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by Szigyarto Tamas, SPBU Applied Mathematics, Department of Computer Modelling and Multiple Processors Systems
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 BrokerCORBA Broker
CORBA Broker
DCOM
DCOM DCOM
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 -> 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
SOAP -> Introduction -> Starting with the service
Delivering SOA Delivering SOA
Natural way to provide SOA is to reverse above trend
Choosing the technology
ProvidingService
Working underService we want
to provide
Backwards into the technology
SOAP -> Introduction -> Starting with the service
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.
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 -> 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 -> What Is SOAP? -> SOAP how it is
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 -> What Is SOAP? -> SOAP how it is
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
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 -> 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> <!-- optional --> <!-- header blocks go here... --> </soap:Header> <soap:Body>
<!-- payload or Fault element goes here--> </soap:Body>
</soap:Envelope>
Envelope
Header: Contains requirements
specific to messageoptional
Body: Information used by application
(object data, error messages, return values)required
SOAP -> What Is SOAP? -> SOAP messaging framework
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 -> What Is SOAP? -> SOAP messaging framework
SOAP responseSOAP response
Response :
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <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 -> What Is SOAP? -> SOAP messaging framework
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 -> What Is SOAP? -> SOAP messaging framework
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:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <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>
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 -> 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:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Header>
<!-- security credentials -->
<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
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 -> What Is SOAP? -> Processing Model
Sophisticated SOAP messagingSophisticated SOAP messaging
• However, SOAP processing model allows for more interesting architectures, which contains multiple intermediary nodes
SOAP -> What Is SOAP? -> Processing Model
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 -> What Is SOAP? -> Processing Model
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
http://www.w3.org/2002/06/soap-envelope/role/none
SOAP nodes MUST NOT act in this role
http://www.w3.org/2002/06/soap-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
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 -> 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 useRemark: the context type header for both HTTP request and response messages must be set
to txt/xml (application/soap+xml in SOAP 1.2)
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 -> 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 Integration Enterprise 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 systemDisadvantages
• 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
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 -> 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
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 -> 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
SOAP -> Web Services Solution -> Stack of Layers
Interaction with Web ServiceInteraction with Web Service
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 -> Web Services Solution -> Example
HTTP POST request and responseHTTP POST request and response
SOAP -> Web Services Solution -> Example
Simple VB script clientSimple VB script client
Everything alrightWith your message
Something gowrong
SOAP -> Web Services Solution -> Example
Everything alright? But, where’s my Everything alright? But, where’s my answer?answer?
Don’t worry! Here is!!!