Introduction

In Part 1, we created a SysML model for an IoT product and the system engineering project for developing the IoT product. This model is represented by the gray blocks in the center of Figure 1.

Figure 1 Total System Model architecture

However, we must recognize that most of the engineering effort takes place in engineering tools like those on the periphery of the figure. Model-Based Engineering (MBE) practice requires us to connect elements in different models to create a single unified model distributed over multiple tools, which we call the Total System Model (TSM).

Building the TSM

To build this network of connections, we used Syndeia, the MBE platform from Intercax. Using a simple drag-and-drop interface, Syndeia can create a variety of inter-model connection types, ranging from simple reference links to full model transforms which allow comparison and synchronization of data between tools. For more information on Syndeia features, consult the Syndeia page on this website.

Viewing the TSM

A major benefit of realizing the TSM is being able to trace connections across the graph, both inter-model connections between tools and intra-model connections inside a single tool. In Syndeia 3.0, we introduced some new visualization capabilities. We can view all the inter-model connections in a chord plot, as in Figure 2, where the peripheral nodes in different colors represent Rhapsody, Teamcenter, DOORS NG, Simulink, NX, GitHub, JIRA, Jama and MySQL. A search box lets us look for specific nodes and connections.

Figure 2 Chord plot of inter-model connections

However, as the total system model becomes large, new methods to identify critical connections efficiently are required. In particular, we want to be able to explore extended chains of connections, where multiple direct links combine to connect system elements in non-obvious ways. It is such extended connections that can give rise to critical emergent behaviors and vulnerabilities that systems engineers are expected to identify.

Querying the TSM

The power of modern graph database technologies makes this possible. Using a prototype of Syndeia 3.1, to be released early in 2017, we export the TSM graph to a Neo4j graph database with powerful query tools. Using its query language Cypher, we can ask the graph database a variety of key questions and see the results as a diagram or a text list.

1. Show all SysML blocks connected to Jama requirements – Figure 3 shows the graphical results to this query. Requirements in Jama are in gray and SysML requirements are in yellow. Inter-model (Model Transform) connections link Jama and SysML elements and intra-model (SysML Containment ) relationships connect the SysML requirements. Note that the graphical output does not display the full element name, but such information is easily read using the text-based format or selecting individual graphical elements.
   

   Figure 3 Query 1 – Show all SysML blocks connected to Jama requirements

2. Show all requirements that impact the front casing part, directly or indirectly – The results in Figure 4 include Dimensions, Mounting and Weight, which are linked indirectly to the front casing as part of the overall product, as well as Appearance, which is linked directly.
   

    Figure 4 Query 2 – Show all requirements linked to front casing part

3. Show any connection between the GitHub file “BluetoothSW” and the Jama requirement “Location_Report” – Results in Figure 5 are shown both as a text list and a diagram. There is one linkage, via a SysML requirement satisfied by a SysML block.

Figure 5 Query 3 – show linkage between GitHub file “BluetoothSW” and the Jama requirement “Location_Report”

Summary

Modern graph database technologies hold out a lot of promise to enable systems engineers to carry out their responsibilities. For further information, visit us at www.intercax.com or contact us at info@intercax.com.

Related articles:

• Modeling Project and Product for the Internet of Things (IoT) | Part 1
• Modeling Project and Product for the Internet of Things (IoT) | Part 2 (This post).

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