This patch proposes an Advertisement Monitoring API for an application to
register a job of monitoring ADV reports with content filter and RSSI
thresholds.
Signed-off-by: Miao-chen Chou <[email protected]>
---
doc/advertisement-monitoring-api.txt | 163 +++++++++++++++++++++++++++
1 file changed, 163 insertions(+)
create mode 100644 doc/advertisement-monitoring-api.txt
diff --git a/doc/advertisement-monitoring-api.txt b/doc/advertisement-monitoring-api.txt
new file mode 100644
index 000000000..070487481
--- /dev/null
+++ b/doc/advertisement-monitoring-api.txt
@@ -0,0 +1,163 @@
+BlueZ D-Bus Advertisement Monitoring API Description
+****************************************************
+
+This API allows an application to specify a job of monitoring advertisements
+by providing a filter with filtering conditions, thresholds of RSSI and timers
+of RSSI thresholds.
+
+Once an application registers a monitoring job, it can expect to get notified
+on its targeted advertisements no matter if there is an ongoing discovery
+session (a discovery session is started/stopped with methods in
+org.bluez.Adapter1 interface).
+
+Advertisement Filter hierarchy
+==============================
+Service org.bluez
+Interface org.bluez.AdvertisementFilter1
+Object path freely definable
+
+Methods void Release() [noreply]
+
+ This gets called as a signal for a client to perform
+ clean-up when BlueZ has invalidated the filter.
+
+ void DeviceInRange(object device, int16 RSSI, int16 TX_power,
+ array{dict} ADV_data,
+ array{uint8} ADV_raw_data)
+
+ If RSSIThreshholdsAndTimers exists, this gets called to
+ notify the client on finding the targeted device when
+ RSSI(s) of the matched advertisement(s) exceed the
+ HighRSSIThreshold at least HighRSSIThresholdTimer.
+ If RSSIThreshholdsAndTimers does not exist, this does
+ not get called.
+
+ Parameters:
+ device The device object path associated with
+ the advertisement.
+ RSSI The RSSI comes along with the
+ advertisement.
+ TX_power The TX power AD data provided in the
+ advertisement. 127 indicates the absence
+ of TX power AD data.
+ ADV_data The signature of adv_data is a{yv} where
+ “y” is the AD data type value and “v” is
+ the value of the AD data where the type
+ may vary depending on the AD data. For
+ instance, if "y" is 0x16, "v" would be
+ an array of bytes.
+ ADV_raw_data The raw bytes of AD data from the
+ advertisement packet.
+
+ void AdvertisementReceived(object device, int16 RSSI,
+ int16 TX_power, array{dict} ADV_data,
+ array{uint8} ADV_raw_data)
+
+ If RSSIThreshholdsAndTimers exists, this gets called
+ every time except for the first time when receiving the
+ matched advertisement(s) exceeding the
+ HighRSSIThreshold. Once DeviceOutOfRange() gets called,
+ this no longer gets called until DeviceInRange() gets
+ called again.
+ If RSSIThreshholdsAndTimers does not exist, this gets
+ called whenever receiving the matched advertisements.
+
+ Parameters:
+ device The device object path associated with
+ the advertisement.
+ RSSI The RSSI comes along with the
+ advertisement.
+ TX_power The TX power AD data provided in the
+ advertisement. 127 indicates the absence
+ of TX power AD data.
+ ADV_data The signature of adv_data is a{yv} where
+ “y” is the AD data type value and “v” is
+ the value of the AD data where the type
+ may vary depending on the AD data. For
+ instance, if "y" is 0x16, "v" would be
+ an array of bytes.
+ ADV_raw_data The raw bytes of AD data from the
+ advertisement packet.
+
+ void DeviceOutOfRange(device object)
+
+ If RSSIThreshholdsAndTimers exists, this gets called
+ when RSSIs of the matched advertisements are lower than
+ LowRSSIThreshold for at least LowRSSIThresholdTimer to
+ notify the client on losing the targeted device.
+ If RSSIThreshholdsAndTimers does not exist, this won’t
+ get called.
+
+Properties uint8 FilterType [read-only]
+
+ This can be the following values. More will be added.
+ 0x01 - Patterns with OR logic relation
+
+ (Int16, Uint16, Int16, Uint16) RSSIThreshholdsAndTimers [read-only, optional]
+
+ The contains HighRSSIThreshold, HighRSSIThresholdTimer,
+ LowRSSIThreshold, LowRSSIThresholdTimer in order. The
+ unit of HighRSSIThreshold and LowRSSIThreshold is dBm.
+ The unit of HighRSSIThresholdTimer and
+ LowRSSIThresholdTimer is second.
+
+ A device is considered in-range when the RSSIs of the
+ received advertisement(s) during HighRSSIThresholdTimer
+ seconds exceed HighRSSIThreshold. Likewise, a device is
+ considered out-of-range when the RSSIs of the received
+ advertisement(s) during LowRSSIThresholdTimer do not
+ reach LowRSSIThreshold.
+
+ array{(uint8, uint8, string)} Patterns [read-only, optional]
+
+ If “PatternsWithORLogicRelation” is supported, this must
+ exist and has at least one entry in the array.
+
+ The structure of a pattern contains the following.
+ uint8 start_position
+ The index in an AD data field where the search
+ should start. The beginning of an AD data field
+ is index 0.
+ uint8 AD_data_type
+ See https://www.bluetooth.com/specifications/
+ assigned-numbers/generic-access-profile/ for
+ the possible allowed value.
+ string content_of_pattern
+ This is the value of the pattern.
+
+Advertisement Monitor hierarchy
+===============================
+Service org.bluez
+Interface org.bluez.AdvertisementMonitor1
+Object path /org/bluez/{hci0,hci1,...}
+
+Methods void RegisterApplication(object filter)
+
+ This registers a job of monitoring advertisement in a
+ power efficient way. Based on the content of the filter
+ upon registration, the filter object can expect to
+ receive the matched advertisements via DeviceInRange()
+ and AdvertisementReceived().
+
+ void UnregisterApplication(filter object)
+
+ This unregisters the job of monitoring advertisement.
+ The filter object can expect to be called on Release()
+ once the removal is done.
+
+ void UnregisterAllApplications()
+
+ This unregisters all jobs of monitoring advertisement.
+ All filter objects can expect to be called on Release()
+ once the removals are done.
+
+Properties array{string} SupportedFilteringFeatures [read-only]
+
+ This reflects the supported features of advertisement
+ monitoring. An application should check this before
+ instantiate an object of org.bluez.AdvertisementFilter1.
+
+ Here are the potential features. More will be added.
+ "SoftwareBasedFiltering"
+ "PatternsWithORLogicRelation"
+ "RSSIMonitoring"
--
2.24.1
Hi Miao-chen,
> This patch proposes an Advertisement Monitoring API for an application to
> register a job of monitoring ADV reports with content filter and RSSI
> thresholds.
>
> Signed-off-by: Miao-chen Chou <[email protected]>
> ---
>
> doc/advertisement-monitoring-api.txt | 163 +++++++++++++++++++++++++++
> 1 file changed, 163 insertions(+)
> create mode 100644 doc/advertisement-monitoring-api.txt
>
> diff --git a/doc/advertisement-monitoring-api.txt b/doc/advertisement-monitoring-api.txt
> new file mode 100644
> index 000000000..070487481
> --- /dev/null
> +++ b/doc/advertisement-monitoring-api.txt
> @@ -0,0 +1,163 @@
> +BlueZ D-Bus Advertisement Monitoring API Description
> +****************************************************
I would name it “Advertisement Monitor”
> +
> +This API allows an application to specify a job of monitoring advertisements
> +by providing a filter with filtering conditions, thresholds of RSSI and timers
> +of RSSI thresholds.
> +
> +Once an application registers a monitoring job, it can expect to get notified
> +on its targeted advertisements no matter if there is an ongoing discovery
> +session (a discovery session is started/stopped with methods in
> +org.bluez.Adapter1 interface).
Just for readability two empty lines here. See the other docs for an example. They should be mostly consistent in their style.
> +
> +Advertisement Filter hierarchy
> +==============================
> +Service org.bluez
> +Interface org.bluez.AdvertisementFilter1
> +Object path freely definable
> +
> +Methods void Release() [noreply]
> +
> + This gets called as a signal for a client to perform
> + clean-up when BlueZ has invalidated the filter.
> +
> + void DeviceInRange(object device, int16 RSSI, int16 TX_power,
> + array{dict} ADV_data,
> + array{uint8} ADV_raw_data)
Actually looking at what the device object already gives you for free, I think you just need this:
void DeviceInRange(object device)
You will have the RSSI and TxPower fields and also the advertising data considered for consumption by the application. If you really really need the raw advertising report data, then we might include them as extra property type, but only if asked for. With advertising extensions these can get rather large.
Just to explain this reasoning to only use the object device here. Don’t see it as a full object, since it is just a reference and more precise a filter to find your object in the list of all objects. So an application can ignore everything else, but just has to filter the device object path out from all objects to find the information of the device it was looking for.
> +
> + If RSSIThreshholdsAndTimers exists, this gets called to
> + notify the client on finding the targeted device when
> + RSSI(s) of the matched advertisement(s) exceed the
> + HighRSSIThreshold at least HighRSSIThresholdTimer.
> + If RSSIThreshholdsAndTimers does not exist, this does
> + not get called.
> +
> + Parameters:
> + device The device object path associated with
> + the advertisement.
> + RSSI The RSSI comes along with the
> + advertisement.
> + TX_power The TX power AD data provided in the
> + advertisement. 127 indicates the absence
> + of TX power AD data.
> + ADV_data The signature of adv_data is a{yv} where
> + “y” is the AD data type value and “v” is
> + the value of the AD data where the type
> + may vary depending on the AD data. For
> + instance, if "y" is 0x16, "v" would be
> + an array of bytes.
