diff --git a/lectures/revealjs/09-lecture-modular.adoc b/lectures/revealjs/09-lecture-modular.adoc
new file mode 100644
index 0000000000000000000000000000000000000000..afafbef75367f2a64db7e38fb071c1d86ba8fc17
--- /dev/null
+++ b/lectures/revealjs/09-lecture-modular.adoc
@@ -0,0 +1,350 @@
+= Modular software
+:customcss: slides.css
+:icons: font
+:includedir: includes/
+:LECTURE_TOPIC: Modular software
+:LECTURE_NO: 9th Lecture
+
+include::{includedir}header.adoc[]
+
+[.smaller-80][.center-paragraph]
+IT1901 Fall 2022 - {LECTURE_NO}
+
+
+== Overview
+- Group deliverable 2 (GD2)
+- Architectural styles
+- Modular projects with Maven and Java
+
+== GD2 - modularisering
+
+* kodingsprosjektet skal deles opp i egnede moduler med avhengigheter
+* bygging styres (fortsatt) av maven og hver modul har hensiktmessig konfigurasjon
+* maven-moduler er et krav, mens Java-moduler er ikke (men i utgangspunktet anbefalt)
+* mer om modularisering senere
+
+[.smaller-80]
+== GD2 - arkitektur
+
+* kjernelogikken (domenelaget) og ui (brukergrensesnittlaget) skal skilles fra hverandre
+* persistens med JSON vha. egnet bibliotek, f.eks. Jackson
+** definere/dokumentere (?) filformat for brukerdata og evt. innstillinger
+* reflektere over og velge mellom dokumentmetafor (desktop) og implisitt lagring (app)
+* alle tre lagene spiller sammen
+
+== GD2 - kodekvalitet
+
+* tester skal skrives for alle modulene
+* testdekningsgrad og (annen) kodekvalitet skal sjekkes av egne maven-tillegg (f.eks. **jacoco**, **checkstyle** og **spotbugs**)
+* rimelig god testdekning av alle lagene
+
+== GD2 - dokumentasjon
+
+* generell dokumentasjon må holdes oppdatert
+* arkitektur med minst et diagram (bruk PlantUML) i tillegg til teksten i readme
+* valg knyttet til arbeidsvaner, arbeidsflyt, testing, bruk av verktøy for sjekking av kodekvalitet (f.eks. innstillinger)
+
+== GD2 - arbeidsvaner
+
+* kodingsoppgaver skal være utgangspunktet for alt arbeid
+* greiner (branch) samler arbeid for hver kodingsoppgave (?)
+** se alternativet **trunk based development**
+* bruk milepæl (milestones) knyttet til innleveringen
+* dere jobber i par og bytter på å kode
+* "produktiv" kode og tester må holde tritt
+
+== GD2 - lær (i smidig ånd)
+
+* hva virker bra og ikke så bra
+* hva er en god oppdeling i og fordeling av arbeidsoppgaver
+* ikke lur dere selv eller andre
+
+[.smaller-80]
+== GD2 - leveranse
+* prosjektet må være gitpod-klart med Gitpod-knapp i gitlab eller merkelapp i README-fila
+* maven skal brukes til kjøring, testing og sjekk av kodekvalitet
+* kode må ligge i master-greina av standard kodelager for gruppa
+* på Blackboard leveres en enkel tekst om at kodelageret er klart for vurdering
+* det er også nå "flytende/anbefalt" frist, så hold kontakt med lærerassistenten om fremdrift
+
+== Architectural styles
+
+An architectural style is a conceptual specification of how a certain
+system will be structured and function.
+
+== Architectural styles
+
+- monolithic applications
+- 3-tier applications
+- REST
+
+== layers vs. tiers
+
+- sometimes the terms are used interchangeably
+- there is a difference
+** layers - logical separation
+** tiers - physical separation
+
+[background-color = "#124990"]
+[color = "#fff6d5"]
+== monolithic applications
+
+== monolithic applications (1)
+
+- All the functionality is packed in a single software unit
+** ui
+** logic
+** data
+- designed without modularity
+- also called single-tiered application
+
+== !
+
+image::../images/lecture12/1tier.png[canvas, size=contain]
+
+[background-color = "#124990"]
+[color = "#fff6d5"]
+== 3-tier applications
+
+== !
+
+image::../images/lecture12/3tier.png[canvas, size=contain]
+
+== 3-tier applications (2)
+
+- application where the various functions are separated
+** presentation tier (UI / frontend)
+** logic tier (business tier)
+** data tier (data storage + data access)
+- also called 3-layer
+- application is modular
+
+== 3-tier applications (3)
+
+- ability to update / replace just parts of the application
+- ability to independently scale the layers
+- ability to re-use layers
+
+[background-color = "#124990"]
+[color = "#fff6d5"]
+== REST
+
+[.smaller-80]
+== REST
+- Representational state transfer (REST)
+- architectural style involving use of Web Services
+- set of constraints are applied
+** client server
+** statelessness (no client context is stored on the server side)
+** cacheability (responses state if they can be cached or not)
+** uniform interface
+** layered system (adding layers like proxy or load balancer)
+
+
+== REST (cont.)
