Enterprise Application -Lesegruppe WebServices -Zusammenfassung von Tianxiang LU

Content From Middleware to Application Integration EAI Middleware: Message Brokers Workflow Management Systems

From Middleware to Application Integration Mainframe → Set of Servers → Multitude of Services 3-tier architectures bridged islands of information created by client/server systems Enterprise Application Integration bridge 3-tier architectures.

An Example of AI quotation supplier and customer mgmt order processing procurement shipment management financial

EAI Middleware: Message Brokers Historical Background –RPC + MOM –ERP : Enterprise resource planning –CRM: Customer relationship management –Message brokers: transport, routing, filtering, processing message

EAI Middleware: Message Brokers Need for Message Brokers: dispatcher inventory management ERPshipping message-oriented middleware month-end closing new PO

EAI Middleware: Message Brokers Extending Basic MOM –MOM: sender defines receiver of a message: point-to-point addressing scheme –Message brokers: factoring the message routing logic out of the senders and placing it into the middleware –Advantage: single place to make changes

message broker core senderreceiver message broker with message brokers, custom message routing logic can be defined at the message broker level or at the queue level in basic MOM it is the sender who specifies the identity of the receivers

EAI Middleware: Message Brokers Extending Basic MOM –Decoupling : messages can be delivered to several queues, depending on the routing logic –Load balancing: multiple threads or applications can then share the load of retrieving and processing messages from a queue –Using content transformation rules –Difficult to debug and maintain

dispatcher (publisher) inventory management (subscriber) ERP (subscriber) shipping (subscriber) message broker month-end closing (subscriber) new PO

EAI Middleware: Message Brokers The Publish/Subscribe Interaction Model –two ways to subscribe: Specify a message type ( type.subtype.subsubtype... ) Specify parameters –In JMS: topic Distributed Administration of a Message Broker –Administrator –Different administrative domains

admin message broker MB-A message broker MB-B client … adminclient … admin message broker MB-C client … administrative domain A administrative domain B administrative domain C

EAI Middleware: Message Brokers EAI with a Message Broker –Fundamental components: Adapters Message broker –Intergration steps: Developing an application that implements the integration logic. Configuing the adapters

DBMS applications message broker SmartQuotation adapter adapter database adapter SmartQuotation SmartForecasting adapter SmartForecasting XYZ adapter XYZ integrating application (contains the composition logic)

message broker SmartQuotation adapter SmartQuotation SmartForecasting adapter SmartForecasting RFQ processing 1A6 BC at systems startup time (can occur in any order, but all must occur before RFQs are executed) A: subscription to message quote B: subscription to message quoteRequest C: subscription to message newQuote at run time: processing of a request for quote. 1: publication of a quoteRequest message 2: delivery of message quoteRequest 3: synchronous invocation of the getQuote function 4: publication of a quote message 5: delivery of message quote 6: publication of a newQuote message 7: delivery of message newQuote 8: invocation of the createForecastEntry procedure

EAI Middleware: Message Brokers A Critical View of Message Brokers as EAI Platforms –Lower development cost. –Lower opportunity costs. –Lower maintenance efforts. For small and medium enterprises more problems

Workflow Management Systems WfMSs facilitate the definition and maintenance of the integration logic Historical Backgroud –Origins: office automation –Administrative workflows -> production workflows (Business process reengineering) –Combine WfMS with EAI –WfMC: Workflow Management Coalition

Workflow Management Systems Workflow Definition –Business process –Workflow(workflow process,process) –Workflow management system Representation –Directed gragh(typically) Work node, Routing node, Start and completion nodes Workflow instance –Petri nets –State –Activity charts –Hierarchical activity decomposition

check if offered product check if worth proceeding get quote from quotation system get quote from supplier enter quote in forecasting system send quote to customer ContractExists=true ContractExists=false Offered=true Offered=false GoAhead=true update quotation system variables: QuoteReferenceNumber: int Customer: String Item: String Quantity: int RequestedDeliveryDate: Date DeliveryAddress: String GoAhead: Bool ContractExists: Bool Offered: Bool else Copyright Springer Verlag Berlin Heidelberg 2004

Workflow Management Systems Workflow Execution workflow engine resource broker completed work items inbound queue resource 1 resource 2 resource n workflow definitions outbound queues workflow designer

Workflow Management Systems Workflow as Programming in the Large –Scale –Granularity at which composition takes place –Failure-handling techniques Forward recovery Backward recovery(sagas: compensating activeity) Exception-handling languages Deadlines (Deadline expiration) –Resource Microprocessor vs. Any kind of resource inkl. Human Need „ resource rules “ Resource broker

Workflow Management Systems Integration of WfMSs with Other Middleware Technologies –TP Monitors –ORB-style brokers –MOMs –Publish/Subscribe systems EAI platform + WfMSs

DBMS applications message broker SmartQuotation adapter adapter database adapter SmartQuotation SmartForecasting adapter SmartForecasting XYZ adapter XYZ WfMS adapter WfMS

Workflow Management Systems Drawback –Same as EAI Expensive software licenses Complex installation and operation Long development cycles –Useful with repetitive, well-defined processes Conventional middleware already in use Cannot do: Integration across wide area networks ……

Summary EAI –Message brocker – important –WFMSs In the future –Across wide area networks –standardization