SOAandWebservices
LenaBuffoni
Title/Lecturer
APRIL 13, 2016
ConceptofSOA
A collection of services
that communicate and
coordinate with each
other
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Title/Lecturer
APRIL 13, 2016
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Title/Lecturer
SOAprinciples
APRIL 12, 2016
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APRIL 13, 2016
Title/Lecturer
Encapsula<on
•  All access through API
•  Explicit API definitions
•  No hidden interactions
•  Explicit data passing
•  Context-free calls
Service logic
A
P
I
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APRIL 13, 2016
Title/Lecturer
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Autonomy
•  Replaced, managed and deployed
independently
Service logic
A
P
I
Service logic
A
P
I
Title/Lecturer
Loosecoupling
Low dependency/connection level in terms of
–  Time
–  Location
–  Type
–  Version
–  Cardinality
–  Lookup
–  Interface
APRIL 13, 2016
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Title/Lecturer
APRIL 13, 2016
Contractdriven
•  Not class driven
API
•  Description based
•  Loose coupling = few
assumptions on
implementation
ex: RMI is
implementation
dependent – not SO
Service
Implemen
ta1on
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Title/Lecturer
SOA-layers
APRIL 13, 2016
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Title/Lecturer
APRIL 13, 2016
SOA-maturity
•  A metric to evaluate SOA quality
–  Defines different levels of maturity (ex: initial,
managed, defined…)
–  Evaluates the different aspects/views of the SOA
according to these maturity criteria
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Title/Lecturer
APRIL 13, 2016
Interoperabilityandstandards
•  Relies on open standards not proprietary APIs
•  All message formats are described using an open
standard, or a human readable description
•  The semantics and syntax for additional information
necessary for successful communication, such as
headers for purposes such as security or reliability,
follow a public specification or standard
•  At least one of the transport (or transfer) protocols
used to interact with the service is a (or is accessible
via a) standard network protocol
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Title/Lecturer
APRIL 13, 2016
Vendor&Technologyindependent
To ensure the utmost accessibility (and therefore, longterm usability), a service must be accessible from any
platform that supports the exchange of messages
adhering to the service interface as long as the
interaction conforms to the policy defined for the
service.
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APRIL 13, 2016
Title/Lecturer
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Composability
ComplexService
Sub-service1
Sub-service3
Sub-service2
Title/Lecturer
APRIL 13, 2016
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Web-services
•  A realization of the SOA paradigm
•  Relies on XML and the Web for implementation
•  Attention: a web service is not necessarily SOA
compliant!
Service
provider
client
Title/Lecturer
XMLformat
•  W3C standard
•  Open & extensible
•  Structured
•  Readable
But
•  Heavy
•  No semantics
APRIL 13, 2016
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Title/Lecturer
APRIL 13, 2016
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Example
<breakfast-menu>
<food>
<name>Belgian Waffles</name>
<price>$5.95</price>
<description>
two of our famous Belgian Waffles
with plenty of real maple syrup
</description>
<calories>650</calories>
</food>
<food>
<name>Strawberry Belgian Waffles</name>
<price>$7.95</price>
<description>
light Belgian waffles covered with
strawberry's and whipped cream
</description>
<calories>900</calories>
</food>
</breakfast-menu>
We need some
way to define
XML structure
APRIL 13, 2016
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XMLSchema:typedefini<on
<item>
<title>EmpireBurlesque</title>
<note>SpecialEdition</note>
<quantity>1</quantity>
<price>10.90</price>
</item>
Item
instance
Item type
definition
<xs:elementname="item"maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:elementname="title"type="xs:string"/>
<xs:elementname="note"type="xs:string"minOccurs="0"/>
<xs:elementname="quantity"type="xs:positiveInteger"/>
<xs:elementname="price"type="xs:decimal"/>
</xs:sequence>
</xs:complexType>
</xs:element>
Title/Lecturer
APRIL 13, 2016
SimpleObjectAccessProtocol(SOAP)
•  XML based message exchange protocol
•  Used for remote procedure calls (RPC)
•  Platform and language independent
•  Uses predefined channels (HTTP, SMTP, TPC)
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Title/Lecturer
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SOAPmessagestructure
<?xmlversion="1.0"?>
<soap:Envelope
xmlns:soap="http://www.w3.org/2003/05/soap-envelope/"
soap:encodingStyle="http://www.w3.org/2003/05/soap-encoding">
<soap:Header>
...
