TWC operates at the EMF level, while MagicDraw operates at the UML level, which is on the top of EMF. REST API, which is the TWC API, also operates at the EMF level.
Therefore, TWC is not affected by UML-specific implementation, and all derived properties may not be saved in the TWC database. The best-known derived property is owner. This is the result when there is no such “setOwner” in REST API.
Even though all non-derived properties are saved in the TWC database, they are saved as raw EMF data. The user is required to have knowledge about UML models to manipulate data. For example, an applied stereotype is saved as a hierarchy of InstanceSpecification, Slot, and ValueSpecification.
This section describes how to traverse into a UML model and create some elements in it.
MagicDraw project
In TWC terminology, a MagicDraw project is referred to as a resource. Although REST API can be used to create a TWC resource, it is only a bare project MagicDraw cannot read. A MagicDraw project is composed of many MagicDraw-specific meta-data such as project options, primary project, and used projects configuration. The best way to create a MagicDraw project is creating to create it by MagicDraw and submit it to the TWC server.
MagicDraw primary project
To traverse through a UML model, the primary project must be identified. The model data starts at the revision level. Issuing GET to /revisions/{revisionId} shows the first-level object in the revision. UUIDs of the first-level object are listed in rootObjectIDs.
Among these entries, the first element with the esiproject:EsiProject type specifies the primary project named main decomposition project. Other esiproject:EsiProject objects are the models (used projects) in a MagicDraw project. The main decomposition project is element 429f969a. You need to load element 429f969a and all their children. An element is represented in the JSONLD JSON-LD format. The attributes of the elements are in kerml:esiData. There will be an element named UML Model. The below code fragment shows the attributes of this element.
The first ID in the rootElements list of the data section will be the ID of the UML model root element in the resource. The root element should always be of the uml:Package type or derived from it.
Traversing to a MagicDraw model
Once a root project is retrieved, the whole hierarchy can be retrieved layer by layer. An element can be retrieved from /elements/{elementId}. Child UUIDs of the resulting element are in kerml:ownedElement.
Multiple elements can be retrieved by POST to /elements. In this case, you need to put UUID in the uuid.txtfile to load elements.
In most cases, loading multiple elements at once is substantially faster than loading them one by one.
Creating elements
To use REST API to create elements, you are required to have knowledge about UML models, especially how to set the owner. A combination of parent-child type yields differences in the owner attribute. For example, if you want to create a class under a class, you need to set the UMLClass attribute in the child class. For a class under a package, you need to set owningPackage in the child class. The easiest way to know which attribute is needed is to try creating it in MagicDraw and get it in REST API.
There are two URLs to create element(s), /resources/{resourceId}/elements and /resources/{resourceId}/elements{elementId}. Please note that the elementId in the latter form is not the parent. An Ecore is needed to create an element. It can be specified in the following ways:
Specified from the elementId in /resources/{resourceId}/elements/{elementId}. This form is used in most cases, except from for creating the first element in the project. The new element data type will be in the same namespace of this specified element.
Applied stereotypes stored in the appliedStereotype attribute are the arrays containing reference objects to stereotype objects. The code below shows an example of an applied stereotype.
The UUID 8dbdc804 is an ID of the applied stereotype whose content is applied via the following command where the UUID 8df9f306 is an ID of the element to which the stereotype is applied:
Tagged values stored in the taggedValue attribute are the arrays containing reference objects to tagged value objects. The code below shows an example of an applied stereotype and tagged values.