Technically DDD C - Speaker Deck

Slide 1

Slide 1 text

No content

Slide 2

Slide 2 text

Technisch gezien DomainDrivenDesign #dotNedSaturday @pelshoff

Slide 3

Slide 3 text

No content

Slide 4

Slide 4 text

No content

Slide 5

Slide 5 text

Vragen?

Slide 6

Slide 6 text

Context Technische bouwblokken Quiz Case study I Case study II

Slide 7

Slide 7 text

No content

Slide 8

Slide 8 text

Context Technische bouwblokken Quiz Case study I Case study II

Slide 9

Slide 9 text

Value objects

Slide 10

Slide 10 text

public class Name { public String LastName { get; } public String FirstName { get; } public Name (String lastName, String firstName) { LastName = lastName; FirstName = firstName; NamePartsMayNotBeNull(); LastNameIsRequired(); } private void NamePartsMayNotBeNull() { if (null == LastName || null == FirstName) { NameIsInvalid.becausePartsAreMissing(); } } private void LastNameIsRequired() { if (LastName.Length < 1) { NameIsInvalid.becauseLastNameIsTooShort(); } ...

Slide 11

Slide 11 text

public class Email { public String EmailAsString { get; } public Email(String email) { EmailAsString = email; EmailMustBeAnActualEmailAddress(); } private void EmailMustBeAnActualEmailAddress() { if (String.IsNullOrWhiteSpace(EmailAsString)) { EmailIsInvalid.becauseEmailIsMissing(); } if (!EmailAsString.Contains('@')) { EmailIsInvalid.becauseAtIsMissing(); } } }

Slide 12

Slide 12 text

Value objects ● Vertegenwoordigen een waarde ● Definiëren toegestane waarden ● Zijn immutable ● Zijn eenvoudig te testen

Slide 13

Slide 13 text

Entities

Slide 14

Slide 14 text

public class Attendee { public Guid Id { get; } private Name _Name; public Name Name { get { return _Name; } set { _Name = value; ValuesMayNotBeNull(); } } private Email _Email; public Email Email { get { return _Email; } set { _Email = value; ValuesMayNotBeNull(); } } public Attendee(Guid id, Name name, Email email) { Id = id; _Name = name; _Email = email; ValuesMayNotBeNull(); } private void ValuesMayNotBeNull() { if (null == _Name || null == _Email) { AttendeeIsInvalid.BecauseValuesAreNull(); } } }

Slide 15

Slide 15 text

Entities ● Hebben identiteit ● Zijn meer dan hun attributes ● Evoluëren over tijd ● Zijn lastiger om te testen

Slide 16

Slide 16 text

Services

Slide 17

Slide 17 text

public class Registration { private RegistrationRepository Repository; public Registration(RegistrationRepository repository) { Repository = repository; } public void RegisterNew(Attendee Attendee) { EmailAddressMustBeUnique(Attendee.Email); Repository.Add(Attendee); } private void EmailAddressMustBeUnique(Email Email) { try { Repository.FindByEmail(Email); } catch (AttendeeNotFound ex) { return; } throw RegistrationFailed.becauseEmailAddressIsNotUnique(); } }

Slide 18

Slide 18 text

Services ● Hebben geen identiteit of attributes (Zijn geen “ding”) ● Zijn geschikt voor cross-concern operations ● Zijn nog lastiger om te testen

Slide 19

Slide 19 text

Context Technische bouwblokken Quiz Case study I Case study II

Slide 20

Slide 20 text

class Address

Slide 21

Slide 21 text

class BicycleService

Slide 22

Slide 22 text

class StreetAddress

Slide 23

Slide 23 text

class Investment

Slide 24

Slide 24 text

Context Technische bouwblokken Quiz Case study I Case study II

Slide 25

Slide 25 text

public class Meeting { public Meeting( Guid id, string title, string description, string code, string startDate, string startTime, string endDate, string endTime, bool isPublished, string subTitle, List program ) { // ... } }

Slide 26

Slide 26 text

new Meeting( Guid.NewGuid(), "DotNed Saturday 2019", "...", "#dotNedSaturday", "2019-01-26", "09:00", "2019-01-26", "18:00", true, "HÉT NEDERLANDSE .NET COMMUNITY EVENEMENT", new List(){ new ProgramSlot("2019-01-26", "09:00", "09:30", "Ontvangst en koffie", ""), new ProgramSlot("2019-01-26", "13:30", "14:30", "Technisch Gezien DDD", "Seminarruimte 1"), } );

