seqdiag {
    edge_length = 200;
    span_height = 15;
    activation = none;
    default_note_color = white;
    'Resource Tracker'; 'Report Client'; Placement; 'Virt Driver';
    'Resource Tracker' -> 'Virt Driver' [label = "update_provider_tree(provider_tree, nodename, allocations=None)"];
    'Resource Tracker' <- 'Virt Driver' [label = "raise ReshapeNeeded", color = red];
    'Resource Tracker' -> 'Report Client' [label = "get_allocations_for_provider_tree()", color = red];
    'Report Client' -> Placement [label = "GET /resource_providers/{uuid}/allocations", color = red];
    'Report Client' <-- Placement [label = "HTTP 200", color = red];
    'Report Client' -> 'Report Client' [label = "get_allocations_for_consumer(context, consumer)", color = red];
    'Report Client' -> Placement [label = "GET /allocations/{consumer_uuid}", color = red];
    'Report Client' <-- Placement [label = "HTTP 200", color = red];
    'Resource Tracker' <-- 'Report Client' [label = "{allocations by consumer}", color = red];
    'Resource Tracker' -> 'Virt Driver' [label = "update_provider_tree(provider_tree, nodename, allocations=allocations)", color = red];
    'Resource Tracker' <-- 'Virt Driver';
    'Resource Tracker' -> 'Report Client' [label = "update_from_provider_tree(
                                                    context, new_tree,
                                                    allocations)"];
    'Report Client' ->  Placement [label = "POST /resource_providers
                                            (create new providers)"];
    'Report Client' <-- Placement [label = "HTTP 200"];
    'Report Client' ->  Placement [label = "POST /resource_providers/{uuid}/aggregates|traits
                                            (fix up aggregates, traits, etc.)"];
    'Report Client' <-- Placement [label = "HTTP 200"];
    'Report Client' ->  Placement [label = "POST /reshaper {transformation payload}"];
    Placement --> Placement [label = "create/modify/
                                      delete
                                      inventories"];
    Placement --> Placement [label = "create/modify/
                                      delete
                                      allocations", color = red];
    'Report Client' <-- Placement [label = "HTTP 204"];
    'Resource Tracker' <-- 'Report Client'
}