HERO Metadata

Metadata

If your HERO network grows larger, managing the large number of HEROs becomes tedious. It is then necessary To classify your HEROs somehow. This is why a HERO carries metadata in it’s discovery information. This metadata is

• The identifier/name of the HERO

• The class it was created from

• An optional list of interfaces it implements

• An optional list of tags attached to the HERO

• An optional dict of extra metadata >=0.14.0

Note

Tags should be used for filtering and sorting of HEROs, while extra_metadata should contain metadata to for example control the behavior of HEROObserver``s, like the ``HEROMonitor.

The information of a LocalHERO that is controlling an RF device could look like the following

{
    "name": "my_rfdevice",
    "class": "vendorlibrary.module.rfdevice_class"
    "implements": ["atomiq.components.electronics.rfsource.RFSource"],
    "tags": ["boss:27ea419fe", "raspberry", "datasource"],
    "extra_metadata": "{'my_option':'20'}"
}

In this case the HERO signals that it implements an atomiq RFSource, it was started by BOSS under a particular ID, it runs on a Raspberry Pi and is a datasource.

While the value for class is automatically determined from the class the LocalHERO has, setting values for the name, implements, extra_metadata and tags fields is up to the user. All four fields can be set through the constructor of the LocalHERO class. Additionally, implements, extra_metadata and tags can be set through class level attributes in your custom class that inherits from LocalHERO like shown in the following:

from heros import LocalHERO


class DummyRFDevice(LocalHERO):
    _hero_implements = ["atomiq.components.electronics.rfsource.RFSource"]
    _hero_tags = ["raspberry", "datasource"]
    _hero_extra_metadata = {"my_option2":"400"}

    def my_method(self):
        pass

...

Note

If values are given to the constructor via arguments (like in the JSON above) and at class level, the lists/dicts are joined. Lists are converted to a set to avoid duplicates.

In a RemoteHERO the metadata is available from the class level attributes that could also be used on the LocalHERO side:

In [1]: from heros import RemoteHERO

In [2]: obj = RemoteHERO("my_rfdevice")

In [3]: obj._hero_implements
Out[3]: {'atomiq.components.electronics.rfsource.RFSource'}

In [4]: obj._hero_tags
Out[4]: {'raspberry', 'datasource'}

In [5]: obj._hero_extra_metadata
Out[5]: {'my_option':'20','my_option2','400'}

Note

Since the metadata is part of the discovery endpoint, it is also available in a HEROObserver.