Diagrams: Architecture, C4, and AWS¶

Three closely related diagram types: ArchitectureDiagram, C4ContainerDiagram, and AWSDiagram. All share the same auto-layout engine and orthogonal-routing connections.

ArchitectureDiagram¶

Draws 4-tier topology: clients, services, databases, and queues.

import engrapha_notes as en
import engrapha_diagrams as ed

arch = ed.ArchitectureDiagram(
    width=450, height=220,
    caption="Fig 9: Web App Architecture",
    orientation="horizontal",  # "vertical"
)

arch.client("web", "Web Client")
arch.service("api", "Gateway API")
arch.service("auth", "Auth Service")
arch.database("db", "PostgreSQL")
arch.queue("q", "Job Queue")

arch.connect("web",  "api",  "HTTPS")
arch.connect("api",  "auth", "gRPC")
arch.connect("api",  "db",   "TCP/5432")
arch.connect("api",  "q",    "AMQP")
arch.connect("auth", "db",   "TCP/5432")

en.add(arch.as_flowable())
en.build_doc("arch.pdf")

Orientation¶

With orientation="vertical" the tiers stack bottom-to-top. Clients at the bottom, databases at the top.

C4ContainerDiagram¶

System and Container nodes arranged on a grid with relationship lines:

c4 = ed.C4ContainerDiagram(
    width=420, height=220,
    caption="Fig 10: C4 Container View",
)

c4.system("user", "Customer")
c4.container("spa",  "SPA (React)", "Provides UI")
c4.container("api",  "API (Go)",    "Business logic")
c4.container("db",   "Postgres",    "Order data")

c4.relate("user", "spa", "Uses")
c4.relate("spa", "api", "Makes API calls")
c4.relate("api", "db", "Reads / Writes")

en.add(c4.as_flowable())

Systems render in darker surface tones; containers render with lighter backgrounds.

AWSDiagram¶

AWS-specific vector icons on top of the ArchitectureDiagram layout:

aws = ed.AWSDiagram(
    width=450, height=220,
    caption="Fig 11: AWS Stack",
    orientation="horizontal",
)

aws.ec2("app",    "EC2 App")
aws.rds("db",     "RDS PostgreSQL")
aws.s3("assets",  "S3 Storage")
aws.lambda_fn("fn", "Handler")
aws.sqs("queue",  "Job Queue")

aws.connect("app", "db",     "SQL Connection")
aws.connect("app", "assets", "Uploads")
aws.connect("app", "fn",     "Invoke")
aws.connect("app", "queue",  "Events")

en.add(aws.as_flowable())

Node types¶

Method	Kind	Visual
`ec2(name, label)`	compute/server	server blade
`rds(name, label)`	database	cylinder
`s3(name, label)`	storage	trapezoidal bucket
`lambda_fn(name, label)`	function	lambda (λ) symbol
`sqs(name, label)`	queue	stadium with slot markers

Auto layout¶

All three handle auto-positioning when nodes are added without x, y coordinates. Only specify coordinates if the auto-layout is unsatisfactory.