Universal Description, Discovery &
Integration)
Service description language WSDL (Web Services Definition
Language)
Messaging SOAP
Transport protocol HTTP, HTTPS, SMTP
Business Issues Management, Quality of service, Security,
Open standards

Interaction with Web ServiceInteraction with Web Service

Accessing & publicationAccessing & publication

SOAP -> Web Services Solution -> Example
Demo service main pageDemo service main page

Demo service method call pageDemo service method call page

SOAP requestSOAP request

SOAP responseSOAP response

HTTP POST request and responseHTTP POST request and response

2 + 3 = what’s the answer?2 + 3 = what’s the answer?

Simple VB script clientSimple VB script client
Everything alright
With your message
Something go
wrong

Everything alright? But, where’s myEverything alright? But, where’s my
answer?answer?
Don’t worry! Here is!!!

What’s go wrong?What’s go wrong?
Here’s the answer:

Thank you for your attention!!!

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