GMF: Synchronized Container Use Cases
In the current state GMF supports two modes of diagram code generation - synchronized and non-synchronised. Toolsmith is able to switch between these two modes by changing GenDiagram.synchronized property. There were a number of discussions concerning diagram behavior in different situations according to the current mode. The idea of this document is to summarize existing requirements to simplify upcoming features development. Once this document will be finalized, corresponding changes should be introduced into the code generator and the runtime part if necessary.
This document will cover common use cases for different type of synchronized/non-synchronized diagrams from the end-user point of view and highlight corresponding places in code generator/runtime to be used to in corresponding conditions.
synchronized element – diagram node or diagram itself always representing actual domain (semantic) model contents. i.e. all the child diagram nodes recognized from the underlying domain model.
canonical container – synchronized element.
non-synchronized element – diagram node or diagram itself representing only selected child diagram nodes recognized from the domain model.
synchronized diagram – diagram itself, all the diagram nodes and sub-nodes are synchronized elements
element-based link – diagram link associated with the element in a domain model connecting link source with link target domain model elements.
reference-only link – diagram link representing reference in a domain model. This reference contained in a link source domain model element and pointing to the link target domain model element.
CanonicalEditPolicy - abstract class in GMF runtime implementing EditPolicy and encapsulating set of functionality useful for synchronizing diagram element contents with the domain model element contents.
CanonicalConnectionEditPolicy – abstract subclass of CanonicalEditPolicy supporting outgoing element-based diagram links synchronization.
This type of the diagram will be generated if GenDiagram.synchronized == true in .gmfgen model. Updating code (CanonicalEditPolicy subclasses) should be generated for each type of the synchronized element available on this diagram.
By default this diagram itself, all the contained nodes and links are synchronized elements. Toolsmith can switch off synchronization for any diagram element/diagram itself by attaching CanonicalStyle with isCanonical() == false to the corresponding diagram element (see below). If synchronization process should be switched off for all the elements of some particular type then corresponding style could be attached to each View instance created by the corresponding ViewFactory. Hint: this could be done by customizing corresponding template.
Each synchronized element should always represent up to date content of the corresponding domain model element. Following cases should be covered:
- domain model was changed in external editor in a way that new child diagram element could be recognized (new child domain element added) - diagram editor content should be updated with new child diagram element on next diagram opening.
- domain model was changed by user code, new child diagram element could be recognized – diagram editor content should be updated with new diagram element on receiving corresponding EMF notification.
- domain model was changed externally/ by user code in a way that existing child diagram element should be removed (child domain element removed) – corresponding child diagram element should be removed on next diagram opening/ corresponding EMF notification.
- if same domain model element could be represented on diagram as a different diagram elements (node-1 or node-2) based on domain model properties and domain model was changed externally/by user code in a way existing domain model element should change diagram representation (not be recognized as node-1 anymore, but should be recognized as node-2) – existing node-1 should be replaced by node-2 on next diagram opening/receiving EMF notification. Node-2 should get size/position of node-1 and all the rest of applicable Styles.
- if this synchronized element was just created by update process (CanonicalEditPolicy) and some child diagram elements could be recognized from the underlying domain model element then update should be triggered for this synchronized element to create corresponding diagram elements. In other words, on any model changes diagram should be updated to always represent actual domain model content.
- Notation model element represented by this synchronized element adorned with CanonicalStyle – it should be possible to switch on/off synchronization with domain model by calling CanonicalStyle.setCanonical(). If the synchronization was switched on then this synchronized element should be immediately synchronized with the model. If the synchronization was switched off then this element should behave like non-synchronized element.
Each synchronized element should perform outgoing links synchronization (both element-based links and reference-only links) in addition to child elements synchronization. Following cases should be covered:
- domain model was changed externally/by user code in a way that new link from this diagram element could be recognized - diagram editor content should be updated with new link on next diagram opening/receiving EMF notification. It is important to correctly process the situation then new link was added into domain model together with the new link destination node, so both elements should be created on diagram. Not created link destination node could be a sub-node of diagram node parent’s sibling node.
- domain model was changed externally/by user code in a way that existing link should be removed from diagram– corresponding link should be removed on next diagram opening/receiving EMF notification.
- if same domain model element (or even reference!) could be represented on diagram as a different links (link-1 or link-2) based on domain model properties and domain model was changed externally/by user in a way existing link-1 should be replaced by link-2 – corresponding diagram update should be performed on next diagram opening/receiving EMF notification. Newly created link-2 should get all bending/connection points of link-1 and all the rest of applicable Styles.
- if this synchronized element was just created by update process (CanonicalEditPolicy) and some outgoing links could be recognized from the underlying domain model then update should create all the necessary links.
- if this synchronized element is a link and some other links could be created starting from this link then corresponding outgoing links should be updated in accordance with domain model content and so forth. If this synchronized element adorned with CanonicalStyle then it should be possible to switch on/off synchronization of outgoing links with domain model by calling CanonicalStyle.setCanonical(). If the synchronization was switched on all the outgoing links should be immediately synchronized with the model.
This type of the diagram will be generated if GenDiagram.synchronized == false in .gmfgen model. No synchronization code should be generated for elements of this diagram. Only selected by user subset of non-synchronized elements should be represented on this diagram. Any non-synchronized element created on this diagram from the toolbar should be immediately visualized on diagram. In addition it should be possible to: - invoke “Import child elements” popup menu action on each non-synchronized element (diagram node or diagram itself). This action will show the dialog with all the child diagram elements recognized from the model element associated with this non-synchronized element, but invisible on diagram currently. It should be possible to select any number of diagram elements from this dialog and add corresponding non-synchronized elements to this diagram.
- invoke “Import outgoing link” popup menu action on each non-synchronized element. This action should show dialog listing all the links recognized from domain model, outgoing from this non-synchronized element and invisible on current diagram. It should be possible to add selected links to the diagram. Note: non-synchronized element could be a link.
- Delete any non-synchronized element from view should remove this element from the diagram and keep domain model unchanged.
- Delete from model action should remove both non-synchronized element and corresponding element/reference (for reference-only links) from the domain model.