> + ADV_raw_data The raw bytes of AD data from the
> + advertisement packet.
> +
> + void AdvertisementReceived(object device, int16 RSSI,
> + int16 TX_power, array{dict} ADV_data,
> + array{uint8} ADV_raw_data)
> +
> + If RSSIThreshholdsAndTimers exists, this gets called
> + every time except for the first time when receiving the
> + matched advertisement(s) exceeding the
> + HighRSSIThreshold. Once DeviceOutOfRange() gets called,
> + this no longer gets called until DeviceInRange() gets
> + called again.
> + If RSSIThreshholdsAndTimers does not exist, this gets
> + called whenever receiving the matched advertisements.
> +
> + Parameters:
> + device The device object path associated with
> + the advertisement.
> + RSSI The RSSI comes along with the
> + advertisement.
> + TX_power The TX power AD data provided in the
> + advertisement. 127 indicates the absence
> + of TX power AD data.
> + ADV_data The signature of adv_data is a{yv} where
> + “y” is the AD data type value and “v” is
> + the value of the AD data where the type
> + may vary depending on the AD data. For
> + instance, if "y" is 0x16, "v" would be
> + an array of bytes.
> + ADV_raw_data The raw bytes of AD data from the
> + advertisement packet.
This differentiation rubs me a bit the wrong way. I think it makes things a bit too complicated.
In case you don’t specify any RSSI thresholds, I would still like to use DeviceInRange and DeviceOutOfRange notifications. We have always used timeouts to indicate that devices are no longer valid and removed them. They needed to be found again. And even without RSSI this will be the case since you have device moving around. So it would be good to indicate that a device is gone.
Now the question is what we do for updates of a device that is currently in range and has been found. I think we don’t have to do anything. Since a client that cares about that device, can just monitor the object properties that we will keep updating as we find the device again. So if the RSSI, TxPower or even the advertising data changes, the client will be informed by a PropertiesChanged signal.
> +
> + void DeviceOutOfRange(device object)
> +
> + If RSSIThreshholdsAndTimers exists, this gets called
> + when RSSIs of the matched advertisements are lower than
> + LowRSSIThreshold for at least LowRSSIThresholdTimer to
> + notify the client on losing the targeted device.
> + If RSSIThreshholdsAndTimers does not exist, this won’t
> + get called.
We could consider doing a pair of DeviceFound + DeviceLost.
And of course we have to split the callback handling with filter properties. When you read the full method name it needs to make sense. So org.bluez.AdvertisementFilter1.DeviceInRange is not really logical.
I would have something like org.bluez.AdvertismentMonitor.DeviceFound for example.
> +
> +Properties uint8 FilterType [read-only]
> +
> + This can be the following values. More will be added.
> + 0x01 - Patterns with OR logic relation
> +
> + (Int16, Uint16, Int16, Uint16) RSSIThreshholdsAndTimers [read-only, optional]
> +
> + The contains HighRSSIThreshold, HighRSSIThresholdTimer,
> + LowRSSIThreshold, LowRSSIThresholdTimer in order. The
> + unit of HighRSSIThreshold and LowRSSIThreshold is dBm.
> + The unit of HighRSSIThresholdTimer and
> + LowRSSIThresholdTimer is second.
> +
> + A device is considered in-range when the RSSIs of the
> + received advertisement(s) during HighRSSIThresholdTimer
> + seconds exceed HighRSSIThreshold. Likewise, a device is
> + considered out-of-range when the RSSIs of the received
> + advertisement(s) during LowRSSIThresholdTimer do not
> + reach LowRSSIThreshold.
> +
> + array{(uint8, uint8, string)} Patterns [read-only, optional]
> +
> + If “PatternsWithORLogicRelation” is supported, this must
> + exist and has at least one entry in the array.
> +
> + The structure of a pattern contains the following.
> + uint8 start_position
> + The index in an AD data field where the search
> + should start. The beginning of an AD data field
> + is index 0.
> + uint8 AD_data_type
> + See https://www.bluetooth.com/specifications/
> + assigned-numbers/generic-access-profile/ for
> + the possible allowed value.
> + string content_of_pattern
> + This is the value of the pattern.
This part I would provide as dict to the RegisterMonitor method (see below).
> +
> +Advertisement Monitor hierarchy
> +===============================
> +Service org.bluez
> +Interface org.bluez.AdvertisementMonitor1
> +Object path /org/bluez/{hci0,hci1,...}
If we follow our current style then it would be org.bluez.AdvertismentMonitorManager.
While writing this email so far, I am kinda tempted to call it org.bluez.DeviceMonitorManager and org.bluez.DeviceMonitor. It is just a temptation at this point and it is good to sleep about it for a bit.
> +
> +Methods void RegisterApplication(object filter)
> +
> + This registers a job of monitoring advertisement in a
> + power efficient way. Based on the content of the filter
> + upon registration, the filter object can expect to
> + receive the matched advertisements via DeviceInRange()
> + and AdvertisementReceived().
RegisterMonitor(object monitor, dict thresholds, dict filter)
Having the thresholds and the filters as dicts here make it clear that you have to destroy the monitor and create a new one of you want to change them. I think that is acceptable and in the end an easy task, since you still can reuse the object monitor that you have already set up. It also make the code for bluetoothd simpler since it doesn’t have to track life changes to the filters and act on them.
> +
> + void UnregisterApplication(filter object)
> +
> + This unregisters the job of monitoring advertisement.
> + The filter object can expect to be called on Release()
> + once the removal is done.
> +
> + void UnregisterAllApplications()
> +
> + This unregisters all jobs of monitoring advertisement.
> + All filter objects can expect to be called on Release()
> + once the removals are done.
I would rather not have an UnregisterAll. We didn’t need it until now and the object monitor was always bound to the lifetime of the application.
> +
> +Properties array{string} SupportedFilteringFeatures [read-only]
> +
> + This reflects the supported features of advertisement
> + monitoring. An application should check this before
> + instantiate an object of org.bluez.AdvertisementFilter1.
> +
> + Here are the potential features. More will be added.
> + "SoftwareBasedFiltering"
> + "PatternsWithORLogicRelation"
> + “RSSIMonitoring”
So all our string values are lower-case and if needed we use - to separate words or logical details.
I think exposing a good interface for selecting the filter patterns will take a bit. I would like to focus on getting the surrounding framework figured out first.
Before finalizing an API, my test was always to write a simple client and check if it meets the requirement for being simple enough. If it becomes cumbersome for the client, then we need to consider putting some of the more complicated parts into bluetoothd.
Let me try to give an example. If the majority of the clients just want to find a device with UUID 0xFE23, then we should have a special casing for that.
RegisterMonitor(monitor, dict{MatchUUID=0xFE23}).
Done. That they have to differentiate between one vendors way of doing this compared to another on how to provide the information should be up to bluetoothd to figure it out (and yes, I know it is not as simple when the AD type is a list).
Regards
Marcel
On Fri, Apr 10, 2020 at 12:47 AM Marcel Holtmann <[email protected]> wrote:
>
> Hi Miao-chen,
>
> > This patch proposes an Advertisement Monitoring API for an application to
> > register a job of monitoring ADV reports with content filter and RSSI
> > thresholds.
> >
> > Signed-off-by: Miao-chen Chou <[email protected]>
> > ---
> >
> > doc/advertisement-monitoring-api.txt | 163 +++++++++++++++++++++++++++
> > 1 file changed, 163 insertions(+)
> > create mode 100644 doc/advertisement-monitoring-api.txt
> >
> > diff --git a/doc/advertisement-monitoring-api.txt b/doc/advertisement-monitoring-api.txt
> > new file mode 100644
> > index 000000000..070487481
> > --- /dev/null
> > +++ b/doc/advertisement-monitoring-api.txt
> > @@ -0,0 +1,163 @@
> > +BlueZ D-Bus Advertisement Monitoring API Description
> > +****************************************************
>
> I would name it “Advertisement Monitor”
>
> > +
> > +This API allows an application to specify a job of monitoring advertisements
> > +by providing a filter with filtering conditions, thresholds of RSSI and timers
> > +of RSSI thresholds.
> > +
> > +Once an application registers a monitoring job, it can expect to get notified
> > +on its targeted advertisements no matter if there is an ongoing discovery
> > +session (a discovery session is started/stopped with methods in
> > +org.bluez.Adapter1 interface).
>
> Just for readability two empty lines here. See the other docs for an example. They should be mostly consistent in their style.
>
> > +
> > +Advertisement Filter hierarchy
> > +==============================
> > +Service org.bluez
> > +Interface org.bluez.AdvertisementFilter1
> > +Object path freely definable
> > +
> > +Methods void Release() [noreply]
> > +
> > + This gets called as a signal for a client to perform
> > + clean-up when BlueZ has invalidated the filter.
> > +
> > + void DeviceInRange(object device, int16 RSSI, int16 TX_power,
> > + array{dict} ADV_data,
> > + array{uint8} ADV_raw_data)
>
> Actually looking at what the device object already gives you for free, I think you just need this:
>
> void DeviceInRange(object device)
>
> You will have the RSSI and TxPower fields and also the advertising data considered for consumption by the application. If you really really need the raw advertising report data, then we might include them as extra property type, but only if asked for. With advertising extensions these can get rather large.
>
> Just to explain this reasoning to only use the object device here. Don’t see it as a full object, since it is just a reference and more precise a filter to find your object in the list of all objects. So an application can ignore everything else, but just has to filter the device object path out from all objects to find the information of the device it was looking for.
My concern is that adopting DeviceInRange(object device) will require
an application to issue following D-Bus calls to read properties
including AdvertisingData, RSSI, Tx power(it may be included in
AdvertisingData) and perhaps a new property RawAdvertisingData. Given
these calls reach bluetoothd, the values of these properties may have
changed, so the reading no longer presents the exact values associated
with the DeviceInRange() event. How do we get around this without
providing the actual values along with DeviceInRange?
