Styles of Applicaton Integration Using Spring

Styles of Application Integration
Using Spring
Bruce Snyder, Senior Software Engineer, SpringSource/VMware

Friday, July 15, 2011

Integrations Are About Coupling

2


Where Coupling Exists, Concerns Arise

• Tight coupling is easy
• Loose coupling can be difficult

• Tight coupling causes issues in the long run
• Loose coupling pays off in the long run

• Integrations are usually tightly coupled
• Integrations should be loosely coupled

• Integrations are commonly addressed using commands
• Integrations should be addressed using events


What is Coupling?

“... the degree to which each program module relies
on each one of the other modules”
(Wikipedia.com)

• Given two lines of code, A and B, they are coupled when B
must change behavior only because A changed

4


Characteristics Tight Coupling

• Components are highly dependent upon one another
• Components are directly linked
• Changes in one component cause a ripple effect
• Less reusability
• More difficult to maintain
• Does not handle unforeseen change well

• Examples
– Clients designed to interact only with specific systems
– Use of proprietary APIs or commands for interaction
– Components designed to work specifically with other
components
5


Characteristics of Loose Coupling

• Components have little or no knowledge of one another
• Components are not directly linked to one another
• Changes in one component do not affect other components
• Increased reusability
• Easier to maintain
• More easily handles unforeseen changes

• Examples
– Dependence upon interfaces instead of concrete classes
– Use of DI encourages looser coupling
– A design using a level of indirection

6


Tight Coupling is Easy

• App design with tight coupling is more widely understood
• App development with tight coupling requires less time
• Debugging a tightly coupled app is easier
• Benefits of tight coupling are seen immediately
• Tightly coupled prototypes commonly live on

7


Loose Coupling is Difficult

• App design with loose coupling is not widely understood
• App development with loosely coupling requires more
thought and more time
• Debugging loosely coupled apps is different
• Benefits of loose coupling are only seen over time

8


Integrations and Coupling

• But it’s easy to write a point-to-point, one-off piece of code
for integration!
• Too many disadvantages
– Difficult to maintain
– No reusability
– Every integration is unique
– Bites you over time

9


Integrations and Coupling

• But designing integrations to be loosely coupled requires
too much work!
• With the right knowledge and preparation, it doesn’t need
to be this way

10


Commands vs. Events

• Commands are not natural
– Verify credit card
• Commands are too specific

• Events are natural
– Order received
• Events are more broad
• Events are what happen in the real world

11


Enterprise Integration Patterns (EIP)

http://enterpriseintegrationpatterns.com/
12


Spring Integration

• Provides both concurrency and messaging
– Message Endpoints
• Connections between services
– Channel Adapters
• Adapter between application and message broker
– Messaging Gateways
• Provides uni-directional or bi-directional messaging
– Service Activators
• Invokes a services based on an incoming message
– Routers
• Determines where to dispatch a message
– Splitters and Aggregators
• Breaks up a message and reassembles it after processing

13


Spring Integration

• Supports
– AMQP
– Email
– File system
– Gemfire
– JMS
– JMX
– MongoDB
– Redis
– Spring Batch
– Testing
– Web Services

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Spring Integration

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Spring Integration

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Spring Integration

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Spring Integration

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Spring Integration

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Spring Integration

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Spring Integration

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Spring Integration

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Spring Integration

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Spring Integration

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Types of Integration

• Intra-application integration
• Inter-application integration
• External system integration

25


Typical Application Layers

26


Intra-Application Integration

27


Spring Integration Config

<int:gateway id="sender"
service-interface="org.bsnyder.spring.integration.simple.Sender"/>

<int:channel id="orderReceived"/>

<int:service-activator input-channel="orderReceived" ref="receiver"
method="receive" />

<bean id="receiver" class="org.bsnyder.spring.integration.simple.Receiver"/>

28


Intra-Application Integration

29


service-interface="org.bsnyder.spring.integration.appa.Sender"/>

<channel id="orderReceived" />

<amqp:outbound-channel-adapter channel="orderReceived"
exchange-name="order.received.exchange"
routing-key="order.received.binding"
amqp-template="amqpTemplate" />

<rabbit:connection-factory id="connectionFactory" />
<rabbit:template id="amqpTemplate" connection-factory="connectionFactory" />
<rabbit:admin connection-factory="connectionFactory" />
<rabbit:queue name="order.received.queue" />
<rabbit:direct-exchange name="order.received.exchange">
<rabbit:bindings>
<rabbit:binding queue="order.received.queue" key="order.received.binding" />
</rabbit:bindings>
</rabbit:direct-exchange>

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<amqp:inbound-channel-adapter channel="orderReceived"
queue-names="order.received.queue"
connection-factory="connectionFactory" />

method="receive" />

<bean id="receiver" class="org.bsnyder.spring.integration.appa.Receiver"/>

<rabbit:bindings>
</rabbit:bindings>

31


Inter-Application Integration

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Inter-Application Integration

34



<channel id="orderReceived" />

<amqp:outbound-channel-adapter channel="orderReceived"
exchange-name="order.received.exchange"
routing-key="order.received.binding"
amqp-template="amqpTemplate" />

<rabbit:bindings>
</rabbit:bindings>

35



<amqp:inbound-channel-adapter channel="orderReceived"
queue-names="order.received.queue"
connection-factory="connectionFactory" />

method="receive" />

<bean id="receiver" class="org.bsnyder.spring.integration.appb.Receiver"/>

<rabbit:bindings>
</rabbit:bindings>

36


External System Integration

38




<bean id="ftpClientFactory"
class="org.springframework.integration.ftp.session.DefaultFtpSessionFactory"
p:host" value="localhost" p:username" value="${user}" p:password="$
{password}"/>
!
<int:channel id="ftpChannel"/>

<int-ftp:outbound-channel-adapter id="ftpOutbound"
channel="ftpChannel"
remote-directory="/foo/bar/baz/"
client-factory="ftpClientFactory"/>

39



<int:channel id="ftpChannel">
<int:queue/>
</int:channel>

<bean id="ftpClientFactory"
class="org.springframework.integration.ftp.session.DefaultFtpSessionFactory"
p:host="localhost" p:username="${user}" p:password="${password}"/>
!
<int-ftp:inbound-channel-adapter id="ftpInbound"
channel="ftpChannel" session-factory="ftpClientFactory"
filename-regex=".*.txt$" auto-create-local-directory="true"
delete-remote-files="false" remote-directory="/foo/bar/baz/"
local-directory="file:local-target-dir">
<int:poller fixed-rate="1000"/>
</int-ftp:inbound-channel-adapter>

<int:service-activator input-channel="ftpChannel" ref="receiver" method="receive" />

<bean id="receiver" class="org.bsnyder.spring.integration.appb.Receiver"/>

40


Combined Integration

42


Thank You!

Q&A


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