Creating, loading and saving UML models
Editing and naviagting UML models
Importing instances from other tools
OCLE allows you to import UML models realized using other state-of-the-art CASE tools, such as Rational Rose, TogetherSoft ControlCenter, Gentleware Poseidon or NoMagic MagicDraw. The precondition is that these models are stored in XMI format. OCLE currently supports a variety of XMI versions, even though not all CASE tools fully conform to the OMG standard. OCLE also allows you to create your own UML models inside its graphical interface and then export them to XMI files, so that you can use them in other tools. Particularly, to reduce consumed disk space, OCLE automatically packs the resulting XML files into a ZIP archive. Currently, UML diagrams produced in OCLE are also saved in XML, but using a proprietary DTD.
In OCLE, models can be used either independently or attached to an OCLE project (see project management for details). One model is the active model. The contents of the active model is always displayed in the model browser.
These options are available in the Model menu of OCLE. To create a new empty model, select the New option. An empty model, named 'NewModel' will be created and displayed in the
model browser. To load an existing UML model, select Open from the Model
menu (or click the corresponding 
toolbar button).
OCLE will allow you to browse for both XML and XML.ZIP files (which
are generated by OCLE when saving UML models). To save the content of the active
model, choose Save or Save as… from the Model menu. The active model will
automatically be packed into the XML.ZIP file you specify at the first save
request.
OCLE provides powerful model editing and navigation facilities. These include the model and metamodel browsers, the property sheet and three types of UML diagrams.
The active model is displayed in the model browser. The main role of this browser is to allow full model representation and navigation. Also, the browser supports customization by letting the user configure a filter to be applied on the types of the model elements represented in the browser. Finally, the browser allows you to edit the model by adding and removing elements.
The browser displays model elements in a way that conforms with the composite relationships in the UML metamodel. Every element is displayed with a name and a suggestive icon. These two characteristics help the user easily identify and differentiate the elements. If the model element does not have a name, a default one is displayed. The icons describe the type of the elements. A few icons may offer additional information about the elements (attribute and operation icons, for instance, are specifically designed to suggest the visibility of the represented feature). The model browser also provides suggestive tool tips for the elements it displays; these are useful when the elements representations are too large to fit in the browser window.
 |
Fig.1 The User model browser |
The browser provides two mechanisms for locating elements. The popup menu of the model browser lets the user search the browser for a certain model element (in a large model it can be difficult to manually find an element; also, sometimes you need to look up for more related elements) or to locate an element in the existing diagrams. The Find in browser dialog is displayed in figure 2 below:
 |
Fig.2 Finding elements in the model browser |
In the Find: region, the user types the text to find or selects it from the history combo box. Elements are searched by their name, not by their representation in the browser. Therefore, you may leave this field blank, meaning that element names will be ignored when searching. The Type: combo box lists all the types shown in the browser (see Filters below, option '<any type>'). These types are in fact the metaclasses in the UML 1.5 metamodel. If the '<any type>' option is selected, all elements are searched. If a specific type if selected (e.g. 'Class', 'Attribute', 'Parameter' and so on) only elements of that type are considered by the search. The Use wildcards option specifies if the text to find should be used as a regular expression or not. Regular expressions use '*' for zero or more characters and '?' for a single character.
Search results are sorted alphabetically and displayed in a table with three columns. The first column contains the name of the element, the second its type and the third contains the context within which the element is defined (e.g. an attribute with the same name can be defined in two classes).
In the example above we searched the Company Example model for attributes having their names starting with 'n'. In this case, two attributes were found, 'name' and 'numberOfEmployees', both located in class 'Company'. Clicking on an item will select that element in the model browser.
The Show in diagram request will lead to a search for the selected element through all loaded diagrams. The diagram that contains the selected model element will be activated for editing. If more than one diagram contains the element, the user is asked to select one for editing (see also supported UML diagrams).
When displaying model elements, the browser applies a filter on them. The filter is responsible for selecting the elements that will be represented in the model browser. The filter holds two lists of elements, one representing the elements that will be shown and another representing the elements that will be ignored by the browser. However, the hidden elements exist in the model and they can be referenced by other means (e.g. property sheet, OCL expressions). They are not shown in the model browser for readability. A few elements (e.g. Model, Package) are always shown in the browser, because without their presence it would be impossible to navigate the model.