</soap:Header>
<soap:Body>
...
<soap:Fault>
...
</soap:Fault>
</soap:Body>
</soap:Envelope>
Define the message as a
soap envelope
Optional, application specific
information
Contains the actual message, can
contain error information
Title/Lecturer
SOAPexample
<?xmlversion="1.0"?>
<soap:Envelope
xmlns:soap="http://www.w3.org/2003/05/soap-envelope/"
soap:encodingStyle="http://www.w3.org/2003/05/soap-encoding">
<soap:Body>
<m:GetPricexmlns:m="http://www.w3schools.com/prices">
<m:Item>Apples</m:Item>
</m:GetPrice>
</soap:Body>
</soap:Envelope>
APRIL 13, 2016
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Title/Lecturer
APRIL 13, 2016
SOAPPros&Cons
+W3C Recommendation (standard)
+ Implements RPC
- Untyped user data, types to encode in the message Interpretation of SOAP messages required
- High overhead / low performance
- Ongoing standardizations
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Title/Lecturer
APRIL 13, 2016
WDSL(WebServicesDescrip<onLanguage)
•  WSDL is an XML format for describing network
services as a set of endpoints operating on messages
containing either document-oriented or procedureoriented information.
•  Used to describe:
–  a service for its clients
–  a standard service for WS implementers
•  W3C standard
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Title/Lecturer
APRIL 13, 2016
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WDSLInterfaceDefini<on
•  defines services as collections of network endpoints,
or ports
•  the abstract definition of endpoints and messages is
separated from their concrete network deployment or
data format bindings
•  messages, which are abstract descriptions of the
data being exchanged, and port types which are
abstract collections of operations
Title/Lecturer
WSDLinterfacestructure
<definitions>
<types>
datatypedefinitions........
</types>
<message>
definitionofthedatabeingcommunicated....
</message>
<portType>
setofoperations......
</portType>
<binding>
protocolanddataformatspecification....
</binding>
</definitions>
APRIL 13, 2016
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Title/Lecturer
WDSLexample:Glossary
<messagename="getTermRequest">
<partname="term"type="xs:string"/>
</message>
<messagename="getTermResponse">
<partname="value"type="xs:string"/>
</message>
<portTypename="glossaryTerms">
<operationname="getTerm">
<inputmessage="getTermRequest"/>
<outputmessage="getTermResponse"/>
</operation>
</portType>
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Title/Lecturer
APRIL 13, 2016
WSDLBindingtoSOAP
•  binding = associating protocol or data format
information with an abstract entity like a message,
operation, or portType
•  SOAP specific elements include:
–  soap:binding
–  soap:operation
–  soap:body
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APRIL 13, 2016
Title/Lecturer
Bindingexample
<bindingtype="glossaryTerms"name="b1">
<soap:bindingstyle="document"
transport="http://schemas.xmlsoap.org/soap/http"/>
<operation>
<soap:operationsoapAction="http://example.com/getTerm"/
>
<input><soap:bodyuse="literal"/></input>
<output><soap:bodyuse="literal"/></output>
</operation>
</binding>
binding of one-way operation over SMTP using a SOAP
Header
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Title/Lecturer
APRIL 13, 2016
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WSDLPros&Cons
WSDL abstracts from underlying
–  Protocol (Binding to HTTP, SOAP, MIME, IIOP…)
–  Component model (Mappings to CORBA, EJB,
DCOM, .NET …)
But:
•  No inheritance on WSDL
•  Not recursively composable
Title/Lecturer
APRIL 13, 2016
Categoriza<onanddiscovery
•  Providers need a way to propose their services
•  Clients need a way to find available services
•  UDDI (Universal Description, Discovery, and
Integration) is an XML-based registry for businesses
worldwide to list themselves on the Internet
•  Like a telephone book for services
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Title/Lecturer
APRIL 13, 2016
UDDI
•  a specification for a distributed registry of web
services.
