Dev Guide
Technical guides for OneStream development — from getting started to advanced patterns.
OneStream
What Is OneStream?
Understand OneStream as a unified Corporate Performance Management platform — what it replaces, how its engines work together, and why developers are central to extending it.
Updated February 16, 2026The OneStream Data Model
Learn how OneStream organizes data — dimensions, cubes, Scenario Types, Point of View, Data Units, and when to use relational tables instead of the cube.
Updated February 16, 2026Data Integration and Transformation
How data flows from source systems into OneStream — staging, mapping, transformation, and seeding actuals as the foundation for budgets and forecasts.
Updated February 16, 2026Building a Budget
Build a budget in OneStream from the ground up — driver-based planning, factor-based adjustments, Cube Views, calculations, and the workflow that ties it all together.
Updated February 16, 2026Forecasts and Custom Planning Solutions
Extend your budget into rolling forecasts, build variance analysis, and create bespoke CRUD processes for specialty planning like headcount and capital projects.
Updated February 16, 2026Business Rules
Getting Started with Business Rules
Learn the fundamentals of OneStream Business Rules — types, structure, and how to write your first rule.
Updated February 14, 2026Organizing Your Business Rule Code
Structure your Business Rules with class-level state, a thin Main dispatcher, and dedicated methods for each function type.
Updated February 14, 2026Debugging Business Rules
Learn the StringBuilder debug logging pattern — how to trace rule execution, understand class vs. function scope, and output debug logs through XFException.
Updated February 14, 2026Finance Rules
Getting Started with Finance Rules
Learn how Finance Business Rules work — function types, the rule skeleton, and execution flow.
Updated February 14, 2026Understanding Data Units
Learn how OneStream breaks calculations into Data Units and how to write efficient guard conditions for better performance.
Updated February 14, 2026Writing Calculations
Master stored calculation techniques in OneStream — api.Data.Calculate, Get/Set Data Buffers, CustomCalculate, and when to use Business Rules vs. Member Formulas.
Updated February 14, 2026The Finance Rules API
Explore the Finance Rules API object, the BRApi static class, BRGlobals caching, and how to share code across Business Rules.
Updated February 14, 2026Workspace Assemblies
Getting Started with Workspace Assemblies
Learn what workspace assemblies are, how they differ from Business Rules, and how to structure your code using workspaces, maintenance units, and the Service Factory pattern.
Updated February 14, 2026Referencing Assemblies and Sharing Code
Set up assembly dependencies, configure shared workspaces, and use reference syntax for XFBR, Dashboard, CubeView, and Service Factory configurations.
Updated February 14, 2026Referencing Dependency Classes in Code
Use the compiled namespace pattern to reference dependency classes in VB.NET and C# code, including Imports/using directives, MainClass patterns, and cross-workspace references.
Updated February 14, 2026