- 1. Enterprise Integration Patternswith Spring
Integration[Mihalache Catalin][Pentalog][25th of October 2014]
2. Agenda Spring Integration 10.000 foot view Enterprise
Integration Patterns - WGRUS What is integration? How to address
integration challenges Messaging / what are EIP Patterns ? EIP with
Spring Integration (SI) WGRUS flows Study resources 3. Spring
Integration 10.000 foot view Enterprise Application Integration
solution integration of systems and applications across an
enterprise Spring Integration pillars (axioms): Spring programming
model probably the most popular Java framework Enterprise
Integration Patterns Gregor Hohpe , Bobby Woolf - 2003 Foreward by
Martin Fowler(Patterns of Enterprise Application Architecture)
Asynchronous, message-driven behaviorwithin a Spring-based
application Intuitive, incremental adoption for existing Spring
users Default integration with HTTP, JMS, AMQP, FTP, JDBC, JPAMail,
Mongo, RMI, Web Services, Twitter, XMPP, File systems 4. EIP What
is integration?Widgets & Gadgets R Us (WGRUS) - an online
retailer that buys widgets and gadgets frommanufacturers and
resells them to customers on multiple channels (by phone, fax
orders, webinterface).WGRUS & external systems WGRUS's internal
systems Call center:C++ desktop application / Oracle database
server it allows customers to place orders via phone. Appssources
cannot / may not be modified. Inbound fax:The inbound fax system
requires manual data entry into a small Microsoft Access
application. Web Interface:JEE custom built web app allowing
customers to browse widgets & gadgets, place orders, monitor
ordersstatus. Apps sources may / can be modified. 5. EIP Why
integration is necessary ?What is neededTake OrdersCustomers can
place orders on multiplechannels - via Web, phone or faxProcessing
OrdersProcessing an order involves multiple steps,including
verifying inventory, shipping the goods andinvoicing the customer
(integrate all backendsystems)New CatalogThe suppliers update their
catalogperiodically. WGRUS needs to update its pricing
andavailability based in the new catalogs.ChallengesNetworks are
unreliableNetworks are slowAny two applications are differentChange
is inevitable 6. EIP How to address integration challenges1. File
Transfer - the MS Officedatabase from the Inbound Fax System
iscopied periodically to a specific network filelocation; the
Integration Solution will recoverit from that location, process it
by importingany new order and later delete it.2. Shared Database -
the Call Centerapplication's sources cannot / may notchanged.
However, since it uses an Oracledatabase server, the creation of
new ordersmight be monitored with a trigger on insert(on the orders
table). That trigger wouldcopy new order details into a new
createdtable orders_si. A separate applicationwould connect to
these database,monitoring the orders_si table and eachtime a new
record is created, it will notify theIntegration Solution with
order details; lateron, that new orders_si record would
bedeleted.3. Remote Procedure Invocation - WGRUS needs to update
its pricingand availability based in the new catalogs by running
some HTTP SOAP webservice calls to Widget Co and Gadget Co external
systems; those systemsrespond back with their current catalogs
& prices. 7. EIP How to address integration challenges4.
Messaging - after a new order isplaced, the web app detects that
orderand publishes a new message on a specificJMS queue. This
message contains neworder's details. And that's it, the web
app'forgets' about that message returning toits job.The messaging
system is notified by theJMS queue with an event about the
neworder. It can start processing that order. 8. EIP Messaging /
what are EIP Patterns ? 9. EIP with Spring Integration -
Messagepublic interface Message {MessageHeaders getHeaders();T
getPayload();}public final class MessageHeadersimplements Map,
Serializable{...}Message message1 =
MessageBuilder.withPayload("test").setHeader("foo",
"bar").build();Spring Integration Messages are immutable!Best
practice: the payload / headers would have to be immutable and
serializable. 10. EIP with Spring Integration - Channel 11. EIP
with Spring Integration - Channel EIP name: Point-to-Point Channel
Message consumer: Event-Driven Consumer A channel that invokes a
single subscriber foreach sent Message. The invocation will occur
inthe sender's thread. It uses anUnicastingDispatcher without a
thread executor.Failover support. 12. EIP with Spring Integration -
Channel EIP name: Point-to-Point Channel Message consumer:
Event-Driven Consumer A channel that invokes a single subscriber