>
> > +
> > + If RSSIThreshholdsAndTimers exists, this gets called to
> > + notify the client on finding the targeted device when
> > + RSSI(s) of the matched advertisement(s) exceed the
> > + HighRSSIThreshold at least HighRSSIThresholdTimer.
> > + If RSSIThreshholdsAndTimers does not exist, this does
> > + not get called.
> > +
> > + Parameters:
> > + device The device object path associated with
> > + the advertisement.
> > + RSSI The RSSI comes along with the
> > + advertisement.
> > + TX_power The TX power AD data provided in the
> > + advertisement. 127 indicates the absence
> > + of TX power AD data.
> > + ADV_data The signature of adv_data is a{yv} where
> > + “y” is the AD data type value and “v” is
> > + the value of the AD data where the type
> > + may vary depending on the AD data. For
> > + instance, if "y" is 0x16, "v" would be
> > + an array of bytes.
> > + ADV_raw_data The raw bytes of AD data from the
> > + advertisement packet.
> > +
> > + void AdvertisementReceived(object device, int16 RSSI,
> > + int16 TX_power, array{dict} ADV_data,
> > + array{uint8} ADV_raw_data)
> > +
> > + If RSSIThreshholdsAndTimers exists, this gets called
> > + every time except for the first time when receiving the
> > + matched advertisement(s) exceeding the
> > + HighRSSIThreshold. Once DeviceOutOfRange() gets called,
> > + this no longer gets called until DeviceInRange() gets
> > + called again.
> > + If RSSIThreshholdsAndTimers does not exist, this gets
> > + called whenever receiving the matched advertisements.
> > +
> > + Parameters:
> > + device The device object path associated with
> > + the advertisement.
> > + RSSI The RSSI comes along with the
> > + advertisement.
> > + TX_power The TX power AD data provided in the
> > + advertisement. 127 indicates the absence
> > + of TX power AD data.
> > + ADV_data The signature of adv_data is a{yv} where
> > + “y” is the AD data type value and “v” is
> > + the value of the AD data where the type
> > + may vary depending on the AD data. For
> > + instance, if "y" is 0x16, "v" would be
> > + an array of bytes.
> > + ADV_raw_data The raw bytes of AD data from the
> > + advertisement packet.
>
> This differentiation rubs me a bit the wrong way. I think it makes things a bit too complicated.
>
> In case you don’t specify any RSSI thresholds, I would still like to use DeviceInRange and DeviceOutOfRange notifications. We have always used timeouts to indicate that devices are no longer valid and removed them. They needed to be found again. And even without RSSI this will be the case since you have device moving around. So it would be good to indicate that a device is gone.
>
> Now the question is what we do for updates of a device that is currently in range and has been found. I think we don’t have to do anything. Since a client that cares about that device, can just monitor the object properties that we will keep updating as we find the device again. So if the RSSI, TxPower or even the advertising data changes, the client will be informed by a PropertiesChanged signal.
In the case where RSSIs thresholds are not enforced, my original
thought was that DeviceInRange and DeviceOutOfRange do not make lots
of sense, since the terms "InRange" and "OutOfRange" implies RSSI
checks. Also DeviceOutOfRange won't be called in this case, since no
timer was given. Unless you see this differently?
In the case where RSSIs thresholds are provided, using only
DeviceInRange and DeviceOutOfRange makes sense.
>
> > +
> > + void DeviceOutOfRange(device object)
> > +
> > + If RSSIThreshholdsAndTimers exists, this gets called
> > + when RSSIs of the matched advertisements are lower than
> > + LowRSSIThreshold for at least LowRSSIThresholdTimer to
> > + notify the client on losing the targeted device.
> > + If RSSIThreshholdsAndTimers does not exist, this won’t
> > + get called.
>
> We could consider doing a pair of DeviceFound + DeviceLost.
>
> And of course we have to split the callback handling with filter properties. When you read the full method name it needs to make sense. So org.bluez.AdvertisementFilter1.DeviceInRange is not really logical.
>
> I would have something like org.bluez.AdvertismentMonitor.DeviceFound for example.
>
DeviceFound() and DeviceLost() sound good to me. Are you suggesting
having two properties, one for HighRSSIThreshold and
HighRSSIThresholdTimer and one for LowRSSIThreshold and
LowRSSIThresholdTimer, so that DeviceFound() is called only if
HighRSSIThresholdAndTimer exists, and DeviceLost() is called only if
LowRSSIThresholdAndTimer exists?
> > +
> > +Properties uint8 FilterType [read-only]
> > +
> > + This can be the following values. More will be added.
> > + 0x01 - Patterns with OR logic relation
> > +
> > + (Int16, Uint16, Int16, Uint16) RSSIThreshholdsAndTimers [read-only, optional]
> > +
> > + The contains HighRSSIThreshold, HighRSSIThresholdTimer,
> > + LowRSSIThreshold, LowRSSIThresholdTimer in order. The
> > + unit of HighRSSIThreshold and LowRSSIThreshold is dBm.
> > + The unit of HighRSSIThresholdTimer and
> > + LowRSSIThresholdTimer is second.
> > +
> > + A device is considered in-range when the RSSIs of the
> > + received advertisement(s) during HighRSSIThresholdTimer
> > + seconds exceed HighRSSIThreshold. Likewise, a device is
> > + considered out-of-range when the RSSIs of the received
> > + advertisement(s) during LowRSSIThresholdTimer do not
> > + reach LowRSSIThreshold.
> > +
> > + array{(uint8, uint8, string)} Patterns [read-only, optional]
> > +
> > + If “PatternsWithORLogicRelation” is supported, this must
> > + exist and has at least one entry in the array.
> > +
> > + The structure of a pattern contains the following.
> > + uint8 start_position
> > + The index in an AD data field where the search
> > + should start. The beginning of an AD data field
> > + is index 0.
> > + uint8 AD_data_type
> > + See https://www.bluetooth.com/specifications/
> > + assigned-numbers/generic-access-profile/ for
> > + the possible allowed value.
> > + string content_of_pattern
> > + This is the value of the pattern.
>
> This part I would provide as dict to the RegisterMonitor method (see below).
>
> > +
> > +Advertisement Monitor hierarchy
> > +===============================
> > +Service org.bluez
> > +Interface org.bluez.AdvertisementMonitor1
> > +Object path /org/bluez/{hci0,hci1,...}
>
> If we follow our current style then it would be org.bluez.AdvertismentMonitorManager.
>
> While writing this email so far, I am kinda tempted to call it org.bluez.DeviceMonitorManager and org.bluez.DeviceMonitor. It is just a temptation at this point and it is good to sleep about it for a bit.
>
> > +
> > +Methods void RegisterApplication(object filter)
> > +
> > + This registers a job of monitoring advertisement in a
> > + power efficient way. Based on the content of the filter
> > + upon registration, the filter object can expect to
> > + receive the matched advertisements via DeviceInRange()
> > + and AdvertisementReceived().
>
> RegisterMonitor(object monitor, dict thresholds, dict filter)
>
> Having the thresholds and the filters as dicts here make it clear that you have to destroy the monitor and create a new one of you want to change them. I think that is acceptable and in the end an easy task, since you still can reuse the object monitor that you have already set up. It also make the code for bluetoothd simpler since it doesn’t have to track life changes to the filters and act on them.
>
This was close to what I proposed earlier where the thresholds and the
filtering conditions are provided upon function calls, and Luiz
suggested adopting advertising API's way. Given that we may want to
provide what Android provides at some point, having a dict to host
filtering conditions may not be sufficient. If we'd like to have AND
logical relation applied among filtering conditions within a filter,
we basically need to change the signature here. For instance, an
application would like to look for advertisements matching service
UUID 0x1234 AND 0x5678 in Manufacturer data. Having filtering
conditions defined as properties make this possible by adding another
property later without changing the function signature.
I'd like to raise the same concern that I had in previous meetings.
Given that we plan to have SW filtering first and then offload the
filtering to the BT controller, there may be logical relations
infeasible by HCI extensions. Should we influence this API by the
capabilities of HCI extensions? I guess the answer is not, and that
means bluetoothd needs to be sophisticated enough to determined the
filtering conditions send to kernel for the first tier filtering and
performs the second tier filtering itself.
> > +
> > + void UnregisterApplication(filter object)
> > +
> > + This unregisters the job of monitoring advertisement.
> > + The filter object can expect to be called on Release()
> > + once the removal is done.
> > +
> > + void UnregisterAllApplications()
> > +
> > + This unregisters all jobs of monitoring advertisement.
> > + All filter objects can expect to be called on Release()
> > + once the removals are done.
>
> I would rather not have an UnregisterAll. We didn’t need it until now and the object monitor was always bound to the lifetime of the application.
Ack.
>
> > +
> > +Properties array{string} SupportedFilteringFeatures [read-only]
> > +
> > + This reflects the supported features of advertisement
> > + monitoring. An application should check this before
> > + instantiate an object of org.bluez.AdvertisementFilter1.
> > +
> > + Here are the potential features. More will be added.
> > + "SoftwareBasedFiltering"
> > + "PatternsWithORLogicRelation"
> > + “RSSIMonitoring”
>
> So all our string values are lower-case and if needed we use - to separate words or logical details.
>
> I think exposing a good interface for selecting the filter patterns will take a bit. I would like to focus on getting the surrounding framework figured out first.
>
> Before finalizing an API, my test was always to write a simple client and check if it meets the requirement for being simple enough. If it becomes cumbersome for the client, then we need to consider putting some of the more complicated parts into bluetoothd.
>
> Let me try to give an example. If the majority of the clients just want to find a device with UUID 0xFE23, then we should have a special casing for that.
>
> RegisterMonitor(monitor, dict{MatchUUID=0xFE23}).
