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WebServices, Application Servers and further concepts. SOAP (Simple Object Access Protocol). Protocol for remote object calls Developed by Microsoft, IBM, Lotus and other partners; Standardization through IETF (Internet Engineering Task Force) - PowerPoint PPT Presentation
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VIII.1
WebServices, Application Servers and further concepts
VIII.2
SOAP (Simple Object Access Protocol)
• Protocol for remote object calls
• Developed by Microsoft, IBM, Lotus and other partners; Standardization through IETF (Internet Engineering Task Force)
• Encoding of calls and parameters via XML (eXtensible Markup Language)
• Realization with HTTP, therefore transferable via Firewalls; especially useful for Internet (in Intranet there is no Firewall-Problem !)
• new security mechanisms are also usable, based on XML (XML Encryption; XML Signature)
VIII.3
SOAP
• independence of special programming languages, however usable with mappings of Java, C++ etc.
• Because of embedding in HTTP, SOAP is less efficient than direct communication with RMI / IIOP / .NET
• no reference parameters, no automatic garbage collection (goal: limitation to a minimal functionality)
• Usable for synchronous calls to objects, but also asynchronous interactions are supported (e.g. Message Passing)
VIII.4POST /BankServer HTTP/Host: www.bank.comContent-Type: text/xmlContent-Length: nnnnSOAPMethodNeme: Some-Namespace-URI#getBalance
<SOAP: Envelope xmlns: SOAP=“urn:schemas-xmlsoap-org:soap“><SOAP: Header>
<t: Transaction xmlns: t=“some-URI“ SOAP: mustUnderstand=“1“>328</t: Transaction>
</SOAP:Header><SOAP: Body>
<m: getBalance “xmlns: m=“Some-Namespace-URI“><AccountIdentification>
<AccountNumber>3044005</AccountNumber><pin>****</pin><name>John Smith</name>
</AccountIdentification></m: getBalance>
</SOAP: Body></SOAP: Envelope>
SOAP: example (method call)
VIII.5
SOAP: example (answer of server)
HTTP 200 okConnection: closeContent-Type: text/xmlContent-Length: nnnn
<SOAP: Envelope xmlns: SOAP= “urn: schemas-xmlsoap-org: soap“><SOAP: Body>
<m:getBalance xmlns: m= “Some-Namespace-URI/ “><return> -1350.50 </return>
</m: getBalance> </SOAP: Body>
</SOAP: Envelope>
VIII.6
SOAP: encoding structure
• embedding in HTTP POST Requests and accompanying responses
• Envelope: definition of logical names and possible specification of own encoding rules for parameter types
• Header: transfer of implicit control parameters (remark: „transaction“ in this context means only request/response-interaction)
• Body: real encoding of call and parameters
VIII.7
SOAP: data type definition (example)
<element name= “AccountIdentification“>
<complexType>
<element name= “accountNumber“ type=“xsd:int“/>
<element name= “pin“ type=“xsd:int“/>
<element name= “name“ type=“xsd:string“/>
</complexType>
</element>
• also all other essential data types specifiable (e.g. (variable) arrays, enumerations etc.)
• Possibility of representation of data types of common programming languages
VIII.8
WebServices
• manufacturer-independent initiative for Web-based services
• base: standardized protocols (e.g. SOAP / XML) and middleware-platforms (Application Server)
• definition: „encapsulated, loosely coupled functions, which are accessible over standard protocols“
• Interface description using WSDL (WebServices Description Language)
• binding of services over UDDI (Universal Description, Discovery and Integration); comparable with Directory Service;http://www.uddi.org
VIII.9
WebServices
• security architecture WS (WebServices)-Security: in addition to SOAP for digital signatures (PKI – Public Key Infrastructure) and encoding
• also extension of firewalls for functions of checking authentication and authorization of SOAP-communication via „http“ („Port 80“)
• altogether: framework for description of network-wide services , which is specialized by manufacturers by system solutions, among others IBM, Microsoft, Sun, BEA Systems etc.
• standardization through W3C andWeb Services Interoperability Organization
VIII.10
WebServices
UDDI Registry
Web Services Client
Web Services Container / Runtime
BusinessApplication
(e.g. on the base of EJB,
further distributed internally)
WSDL
SOAP
DiscoveryDescription
Firewall
VIII.11
WSDL (WebServices Description Language)
example (shortened):<binding name=“BankServer“ type=“tns:BankServerPortType“>
<soap:binding style = “rpc“ transport = “http://... “/>
<operation name = “getBalance“>
<soap:operation soapAction = “urn:xmethodsBankServer“/>
<input> ... </input>
<output> ... </output>
</operation>
</binding>
Call modes: oneway ; request-response (Client/Server)
notification ; solicit-response (Server/Client)
VIII.12
WebServices: possible use phases
1. Closed application fields : e.g. automation of office processes incl. legacy-integration
2. “Selective Outsourcing”: access to services of external partners
with close contractual relationship
1. “Dynamic Business-Web”: Interaction of many loosely coupled systems; e.g. between manufacturers and suppliers
2. “Agile company”: comprehensive integration, also with customer - and partner enterprises
VIII.13
WebServices: Summary
• comfortable, web-based call mechanism
• also applicable via firewalls using SOAP / HTTP
• possibility of automatic generation of interface descriptions from design representations through tools
• but: no replacement of EJB or .NET, but access technology from client to server, especially over Internet
VIII.14
Message Oriented Middleware
• Products : IBM MQ Series, BEA MessageQ, Tibco etc.