foreach sent Message. The invocation will occur onexecutor's
threads. It uses anUnicastingDispatcher with a thread
executor.Failover support. 13. EIP with Spring Integration -
Channel EIP name: Publish-Subscribe Channel Message consumer:
Event-Driven Consumer A channel that sends the Message to each one
of itssubscribers. The invocation occurs on the sender'sthread (if
no executor is specified) or on separatethreads for each receiver
(if an executor is specified).It uses an BroadcastingDispatcher
with an optionalthread executor. 14. EIP with Spring Integration -
Channel EIP name: Point-to-Point Channel Message consumer: Polling
Consumer Simple implementation of a message channel. EachMessage is
placed in a BlockingQueue whose capacitymay be specified upon
construction. By default, it usesa LinkedBlockingQueue but a
MessageGroupQueuemight be used to store messages on a
persistentcontext (like a relational database) basically, using
aMessageStore 15. EIP with Spring Integration - Channel Sending
messages on a channel:@Autowired@Qualifier(myChannelID);private
DirectChannel channel;public void sendMessage(String msgPayload)
{final MessagingTemplate mt = new MessagingTemplate();final Message
msg
=MessageBuilder.withPayload(msgPayload).build();mt.send(channel,
msg);} 16. EIP with SI Polling Consumer Polling consumers: a
consumer with a PollableChannel as its input channel Sync / Async
polling consumers 17. EIP with SI Event-driven Consumers Event
driven consumers: a consumer with a SubscribableChannel as its
input channel 18. EIP with SI Channel Adapter A Channel Adapter is
a component that connects a single sender or receiver to a Message
Channel.(outside of the sender/receiver; one way communication) JMS
inbound channel adapter: JMS outbound channel adapter: Predefined
channel adapters: JMS, AMQP, JDBC, JPA, Mongo, Redis, FTP, Twitter
19. EIP with SI Gateways A Gateway is a Message Endpoint that
connects an application that is both a sender and receiver to
aMessage Channel. (inside the application; two-way communication).
The 'default' gateway allows Java code to call a Spring Integration
flow as a Spring service: Async gateways:public interface MyGateway
{public String process(String thing, Predefined gateways: JMS,
AMQP, HTTP, Web Services, Redis,
JDBC@Header(FileHeaders.FILENAME)String fileName);}public interface
MyGateway {public Feature process(String
thing,@Header(FileHeaders.FILENAME)String fileName);} 20. EIP with
SI Service Activator A service activator in Spring Integration
simply connects any existing Spring-managed bean to a channel.These
Spring service beans may or may not return a result.
@Service("barista")public class Barista {@Transactionalpublic Drink
prepareHotDrink(OrderItem orderItem) {...}} 21. EIP with SI
Transformerpublic class CallCenterOrderTransformer {public
CanonicalOrder transform(CallCenterOrder order) {...;}} 22. EIP
with SI Claim Check 23. EIP with SI Filterpublic class PetFilter
{public boolean dogsOnly(String input) {return
input.toLowerCase().contains("dog");}} 24. EIP with SI
Splitterpublic class OrdersSplitter {public List
splitOrder(CanonicalOrder order) {return null;}}The Splitter adds
following headers in Item messages (for an Order with 2
items):{correlationId=d7c96f28-b9b5-1c8b-1881-8d4b09d83c6b,
sequenceSize=2, sequenceNumber=1}{
correlationId=d7c96f28-b9b5-1c8b-1881-8d4b09d83c6b, sequenceSize=2,
sequenceNumber=2} 25. EIP with SI Aggregatorpublic class
ItemsAggregator {public CanonicalOrder splitOrder(List items)
{...}}CorrelationId, SequenceSize, SequenceNumberStatefull
component - it might use a message store to keep messages upon
completion.Correlation Strategy how to identify thow messages
belong to the same groupReleaseStrategy how to detect that a group
of messages is completeTimeouts time to wait a group of messages
upon completionDiscard channel where expired messages will be
publishedPartial Aggregation if not all expected messages are to
come 26. EIP with SI Routerpublic class OrderRouter {public String
route(CanonicalOrderItem order) {...}} 27. Spring Integration Error
HandlingDefault channels:errorChannelused internally for sending
error messages and may be overridden with a custom
configurationnullChannelacts like /dev/null, simply logging any
Message sent to it at DEBUG level and returning immediately 28.
WGRUS Taking Orders 29. WGRUS Processing Orders 30. Study
resourcesSpring Integration in Action written by SI's
creatorsEnterprise Integration Patterns 31. Please fill the online
evaluation form after event[Enterprise Integration Patterns with
Spring Integration][Mihalache Catalin][Pentalog][25th of October
2014]
