Melody™ is the SysML parametric solver and integrator plugin for IBM Rational Rhapsody. With Melody™, system engineers can for the first time execute parametric models in Rhapsody to explore system performance and other measures-of-effectiveness (MoEs), automatically verify requirements, run trade studies, orchestrate simulations, estimate cost and allocate resources, keep diverse system models in-sync (e.g. logical and physical, hardware and software), and do much more. Links between SysML and Excel® make it easy to import and export data, and generate graphs and charts. The MATLAB/Simulink® connection and the custom Mathematica® connection allow users to wrap existing MATLAB M-files and custom Mathematica functions as SysML constraint blocks, build high-fidelity analysis models (e.g. cost, performance, risk), and execute them in the context of the system-of-interest.

Melody™ R3 requires Rhapsody 7.5.2, and is available in Standard and Pro editions.

New in Melody™ R3

Melody™ R3 offers significant end-user improvements compared to the previous version (Melody™ R2). The key end-user improvements are as follows. For details, see section 2 of the Users Guide.

Execute complex aggregate relationships

With Melody™ R3, users can execute complex aggregate relationships. Complex aggregate relationships allow users to express parametric relations over a set of part / reference / shared properties, e.g. summation of weight and cost variables for a collection of parts. Top

Reuse blocks and constraint blocks

Melody™ R3 can work with block structures and parametric models that reuse blocks and constraint blocks. It builds on improvements in parametric modeling in Rhapsody 7.5.2 and additional workarounds to provide this feature. Top

Support for packaging structures

Melody™ R3 can work with blocks and instances irrespective of the packaging structure. This provides users complete flexibility in organizing libraries of blocks, constraint blocks, and block instances, and reuse them for defining and evaluating different system alternatives. Top

Execute parametric models involving nested parts

Melody™ R3 provides a workaround for creating parametric models involving nested parts. Users can create parametric models with arbitrarily nested part, reference, or shared properties, and execute them with Melody™ R3. Top

Execute parametric models involving reference / shared properties

Melody™ R3 provides a workaround for creating and executing parametric models involving reference and shared properties. Top

Support for inheritance

With Melody™ R3, users can execute parametric models involving inherited value properties, value properties owned by inherited part / reference / shared properties, and inherited constraint properties. Top

Incremental testing and verification

Melody™ R3 offers users the ability to build, test, and verify parametric models incrementally. The key enabler here is that parametric execution can be invoked for any block instance in the instance model hierarchy, e.g. part instance, sub-system instance, or system instance, by selecting the subject instance in the model tree or the instance diagram. When invoked for a block instance, Melody™ executes the parametric models for that instance and all instances populating its part, reference, and shared properties, recursively. Melody™ R3 eliminates the need to create CXS and CXI heading blocks to identify the top-level block and instance. Top

Warning users of incompatible value / data types

Melody™ R3 warns users if parametric models involve binding connectors that connect value properties or constraint parameters with incompatible value or data types. Top


Melody™ R3 provides utilities for efficient model building and debugging. This includes utilities for refactoring binding connectors from packages to blocks, creating instance model elements and diagrams, and adding instances to populate aggregate part / reference / shared properties. Top