>
> Done. That they have to differentiate between one vendors way of doing this compared to another on how to provide the information should be up to bluetoothd to figure it out (and yes, I know it is not as simple when the AD type is a list).
Again, this was close to what I proposed earlier where the thresholds
and the filtering conditions are provided upon function call. Please
see my above comments on why I think this may not be sufficient.
Thanks,
Miao
Hi Miao-chen,
>>> This patch proposes an Advertisement Monitoring API for an application to
>>> register a job of monitoring ADV reports with content filter and RSSI
>>> thresholds.
>>>
>>> Signed-off-by: Miao-chen Chou <[email protected]>
>>> ---
>>>
>>> doc/advertisement-monitoring-api.txt | 163 +++++++++++++++++++++++++++
>>> 1 file changed, 163 insertions(+)
>>> create mode 100644 doc/advertisement-monitoring-api.txt
>>>
>>> diff --git a/doc/advertisement-monitoring-api.txt b/doc/advertisement-monitoring-api.txt
>>> new file mode 100644
>>> index 000000000..070487481
>>> --- /dev/null
>>> +++ b/doc/advertisement-monitoring-api.txt
>>> @@ -0,0 +1,163 @@
>>> +BlueZ D-Bus Advertisement Monitoring API Description
>>> +****************************************************
>>
>> I would name it “Advertisement Monitor”
>>
>>> +
>>> +This API allows an application to specify a job of monitoring advertisements
>>> +by providing a filter with filtering conditions, thresholds of RSSI and timers
>>> +of RSSI thresholds.
>>> +
>>> +Once an application registers a monitoring job, it can expect to get notified
>>> +on its targeted advertisements no matter if there is an ongoing discovery
>>> +session (a discovery session is started/stopped with methods in
>>> +org.bluez.Adapter1 interface).
>>
>> Just for readability two empty lines here. See the other docs for an example. They should be mostly consistent in their style.
>>
>>> +
>>> +Advertisement Filter hierarchy
>>> +==============================
>>> +Service org.bluez
>>> +Interface org.bluez.AdvertisementFilter1
>>> +Object path freely definable
>>> +
>>> +Methods void Release() [noreply]
>>> +
>>> + This gets called as a signal for a client to perform
>>> + clean-up when BlueZ has invalidated the filter.
>>> +
>>> + void DeviceInRange(object device, int16 RSSI, int16 TX_power,
>>> + array{dict} ADV_data,
>>> + array{uint8} ADV_raw_data)
>>
>> Actually looking at what the device object already gives you for free, I think you just need this:
>>
>> void DeviceInRange(object device)
>>
>> You will have the RSSI and TxPower fields and also the advertising data considered for consumption by the application. If you really really need the raw advertising report data, then we might include them as extra property type, but only if asked for. With advertising extensions these can get rather large.
>>
>> Just to explain this reasoning to only use the object device here. Don’t see it as a full object, since it is just a reference and more precise a filter to find your object in the list of all objects. So an application can ignore everything else, but just has to filter the device object path out from all objects to find the information of the device it was looking for.
> My concern is that adopting DeviceInRange(object device) will require
> an application to issue following D-Bus calls to read properties
> including AdvertisingData, RSSI, Tx power(it may be included in
> AdvertisingData) and perhaps a new property RawAdvertisingData. Given
> these calls reach bluetoothd, the values of these properties may have
> changed, so the reading no longer presents the exact values associated
> with the DeviceInRange() event. How do we get around this without
> providing the actual values along with DeviceInRange?
You get them via InterfacesAdded and PropertiesChanged standard signal. Similar to what is done when we are doing discovery.
>>> +
>>> + If RSSIThreshholdsAndTimers exists, this gets called to
>>> + notify the client on finding the targeted device when
>>> + RSSI(s) of the matched advertisement(s) exceed the
>>> + HighRSSIThreshold at least HighRSSIThresholdTimer.
>>> + If RSSIThreshholdsAndTimers does not exist, this does
>>> + not get called.
>>> +
>>> + Parameters:
>>> + device The device object path associated with
>>> + the advertisement.
>>> + RSSI The RSSI comes along with the
>>> + advertisement.
>>> + TX_power The TX power AD data provided in the
>>> + advertisement. 127 indicates the absence
>>> + of TX power AD data.
>>> + ADV_data The signature of adv_data is a{yv} where
>>> + “y” is the AD data type value and “v” is
>>> + the value of the AD data where the type
>>> + may vary depending on the AD data. For
>>> + instance, if "y" is 0x16, "v" would be
>>> + an array of bytes.
>>> + ADV_raw_data The raw bytes of AD data from the
>>> + advertisement packet.
>>> +
>>> + void AdvertisementReceived(object device, int16 RSSI,
>>> + int16 TX_power, array{dict} ADV_data,
>>> + array{uint8} ADV_raw_data)
>>> +
>>> + If RSSIThreshholdsAndTimers exists, this gets called
>>> + every time except for the first time when receiving the
>>> + matched advertisement(s) exceeding the
>>> + HighRSSIThreshold. Once DeviceOutOfRange() gets called,
>>> + this no longer gets called until DeviceInRange() gets
>>> + called again.
>>> + If RSSIThreshholdsAndTimers does not exist, this gets
>>> + called whenever receiving the matched advertisements.
>>> +
>>> + Parameters:
>>> + device The device object path associated with
>>> + the advertisement.
>>> + RSSI The RSSI comes along with the
>>> + advertisement.
>>> + TX_power The TX power AD data provided in the
>>> + advertisement. 127 indicates the absence
>>> + of TX power AD data.
>>> + ADV_data The signature of adv_data is a{yv} where
>>> + “y” is the AD data type value and “v” is
>>> + the value of the AD data where the type
>>> + may vary depending on the AD data. For
>>> + instance, if "y" is 0x16, "v" would be
>>> + an array of bytes.
>>> + ADV_raw_data The raw bytes of AD data from the
>>> + advertisement packet.
>>
>> This differentiation rubs me a bit the wrong way. I think it makes things a bit too complicated.
>>
>> In case you don’t specify any RSSI thresholds, I would still like to use DeviceInRange and DeviceOutOfRange notifications. We have always used timeouts to indicate that devices are no longer valid and removed them. They needed to be found again. And even without RSSI this will be the case since you have device moving around. So it would be good to indicate that a device is gone.
>>
>> Now the question is what we do for updates of a device that is currently in range and has been found. I think we don’t have to do anything. Since a client that cares about that device, can just monitor the object properties that we will keep updating as we find the device again. So if the RSSI, TxPower or even the advertising data changes, the client will be informed by a PropertiesChanged signal.
> In the case where RSSIs thresholds are not enforced, my original
> thought was that DeviceInRange and DeviceOutOfRange do not make lots
> of sense, since the terms "InRange" and "OutOfRange" implies RSSI
> checks. Also DeviceOutOfRange won't be called in this case, since no
> timer was given. Unless you see this differently?
> In the case where RSSIs thresholds are provided, using only
> DeviceInRange and DeviceOutOfRange makes sense.
We can fine-tune the naming, but from an API complexity point of view, two method calls for “found the device” and “device no longer available” that work no matter if RSSI ranges are given are better.
>>
>>> +
>>> + void DeviceOutOfRange(device object)
>>> +
>>> + If RSSIThreshholdsAndTimers exists, this gets called
>>> + when RSSIs of the matched advertisements are lower than
>>> + LowRSSIThreshold for at least LowRSSIThresholdTimer to
>>> + notify the client on losing the targeted device.
>>> + If RSSIThreshholdsAndTimers does not exist, this won’t
>>> + get called.
>>
>> We could consider doing a pair of DeviceFound + DeviceLost.
>>
>> And of course we have to split the callback handling with filter properties. When you read the full method name it needs to make sense. So org.bluez.AdvertisementFilter1.DeviceInRange is not really logical.
>>
>> I would have something like org.bluez.AdvertismentMonitor.DeviceFound for example.
>>
> DeviceFound() and DeviceLost() sound good to me. Are you suggesting
> having two properties, one for HighRSSIThreshold and
> HighRSSIThresholdTimer and one for LowRSSIThreshold and
> LowRSSIThresholdTimer, so that DeviceFound() is called only if
> HighRSSIThresholdAndTimer exists, and DeviceLost() is called only if
> LowRSSIThresholdAndTimer exists?
I am suggesting that if you have RSSI thresholds or not, we use DeviceFound and DeviceLost (or whatever naming we finally agree on). For me the RSSI thresholds are just a method to reduce the range of what is reported.
>>> +
>>> +Properties uint8 FilterType [read-only]
>>> +
>>> + This can be the following values. More will be added.
>>> + 0x01 - Patterns with OR logic relation
>>> +
>>> + (Int16, Uint16, Int16, Uint16) RSSIThreshholdsAndTimers [read-only, optional]
>>> +
>>> + The contains HighRSSIThreshold, HighRSSIThresholdTimer,
>>> + LowRSSIThreshold, LowRSSIThresholdTimer in order. The
>>> + unit of HighRSSIThreshold and LowRSSIThreshold is dBm.
>>> + The unit of HighRSSIThresholdTimer and
>>> + LowRSSIThresholdTimer is second.
>>> +
>>> + A device is considered in-range when the RSSIs of the
>>> + received advertisement(s) during HighRSSIThresholdTimer
>>> + seconds exceed HighRSSIThreshold. Likewise, a device is
>>> + considered out-of-range when the RSSIs of the received
>>> + advertisement(s) during LowRSSIThresholdTimer do not
>>> + reach LowRSSIThreshold.
>>> +
>>> + array{(uint8, uint8, string)} Patterns [read-only, optional]
>>> +
>>> + If “PatternsWithORLogicRelation” is supported, this must
>>> + exist and has at least one entry in the array.
>>> +
>>> + The structure of a pattern contains the following.
>>> + uint8 start_position
>>> + The index in an AD data field where the search
>>> + should start. The beginning of an AD data field
>>> + is index 0.
