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https://github.com/opennetworkinglab/onos/tree/master/web/gui2
https://github.com/opennetworkinglab/onos/tree/master/web/gui2-fw-lib
https://github.com/opennetworkinglab/onos/tree/master/web/gui2-topo-lib
There is also an external documentation (in the form of Stack Overflow answer) to build a custom gui2 app using source code with two types of implementations. The link for the same is below :-
Archetype
For creating a new GUI2 application inside ONOS - please use the ui2 archetype
General Instructions at https://wiki.onosproject.org/display/ONOS/Template+Application+Tutorial
and the UI2 archetype is at https://github.com/opennetworkinglab/onos/tree/master/tools/package/archetypes/ui2
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