What is an Assembly Step?
A Transloadit Assembly Step is one file-processing operation, such as encoding, resizing, or format conversion. Steps have chosen names and can supply their results to later Steps in the Instructions.
How Assembly Steps work
A Step is a named node in the Assembly’s processing graph, combining one Robot operation with a declared source of files. Its output can become a final deliverable, an intermediate representation, or input to several later nodes. Step names provide the graph’s internal addressing and also group results in status data. Designers compose small operations into branches so transformations and exports remain observable independently.
Key facts
- 1A Step may receive uploads directly or select results from one or more earlier Steps, which makes input references part of the workflow’s executable dependency graph.
- 2Two Steps can invoke the same Robot with different parameters, for example producing separate rendition sizes while preserving distinct names and result groups.
- 3Failure behavior is graph-sensitive: a downstream node cannot produce output when its required upstream branch yields no usable file, even if unrelated branches complete.
When Assembly Steps matter
Name Steps by purpose so dependencies and returned results remain understandable. Reference the correct upstream Step, because a mistaken name can process the wrong files or leave a branch without input.
Common use cases for platform workflows
These examples cover platform workflows broadly, not specifically Assembly Steps.
- Running repeatable upload, import, processing, AI, storage, and notification pipelines.
- Tracking long-running media work independently from an application request.
- Referencing centrally stored credentials by name instead of sending storage secrets with each request.
Working with platform workflows
This guidance covers platform workflows broadly, not just Assembly Steps.
A client authenticates and submits files or references together with workflow instructions. The platform validates the request, schedules dependent operations, records state transitions, and exposes results through a response, polling endpoint, or notification.
Platform concepts become reliable only when their lifecycle is explicit. Authentication, idempotency, retries, timeouts, observability, quotas, and terminal states should be designed together rather than added after failures occur.
What you gain
- Reusable workflows separate application intent from processing infrastructure.
- Stable job identifiers and lifecycle events improve observability and recovery.
- Managed queues and workers let products scale without embedding every media tool.
What it costs
- Synchronous responses are simple but keep connections open while long work executes.
- Aggressive retries improve recovery from transient faults but can duplicate work or overload a dependency.
- Higher concurrency reduces queue time until resource contention or a downstream limit becomes the bottleneck.
Before production
- 1Define authentication, authorization, idempotency, retries, and terminal error behavior.
- 2Observe queue time, execution time, callbacks, and partial results with stable identifiers.
- 3Exercise malformed, duplicate, interrupted, and unauthorized requests before launch.