Enterprise ApplicationEnterprise ApplicationEnterprise ApplicationEnterprise Application

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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

quotationsupplier andcustomer 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:

dispatcherinventory

managementERP shipping

message-oriented middleware

month-end closing

new PO new PO new PO 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

sender receiver

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 new PO new PO new PO 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 client …

admin

client client …

admin

message broker MB-C

client 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

SmartQuotationadapter

e-mailadapter

databaseadapter

SmartQuotation

SmartForecastingadapter

SmartForecasting

XYZadapter

XYZ

integrating application (contains the composition

logic)

message broker

SmartQuotationadapter

SmartQuotation

SmartForecastingadapter

SmartForecasting

RFQ processing

1A 6

B C 72 4

3

5

8

at systems startup time (can occur in any order, but all must occur before RFQs are executed)

A: subscription to message quoteB: subscription to message quoteRequestC: 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 quote6: publication of a newQuote message

7: delivery of message newQuote8: 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 quotein 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

1

2

4 53

workflow definitionsoutbound 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

SmartQuotationadapter

e-mailadapter

databaseadapter

SmartQuotation

SmartForecastingadapter

SmartForecasting

XYZadapter

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