The Browser customization dialog is shown in figure 3 below.
 |
Fig.3 Browser customization |
The list on the left holds the types of elements to be
shown in the browser; the list on the right shows the types of elements not
to be shown. You can double click on an element to move it from one list to
another. Also you can select more types and press the 'Show' 
or 'Hide'
buttons, according to your intentions. To show all
types simply press the 'Show all' 
button.
Pressing the 'Defaults' button, the filter is reset to the default configuration, which is
shown in figure 3 above.
The context sensitive browser popup menu provides the user with the means to edit the model: create and remove elements (except relations which can be added only through the diagram editors) and diagrams, create and set stereotypes. When an element is created, its attributes (properties) are set to default values so that the Well-formedness Rules are satisfied (OCLE 2.0 does not yet fully implement this requirement). The properties may be modified using the property sheet (see below).
Stereotypes are treated in a special way. When created, they are always linked to the model, as owned elements. The 'base class' attribute is initially set to the type of the element where they have been created. Stereotypes are attached using a dialog that displays all the stereotypes that can be applied to the selected element. The user can select stereotypes by marking the check boxes on the left (see figure 4).
 |
Fig.4 Attaching stereotypes |
When OCLE starts, the UML 1.5 metamodel is loaded. This model is loaded only once and is set to be read-only. If you want to load the UML 1.5 model for performing operations upon it, it is strongly recommended that you make a copy for this purpose. Loading this project from the 'metamodel' directory of the application and altering it may result in future malfunctions.
Beside the user model browser, OCLE also provides a metamodel browser. Both the model and the metamodel browsers share the property sheet. This means that when you select an element in either of these browsers, its properties will be displayed by the property sheet. The metamodel browser allows for the same operations as the ordinary model browser, except for editing operations (creating and removing elements).
The property sheet is a grid that displays the individual properties for an element (e.g. name, visibility, owner, stereotypes and so on).
The main responsibility of the property sheet is to provide a view on an element from the model and a mechanism for modifying its properties. It is also possible to navigate between related elements (e.g. from a class to its attributes and vice-versa).
The property sheet has two columns. The column on the left shows the names of the properties while the column on the right shows their values. The grid provides appropriate editors to change these values. For properties having (almost) infinite value domains, such as 'Name' or 'Initial value', a text box is used. After editing the value of such a property, you must press 'Enter' to update it. For properties having finite value domains, such as 'Visibility' or 'Type', a combo box with all possible values is provided. A property whose value is another element (such as the owner of an attribute or operation) has an associated button that allows you to navigate to the referred element.
 |
Fig.5 The Property Sheet |
If properties are queried upon a malformed element an error message will be displayed in the Messages panel. Usually this happens when properties are not set for some elements. Warnings may be raised if properties are set but have an unexpected value (it is the case when a property’s value is out of the possible range).
Some properties (e.g. stereotypes, attributes, operations etc.) are grouped into collections that can be expanded or collapsed depending on the user needs, as shown in figure 5.
OCLE supports (in its current version) three kinds of UML diagrams:
In order to create any kind of these three diagrams, right-click in the model browser the model element which you would like to be the parent for that diagram (this element can only be a package or the model itself). From the pop-up menu that appears, select New and then the kind of diagram you want:
 |
Fig.6 Creating a new Diagram |
Once you have created a new Class Diagram, the Worksheet together with the specific toolbar appear:
 |
Fig.7 The Worksheet and the Toolbar |
The Worksheet is where you place the objects in the Diagram. The toolbar is where you select these objects from.
There are 2 ways in which you can use class diagrams:
1. To see graphically elements that already exist in the model
2. To create new elements / relations
1) In order to see elements that already exist in the model, you drag & drop them from the browser onto the Worksheet. Please note of the following when drag & dropping:
1. Although you can drag & drop any kind of model element onto the class diagram, only classes, interfaces and packages will be represented.