>>> + uint8 AD_data_type
>>> + See https://www.bluetooth.com/specifications/
>>> + assigned-numbers/generic-access-profile/ for
>>> + the possible allowed value.
>>> + string content_of_pattern
>>> + This is the value of the pattern.
>>
>> This part I would provide as dict to the RegisterMonitor method (see below).
>>
>>> +
>>> +Advertisement Monitor hierarchy
>>> +===============================
>>> +Service org.bluez
>>> +Interface org.bluez.AdvertisementMonitor1
>>> +Object path /org/bluez/{hci0,hci1,...}
>>
>> If we follow our current style then it would be org.bluez.AdvertismentMonitorManager.
>>
>> While writing this email so far, I am kinda tempted to call it org.bluez.DeviceMonitorManager and org.bluez.DeviceMonitor. It is just a temptation at this point and it is good to sleep about it for a bit.
>>
>>> +
>>> +Methods void RegisterApplication(object filter)
>>> +
>>> + This registers a job of monitoring advertisement in a
>>> + power efficient way. Based on the content of the filter
>>> + upon registration, the filter object can expect to
>>> + receive the matched advertisements via DeviceInRange()
>>> + and AdvertisementReceived().
>>
>> RegisterMonitor(object monitor, dict thresholds, dict filter)
>>
>> Having the thresholds and the filters as dicts here make it clear that you have to destroy the monitor and create a new one of you want to change them. I think that is acceptable and in the end an easy task, since you still can reuse the object monitor that you have already set up. It also make the code for bluetoothd simpler since it doesn’t have to track life changes to the filters and act on them.
>>
> This was close to what I proposed earlier where the thresholds and the
> filtering conditions are provided upon function calls, and Luiz
> suggested adopting advertising API's way. Given that we may want to
> provide what Android provides at some point, having a dict to host
> filtering conditions may not be sufficient. If we'd like to have AND
> logical relation applied among filtering conditions within a filter,
> we basically need to change the signature here. For instance, an
> application would like to look for advertisements matching service
> UUID 0x1234 AND 0x5678 in Manufacturer data. Having filtering
> conditions defined as properties make this possible by adding another
> property later without changing the function signature.
>
> I'd like to raise the same concern that I had in previous meetings.
> Given that we plan to have SW filtering first and then offload the
> filtering to the BT controller, there may be logical relations
> infeasible by HCI extensions. Should we influence this API by the
> capabilities of HCI extensions? I guess the answer is not, and that
> means bluetoothd needs to be sophisticated enough to determined the
> filtering conditions send to kernel for the first tier filtering and
> performs the second tier filtering itself.
>>> +
>>> + void UnregisterApplication(filter object)
>>> +
>>> + This unregisters the job of monitoring advertisement.
>>> + The filter object can expect to be called on Release()
>>> + once the removal is done.
>>> +
>>> + void UnregisterAllApplications()
>>> +
>>> + This unregisters all jobs of monitoring advertisement.
>>> + All filter objects can expect to be called on Release()
>>> + once the removals are done.
>>
>> I would rather not have an UnregisterAll. We didn’t need it until now and the object monitor was always bound to the lifetime of the application.
> Ack.
>>
>>> +
>>> +Properties array{string} SupportedFilteringFeatures [read-only]
>>> +
>>> + This reflects the supported features of advertisement
>>> + monitoring. An application should check this before
>>> + instantiate an object of org.bluez.AdvertisementFilter1.
>>> +
>>> + Here are the potential features. More will be added.
>>> + "SoftwareBasedFiltering"
>>> + "PatternsWithORLogicRelation"
>>> + “RSSIMonitoring”
>>
>> So all our string values are lower-case and if needed we use - to separate words or logical details.
>>
>> I think exposing a good interface for selecting the filter patterns will take a bit. I would like to focus on getting the surrounding framework figured out first.
>>
>> Before finalizing an API, my test was always to write a simple client and check if it meets the requirement for being simple enough. If it becomes cumbersome for the client, then we need to consider putting some of the more complicated parts into bluetoothd.
>>
>> Let me try to give an example. If the majority of the clients just want to find a device with UUID 0xFE23, then we should have a special casing for that.
>>
>> RegisterMonitor(monitor, dict{MatchUUID=0xFE23}).
>>
>> Done. That they have to differentiate between one vendors way of doing this compared to another on how to provide the information should be up to bluetoothd to figure it out (and yes, I know it is not as simple when the AD type is a list).
> Again, this was close to what I proposed earlier where the thresholds
> and the filtering conditions are provided upon function call. Please
> see my above comments on why I think this may not be sufficient.
I fully realize that not all will be possible. Especially when it comes to UUID lists. But for something like match on vendor specific AD with company id x it might be.
Regards
Marcel
Hi Marcel and Luiz,
On Fri, Apr 10, 2020 at 11:19 PM Marcel Holtmann <[email protected]> wrote:
>
> Hi Miao-chen,
>
> >>> This patch proposes an Advertisement Monitoring API for an application to
> >>> register a job of monitoring ADV reports with content filter and RSSI
> >>> thresholds.
> >>>
> >>> Signed-off-by: Miao-chen Chou <[email protected]>
> >>> ---
> >>>
> >>> doc/advertisement-monitoring-api.txt | 163 +++++++++++++++++++++++++++
> >>> 1 file changed, 163 insertions(+)
> >>> create mode 100644 doc/advertisement-monitoring-api.txt
> >>>
> >>> diff --git a/doc/advertisement-monitoring-api.txt b/doc/advertisement-monitoring-api.txt
> >>> new file mode 100644
> >>> index 000000000..070487481
> >>> --- /dev/null
> >>> +++ b/doc/advertisement-monitoring-api.txt
> >>> @@ -0,0 +1,163 @@
> >>> +BlueZ D-Bus Advertisement Monitoring API Description
> >>> +****************************************************
> >>
> >> I would name it “Advertisement Monitor”
> >>
> >>> +
> >>> +This API allows an application to specify a job of monitoring advertisements
> >>> +by providing a filter with filtering conditions, thresholds of RSSI and timers
> >>> +of RSSI thresholds.
> >>> +
> >>> +Once an application registers a monitoring job, it can expect to get notified
> >>> +on its targeted advertisements no matter if there is an ongoing discovery
> >>> +session (a discovery session is started/stopped with methods in
> >>> +org.bluez.Adapter1 interface).
> >>
> >> Just for readability two empty lines here. See the other docs for an example. They should be mostly consistent in their style.
> >>
> >>> +
> >>> +Advertisement Filter hierarchy
> >>> +==============================
> >>> +Service org.bluez
> >>> +Interface org.bluez.AdvertisementFilter1
> >>> +Object path freely definable
> >>> +
> >>> +Methods void Release() [noreply]
> >>> +
> >>> + This gets called as a signal for a client to perform
> >>> + clean-up when BlueZ has invalidated the filter.
> >>> +
> >>> + void DeviceInRange(object device, int16 RSSI, int16 TX_power,
> >>> + array{dict} ADV_data,
> >>> + array{uint8} ADV_raw_data)
> >>
> >> Actually looking at what the device object already gives you for free, I think you just need this:
> >>
> >> void DeviceInRange(object device)
> >>
> >> You will have the RSSI and TxPower fields and also the advertising data considered for consumption by the application. If you really really need the raw advertising report data, then we might include them as extra property type, but only if asked for. With advertising extensions these can get rather large.
> >>
> >> Just to explain this reasoning to only use the object device here. Don’t see it as a full object, since it is just a reference and more precise a filter to find your object in the list of all objects. So an application can ignore everything else, but just has to filter the device object path out from all objects to find the information of the device it was looking for.
> > My concern is that adopting DeviceInRange(object device) will require
> > an application to issue following D-Bus calls to read properties
> > including AdvertisingData, RSSI, Tx power(it may be included in
> > AdvertisingData) and perhaps a new property RawAdvertisingData. Given
> > these calls reach bluetoothd, the values of these properties may have
> > changed, so the reading no longer presents the exact values associated
> > with the DeviceInRange() event. How do we get around this without
> > providing the actual values along with DeviceInRange?
>
> You get them via InterfacesAdded and PropertiesChanged standard signal. Similar to what is done when we are doing discovery.
From a D-Bus client perspective, I'd argue that it requires much more
work for an application to register the monitoring job on one
interface. For the case where the device exists already, the
application needs to listen to the device interface for multiple
PropertiesChanged signals (AdvertisingData, RSSI, TxPower,
ManufacturerData, ServiceData and AdvertisingFlags) where these
signals could arrived earlier than the time DeviceFound() got called.
In the case a new device was created, the application also needs to
listen to InterfacesAdded signal and then reads on multiple
properties; by the time the application reads the values, they could
be changed already.
Instead, if we simply provide the parsed dict containing all valid
fields along with RSSI and TX power(this may not be provided), it
eliminates the needs of all above work for the application. I'd like
to highlight that the intention here is to make the life of the
application easier by providing only the matched AD data without the
above extra work. Another thing that I'd like to highlight here is
that we are introducing a new API whose use case is different from
discovery, reporting a device object and reporting an ADV can be
orthogonal. In fact, the reason for providing the device object path
in DeviceFound is to make it easier for the application to take
further action on the device (such as pairing or connection) so that
it doesn't need to figure out which device is associated with the
received ADV. The only downside that I can think of is the case where
the device exists, and this makes DeviceFound call with AD data where
they are emitted via device interface. In the case where the device is
new, there is no duplicate data passing.
>
> >>> +
> >>> + If RSSIThreshholdsAndTimers exists, this gets called to
> >>> + notify the client on finding the targeted device when
> >>> + RSSI(s) of the matched advertisement(s) exceed the
> >>> + HighRSSIThreshold at least HighRSSIThresholdTimer.
> >>> + If RSSIThreshholdsAndTimers does not exist, this does
> >>> + not get called.