+
+- Web services that implement REST are called RESTful APIs
+- a base URI, example: https://gitlab.stud.idi.ntnu.no/api/v4
+- standard HTTP methods (e.g., GET, POST, PUT, PATCH and DELETE);
+- data formats for requests and responses (json, xml, etc)
+
+== !
+
+image::../images/lecture12/itodo.png[canvas, size=contain]
+
+== !
+
+image::../images/lecture12/mtodo.png[canvas, size=contain]
+
+
+== !
+
+image::../images/lecture12/rtodo.png[canvas, size=contain]
+
+
+[background-color = "#124990"]
+[color = "#fff6d5"]
+== Modularity
+
+== Modularity
+
+- means for splitting a large problems into parts
+** distribute and isolate work
+** distribute artifacts for use and reuse
+- more or less supported by tools and languages
+** maven - modular build
+** java - strong encapsulatation
+
+[background-color = "#124990"]
+[color = "#fff6d5"]
+== Modularity with maven
+
+== Modular projects with Maven
+
+- main "parent" module with common configuration
+- sub-modules with dependencies
+** libraries (and plugins) are modules
+** own modules follow architecture
+- manages build tasks
+** sequenced according to dependencies
+** execute in appropriate context e.g. classpath
+
+== Modular projects with Maven
+
+- use of inheritance
+- parent `pom` has configuration that is inherited by modules' `pom`
+- the descendent `pom` can override inherited configuration elements
+- descendant `pom` inherits most elements with the exception of things like artifactid, name which are used to identify the parent `pom`
+
+== Modular projects with Maven (2)
+
+- reduce complexity and size of individual build files
+- reliably use consistent versions for dependencies and plugins
+
+== Parent pom example
+
+[.smaller-40]
+```xml
+<?xml version="1.0" encoding="UTF-8" ?>
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+ <modelVersion>4.0.0</modelVersion>
+
+ <groupId>it1901.todolist</groupId>
+ <artifactId>parent</artifactId>
+ <version>0.0.1-SNAPSHOT</version>
+ <packaging>pom</packaging>
+
+ <properties>
+ <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+ </properties>
+
+ <dependencyManagement>
+ <dependencies>
+ <dependency>
+ ...
+ </dependency>
+ ...
+ </dependencies>
+ </dependencyManagement>
+
+ <build>
+ <pluginManagement>
+ <plugins>
+ <plugin>
+ ...
+ </plugin>
+ ...
+ </plugins>
+ </pluginManagement>
+ </build>
+
+ <modules>
+ <module>core</module>
+ <module>fxui</module>
+ </modules>
+</project>
+
+```
+
+== Descendant pom example
+
+[.smaller-40]
+```xml
+<?xml version="1.0" encoding="UTF-8" ?>
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+ <modelVersion>4.0.0</modelVersion>
+
+ <parent>
+ <groupId>it1901.todolist</groupId>
+ <artifactId>parent</artifactId>
+ <version>0.0.1-SNAPSHOT</version>
+ </parent>
+
+ <artifactId>fxui</artifactId>
+
+ <dependencies>
+ <dependency>
+ ...
+ </dependency>
+ ...
+ </dependencies>
+
+ <build>
+ <plugins>
+ <plugin>
+ ...
+ </plugin>
+ ...
+ </plugins>
+ </build>
+</project>
+
+```
+
+[background-color = "#124990"]
+[color = "#fff6d5"]
+== Modularity with Java
+
+== Java modules
+
+[.smaller-80]
+* corresponds to a set of packages
+* strong encapsulation
+** explicitly export packages
+** explicitly state dependencies
+** also enforced during runtime
+* advantages
+** avoid relying on internals
+** build lighter apps
+* disadvantages...
+
+== core - module-info.java
+
+```java
+module todolist.core {
+ requires transitive com.fasterxml.jackson.databind;
+
+ exports todolist.core;
+ exports todolist.json;
+}
+```
+
+== core - https://gitlab.stud.idi.ntnu.no/it1901/todo-list/-/blob/master/todolist/core/src/main/java/module-info.java[module-info.java]
+
+* module name
+** how to get (guess) name of libraries
+* **requires** - what this module needs
+** **transitive** - others will need this too
+** **exports** - what others may use
+
+== fxui - https://gitlab.stud.idi.ntnu.no/it1901/todo-list/-/blob/master/todolist/fxui/src/main/java/module-info.java[module-info.java]
+
+```java
+module todolist.ui {
+ requires com.fasterxml.jackson.databind;
+
+ requires java.net.http;
+
+ requires javafx.base;
+ requires javafx.controls;
+ requires javafx.fxml;
+
+ requires todolist.core;
+ requires fxutil;
+
+ opens todolist.ui to javafx.graphics, javafx.fxml;
+}
+```
+
+== fxui - module-info.java
+
+* **opens** ... *to* - allow getting runtime info about classes using so-called _reflection_
+** fxml
+** REST frameworks
+** test frameworks
+* **--add-opens** command line option
+** support unmodularized mode
+
+include::{includedir}footer.adoc[]
\ No newline at end of file