1 © Talend 2014 Service Locator Talend ESB Training 2014 Jan Bernhardt [email protected] Zsolt Beothy-Elo [email protected].

1© Talend 2014

Service LocatorTalend ESB Training 2014

Jan [email protected]

Zsolt [email protected]

2© Talend 2014

Agenda

➜ Introduction to Service Locator• Problem Definition• Concepts

• Loose Coupling• Automatic Failover• Selection Strategies

• Common Pitfalls➜ Hands-on

• Installation & Configuration• Demo Service using Service Locator

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Introduction toService Locator

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Problem: Tight Coupling

➜ Direct invocation from Application A to Service X• Static endpoint address

Application A Service Xinvokes

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Application A Service Xinvokes

Problem: Tight Coupling (Service Blackout)

➜ Service X goes offline• Application A stops working as well• Application A needs to be fixed

• Reconfiguration• or even redeployment

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Application Ainvokes

Problem: Tight Coupling (Relocation)

➜ Service X was moved to a new location• Application A stops working• Application A needs to be fixed

• Reconfiguration• or even redeployment

Application A Service X

Service X

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Solution: Loose Coupling

Application A

Service Locator

SL Client Service X

SL Client

2: perfo

rms lo

okup

3: returns a

ddress

4: invokes

1: registers

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Solution: Loose Coupling

Application A Service X

Service Locator

1: registers

SL Client

SL Client

Service X

SL Client

Service Y

SL Client

1: registers1: registers

3: invokes

2: perfo

rms lo

okup

3: returns a

ddress

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Solution: Transparent Failover

Application A Service X

Service Locator

SL Client

Service X

SL Client

SL Client

Service Y

SL Client

1: invokes

4: invokes

Heartbeat

Heartbeat

2: perfo

rms lo

okup

3: returns a

ddress

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Highlights

➜ Automatic endpoint registration• Easy to use

➜ Dynamic lookup of endpoints• No reconfiguration needed

➜ Automatic failover• Error handling is transparent to application

➜ Status monitoring• Only active endpoints are used

➜ Transparent extension• No Custom Code inside Application required

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Problem: Single Point of Failure

Application A Service X

3: performs lookup

2: registers

SL Client

SL Client

Service X

SL Client

Service Y

SL Client

1: registers

2: registers

Service Locator

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Solution: Distributed Services

Application A Service X

Service Locator

SL Client

Service X

Service Y

SL Client

Service Locator

Service Locator

Sync

Sync Sync

SL Client

SL Client3: performs lookup

2: registers

1: registers

2: registers

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Solution: Distributed Services

Application A Service X

Service Locator

SL Client

SL Client

Service X

SL Client

Service Y

SL Client

Service Locator

Service Locator

Sync

Sync Sync

2: p

erfo

rms l

ooku

p

1: registers1: registers

4: invokes

3: re

turn

s add

ress

Heartbeat

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Problem: Bad Selection

➜ Quality of Service• Poor network connectivity• Services running on weak hardware• Overload of one Service chosen by all clients

➜ Services provide different content• Video Surveillance Stream• Package Counter

➜ Producing additional costs• Some providers may charge each service invocation

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Solution: Flexible Selection Strategies

➜ Round Robin• Automatic Load Balancer

➜ Metadata Selection• Localize preferred services

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Common Pitfalls

➜ Stateful Services• Session State would be lost or needs to be synchronized• Sticky Selection Strategy recommended

➜ Even number of SL instances• Majority required to re-sync lost nodes

➜ Insufficient Configuration• Client needs to know multiple SL instances

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Hands-on

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Hands-on: Service Locator

Application A

Service Locator

SL Client Service X

SL Client

2: perfo

rms lo

okup

3: returns a

ddress

4: invokes

1: registers

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Hands-on: Enable Locator

➜ Prepare services for locator feature• Add locator feature to service consumer & provider• Set Consumer address to locator://

➜ Install locator service• Locator Server• REST Interface

➜ Install service provider• One on each container

➜ Validate Results• Perform SL lookup (REST)

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Hands-on: Metadata Selection

➜ Add config admin support• Add Property-Placeholder in Blueprint

• enable automatic bundle reload

• Create config file in ./etc folder➜ Add metadata to service provider

• Make location configurable➜ Add metadata filter on consumer side

• location = Bonn➜ Validate Results

• Perform SL lookup (REST)

22© Talend 2014

Thank You!