> >>> +
> >>> + Parameters:
> >>> + device The device object path associated with
> >>> + the advertisement.
> >>> + RSSI The RSSI comes along with the
> >>> + advertisement.
> >>> + TX_power The TX power AD data provided in the
> >>> + advertisement. 127 indicates the absence
> >>> + of TX power AD data.
> >>> + ADV_data The signature of adv_data is a{yv} where
> >>> + “y” is the AD data type value and “v” is
> >>> + the value of the AD data where the type
> >>> + may vary depending on the AD data. For
> >>> + instance, if "y" is 0x16, "v" would be
> >>> + an array of bytes.
> >>> + ADV_raw_data The raw bytes of AD data from the
> >>> + advertisement packet.
> >>> +
> >>> + void AdvertisementReceived(object device, int16 RSSI,
> >>> + int16 TX_power, array{dict} ADV_data,
> >>> + array{uint8} ADV_raw_data)
> >>> +
> >>> + If RSSIThreshholdsAndTimers exists, this gets called
> >>> + every time except for the first time when receiving the
> >>> + matched advertisement(s) exceeding the
> >>> + HighRSSIThreshold. Once DeviceOutOfRange() gets called,
> >>> + this no longer gets called until DeviceInRange() gets
> >>> + called again.
> >>> + If RSSIThreshholdsAndTimers does not exist, this gets
> >>> + called whenever receiving the matched advertisements.
> >>> +
> >>> + Parameters:
> >>> + device The device object path associated with
> >>> + the advertisement.
> >>> + RSSI The RSSI comes along with the
> >>> + advertisement.
> >>> + TX_power The TX power AD data provided in the
> >>> + advertisement. 127 indicates the absence
> >>> + of TX power AD data.
> >>> + ADV_data The signature of adv_data is a{yv} where
> >>> + “y” is the AD data type value and “v” is
> >>> + the value of the AD data where the type
> >>> + may vary depending on the AD data. For
> >>> + instance, if "y" is 0x16, "v" would be
> >>> + an array of bytes.
> >>> + ADV_raw_data The raw bytes of AD data from the
> >>> + advertisement packet.
> >>
> >> This differentiation rubs me a bit the wrong way. I think it makes things a bit too complicated.
> >>
> >> In case you don’t specify any RSSI thresholds, I would still like to use DeviceInRange and DeviceOutOfRange notifications. We have always used timeouts to indicate that devices are no longer valid and removed them. They needed to be found again. And even without RSSI this will be the case since you have device moving around. So it would be good to indicate that a device is gone.
> >>
> >> Now the question is what we do for updates of a device that is currently in range and has been found. I think we don’t have to do anything. Since a client that cares about that device, can just monitor the object properties that we will keep updating as we find the device again. So if the RSSI, TxPower or even the advertising data changes, the client will be informed by a PropertiesChanged signal.
> > In the case where RSSIs thresholds are not enforced, my original
> > thought was that DeviceInRange and DeviceOutOfRange do not make lots
> > of sense, since the terms "InRange" and "OutOfRange" implies RSSI
> > checks. Also DeviceOutOfRange won't be called in this case, since no
> > timer was given. Unless you see this differently?
> > In the case where RSSIs thresholds are provided, using only
> > DeviceInRange and DeviceOutOfRange makes sense.
>
> We can fine-tune the naming, but from an API complexity point of view, two method calls for “found the device” and “device no longer available” that work no matter if RSSI ranges are given are better.
>
> >>
> >>> +
> >>> + void DeviceOutOfRange(device object)
> >>> +
> >>> + If RSSIThreshholdsAndTimers exists, this gets called
> >>> + when RSSIs of the matched advertisements are lower than
> >>> + LowRSSIThreshold for at least LowRSSIThresholdTimer to
> >>> + notify the client on losing the targeted device.
> >>> + If RSSIThreshholdsAndTimers does not exist, this won’t
> >>> + get called.
> >>
> >> We could consider doing a pair of DeviceFound + DeviceLost.
> >>
> >> And of course we have to split the callback handling with filter properties. When you read the full method name it needs to make sense. So org.bluez.AdvertisementFilter1.DeviceInRange is not really logical.
> >>
> >> I would have something like org.bluez.AdvertismentMonitor.DeviceFound for example.
> >>
> > DeviceFound() and DeviceLost() sound good to me. Are you suggesting
> > having two properties, one for HighRSSIThreshold and
> > HighRSSIThresholdTimer and one for LowRSSIThreshold and
> > LowRSSIThresholdTimer, so that DeviceFound() is called only if
> > HighRSSIThresholdAndTimer exists, and DeviceLost() is called only if
> > LowRSSIThresholdAndTimer exists?
>
> I am suggesting that if you have RSSI thresholds or not, we use DeviceFound and DeviceLost (or whatever naming we finally agree on). For me the RSSI thresholds are just a method to reduce the range of what is reported.
Agreed, I will address the changes in v2.
>
> >>> +
> >>> +Properties uint8 FilterType [read-only]
> >>> +
> >>> + This can be the following values. More will be added.
> >>> + 0x01 - Patterns with OR logic relation
> >>> +
> >>> + (Int16, Uint16, Int16, Uint16) RSSIThreshholdsAndTimers [read-only, optional]
> >>> +
> >>> + The contains HighRSSIThreshold, HighRSSIThresholdTimer,
> >>> + LowRSSIThreshold, LowRSSIThresholdTimer in order. The
> >>> + unit of HighRSSIThreshold and LowRSSIThreshold is dBm.
> >>> + The unit of HighRSSIThresholdTimer and
> >>> + LowRSSIThresholdTimer is second.
> >>> +
> >>> + A device is considered in-range when the RSSIs of the
> >>> + received advertisement(s) during HighRSSIThresholdTimer
> >>> + seconds exceed HighRSSIThreshold. Likewise, a device is
> >>> + considered out-of-range when the RSSIs of the received
> >>> + advertisement(s) during LowRSSIThresholdTimer do not
> >>> + reach LowRSSIThreshold.
> >>> +
> >>> + array{(uint8, uint8, string)} Patterns [read-only, optional]
> >>> +
> >>> + If “PatternsWithORLogicRelation” is supported, this must
> >>> + exist and has at least one entry in the array.
> >>> +
> >>> + The structure of a pattern contains the following.
> >>> + uint8 start_position
> >>> + The index in an AD data field where the search
> >>> + should start. The beginning of an AD data field
> >>> + is index 0.
> >>> + uint8 AD_data_type
> >>> + See https://www.bluetooth.com/specifications/
> >>> + assigned-numbers/generic-access-profile/ for
> >>> + the possible allowed value.
> >>> + string content_of_pattern
> >>> + This is the value of the pattern.
> >>
> >> This part I would provide as dict to the RegisterMonitor method (see below).
> >>
> >>> +
> >>> +Advertisement Monitor hierarchy
> >>> +===============================
> >>> +Service org.bluez
> >>> +Interface org.bluez.AdvertisementMonitor1
> >>> +Object path /org/bluez/{hci0,hci1,...}
> >>
> >> If we follow our current style then it would be org.bluez.AdvertismentMonitorManager.
> >>
> >> While writing this email so far, I am kinda tempted to call it org.bluez.DeviceMonitorManager and org.bluez.DeviceMonitor. It is just a temptation at this point and it is good to sleep about it for a bit.
> >>
> >>> +
> >>> +Methods void RegisterApplication(object filter)
> >>> +
> >>> + This registers a job of monitoring advertisement in a
> >>> + power efficient way. Based on the content of the filter
> >>> + upon registration, the filter object can expect to
> >>> + receive the matched advertisements via DeviceInRange()
> >>> + and AdvertisementReceived().
> >>
> >> RegisterMonitor(object monitor, dict thresholds, dict filter)
> >>
> >> Having the thresholds and the filters as dicts here make it clear that you have to destroy the monitor and create a new one of you want to change them. I think that is acceptable and in the end an easy task, since you still can reuse the object monitor that you have already set up. It also make the code for bluetoothd simpler since it doesn’t have to track life changes to the filters and act on them.
> >>
> > This was close to what I proposed earlier where the thresholds and the
> > filtering conditions are provided upon function calls, and Luiz
> > suggested adopting advertising API's way. Given that we may want to
> > provide what Android provides at some point, having a dict to host
> > filtering conditions may not be sufficient. If we'd like to have AND
> > logical relation applied among filtering conditions within a filter,
> > we basically need to change the signature here. For instance, an
> > application would like to look for advertisements matching service
> > UUID 0x1234 AND 0x5678 in Manufacturer data. Having filtering
> > conditions defined as properties make this possible by adding another
> > property later without changing the function signature.
> >
> > I'd like to raise the same concern that I had in previous meetings.
> > Given that we plan to have SW filtering first and then offload the
> > filtering to the BT controller, there may be logical relations
> > infeasible by HCI extensions. Should we influence this API by the
> > capabilities of HCI extensions? I guess the answer is not, and that
> > means bluetoothd needs to be sophisticated enough to determined the
> > filtering conditions send to kernel for the first tier filtering and
> > performs the second tier filtering itself.
> >>> +
> >>> + void UnregisterApplication(filter object)
> >>> +
> >>> + This unregisters the job of monitoring advertisement.
> >>> + The filter object can expect to be called on Release()
> >>> + once the removal is done.
> >>> +
> >>> + void UnregisterAllApplications()
> >>> +
> >>> + This unregisters all jobs of monitoring advertisement.
> >>> + All filter objects can expect to be called on Release()
> >>> + once the removals are done.
> >>
> >> I would rather not have an UnregisterAll. We didn’t need it until now and the object monitor was always bound to the lifetime of the application.
> > Ack.
> >>
> >>> +
> >>> +Properties array{string} SupportedFilteringFeatures [read-only]
> >>> +
> >>> + This reflects the supported features of advertisement
> >>> + monitoring. An application should check this before
> >>> + instantiate an object of org.bluez.AdvertisementFilter1.
