Building high quality services using Azure Service Fabric

Loek Duys

@LDuys

Introduction

No introduction to Service Fabric

Learn about partitioning

Creating testable code

Service Programming Model

PartitionsService

Types

Application

Types

App

Stateful

Svc

1

2

x

Stateless

Svc1

Why?

State

Number of partitions

Address space divided across partitions

PARTITION 1 PARTITION 2INT64 MIN INT64 MAX

PARTITION 4PARTITION 3PARTITION 2PARTITION 1

-9,223,372,036,854,775,808 9,223,372,036,854,775,807

Partitions vs. Nodes

Node 1

Primary

Replica 1

Secondary

Replica 2

Node 2

Primary

Replica 2

Secondary

Replica 1

Partition 1

Partition 2

Copy of partition 2

Copy of partition 1

Read + Write

Read only

Read + Write

Read only

Partitioning strategies

Monastery: Hand-written books

Order:

Write a dictionary (26.000 words)

Can span multiple books / volumes

Reader constraints:

Search max. one book for one word.

Writer constraints:

1. One monk writes one book (Service Fabric rule)

2. Average writing speed for monk, is 1.000 dictionary words per year

3. Monastery has 52 writing monks

The partitioning problem

Partition by first letter Consequences

Introduce a Librarian

Add/Lookup

wordLibrarian

Book 1

Book 2

Book ..

Book x

Add/Lookup

word

Index

service

Dictionary

Service

Partition 1

Dictionary

Service

Partition 2

Dictionary

Service

Partition ..

Dictionary

Service

Partition x

Introduce an index

Creating a good Index service

Good LibrarianMust distribute words evenly across the books.

So all books have similar page count.

So work load is equal for all monks

So you can add more monks & books

using 26 monks: done in 1 year

using 52 monks: done in 0.5 year

Good Index serviceMust distribute data evenly across the partitions.

So every partition holds same amount of data

So user load on partitions is equal

So your services can scale linearly

Inside Index Serviceuse proper hash algorithm

Example:

word hash number partition address

Outcome must be well distributed

Great choicesFNV

Murmur

Load distribution, using 4 partitions

good

bad

Attribute Result

Id User data in one partition

Organization Users grouped by Organization

Location Amsterdam data grouped

Attribute Result

Low distribution Uneven use of partitions

High

distribution

Even use of partitions

public class User { public int Id; public Organization Organization;public string Location;

}

Inside Cluster

On top of Cluster,

API management

solution

Dictionary Service

Partition 1

Dictionary Service

Partition 2

Index Service

Dictionary Service

Partition 1

Dictionary Service

Partition 2

Index Service in cluster

Index Service on top of cluster

API management

solution

Dictionary Service

Partition 1

Dictionary Service

Partition 2

Index Service

Dictionary Service

Partition 1

Dictionary Service

Partition 2

Identifier Service Instance

app1/dictionarysvc1 fabric:/application1/dictionaryservice1

app2/dictionarysvc10 fabric:/application2/dictionaryservice10

.. ..

Example: Web API

app1 dictionarysvc word=cloud

Partition

Service

Application

Create Backups

Failure is always an option

Human error

Cluster failure

Stateful Service backups work at partition level

Can restore to different Service

Little tooling available

Tips

Store backups outside the cluster

Check out my project ServiceFabric.BackupRestore

(Github & Nuget)

Contains tools that help create, restore and store backup data

Creating quality code

Difficulties while testing

Services expect to be running inside clusterStateManager

Service Fabric Remoting using Proxies

Cut dependenciesUse Dependency Injection pattern

Pass dependencies to Service constructor

Inject cluster based objects at run-time

Inject ‘fake’ objects at test-time (Mocks)

Index Service Dictionary Service

Dependency injection 1

How to test Dictionary Service State Tips

public DictionaryService(StatefulServiceContext context, IReliableStateManagerReplica2 stateManager): base(context, stateManager)

{..}

ServiceRuntime.RegisterServiceAsync("ServiceFabric.Dictionary.DictionaryServiceType", context => new DictionaryService(context,

new ReliableStateManager(context))).GetAwaiter().GetResult();

var dictionaryService = new DictionaryService(MockStatefulServiceContextFactory.Default,new MockReliableStateManager());

Dependency injection 2

How to test Index Service Communication

public IndexService(StatelessServiceContext context,IServiceProxyFactory serviceProxyFactory,IHashingHelper hashingHelper) : base(context)

{..}

ServiceRuntime.RegisterServiceAsync("ServiceFabric.Dictionary.IndexServiceType",context => new IndexService(context,

new ServiceProxyFactory(),new HashingHelper())

).GetAwaiter().GetResult();

//Configure Mock Service Proxy Factory to return the svc we //created on previous slidevar mockServiceProxyFactory = new MockServiceProxyFactory(); mockServiceProxyFactory.RegisterService(

dictionaryServiceUri,dictionaryService);

//inject mock proxy factoryvar indexService = new IndexService(

MockStatelessServiceContextFactory.Default,mockServiceProxyFactory,new MockHashingHelper());

Tips

Bringing it together

We can now

//arrange: not displayed

const string tesMeaning = "testmeaning"; const string testWord = "testword";

//actawait indexService.Add(testWord, testMeaning)

.ConfigureAwait(false);

var actual = await indexService.Lookup(testWord).ConfigureAwait(false);

//assertAssert.AreEqual(testMeaning, actual);

var proxy = ServiceProxy.Create<IDictionaryService>(

DictionaryServiceUri,partitionKey);

var proxy = _dictionaryServiceProxyFactory.CreateServiceProxy<IDictionaryService>(

DictionaryServiceUri,partitionKey);

Building Actor systems with Azure Service Fabric

Azure API management usage in practice

Codehttps://github.com/loekd/ServiceFabric.Dictionary

Pictures courtesy of https://unsplash.comhttps://pexels.comhttps://gratisography.com

Building Actor systems with Azure Service Fabric

Today at 14:00 E102 - Sander Molenkamp

Azure API management usage in practice

Tomorrow at 08:00 E104/105 - Chris van Sluijsveld

https://github.com/loekd/ServiceFabric.Dictionary