«Spring Integration as Integration Patterns Provider»

Spring Integration
as Integration Patterns
provider
Blynov Viacheslav
Dnepropetrovsk
24 June 2014

3
Spring Integration Goals
 Provide a simple model for implementing complex enterprise integration
solutions.
 Facilitate asynchronous, message-driven behavior within a Spring-based
application.
 Promote intuitive, incremental adoption for existing Spring users.
Spring Integration Introduction
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4
Spring Integration Features
 Implementation of most of the Enterprise Integration Patterns
– Endpoint
– Channel
– Aggregator
– Filter
– …
 Integration with External Systems
– REST/HTTP
– FTP
– Twitter
– JMS
– …
 The framework has extensive JMX support
– exposing framework components as MBeans
– adapters to obtain attributes from MBeans, invoke operations, send/receive notifications
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5
Spring Integration Endpoints
 AMQP
 Spring Application Events
 File System
 FTP
 Gemfire
 HTTP/REST
 JDBC
 JMX
 JPA
 Mail
 MongoDB
 Redis
 RMI
 TCP
 Twitter
 UDP
 XMPP
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7
Main Components
 Message
 Message Channel
 Message Endpoint
– Transformer
– Filter
– Router
– Splitter
– Aggregator
– Service Activator
– Channel Adapter
– Gateway
Spring Integration Main Components
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8
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Message
 Message is a generic wrapper
for any Java object combined
with metadata used by the
framework while handling that
object

9
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Message Channel
 Point-To-Point Channel
 Publish/Subscribe Channel
 Pollable Channels
 Message-Driven Channels

10
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Message Endpoint
Encapsulates communication-
specific details:
 converts/extracts business data
to/from message
 sends/receives messages
to/from message channel

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Transformer
 Message Transformer is
responsible for converting a
Message's content or structure
and returning the modified
Message

12
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Filter
 Message Filter determines
whether a Message should be
passed to an output channel at
all

13
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Splitter
 Splitter is another type of
Message Endpoint whose
responsibility is to accept a
Message from its input channel,
split that Message into multiple
Messages, and then send each
of those to its output channel.

14
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Service Activator
Service Activator is a generic endpoint for connecting a service
instance to the messaging system.
The input Message Channel must be configured, and if the service
method to be invoked is capable of returning a value, an output
Message Channel may also be provided.

15
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Gateway
The Gateway encapsulates messaging-specific code (e.g.,
the code required to send or receive a message) and separates it
from the rest of the application code. The Messaging
Gateway exposes a business function to the rest of the application
so that instead of requiring the application to set properties like
Message.

17
Task
 We receive JMS messages with some CompoundObject in JSON format
 CompoundObject is-a list of some Objects
 We need to extract all Objects from CompoundObject and save them to database
(possibly performing some other business logic)
 Those Objects which are considered “good” (verified against some rule) should
be sent via JMS to another queue in JSON format
Spring Integration Example
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 We need to add the following dependencies in pom.xml

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 Specify JMS connection factory

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 Configure Spring Integration context

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CompObjectDTO parseCompoundObject(String
payload)

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payload)
List<ObjectDTO> splitCompound(CompObjectDTO dto)

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payload)
Object convertToEntity(ObjectDTO dto)

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payload)
Object saveEntity(Object obj)

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payload)
boolean isGoodObject(Object obj)

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payload)
ObjectDTO convertToDTO(Object obj)

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payload)
ObjectDTO convertToDTO(Object obj)
String serializeObjectDTO(ObjectDTO obj)

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Receiving messages via HTTP REST

29
Another option: JMS backed message channels
Channel adapter are intended for applications that are integrating with
other external systems. There are cases where both the producer and consumer
for a given JMS Destination are intended to be part of the same application,
running within the same process.
<int-jms:channel id="jmsChannel" queue="exampleQueue"/>
<int-jms:publish-subscribe-channel id="jmsChannel" topic="exampleTopic"/>
 Support of transactions (“transaction-manager” atrribute)
 Support for connection (session, consumer) cache
 Concurrency (number of concurrent sessions/consumers to start for each listener)
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Task 2
 An exteranl system feeds us with stream of JSON objects putting them to JMS
queue
 We need to make some calculations (business logic) using these objects in the
order as they come
 Depending on calculationd results we could change the persistent state of our
domain objects
 Incoming objects should be saved to our DB
 Finally, the results of calculation should be sent in JSON format to another JMS
queue
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Basic Flow
24 June 2014
Receive objects
Validation
convertion to entity
Calculation
Analyze and save
results
Send to outbound
JMS
Save entities to DB

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Router
24 June 2014
• Payload Type Router
• Header Value Router
• Recipient List Router
• XPath Router (Part of the XML Module)
• Error Message Exception Type Router
• (Generic) Router

33
Problem
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The incoming messages could arrive very
frequently

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Aggregator
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• Message Store
• Correlation Strategy (delaults to grouping be MessageHeader.CORRELATION_ID)
• Release Strategy
• Expiration policy

35
Back to task 2: receive and aggregate
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Back to task 2: receive and aggregate
24 June 2014
boolean canReleaseMessages(List<IncObject>)
List<IncObject> aggregate(List<IncObject>)
Object getCorrelationKey(IncObject)

37
Back to task 2: routing
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Back to task 2: via publish-subscribe channel
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39
Task summary
 Built on the top of other Spring modules (e. g. Spring JMS)
 Every element of the chain – just a simple POJO
 High cohesion
 Easy to cover with unit-tests
 “Convention over configuration” – bean with name “connectionFactory” will be
found automatically
 Change the whole business flow only by configuration
24 June 2014

4024 June 2014
Spring
Integration VS
Apache Camel

41
 Both projects aim to fill similar need: light-weight integration library with full
implementations of EIP
 Apache Camel introduces DSL (Java, Scala, Groovy). Spring Integration - only
XML
 Apache Camel supports longer list of technologies
 Apache Camel offers rich support for both integration and unit-testing. Spring
Integration supports just generic Spring Test
 Apache Camel Community is larger, documentation is better
Spring Integration Spring Integration VS Apache Camel
24 June 2014

42
Apache Camel Java DSL Example
final JaxbDataFormat jaxbDataFormat = new JaxbDataFormat();
jaxbDataFormat.setContextPath(“test.ns.oxm");
jaxbDataFormat.setPartClass(“test.ns.oxm.ABSPartnerChangesEventType");
from("activemq:incoming.partner")
.log("log:test.log")
.choice() .when(header("EVENTTYPE").isEqualTo(“TESTVALUE")).to("direct:createPartner“)
.when(header("EVENTTYPE").isEqualTo(“TESTVALUE2")).to("direct:updatePartner");
from("direct:createPartner")
.errorHandler(noErrorHandler())
.unmarshal(jaxbDataFormat)
.beanRef(“partnerChangeHandler", "createPartner");
from("direct:updatePartner")
.errorHandler(noErrorHandler())
.unmarshal(jaxbDataFormat)
.beanRef(“partnerChangeHandler", "updatePartner");
Spring Integration Spring Integration VS Apache Camel
24 June 2014

43
Recent changes
 Spring EL support (3.0.2)
 HTTP request mapping (based on Spring MVC infrastructure) (3.0.2)
 Enhanced support for MongoDB, Redis and JPA (3.0.2)
 @EnableIntegration, @IntegrationComponentScan (4.0.2)
 Requires Spring 4.0 (4.0.2)
24 June 2014

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