> >>> +
> >>> + Here are the potential features. More will be added.
> >>> + "SoftwareBasedFiltering"
> >>> + "PatternsWithORLogicRelation"
> >>> + “RSSIMonitoring”
> >>
> >> So all our string values are lower-case and if needed we use - to separate words or logical details.
> >>
> >> I think exposing a good interface for selecting the filter patterns will take a bit. I would like to focus on getting the surrounding framework figured out first.
> >>
> >> Before finalizing an API, my test was always to write a simple client and check if it meets the requirement for being simple enough. If it becomes cumbersome for the client, then we need to consider putting some of the more complicated parts into bluetoothd.
> >>
> >> Let me try to give an example. If the majority of the clients just want to find a device with UUID 0xFE23, then we should have a special casing for that.
> >>
> >> RegisterMonitor(monitor, dict{MatchUUID=0xFE23}).
> >>
> >> Done. That they have to differentiate between one vendors way of doing this compared to another on how to provide the information should be up to bluetoothd to figure it out (and yes, I know it is not as simple when the AD type is a list).
> > Again, this was close to what I proposed earlier where the thresholds
> > and the filtering conditions are provided upon function call. Please
> > see my above comments on why I think this may not be sufficient.
>
> I fully realize that not all will be possible. Especially when it comes to UUID lists. But for something like match on vendor specific AD with company id x it might be.
I am not sure what you refer to by "company id". For now, the known
use cases don't come along with any specific company information.
Thanks,
Miao
Hi Marcel and Luiz,
On Sat, Apr 11, 2020 at 12:23 AM Von Dentz, Luiz
<[email protected]> wrote:
>
> Hi Miao, Marcel,
>
> On Fri, Apr 10, 2020 at 12:47 AM Marcel Holtmann <[email protected]> wrote:
>>
>> > +Properties uint8 FilterType [read-only]
>> > +
>> > + This can be the following values. More will be added.
>> > + 0x01 - Patterns with OR logic relation
>
>
> We already have Filter in interface name so I guess we can go with just Type.
Sounds good to me.
>
>>
>> > + (Int16, Uint16, Int16, Uint16) RSSIThreshholdsAndTimers [read-only, optional]
>> > +
>> > + The contains HighRSSIThreshold, HighRSSIThresholdTimer,
>> > + LowRSSIThreshold, LowRSSIThresholdTimer in order. The
>> > + unit of HighRSSIThreshold and LowRSSIThreshold is dBm.
>> > + The unit of HighRSSIThresholdTimer and
>> > + LowRSSIThresholdTimer is second.
>> > +
>> > + A device is considered in-range when the RSSIs of the
>> > + received advertisement(s) during HighRSSIThresholdTimer
>> > + seconds exceed HighRSSIThreshold. Likewise, a device is
>> > + considered out-of-range when the RSSIs of the received
>> > + advertisement(s) during LowRSSIThresholdTimer do not
>> > + reach LowRSSIThreshold.
>> > +
>> > + array{(uint8, uint8, string)} Patterns [read-only, optional]
>> > +
>> > + If “PatternsWithORLogicRelation” is supported, this must
>> > + exist and has at least one entry in the array.
>> > +
>> > + The structure of a pattern contains the following.
>> > + uint8 start_position
>> > + The index in an AD data field where the search
>> > + should start. The beginning of an AD data field
>> > + is index 0.
>> > + uint8 AD_data_type
>> > + See https://www.bluetooth.com/specifications/
>> > + assigned-numbers/generic-access-profile/ for
>> > + the possible allowed value.
>> > + string content_of_pattern
>> > + This is the value of the pattern.
>>
>> This part I would provide as dict to the RegisterMonitor method (see below).
>>
>> > +
>> > +Advertisement Monitor hierarchy
>> > +===============================
>> > +Service org.bluez
>> > +Interface org.bluez.AdvertisementMonitor1
>> > +Object path /org/bluez/{hci0,hci1,...}
>>
>> If we follow our current style then it would be org.bluez.AdvertismentMonitorManager.
>>
>> While writing this email so far, I am kinda tempted to call it org.bluez.DeviceMonitorManager and org.bluez.DeviceMonitor. It is just a temptation at this point and it is good to sleep about it for a bit.
>>
>> > +
>> > +Methods void RegisterApplication(object filter)
>> > +
>> > + This registers a job of monitoring advertisement in a
>> > + power efficient way. Based on the content of the filter
>> > + upon registration, the filter object can expect to
>> > + receive the matched advertisements via DeviceInRange()
>> > + and AdvertisementReceived().
>>
>> RegisterMonitor(object monitor, dict thresholds, dict filter)
>>
>> Having the thresholds and the filters as dicts here make it clear that you have to destroy the monitor and create a new one of you want to change them. I think that is acceptable and in the end an easy task, since you still can reuse the object monitor that you have already set up. It also make the code for bluetoothd simpler since it doesn’t have to track life changes to the filters and act on them.
>
>
> Actually I rather not do this since there could multiple filters being registered not just a single object, if is quite a pain if we would need to build an array that matches the listing of ObjectManagers which might get very tricky for the client to do properly since some of them actually use a hash table for the objects which may reorder them, with our dbus client is not that difficult to update the filters if they change so Id just let the client change while registered so we don't have to unregister/register the whole object tree if there are updates.
My understanding here is that only one monitor (this is in fact a
filter - which we have been using from the very beginning, and Marcel
suggested to rename it to monitor) can be registered via
RegisterMonitor at a time, and there can be multiple filtering
conditions (such as UUID and other AD data type) within a monitor
depending on the type of the monitor.
My concern with providing filtering conditions as a dictionary is that
it cannot be extended to adopt logical relation among filter
conditions later. For simplicity, we probably don't want to allow an
application to update filter and expect the changes would be reflected
right away (once HCI vendor extensions are in place, this can be
expensive), so we honor whatever filtering conditions read from the
monitor upon RegisterMonitor().
>
>>
>>
>> > +
>> > + void UnregisterApplication(filter object)
>> > +
>> > + This unregisters the job of monitoring advertisement.
>> > + The filter object can expect to be called on Release()
>> > + once the removal is done.
>> > +
>> > + void UnregisterAllApplications()
>> > +
>> > + This unregisters all jobs of monitoring advertisement.
>> > + All filter objects can expect to be called on Release()
>> > + once the removals are done.
>>
>> I would rather not have an UnregisterAll. We didn’t need it until now and the object monitor was always bound to the lifetime of the application.
>
>
> Actually we just need one method with ObjectManager which would remove the entire root tree of objects, removing just a single filter is just a matter of emitting InterfacesRemoved, same thing if you want to add another filter just emit InterfacesAdded with the new filter, we can either use the Release or a dedicate methot to notify if the filter is malformed or something like that.
I'd rather have this interface work the same as the Advertising API,
since we need to report failures upon registering an ADV monitor, e.g.
there may be no resources to allocate HW filtering or maybe the
filtering conditions cannot be fulfilled.
>
>>
>>
>> > +
>> > +Properties array{string} SupportedFilteringFeatures [read-only]
>> > +
>> > + This reflects the supported features of advertisement
>> > + monitoring. An application should check this before
>> > + instantiate an object of org.bluez.AdvertisementFilter1.
>> > +
>> > + Here are the potential features. More will be added.
>> > + "SoftwareBasedFiltering"
>> > + "PatternsWithORLogicRelation"
>> > + “RSSIMonitoring”
>>
>> So all our string values are lower-case and if needed we use - to separate words or logical details.
>>
>> I think exposing a good interface for selecting the filter patterns will take a bit. I would like to focus on getting the surrounding framework figured out first.
>>
>> Before finalizing an API, my test was always to write a simple client and check if it meets the requirement for being simple enough. If it becomes cumbersome for the client, then we need to consider putting some of the more complicated parts into bluetoothd.
>>
>> Let me try to give an example. If the majority of the clients just want to find a device with UUID 0xFE23, then we should have a special casing for that.
>>
>> RegisterMonitor(monitor, dict{MatchUUID=0xFE23}).
>>
>> Done. That they have to differentiate between one vendors way of doing this compared to another on how to provide the information should be up to bluetoothd to figure it out (and yes, I know it is not as simple when the AD type is a list).
>>
>
> Im a little confused here, doesn't there need to match the filter Type? That would be much simpler for the client then to know what filter it would be able to register, then we can go with SupportedFilterTypes which would enumerate whatever possible values for filter types.
There are basically two ways how we can register an ADV monitor.
(1) RegisterMonitor(object monitor)
The monitor object would have properties that represent the type of
filter, the filtering conditions, RSSI thresholds and their timers.
It's more flexible to have properties representing criteria for filtering.
(2) RegisterMonitor(object monitor, dict thresholds, dict filter)
The monitor object would not have any property at all. This enforces
the no-reuse policy on an ADV monitor by not providing any property to
update. However, this does not fulfill the future use cases where the
filtering can be more complex.
Other the topic on what parameters we should send along with
DeviceFound(), this is the other blocker for settling the API.
Approach (1) seems to be the right way to go, what do you think?
Thanks,
Miao
Hi Luiz,
Please see my inline replies below.
On Mon, Apr 13, 2020 at 5:55 PM Von Dentz, Luiz
<[email protected]> wrote:
>
> Hi Miao,
>
> On Mon, Apr 13, 2020 at 5:18 PM Miao-chen Chou <[email protected]> wrote:
>>
>> Hi Marcel and Luiz,
>>
>> On Sat, Apr 11, 2020 at 12:23 AM Von Dentz, Luiz
>> <[email protected]> wrote:
>> >
>> > Hi Miao, Marcel,
>> >
>> > On Fri, Apr 10, 2020 at 12:47 AM Marcel Holtmann <[email protected]> wrote:
>> >>
>> >> > +Properties uint8 FilterType [read-only]
>> >> > +
>> >> > + This can be the following values. More will be added.
