Glossary

Auto-scaling. A part that runs more copies of itself as traffic grows. See auto-scaling.

Blast radius. Everything a failure touches, and how much of the traffic fails where it starts. See failure drills.

Bundle. One .flozu-bundle.json file holding several maps, with their folders and, if you like, their versions and proposals. See import and export.

Buffer. How much a queue or topic can hold while it waits to be worked through. Shown as Holds in the inspector.

Capacity. The most a part can handle each second. More than this backs up.

Copy. One running instance of a part that auto-scales.

Draft. A scenario you’ve changed but not saved with the map. It belongs to this window only.

Drawing. The small live picture in a part’s panel. Any part can show any drawing.

Drill. A scenario that takes a part, a line or a zone down for a while, to see what fails and what takes over. See failure drills.

Entry point. A part no line flows into, such as people or an app. Scenarios scale the traffic that starts there.

Estimate. A scenario’s rough figure for how long requests take, how much fails, or what the map costs to run, worked out from the map rather than measured. See response times and cost.

Limit. The most a part lets through each second. The rest is turned away.

Line. A connection between two parts, carrying requests or messages. Called a connection in the file format.

Map. One document holding parts, lines, zones, notes, views, stories and saved scenarios.

Map inside. Another map a part opens into, to show what’s inside it. See maps inside parts.

Message. Traffic that’s sent and left, like an event or a job. Drawn as a dashed lime line.

Moment. A point in a scenario worth stopping at, such as the busiest moment or when a part first runs over.

Note. Plain words on the canvas.

Part. A piece of the system, such as a service or a database. Called a component in the file format.

Preset. A ready-made part on the library’s Presets shelf, such as a Redis cache.

Project. A folder at the top level, holding maps and folders. The Maps panel lists each one as a tree.

Proposal. A copy of a map to change freely, which remembers where it began so it can be compared and adopted.

Rate. How much a line carries each second at the busiest moment of a normal day.

Replay. The same scenario played on two maps, such as a proposal and where it began, to see what a change does to how the map copes. See replay a scenario.

Request. Traffic that asks and waits for an answer, like an HTTP call. Drawn as a solid pale blue line.

Response time. How long a request takes, its part’s own time and the time of the requests that part makes in turn. A scenario estimates it.

Run by someone else. A part another company runs, drawn with a dashed outline.

Scenario. A “what if?” played over time on a map, such as Black Friday.

Single point of failure. A part or zone that nothing takes over from, so traffic fails when it goes down. Fixed by a change to the map’s shape, such as a standby copy beside it. See failure drills.

Spare room. How much headroom a part should keep. A part past it is tight. 30% by default.

Standby line. A line that carries nothing until a line beside it fails, like a failover to a replica. See lines.

Story. A walk through a map, one step at a time, for presenting it.

Tight. Busier than its spare room allows, but not yet over its capacity.

Uses line. A dotted grey line saying one part depends on another, such as code using a library. It carries no traffic.

Version. The map as it was at one moment, kept beside it.

Weak spot. A part or zone the map can least afford to lose, found by taking each down in turn. See failure drills.

View. One way of showing a map to one audience, with things hidden and plain wording.

Zone. A frame around parts that belong together, such as a region or a team. Called a group in the file format.