Slide 27

Slide 27 text

Meetings mogen niet eindigen voor ze gestart zijn

Slide 28

Slide 28 text

De Aanpak™ 1. Implementeren in Entity 2. Extract Value Object 3. Refactor Value Object

Slide 29

Slide 29 text

public class Meeting { public Meeting(/* */) { // ... MeetingsCannotEndBeforeStart(); } private void MeetingsCannotEndBeforeStart() { if (StartDate.CompareTo(EndDate) == -1) { return; } if (StartDate.CompareTo(EndDate) == 1) { MeetingIsInvalid.becauseMeetingEndsBeforeStarting(); } if (StartTime.CompareTo(EndTime) == 1) { MeetingIsInvalid.becauseMeetingEndsBeforeStarting(); } } }

Slide 30

Slide 30 text

public class Meeting { // ... private MeetingDuration Duration; // ... public Meeting( Guid id, string title, string description, string code, MeetingDuration duration, bool isPublished, string subTitle, List program ) { // ... Duration = duration; // ... } }

Slide 31

Slide 31 text

public class MeetingDuration { // ... public MeetingDuration(string startDate, string startTime, string endDate, string endTime) { // ... MeetingsCannotEndBeforeStart(); } private void MeetingsCannotEndBeforeStart() { if (StartDate.CompareTo(EndDate) == -1) { return; } if (StartDate.CompareTo(EndDate) == 1) { MeetingIsInvalid.becauseMeetingEndsBeforeStarting(); } if (StartTime.CompareTo(EndTime) == 1) { MeetingIsInvalid.becauseMeetingEndsBeforeStarting(); } } }

Slide 32

Slide 32 text

Slide 33

Slide 33 text

new Meeting( Guid.NewGuid(), "DotNed Saturday 2019", "...", "#dotNedSaturday", new MeetingDuration( new DateTime(2019, 01, 26 , 9, 0, 0), new DateTime(2019, 01, 26 , 18, 0, 0) ), true, "HÉT NEDERLANDSE .NET COMMUNITY EVENEMENT", new List(){ new ProgramSlot("2019-01-26", "09:00", "09:30", "Ontvangst en koffie", ""), new ProgramSlot("2019-01-26", "13:30", "14:30", "Technisch Gezien DDD", "Seminarruimte 1"), } );

Slide 34

Slide 34 text

Context Technische bouwblokken Quiz Case study I Case study II

Slide 35

Slide 35 text

Programmaonderdelen mogen niet plaatsvinden op hetzelfde moment in dezelfde ruimte

Slide 36

Slide 36 text

Slide 37

Slide 37 text

private void ProgramSlotsCannotOccurInTheSameRoomAtTheSameTime() { foreach (var slotA in Program) { foreach (var slotB in Program) { if (slotA == slotB) { continue; } if (!slotA.Room.Equals(slotB.Room)) { continue; } if (!slotA.Date.Equals(slotB.Date)) { continue; } if (slotA.StartTime.CompareTo(slotB.EndTime) == 1) { continue; } if (slotA.EndTime.CompareTo(slotB.StartTime) == -1) { continue; } MeetingIsInvalid.becauseProgramSlotsOverlap(); } } // ...

Slide 38

Slide 38 text

public class Meeting { // ... private Program Program; public Meeting( Guid id, string title, string description, string code, MeetingDuration duration, bool isPublished, string subTitle, Program program ) { // ... Program = program; } }

Slide 39

Slide 39 text

public class Program { private List Slots; public Program(List program) { Slots = program; ProgramSlotsCannotOccurInTheSameRoomAtTheSameTime(); } private void ProgramSlotsCannotOccurInTheSameRoomAtTheSameTime() { foreach (var slotA in Slots) { foreach (var slotB in Slots) { if (slotA == slotB) { continue; } // ... } } }

Slide 40

Slide 40 text

Slide 41

Slide 41 text

public class ProgramSlot { public MeetingDuration Duration; public string Title; public string Room; public ProgramSlot(MeetingDuration duration, string title, string room) { Duration = duration; Title = title; Room = room; } public bool OverlapsWith(ProgramSlot that) { return this.Room == that.Room && this.Duration.OverlapsWith(that.Duration); } }