>> >> > + 0x01 - Patterns with OR logic relation
>> >
>> >
>> > We already have Filter in interface name so I guess we can go with just Type.
>> Sounds good to me.
>> >
>> >>
>> >> > + (Int16, Uint16, Int16, Uint16) RSSIThreshholdsAndTimers [read-only, optional]
>> >> > +
>> >> > + The contains HighRSSIThreshold, HighRSSIThresholdTimer,
>> >> > + LowRSSIThreshold, LowRSSIThresholdTimer in order. The
>> >> > + unit of HighRSSIThreshold and LowRSSIThreshold is dBm.
>> >> > + The unit of HighRSSIThresholdTimer and
>> >> > + LowRSSIThresholdTimer is second.
>> >> > +
>> >> > + A device is considered in-range when the RSSIs of the
>> >> > + received advertisement(s) during HighRSSIThresholdTimer
>> >> > + seconds exceed HighRSSIThreshold. Likewise, a device is
>> >> > + considered out-of-range when the RSSIs of the received
>> >> > + advertisement(s) during LowRSSIThresholdTimer do not
>> >> > + reach LowRSSIThreshold.
>> >> > +
>> >> > + array{(uint8, uint8, string)} Patterns [read-only, optional]
>> >> > +
>> >> > + If “PatternsWithORLogicRelation” is supported, this must
>> >> > + exist and has at least one entry in the array.
>> >> > +
>> >> > + The structure of a pattern contains the following.
>> >> > + uint8 start_position
>> >> > + The index in an AD data field where the search
>> >> > + should start. The beginning of an AD data field
>> >> > + is index 0.
>> >> > + uint8 AD_data_type
>> >> > + See https://www.bluetooth.com/specifications/
>> >> > + assigned-numbers/generic-access-profile/ for
>> >> > + the possible allowed value.
>> >> > + string content_of_pattern
>> >> > + This is the value of the pattern.
>> >>
>> >> This part I would provide as dict to the RegisterMonitor method (see below).
>> >>
>> >> > +
>> >> > +Advertisement Monitor hierarchy
>> >> > +===============================
>> >> > +Service org.bluez
>> >> > +Interface org.bluez.AdvertisementMonitor1
>> >> > +Object path /org/bluez/{hci0,hci1,...}
>> >>
>> >> If we follow our current style then it would be org.bluez.AdvertismentMonitorManager.
>> >>
>> >> While writing this email so far, I am kinda tempted to call it org.bluez.DeviceMonitorManager and org.bluez.DeviceMonitor. It is just a temptation at this point and it is good to sleep about it for a bit.
>> >>
>> >> > +
>> >> > +Methods void RegisterApplication(object filter)
>> >> > +
>> >> > + This registers a job of monitoring advertisement in a
>> >> > + power efficient way. Based on the content of the filter
>> >> > + upon registration, the filter object can expect to
>> >> > + receive the matched advertisements via DeviceInRange()
>> >> > + and AdvertisementReceived().
>> >>
>> >> RegisterMonitor(object monitor, dict thresholds, dict filter)
>> >>
>> >> Having the thresholds and the filters as dicts here make it clear that you have to destroy the monitor and create a new one of you want to change them. I think that is acceptable and in the end an easy task, since you still can reuse the object monitor that you have already set up. It also make the code for bluetoothd simpler since it doesn’t have to track life changes to the filters and act on them.
>> >
>> >
>> > Actually I rather not do this since there could multiple filters being registered not just a single object, if is quite a pain if we would need to build an array that matches the listing of ObjectManagers which might get very tricky for the client to do properly since some of them actually use a hash table for the objects which may reorder them, with our dbus client is not that difficult to update the filters if they change so Id just let the client change while registered so we don't have to unregister/register the whole object tree if there are updates.
>> My understanding here is that only one monitor (this is in fact a
>> filter - which we have been using from the very beginning, and Marcel
>> suggested to rename it to monitor) can be registered via
>> RegisterMonitor at a time, and there can be multiple filtering
>> conditions (such as UUID and other AD data type) within a monitor
>> depending on the type of the monitor.
>> My concern with providing filtering conditions as a dictionary is that
>> it cannot be extended to adopt logical relation among filter
>> conditions later. For simplicity, we probably don't want to allow an
>> application to update filter and expect the changes would be reflected
>> right away (once HCI vendor extensions are in place, this can be
>> expensive), so we honor whatever filtering conditions read from the
>> monitor upon RegisterMonitor().
>
>
> You mean you can only have 1 filter object per application? I thought you guys suggesting having more than one filter, I recall commenting that with ObjectManager you will be able to register multiple objects at once and if Im not mistaken this is kind a must have filter otherwise you will have to register filter one by one and in each and every case update the filter at HCI layer, meaning not only we have several rounds trips at D-Bus layer but also at HCI, my impression is that this would not scale well at startup because that would make application all try to register their filters at once making the whole procedure quite slow, this is actually the reason we switch to use ObjectManager since GetManagedObjects packs every object registered we can then register all filters in 1 single round-trip.
There was a misunderstanding here, and I'd glad you pointed out. Your
impression was correct that we propose to allow a D-Bus client to
register multiple monitors(filters), and my above comments were around
the function RegisterMonitor() where it only allows a client to
register one monitor. Indeed RegisterMonitor has the drawback you
pointed out, so using ObjectManager is better which I also agreed
with. However, I was concerned about how we inform the client about
whether its monitors were honored or not, since there is no existing
example. One option is to introduce an extra function in
org.bluez.AdvertisementMonitor1, perhaps Activate(), to indicate the
monitor was adopted, and Release() should be called to inform the
failures. What do you think?
>
>>
>> >
>> >>
>> >>
>> >> > +
>> >> > + void UnregisterApplication(filter object)
>> >> > +
>> >> > + This unregisters the job of monitoring advertisement.
>> >> > + The filter object can expect to be called on Release()
>> >> > + once the removal is done.
>> >> > +
>> >> > + void UnregisterAllApplications()
>> >> > +
>> >> > + This unregisters all jobs of monitoring advertisement.
>> >> > + All filter objects can expect to be called on Release()
>> >> > + once the removals are done.
>> >>
>> >> I would rather not have an UnregisterAll. We didn’t need it until now and the object monitor was always bound to the lifetime of the application.
>> >
>> >
>> > Actually we just need one method with ObjectManager which would remove the entire root tree of objects, removing just a single filter is just a matter of emitting InterfacesRemoved, same thing if you want to add another filter just emit InterfacesAdded with the new filter, we can either use the Release or a dedicate methot to notify if the filter is malformed or something like that.
>> I'd rather have this interface work the same as the Advertising API,
>> since we need to report failures upon registering an ADV monitor, e.g.
>> there may be no resources to allocate HW filtering or maybe the
>> filtering conditions cannot be fulfilled.
>> >
>> >>
>> >>
>> >> > +
>> >> > +Properties array{string} SupportedFilteringFeatures [read-only]
>> >> > +
>> >> > + This reflects the supported features of advertisement
>> >> > + monitoring. An application should check this before
>> >> > + instantiate an object of org.bluez.AdvertisementFilter1.
>> >> > +
>> >> > + Here are the potential features. More will be added.
>> >> > + "SoftwareBasedFiltering"
>> >> > + "PatternsWithORLogicRelation"
>> >> > + “RSSIMonitoring”
>> >>
>> >> So all our string values are lower-case and if needed we use - to separate words or logical details.
>> >>
>> >> I think exposing a good interface for selecting the filter patterns will take a bit. I would like to focus on getting the surrounding framework figured out first.
>> >>
>> >> Before finalizing an API, my test was always to write a simple client and check if it meets the requirement for being simple enough. If it becomes cumbersome for the client, then we need to consider putting some of the more complicated parts into bluetoothd.
>> >>
>> >> Let me try to give an example. If the majority of the clients just want to find a device with UUID 0xFE23, then we should have a special casing for that.
>> >>
>> >> RegisterMonitor(monitor, dict{MatchUUID=0xFE23}).
>> >>
>> >> Done. That they have to differentiate between one vendors way of doing this compared to another on how to provide the information should be up to bluetoothd to figure it out (and yes, I know it is not as simple when the AD type is a list).
>> >>
>> >
>> > Im a little confused here, doesn't there need to match the filter Type? That would be much simpler for the client then to know what filter it would be able to register, then we can go with SupportedFilterTypes which would enumerate whatever possible values for filter types.
>> There are basically two ways how we can register an ADV monitor.
>> (1) RegisterMonitor(object monitor)
>> The monitor object would have properties that represent the type of
>> filter, the filtering conditions, RSSI thresholds and their timers.
>> It's more flexible to have properties representing criteria for filtering.
>> (2) RegisterMonitor(object monitor, dict thresholds, dict filter)
>> The monitor object would not have any property at all. This enforces
>> the no-reuse policy on an ADV monitor by not providing any property to
>> update. However, this does not fulfill the future use cases where the
>> filtering can be more complex.
>> Other the topic on what parameters we should send along with
>> DeviceFound(), this is the other blocker for settling the API.
>> Approach (1) seems to be the right way to go, what do you think?
>
>
> Well if you do use ObjectManager 2 might not even be possible, so we need to settle on that first, or there was some discussing on that regard that made you guys change the idea of using ObjectManager to list the application filters, lake I said that wouldn't escale very else, except if we were to limit the filter each application can register to 1, but I thought that wouldn't go well in Chrome OS given there is a single D-Bus connection all the application filter would need to be combined in one to be registered.
I should have listed (3), which is to adopt ObjectManager which
eliminates the need of registration. As you recalled here, we'd like
to allow one client to have multiple monitors and (3) is a better
option in this case. The only thing that bothers me is how we inform
whether a given monitor was activated or not.
>
>>
>>
>> Thanks,
>> Miao