WebServices, Application Servers and further concepts

1. WebServices, Application Servers and further concepts

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)

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)

4. SOAP: example (method call) • POST /BankServer HTTP/ • Host: www.bank.com • Content-Type: text/xml • Content-Length: nnnn • SOAPMethodNeme: 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>

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>

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

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

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

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

10. WebServices Business Application (e.g. on the base of EJB, further distributed internally) UDDI Registry WSDL Description Discovery Web Services Container / Runtime Web Services Client SOAP Firewall

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)

12. WebServices: possible use phases • Closed application fields : e.g. automation of office processes incl. legacy-integration • “Selective Outsourcing”: access to services of external partners • with close contractual relationship • “Dynamic Business-Web”: Interaction of many loosely coupled systems; e.g. between manufacturers and suppliers • “Agile company”: comprehensive integration, also with customer - and partner enterprises

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

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

15. Example scenario PC A PC B Queue Manager Queue Manager MQPUT MQGET Appli-cation 1 Queue Manager Queue Manager appli-cation 2 MessageChannel MQPUT MQGET • decoupling of applications through Queue Manager: • Message forwarding is possible even if application isn’t running

16. N:M - communication Load balancing (selective delivery) or Parallel processing (replicated delivery) Access to Servervia multiple Clients C A D B Queue, with optional support of message priorities E

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

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

19. Architecture Web-Server HTML-Dokumente HTML-Dokumente HTML-Documents HTML-Dokumente HTML-Dokumente CGI-Scripts (optional) Java RMI, Internet Inter-ORB Protocol, SOAP Application-Server Transaction-Monitors proprietaryProtocols HTTP Java- Client Businesssoftware proprietaryProtocols Inner Firewall outer Firewall Mainframe-applications proprietaryProtocols HTML-Client HTTP Stateful-connection Data bases Stateless-connection

20. Development cycle Generation Instantiation requests CORBA, EJB Container, .NET CORBA / EJB / .NET UML (Unified Modeling Language) component development Installation / Deployment user layout / modeling runtime/ component use

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

22. 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>

23. Application 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.)

24. Enterprise 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)

25. 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)

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.