Transcript Kein Folientitel

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)
POST /BankServer HTTP/
Host: www.bank.com
SOAP: example (method
Content-Type: text/xml
Content-Length: nnnn
SOAPMethodNeme: Some-Namespace-URI#getBalance
call)
<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>
VIII.4
VIII.5
SOAP: example (answer of server)
HTTP 200 ok
Connection: close
Content-Type: text/xml
Content-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/responseinteraction)
• 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 middlewareplatforms (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 and
Web Services Interoperability Organization
VIII.10
WebServices
UDDI Registry
WSDL
Description
Discovery
Web Services
Container / Runtime
Web Services Client
SOAP
Firewall
Business
Application
(e.g. on the base
of EJB,
further distributed
internally)
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
PC B
Queue
Manager
AppliQueue
cation
Manager
1
MQPUT
Queue
Manager
Message
Channel
Queue
Manager
MQGET
application
2
decoupling of applications through Queue Manager:
Message forwarding is possible even if application
isn’t running
VIII.16
N:M - communication
Access to Server
via multiple Clients
Load balancing (selective
delivery) or
Parallel processing
(replicated delivery)
C
A
D
B
Queue, with
optional support of
message priorities
E
VIII.17
Message 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 Computing
Disadvantages
- 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
Architecture
VIII.19
Java RMI, Internet Inter-ORB Protocol, SOAP
HTMLClient
Web-Server
HTMLHTMLHTMLDokumente
Dokumente
Documents
Inner Firewall
JavaClient
outer Firewall
HTTP
proprietary
Protocols
Application- proprietary
Protocols
Server
proprietary
Protocols
HTMLCGIHTMLDokumente
Scripts
Dokumente
(optional)
HTTP
TransactionMonitors
Business
software
Mainframeapplications
Stateful-connection
Stateless-connection
Data bases
Development cycle
Generation
Instantiation
requests
UML (Unified
Modeling Language)
user
layout / modeling
VIII.20
CORBA /
EJB / .NET
component
development
runtime/ component use
CORBA,
EJB Container,
.NET
Installation /
Deployment
VIII.21
Modeling and Generation
UML
layout /
modeling
<?xml version="... "?
<component name="Bank">
<interface name="Bank">
Generation
Component description
XML (eXtensible Markup Language)
as intermediate representation:
• Standardization, Portability
• Formalization (DTD - Document Type Definition
or XML schema)
• tool support
CORBA /
EJB / .NET
component
development
Interface 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.22
Application Servers
VIII.23
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.)
Enterprise Application Integration (EAI)
VIII.24
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)
Enterprise 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.25
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 .NET
Open Source, among others:
• Enhydra
• Jonas
• Jboss
• Zope etc.