2. The relations between them (that already exist in the model) will be automatically drawn. Moreover, dragging a relation from the browser to the class diagram has no effect.
2) In order to create new elements / relations, you use the toolbar:
The select 
tool enables you to select any kind of object in the diagram, including relations. If you select
a single object, it will automatically be displayed and selected in the browser and its properties will be shown in the property sheet.
Please note that the browser displays the selected element only if the current filter allows it. For more information on the browser and the
property sheet, please refer to the section on model navigation. However, using the select tool, you may select
multiple objects. To do this, select the desired elements in the diagram holding down the CTRL key.
Creating elements - you simply click the button for the element you wish to create (Class, Interface or Package) and then click on the Worksheet. The element will appear in the diagram and will also be created in the model. If you wish to create more elements of the same kind, without having to repeatedly click the toolbar button, you can hold down the CTRL key, click the button, and while CTRL is down you can click on the worksheet. A new element of the selected kind will be created for each click.
Creating relations – to add a relation between 2 elements, you click the toolbar button for the desired relation type (Association, Generalization, Dependency, Permission, Realization or Association Class), then click the element which will be the source and drag the mouse to the element which will be the target. Please note that for association classes, the source of the relation must be the class you wish to convert to an association class and the target the corresponding association.
Zooming – allows you to increase/decrease the scale of the diagram.
Undo / Redo – in the current version of OCLE, undo/redo may be used only at the graphical level, meaning that any changes to the model cannot be undone. Only the movements and insertion/deletion of objects in the diagram can be undone.
Quick View – allows you to see an overview of the active diagram. It can be very useful for large diagrams. Please note that selecting objects and relations in the quick view window will also trigger their selection in the diagram target diagram.
 |
Fig.8 Class Diagram Quick View |
Please read the additional diagram info.
Use-Case diagrams behave exactly like class diagrams. They can be created and used in same way as class diagrams. Please read the above section on class diagrams. A use case diagram looks like this:
 |
Fig.9 Use-Case Diagram |
The toolbar of a use-case diagram is to a great extent similar to the toolbar for class diagrams. The only difference is the actor and the use case tools, which allow you to add these two kinds of elements to the diagram. Most of things like changing the graphical attributes, deleting elements from diagram and modifying the properties are the same as for class diagrams. Please read the additional diagram info for more information.
Snapshot diagrams, which are a sort of object diagrams, are used to view and create objects and links between them.
 |
Fig.10 A Snap-Shot Diagram |
To create a new snapshot diagram, you will have to define (create) a collaboration. Once the collaboration is available in the model browser, right click it and choose New and then Object diagram.
To create a new object in the snapshot diagram use the Object 
toolbutton, or the model browser, by right-clicking a collaboration and selecting
New object. The instance creation dialog shown in figure 11 should appear.
You may use the model browser to create a collaboration
or you may import instances from other tools
in order to have a collaboration available.
 |
Fig.11 Instance creation dialog |
In this dialog you may specify the name of the new object and the class it instantiates. Once you have selected the class to instantiate, a table appears that allows you to specify the values of the attributes for the newly created object. Click 'OK' to have the object created with the specified values and the dialog closed. If you don't set the attributes' values, implicit values will be set. To change the attributes values for an object, right-click the object in the model browser and choose Edit Object. The instance creation dialog will appear and you can set in the attributes table the values of object's attributes.
Drag & drop is also available for snapshot diagrams. Once you have some
objects created / imported, drag them to the active snapshot diagram. Any existent
links between them are automatically drawn in the diagram. However, you may
create additional links between existent objects using the Link
toolbutton. You will have to specify which association you want to instantiate.
For qualified link ends, an edit dialog will apear (see figure 12), where you
can specify the values of qualifiers.
 |
Fig.12 Edit qualifiers dialog |
If you don't set the qualifiers' values, implicit values will be set. To change the values of qualifiers, from model browser choose the qualifier and go in the property sheet and double-click the value property, then set the name of the DataValue to the desired value.
Note: The instance creation dialog also becomes available when you draw a link object between two objects on the snapshot diagram.
