The HarnessXML extension turns a Rumima map into an executable workflow.
Draw the graph, export .hxml, and run it on any conforming runtime —
including ones VisML did not write.
A Rumima document is saved as .rmmx. Inside it, the .visml markup standard carries everything Rumima needs that a workflow does not — canvas layout, colours, grouping, editor state, and the finetuning and attribute injection described below.
Embedded in that document is a complete HarnessXML element. Export lifts it out; import wraps it back. Nothing is translated, so nothing is lost in translation — which is what makes the round trip safe to rely on.
Only .hxml crosses the boundary. The runtime is handed the
exported document and never sees .rmmx or .visml. That is
deliberate: it is what makes the runtime replaceable, and it is why the workflow you
design here is not hostage to this tool.
A Rumima map where every node is a step. The tree is the workflow — not a picture of it.
document_triage.rmmx
├─ receive source → document, filename
├─ extract_text transform → text [retry ×3]
├─ classify inference → category, confidence
│ [model: claude-opus-5]
│ [retry ×4, rate_limit transient]
├─ route decision
│ ├─ confidence ≥ 0.90 → auto_file
│ └─ otherwise → human_review
├─ auto_file task
├─ human_review human [NOT idempotent]
└─ notify_failure sink ← error edge from classify.rmmx
The container holds the map. The .visml markup carries presentation and
tuning; the embedded <harness> carries the executable workflow:
<visml xmlns="https://visml.com/schema/1.0" product="rumima">
<rumima-document version="1">
<!-- Presentation. Never leaves the .rmmx: a workflow's meaning
cannot depend on where a box sits. -->
<canvas>
<place node="classify" x="420" y="180" colour="#f0b04e"/>
<place node="route" x="640" y="180"/>
</canvas>
<!-- Finetuning. Resolved AT EXPORT into concrete values. -->
<tuning>
<weight node="classify" attribute="confidenceFloor" value="0.90"/>
<variant name="conservative" confidenceFloor="0.95"/>
<variant name="throughput" confidenceFloor="0.80"/>
</tuning>
<!-- The executable workflow: a COMPLETE HarnessXML document. -->
<harness xmlns="https://harnessxml.com/spec/1.0"
id="document_triage" specVersion="1.0" entry="receive">
<resources>
<resource id="classifier" type="model" provider="anthropic">
<property name="model" value="claude-opus-5"/>
<credential ref="ANTHROPIC_API_KEY" store="vault"/>
</resource>
</resources>
<nodes>
<node id="classify" type="inference">
<outputs>
<output name="category" type="string"/>
<output name="confidence" type="number"/>
</outputs>
<resourceRef ref="classifier" role="model"/>
<retry maxAttempts="4" backoff="exponential"
retryOn="rate_limit transient"/>
<timeout duration="PT3M" onTimeout="retry"/>
</node>
<node id="route" type="decision">
<cases>
<case when="${classify.confidence >= 0.90}" to="auto_file"/>
<otherwise to="human_review"/>
</cases>
</node>
<node id="human_review" type="human" idempotent="false"/>
</nodes>
<edges>
<edge from="classify" to="route" type="control"/>
<edge from="classify" to="notify_failure" type="error"/>
</edges>
</harness>
</rumima-document>
</visml>
Export lifts the <harness> element out unchanged. The result validates
against the published schema and runs anywhere:
$ harnessxml validate document_triage.hxml
document_triage.hxml: valid
$ harnessxml run document_triage.hxml --scenario rate-limited.txt
classify SUCCEEDED (attempt 3, after 2 retries)
route SUCCEEDED routed to 'auto_file'
human_review PENDING (never reached)
document_triage.hxml: succeeded
Both screenshots below are captures of Rumima Enterprise Studio rendering the
.rmmx documents linked beside them. Not mock-ups — the maps are
published, and you can open them yourself.
A node showing green is Rumima's current selection highlight, not a harness colour. Every node's description carries its HarnessXML fragment, so the maps are readable as documentation even without the extension.
Anyone can draw prompt → model → output. What breaks in production is rate limits, partial failures, silent fallbacks and steps that must never be retried. Those are invisible in code and obvious in a graph — which is the whole reason to design one visually.
Control, data, dependency, error and compensation are distinct edge types with distinct scheduling meaning — and distinct rendering on the canvas.
If you cannot tell an error path from a data path at a glance, the picture is not showing you the workflow.
A step marked non-idempotent is flagged on the canvas itself, and the studio refuses to attach a retry policy to it.
Getting this wrong charges the card twice. It deserves to be visible without clicking.
Every rule in the specification carries an HX-nnnn code. They surface
on the canvas, at the node, as you work — not in a modal after export.
A dangling edge or an unbounded loop should never survive to a build.
A loop will not draw without maxIterations. There is no unbounded
form to reach for.
An unbounded loop in an unattended workflow is a defect, not a feature — and with LLM calls it is also a bill.
Script the outcomes — “the model rate-limits twice, then returns 0.62 confidence” — and watch the escalation path execute with zero API calls.
Prove the low-confidence path works before a customer discovers it does not.
Execution traces are part of the specification, so a run from any conforming runtime replays here: nodes light up SUCCEEDED, RETRYING with its backoff, FAILED, COMPENSATED — and the branch not taken stays dim.
Only a visual tool can do this, and it is the fastest way to understand what actually happened.
Loop bounds and concurrency are declared in the document, so the worst-case number of model calls is computable before a single one is made.
“This design can make 480 calls” is worth knowing in the designer, not on the invoice.
Tune thresholds, weights and attributes as named variants in the map, and export
each as its own concrete, validated .hxml.
Every variant is a real document with its own identity, so you can always say which one ran.
The format this extension writes is not ours to withhold. HarnessXML is an open specification: the text is CC BY 4.0, the schema and reference code are Apache 2.0, and anyone may implement it commercially without permission, royalty or an agreement to sign.
| Your workflows | plain .hxml files, diffable and reviewable in a pull request |
|---|---|
| Your runtime | any conforming implementation — three already pass the suite, in Rust, Python and Go |
| Your editor | build your own against the published schema; nothing here is required |
| If VisML stops | the licences already granted are irrevocable; the specification stays forkable |
VisML both stewards the specification and sells this extension. That is a real conflict of interest, and it is named explicitly in the published governance model — along with the structural limits on it: Rumima gets no privileged extension point, the reference runtime is not Rumima, and conformance is decided by a public test suite rather than by agreement with our product.
If Rumima and the specification ever disagree, the specification is right and Rumima has a bug. That is a published commitment, not a courtesy.
Which leaves exactly one honest reason to license this extension: because designing a harness visually is faster and clearer than writing one by hand — not because leaving would cost you your work.
HarnessXML support is built into Rumima Enterprise Studio and activated with a licence key. It is an additional licensed feature on top of a Studio seat.
| Model | Subscription add-on to a Rumima Enterprise Studio seat |
|---|---|
| Pricing | By quote. It depends on seat count, deployment shape and whether you self-host the collaboration hub — so we would rather give you a real number than a misleading list price |
| Requires | Rumima Enterprise Studio, any seat tier |
| Activation | licence key; the 10-day offline window applies as usual |
| Specification | HarnessXML 1.0 — draft |
| Export | .hxml, validated on write |
Tell us roughly how many seats, whether you self-host, and what you are building — LLM orchestration, robotics, network or business automation. We will come back with a figure and a trial licence.