•  platform-independent, open framework.
•  can communicate via SOAP, CORBA, Java RMI
Protocol.
•  Uses WSDL to describe interfaces to web
services.
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Title/Lecturer
APRIL 13, 2016
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Title/Lecturer
APRIL 13, 2016
UDDIExample
<tModel authorizedName="..." operator="..." tModelKey="...">!
<name>HertzReserveService</name>!
<description xml:lang="en">!
WSDL description of the Hertz reservation service interface!
</description>!
!
<overviewDoc>!
<description xml:lang="en">!
WSDL source document.!
</description>!
<overviewURL>!
http://mach3.ebphost.net/wsdl/hertz_reserve.wsdl!
</overviewURL>!
</overviewDoc>!
!
<categoryBag>!
<keyedReference tModelKey="uuid:C1ACF26D-9672-4404-9D70-39B756E62AB4"!
keyName="uddi-org:types" keyValue="wsdlSpec"/>!
</categoryBag>
!
</tModel>
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Title/Lecturer
APRIL 13, 2016
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BusinessProcessExecu<onLanguage(BPEL)
BPEL is used to model the behavior of both executable
and abstract processes. The scope includes:
–  Sequencing of process activities, especially Web
Service interactions
–  Correlation of messages and process instances
–  Recovery behavior in case of failures and
exceptional conditions
–  Bilateral Web Service based relationships between
process roles
Title/Lecturer
APRIL 13, 2016
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Title/Lecturer
APRIL 13, 2016
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Receiveac<vity
APRIL 13, 2016
<receive name="receiveInput" partnerLink="client"
portType="client:NflowHotels" operation="initiate" variable="inputVariable"
createInstance="yes"/>
<!-The 'count()' Xpath function is used to get the number of hotelName
noded passed in.
An intermediate variable called "NbParallelFlow" is
used to store the number of N flows being executed
-->
<assign name="getHotelsN">
<copy>
<from
expression="count(bpws:getVariableData('inputVariable','payload','/client:Nflow
HotelsProcessRequest/client:ListOfHotels/client:HotelName'));"/>
<to variable="NbParallelFlow"/>
</copy>
</assign>
<!-- Initiating the FlowN activity
The N value is initialized with the value stored in the
"NbParallelFlow" variable
The variable call "Index" is defined as the index variable
NOTE: Both "NbParallelFlow" and "Index" variables have to be declared
-->
class="example"
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Title/Lecturer
APRIL 13, 2016
SOAandSecurity
•  Confidentiality, Integrity, Authenticity: XML
Encryption, XML Signature.
•  Message-Level Security: WS-Security.
•  Secure Message Delivery: WS-Addressing, WSReliableMessaging.
•  Metadata: WS-Policy, WS-SecurityPolicy.
•  Trust Management: SAML, WS-Trust, WSSecureConversation, WS- Federation.
•  Public Key Infrastructure: PKCS, PKIX, XKMS
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APRIL 13, 2016
Title/Lecturer
SOA&CloudCompu<ng
•  Cloud computing is a model for enabling ubiquitous,
convenient, on-demand network access to a shared
pool of configurable computing resources (The NIST
Definition of Cloud Computing) SOA
SOA
Cloud
Compu1ng
Web
Services
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Title/Lecturer
SummaryandContext
APRIL 13, 2016
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Title/Lecturer
SummaryandContext
APRIL 13, 2016
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Ques<ons?
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