Slide 42

Slide 42 text

public class MeetingDuration { private DateTime Start; private DateTime End; public MeetingDuration(DateTime start, DateTime end) { Start = start; End = end; MeetingsCannotEndBeforeStart(); } private void MeetingsCannotEndBeforeStart() { /*...*/ } public bool OverlapsWith(MeetingDuration that) { return this.Start.CompareTo(that.Start) >= 0 && this.Start.CompareTo(that.End) < 1 || this.End.CompareTo(that.Start) >= 0 && this.End.CompareTo(that.End) < 1; } }

Slide 43

Slide 43 text

public class MeetingDuration { private DateTime Start; private DateTime End; public MeetingDuration(DateTime start, DateTime end) { Start = start; End = end; MeetingsCannotEndBeforeStart(); } private void MeetingsCannotEndBeforeStart() { /*...*/ } public bool OverlapsWith(MeetingDuration that) { return this.Contains(that.Start) || this.Contains(that.End); } private bool Contains(DateTime Date) { return this.Start.CompareTo(Date) < 1 && this.End.CompareTo(Date) >= 0; } }

Slide 44

Slide 44 text

public class MeetingDuration { private DateTime Start; private DateTime End; public MeetingDuration(DateTime start, DateTime end) { Start = start; End = end; MeetingsCannotEndBeforeStart(); } private void MeetingsCannotEndBeforeStart() { /*...*/ } public bool OverlapsWith(MeetingDuration that) { return !(this.Start.CompareTo(that.End) == 1 || this.End.CompareTo(that.Start) == -1); } }

Slide 45

Slide 45 text

public class MeetingDuration { private DateTime Start; private DateTime End; public MeetingDuration(DateTime start, DateTime end) { Start = start; End = end; MeetingsCannotEndBeforeStart(); } private void MeetingsCannotEndBeforeStart() { /*...*/ } public bool OverlapsWith(MeetingDuration that) { return !this.IsBefore(that) && !that.IsBefore(this); } private bool IsBefore(MeetingDuration that) { return this.Start.CompareTo(that.End) == 1; } }

Slide 46

Slide 46 text

new ProgramSlot( "2019-01-26", "13:30", "14:30", "Technisch Gezien DDD", "Seminarruimte 1" ) private bool IsBefore(MeetingDuration that) { return this.Start.CompareTo(that.End) == 1; }

Slide 47

Slide 47 text

public class SlotDuration { private DateTime Start; private DateTime End; public SlotDuration(DateTime start, DateTime end) { Start = start; End = end; MeetingsCannotEndBeforeStart(); SlotMustStartAndEndOnSameDay(); } /*...*/ public bool OverlapsWith(SlotDuration that) { return !this.IsBefore(that) && !that.IsBefore(this); } private bool IsBefore(SlotDuration that) { return this.Start.CompareTo(that.End) >= 0; } }

Slide 48

Slide 48 text

Slide 49

Slide 49 text

new Meeting( Guid.NewGuid(), "DotNed Saturday 2019", "...", "#dotNedSaturday", new MeetingDuration(new DateTime(2019, 01, 26 , 9, 0, 0), new DateTime(2019, 01, 26 , 18, 0, 0)), True, "HÉT NEDERLANDSE .NET COMMUNITY EVENEMENT", new Program( new List(){ new ProgramSlot( new SlotDuration(new DateTime(2019, 1, 26, 9, 0, 0), new DateTime(2019, 1, 26, 9, 30, 0)), "Ontvangst en koffie", "" ), new ProgramSlot( new SlotDuration(new DateTime(2019, 1, 26, 13, 30, 0), new DateTime(2019, 1, 26, 14, 30, 0)), "Technisch Gezien DDD", "Seminarruimte 1" ), } ) );

Slide 50

Slide 50 text

Een meeting moet herpland kunnen worden

Slide 51

Slide 51 text

Meer weten? “Domain-Driven Design: Tackling Complexity in the Heart of Software”, Eric Evans “Domain-Driven Design Distilled”, Vaughn Vernon https://github.com/procurios/diconverg ent

Slide 52

Slide 52 text

Pim Elshoff developer.procurios.com @pelshoff https://speakerdeck.com/pelshoff/technically-ddd-c

Slide 53

Slide 53 text

No content