Hmmm ... I like the idea.
So your getField(name) doesn't return the field used in the subscription, but
the real value ...
In my case when subscribing to "hurz = */*/*" (evertything) in my KNX
environment, then if I do a "getField("hurz")", I might get "1/2/3" ...
Is that what you mean?
I could probably even access the original field by doing
"getRequest().getField("hurz")" ...
If yes: I like it :-) if not: please explain a bit more.
Chris
Am 16.11.20, 00:22 schrieb "Łukasz Dywicki" <[email protected]>:
I have similar case with CANopen and I did register different instances
of callback for each subscription:
https://github.com/splatch/canopen-cmi-uvr-playground/blob/master/reader/src/main/java/brute/force/scanner/UVR16Printer.java#L125L136
I believe the ultimate solution would be access to actual field instance
through subscription event. Currently it is (in theory) doable through:
String name = event.getFieldNames().iterator().next(); // in case of
wildcard subscription name doesn't matter much
PlcField field = event.getFiled(name);
I know it is a bit awkward - but it does work with current API. Even if
an subscription might bring 1..N updates for bus systems it is usually
1..1. Exceptionally, even with group addresses supported by KNX you'll
probably have 1..1 event as whole invention is to reduce bus load. Maybe
it is good idea to have different field type for groups?
I was also thinking of how to handle "patterns" for CANopen. there are
heartbeat events sent by nodes. I assumed that nodeId==0 means all nodes
and nodeId > 0 means specific node. There is just one case when field
becomes a wildcard and it does not require extra regexp.
My point in all above is to balance amount of regexps, cause they might
differ between languages and become a trouble above certain complexity
threshold.
Best,
Łukasz
On 13.11.2020 13:55, Christofer Dutz wrote:
> Another thing a came across, was that with subscriptions (at least for
KNX) it makes sense to have field addresses that allow matching multiple values.
>
> For example if I have an address */*/12, I get all the actual temperature
values for all rooms in my house.
>
> The problem now is, that if I simply return a PlcValue (or multiple) ...
we no longer know which address a value belongs to.
>
> So I was thinking:
> - We distinguish between pattern-fields and normal fields. Normal fields
identify only one element, Pattern Fields can identify multiple values.
> - If a normal field is used, a normal PlcValue is returned
> - If a pattern field is used, a PlcStruct is returned (even if it's only
one element) where the name of the property name is a stringified
representation of the address and the value is the PlcValue
>
> Does this make sense?
>
>
> Chris
>
>
> Am 12.11.20, 23:15 schrieb "Łukasz Dywicki" <[email protected]>:
>
> Looking at subscription methods - I am not sure if there is one
standard
> which can support all three kinds at the same time.
> Some kind of distinguish is necessary, but for an end user (counting
> myself) - multiple types of subscription happening at the same time
are
> rather unlikely to happen.
>
> Looking from canopen perspective - there is possibility to subscribe
to
> some messages happening directly on the bus if plc4x becomes a
so-called
> master node (that's the way its implemented currently using EVENT
> subscription kind).
> There is also possibility to subscribe over coordinator node which is
> specified by yet another specification which number I don't remember
> right now. In theory - we could also subscribe to other node messages
> since canbus is still a bus system so everyone sees everything.
> Later two cases are currently left unimplemented.
>
> Best,
> Łukasz
>
>
> On 12.11.2020 18:33, Christofer Dutz wrote:
> > Hi all,
> >
> > I’m currently implementing the different subscription types in
KNX4Go … and here I noticed something.
> > We create a SubscriptionRequestBuilder and here can add different
types of fields and even combinations.
> > So we could create a subscription request with some on-value-change
fields, some periodically pulled fields and some events/alarms.
> >
> > Now does it actually make sense to have this sort of combinations?
I mean the program processing the results has to be very flexible in this case.
> >
> > Wouldn’t it make sense to have 3 different types of subscription
requests?
> >
> > Chris
> >
>
