V-model with graphviz

Question

I want to draw a V-Modell for software development. I want to use graphviz to keep it more maintainable than in Visio.

How can I get the typical V-structure in Graphviz?

I think I need horizontal and vertical alignment. I tried to work with dummy-nodes but the layout is still poor.

Answer 1

This code works for me. It has a bit of a workaround in it to create the V shape. I use an invisible node and invisible edges to create a wedge between the 2 sides of the V-model.

digraph Vmodel {
// Transparent background
graph [bgcolor=none]

// Node style
node [
    shape=record
    style="rounded, filled"
    width=2.5
    height=0.8
    fillcolor=white 
];

// Create the nodes
user_req_models     [label="User\nRequirements\nModels"]
sys_req_models      [label="System\nRequirements\Models"]
arch_models         [label="Architectural\Models"]
comp_design_models  [label="Component\Design\Models"]
unit_design_models  [label="Unit\nDesign\nModels"]
units               [label="Units\n(SW, HW and Data)"]
components          [label="Components\n(SW, HW and Data)"]
subsystems          [label="Subsystems"]
integrated_system   [label="Integrated System"]
operational_system  [label="Operational System"]

// Create a hidden node to form a V-shaped wedge
hidden              [style="invis"]

// Create the basic layout of the V model
user_req_models->sys_req_models
sys_req_models->arch_models
arch_models->comp_design_models
comp_design_models->unit_design_models
unit_design_models->units
units->components
components->subsystems
subsystems->integrated_system
integrated_system->operational_system

// Create the dashed edges
user_req_models->operational_system [style="dashed", constraint=false]
sys_req_models->integrated_system   [style="dashed", constraint=false]
arch_models->subsystems             [style="dashed", constraint=false]
comp_design_models->components      [style="dashed", constraint=false]

// Create a wedge between the two parts
hidden->user_req_models         [style="invis"]
hidden->sys_req_models          [style="invis"]
hidden->arch_models             [style="invis"]
hidden->comp_design_models      [style="invis"]
hidden->operational_system      [style="invis"]
hidden->integrated_system       [style="invis"]
hidden->subsystems              [style="invis"]
hidden->components              [style="invis"]
hidden->unit_design_models      [style="invis"]
hidden->units                   [style="invis"]

// Ranking on the same level
{rank=same; user_req_models, operational_system}
{rank=same; sys_req_models, integrated_system}
{rank=same; arch_models, subsystems}
{rank=same; comp_design_models, components}
{rank=same; unit_design_models, units}
}