• Base: Messages, Queues with Queue Manager
• Dynamic coupling between application and local Queues based on logon / logout
• Use of Queues for sending or receiving; also mixed use is possible
• Coupling of distributed Queue Managers via Message Channels
• C++-and Java-Support (conformant to JMS)
• use of XML (eXtensible Markup Language) for description of transferred contents
• support of essential OS-platforms
VIII.15
Example scenario
PC A
Queue Manager
Queue Manager
Appli-cation
1 MQPUT
MQGET
PC B
Queue Manager
Queue Manager
appli-cation
2MQGET
MQPUT
MessageChannel
decoupling of applications through Queue Manager:
Message forwarding is possible even if application isn’t running
VIII.16
N:M - communication
A
B
C
D
EQueue, with
optional support of message priorities
Access to Servervia multiple Clients
Load balancing (selective delivery) orParallel processing (replicated delivery)
VIII.17Message Queuing: Assessment
Advantages+ simple manageability+ robust message delivery + flexible application fields (for instance load balancing,
parallelization, batch-transmission of branch data etc.)+ relevant for easy coupling of programs, for instance via Internet,
or for Mobile ComputingDisadvantages- limited communication semantics- interaction model is different than with procedures/method
invocations- limited accessibility of higher services- only several proprietary solutions up to now, only step-by-step
standardization
VIII.18
Application Servers
• interface-server between Web/Java-Client and services of enterprise data processing („middle-tier“)
• Tasks:– data- and call adaptation
– legacy-integration; transactions
– access control
– load sharing
VIII.19Architecture
HTML-Client
Java-Client
Transaction-Monitors
Businesssoftware
Mainframe-applications
Data bases
oute
r F
irew
all
Inne
r F
irew
all
Web-Server
HTML-Dokumente
HTML-DokumenteHTML-
Dokumente
HTML-DokumenteHTML-
Documents
HTML-Documents
HTML-Dokumente
HTML-DokumenteHTML-
Dokumente
HTML-Dokumente
CGI-Scripts
(optional)
CGI-Scripts
(optional)
Application-Server
proprietaryProtocols
proprietaryProtocols
proprietaryProtocols
HTTP
Stateless-connection
Stateful-connection
Java RMI, Internet Inter-ORB Protocol, SOAP
HTTP
VIII.20Development cycle
UML (Unified Modeling Language)
CORBA / EJB / .NET
CORBA, EJB Container,
.NET
Generation Instantiation
layout / modeling componentdevelopment
Installation /Deployment
runtime/ component use
requests
user
VIII.21
Modeling and Generation
UML
CORBA / EJB / .NET
layout / modeling
componentdevelopment
<?xml version="... "?<component name="Bank"><interface name="Bank">
Component description
XML (eXtensible Markup Language) as intermediate representation:• Standardization, Portability• Formalization (DTD - Document Type Definition or XML schema)• tool support
Generation
VIII.22Interface description in XML („XMI“)
<interface name="Bank"><superclass> General </superclass><operation name="TransferRequest">
<visibility> public </visibility><returnType> long </returnType><oneway> false </oneway>
</operation><attribute name="Description">
<type> string </type><visibility> public </visibility><isReadonly> true </isReadonly>
</attribute></interface>
VIII.23Application Servers
Essential functionality:• Development and distribution of Java applications (“Three-Tier”)• scalability (>100 Server, >10000 Clients): Multithreading, connection
reuse etc.• Component model (Enterprise JavaBeans, .NET etc.)• Support of transactions• Access to distributed data bases (Oracle, MS SQL Server, Sybase, DB2)• security (Authentication, access control)• Support of actual Java APIs (JDBC, JNDI, JMS etc.)• Replication and load sharing • Integration of development environment (e.g. IBM Websphere Studio,
Borland JBuilder, BEA Weblogic Workshop, MS Visual J++ / J#, C#, Rational Rose, Arcstyler etc.)
• Support of WWW-services (e.g. installation of HTML, Servlets etc.)
VIII.24Enterprise Application Integration (EAI)
Goal:• Integration of different applications (Backend)• examples:
- Enterprise Resource Planning (ERP)- Customer Relationship Management (CRM)- Supply Chain Management (SCM)
Technological Base:• Middleware and Application Servers
(e.g. of IBM, BEA, Forte etc.)• Additional product specific adapters
Integration approaches:• Data integration• Interface based integration (API-Integration)• Workflow- / Process-oriented integration (complex processes with more
than 5 applications)
VIII.25Enterprise Application Integration
Products:
- BEA Systems eLink - adapter for SAP R/3 Integration
- Delta Software Technology, Vienna: SCORE/ Integration Suite
- WRQ VeraStream EAI Suite: SAP R/3 Integration
- Sybase Integration Services:SAP, Peoplesoft, Oracle (ERP)Siebel, Vantive (CRM)
VIII.26
Application Servers: Product examples
• BEA Weblogic• IBM Websphere• Borland Application Server• IONA Orbix• Oracle Application Server / .Now• Sybase Enterprise Application Server• Sun: Open Net Environment (One) / iPlanet• Software AG EntireX• Microsoft .NETOpen Source, among others:• Enhydra• Jonas• Jboss• Zope etc.