Graphical properties
It is possible to modify the graphical properties of the objects in a diagram. Just right click the desired graphical representation. This will bring up a popup menu that will allow you to modify attributes like: outline color, fill color, title font size, body font size and some special things as well. These special things include: adding attributes / methods, changing the name of the element and filtering it. The ability to add an attribute/method and the filters property may only be applied to classes. Filters allow you to choose what kind of attributes/methods will be displayed for a class, according to their visibility, as well as whether the stereotype of a class should be displayed or not. The modification of graphical properties works for multiple selection also.
Fig.13 Modifying the graphical properties of the objects in a diagramStraighten lines
If you have a relation (of any kind) between two objects that is not represented as a straight line, but broken into many segments, you can straighten that line by selecting it, and then holding down CTRL key + right click on it. There are actually two modes in which the lines can be drawn in a diagram (any kind of diagram): the free-form mode (which is the default drawing mode) and the orthogonal mode which you can trigger on/off by selecting the desired relation (graphical line) and pressing: CTRL + SHIFT + L. Also, if you have a relation or multiple relations between the same two elements, you can use the CTRL + SHIFT + K shortcut in order to arrange those relations.
Align association ends
An association has labels tied to its ends, which specify the role name and multiplicity of that association. In a class diagram, these labels are not tied to the association, meaning that you can put the labels wherever you like. However, in order to avoid any confusion, double clicking on an association will cause the roles to gather around the association ends, accordingly.
Delete objects
Any object (including relations) in a UML diagram can be deleted by selecting it and pressing the DEL key. Deleting an object from a certain diagram does not delete that element from the current model. The model browser should be used for this purpose.
Diagram graphical properties
By right-clicking on any diagram (but not on an element in it), you bring up a pop-up menu that allows you to: change the background color of the diagram, show/hide the grid and lock the diagram. Locking the diagram means that any elements / relations will not be able to be moved until the diagram is unlocked.
Line control points
In order to add/remove a control point to an edge, you simply right-click on that edge. This will only work in the free-form drawing mode. Control points are useful when you want to manipulate the lines in a more flexible way.
Handling diagrams in the model browser
Since UML diagrams are also displayed in the model browser, you may use this browser to rename, open or delete a diagram. Clicking its name in the model browser will allow you to rename it in the property sheet. Right click the diagram in the browser and select Open, Delete or Filter classes as desired. The Filter classes option is only available for class diagrams in this version.
Importing instances from other tools
Besides the capabilities to create class instances provided by the model browser and snapshot diagrams, OCLE allows you to import instances from files generated by other tools. Currently, two state-of-the-art tools are supported: the USE open-source project and the ModelRUN commercial tool. This functionality is very useful when you want to evaluate business constraints, because you need concrete objects (instances) to set the context for certain rules. Please refer to model checking for details on business constraints evaluation.
Importing objects from USE
USE stores commands that create objects in CMD text files. OCLE is able to process the commands in these files and create the corresponding objects. In UML, objects are represented by the Object metaclass, their attributes by the AttributeLink metaclass and the values of the attributes by the DataValue metaclass, the associations by the Link metaclass and the association ends by the LinkEnd metaclass. The properties for the created objects are set according to the values specified in the source CMD file.
Using the Import objects from USE … command from the Model menu you can select a CMD file to be imported into OCLE. The effect of importing objects can be observed in the user model browser. The objects imported for a class will be owned by that class. They are shown inside a collaboration specifically created for them. The collaboration will have its name starting with 'Objects imported from USE'. Expanding the corresponding collaboration node and applying the appropriate browser filter will make them visible (see the model and metamodel browsers). You can subsequently edit the properties of the imported instances (in the property sheet) and then save the new values in your model.
Importing objects from ModelRUN
The process of importing objects from ModelRun is the same as for USE. The Import objects from ModelRun … is provided for this purpose in the Model menu. You will have to provide an XML file generated by ModelRUN (the Persistence option in the File menu in ModelRUN can be used to export instances to an object stream, in XML format). The imported objects and their links are placed in a collaboration having its name starting with 'Objects imported from ModelRUN'.
See also
Back to main index
