Plantuml on Micha Kops' Tech Notes

Modeling AWS Structures with PlantUML and AsciiDoc

Tue, 08 Nov 2022 00:00:00 +0100

The AWS shapes are included in the PlantUML stdlib .. simply include them as shown here:

example.puml

@startuml
!include <awslib/AWSCommon>
!include <awslib/Analytics/ManagedStreamingforKafka>
!include <awslib/Database/RDS>
!include <awslib/General/Users>
!include <awslib/General/InternetGateway>

!include <kubernetes/k8s-sprites-labeled-25pct>

skinparam linetype ortho

title "AWS Context Diagram"


package "EKS Kubernetes Cluster" as eks_cluster {
    component "<$pod>\napp1" as pod1
    component "<$pod>\napp2" as pod2
}

ManagedStreamingforKafka(kafka_pod, "Amazon MSK", "Apache Kafka")

RDS(pg_rds, "PostgreSQL", "Sample Schema")


Users(users, "AppUsers","editors, admins")

InternetGateway(igw1, "Customer Gateway", "Customer access to internal services")

users -> igw1
igw1 --> pod1
igw1 --> pod2
pod1 --> pg_rds
pod1 --> kafka_pod
pod2 --> pg_rds
pod2 --> kafka_pod

@enduml

C4 Modeling with PlantUML and AsciiDoc

Tue, 01 Nov 2022 00:00:00 +0100

C4 models allow us to visualize software architecture by decomposition in containers and components.

Viewpoints are organized in hierarchical levels:

Context Diagrams (Level 1)
Container Diagrams (Level 2)
Component Diagrams (Level 3)
Code Diagrams (Level 4)

C4-PlantUML offers a variety of macros and stereotypes that make modeling fun.

An example in PlantUML:

sample.puml

@startuml
!include <c4/C4_Context.puml>
!include <c4/C4_Container.puml>

left to right direction

Person(user, "User")

System_Ext(auth, "AuthService", "Provides authentication and authorization via OIDC")

System_Boundary(zone1, "Some system boundary") {


    System(lb, "Load Balancer")

    System_Boundary(az, "App Cluster") {
        System(app, "App Servers") {
            Container(app1, "App1", "Docker", "Does stuff")
            Container(app2, "App1", "Docker", "Does stuff")

            ContainerDb(dbSess, "Session DB", "Redis")
            ContainerDb(db1, "RBMS 1", "AWS RDS Postgres")
            ContainerDb(db2, "RBMS 2", "AWS RDS Postgres")

            ' both app servers sync sessions via redis
            Rel(app1, dbSess, "Uses", "Sync Session")
            Rel(app2, dbSess, "Uses", "Sync Session")

            ' both app servers persist data in RDBMS
            Rel(app1, db1, "Uses", "Persist/query relational data")
            Rel(app2, db2, "Uses", "Persist/query relational data")
        }
    }
}

Rel(user, lb, "call")
Rel(lb, app1, "delegate")
Rel(lb, app2, "delegate")
Rel(app1, auth, "Verify", "User auth")
Rel(app2, auth, "Verify", "User auth")

SHOW_FLOATING_LEGEND()

@enduml

Snippet: Adding Legends to PlantUML Diagrams

Fri, 21 Oct 2022 00:00:00 +0200

The following hack allows us to draw a diagram in a diagram in a table in a legend :D

example-diagram.puml

@startuml
skinparam legendBackgroundColor transparent
skinparam legendBorderColor transparent

actor Editor as editor
queue Queue as "Message\nQueue"
editor -> [Component] : call
[Component] --> Queue : publish


legend right
{{
   scale 0.7
   skinparam defaultFontSize 14
   skinparam BackGroundColor transparent
   skinparam defaultBackgroundColor white

   !procedure $entry($type, $label, $scale=1)
      {{\nscale $scale \nskinparam backgroundcolor transparent\nlabel " " as A\nlabel " " as B\n $type \n}} => $label
   !endprocedure

   map "<b>Legend</b>" as legend #white {
      $entry(":Editor:","\nEditor for Data xyz", 0.6)
      $entry("[Component]","\nSome Component", 0.8)
      $entry("queue Queue","\nKafka-Topic", 1)
      $entry("A -> B","Data-Flow")
   }
}}

endlegend
@enduml

Reactive Streams – Java 9 Flow API, RxJava, Akka and Reactor Examples

Sun, 14 Jan 2018 00:00:00 +0100

Reactive Streams is an initiative trying to standardize asynchronous stream processing with non-blocking back-pressure. With Java 9, new classes in the java.util.concurrent.flow package offer a semantically equivalent counterpart to this standard that may be adopted by other frameworks.

In the following short tutorial we’re implementing examples for reactive streams with Java 9 and the Flow API, with RxJava2, with Akka, with Reactor and finally there is an example in RxJava1, too though it does not follow the standard.