Hi Luiz, Thank you so much for your information. I created a test GATT server from the sample code(https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/test/example-gatt-server). I have 2 python scripts. In the "bt_read.py" I created, the Heart Rate Measurement(2A37) and Body Sensor Location(2A38) only have Read attribute. In the "bt_notify.py" I created, the Heart Rate Measurement(2A37) and Body Sensor Location(2A38) only have both the Read and Notify attribute. Here is what I did: I ran the "bt_read.py" and captured the btmon log. Then I ran "bt_notify.py" and captured the btmon log. I read both logs. But I don't see there is any info regarding the "Service Changed Indication". Here is the btmon log with both the Read and Notify attributes below. Thanks again for your help! ========================================================================= Bluetooth monitor ver 5.48 = Note: Linux version 4.19.35-g92e18fefc77 (armv7l) 0.809169 = Note: Bluetooth subsystem version 2.22 0.809182 = New Index: 00:16:A4:4A:2D:27 (Primary,UART,hci0) [hci0] 0.809187 = Open Index: 00:16:A4:4A:2D:27 [hci0] 0.809190 = Index Info: 00:16:A4:4.. (Cypress Semiconductor Corporation) [hci0] 0.809194 @ MGMT Open: bluetoothd (privileged) version 1.14 {0x0002} 0.809200 @ MGMT Open: bluetoothd (privileged) version 1.14 {0x0001} 0.809203 @ MGMT Open: btmon (privileged) version 1.14 {0x0003} 0.809276 > ACL Data RX: Handle 65 flags 0x02 dlen 8 #1 [hci0] 4.543721 ATT: Handle Value Notification (0x1b) len 3 Handle: 0x0016 Data: 64 > ACL Data RX: Handle 65 flags 0x02 dlen 11 #2 [hci0] 6.883753 ATT: Read By Group Type Request (0x10) len 6 Handle range: 0x0001-0xffff Attribute group type: Primary Service (0x2800) < ACL Data TX: Handle 65 flags 0x00 dlen 30 #3 [hci0] 6.884412 ATT: Read By Group Type Response (0x11) len 25 Attribute data length: 6 Attribute group list: 4 entries Handle range: 0x0001-0x0005 UUID: Generic Access Profile (0x1800) Handle range: 0x0006-0x0009 UUID: Generic Attribute Profile (0x1801) Handle range: 0x0234-0x023c UUID: Heart Rate (0x180d) Handle range: 0x023d-0x0240 UUID: Battery Service (0x180f) > ACL Data RX: Handle 65 flags 0x02 dlen 11 #4 [hci0] 6.944638 ATT: Read By Group Type Request (0x10) len 6 Handle range: 0x0241-0xffff Attribute group type: Primary Service (0x2800) < ACL Data TX: Handle 65 flags 0x00 dlen 26 #5 [hci0] 6.945293 ATT: Read By Group Type Response (0x11) len 21 Attribute data length: 20 Attribute group list: 1 entry Handle range: 0x0241-0x0250 UUID: Vendor specific (12345678-1234-5678-1234-56789abcdef0) > ACL Data RX: Handle 65 flags 0x02 dlen 11 #6 [hci0] 7.004723 ATT: Read By Group Type Request (0x10) len 6 Handle range: 0x0251-0xffff Attribute group type: Primary Service (0x2800) < ACL Data TX: Handle 65 flags 0x00 dlen 9 #7 [hci0] 7.005369 ATT: Error Response (0x01) len 4 Read By Group Type Request (0x10) Handle: 0x0251 Error: Attribute Not Found (0x0a) > HCI Event: Number of Completed Packets (0x13) plen 5 #8 [hci0] 7.005549 Num handles: 1 Handle: 65 Count: 2 > ACL Data RX: Handle 65 flags 0x02 dlen 11 #9 [hci0] 7.064450 ATT: Read By Type Request (0x08) len 6 Handle range: 0x0234-0x023c Attribute type: Characteristic (0x2803) < ACL Data TX: Handle 65 flags 0x00 dlen 27 #10 [hci0] 7.065112 ATT: Read By Type Response (0x09) len 22 Attribute data length: 7 Attribute data list: 3 entries Handle: 0x0235 Value: 123602372a Handle: 0x0238 Value: 123902382a Handle: 0x023b Value: 083c02392a > ACL Data RX: Handle 65 flags 0x02 dlen 11 #11 [hci0] 7.124428 ATT: Read By Type Request (0x08) len 6 Handle range: 0x023d-0x0240 Attribute type: Characteristic (0x2803) < ACL Data TX: Handle 65 flags 0x00 dlen 13 #12 [hci0] 7.125226 ATT: Read By Type Response (0x09) len 8 Attribute data length: 7 Attribute data list: 1 entry Handle: 0x023e Value: 123f02192a > HCI Event: Number of Completed Packets (0x13) plen 5 #13 [hci0] 7.125376 Num handles: 1 Handle: 65 Count: 2 > ACL Data RX: Handle 65 flags 0x02 dlen 11 #14 [hci0] 7.184416 ATT: Read By Type Request (0x08) len 6 Handle range: 0x0241-0x0250 Attribute type: Characteristic (0x2803) < ACL Data TX: Handle 65 flags 0x00 dlen 69 #15 [hci0] 7.185101 ATT: Read By Type Response (0x09) len 64 Attribute data length: 21 Attribute data list: 3 entries Handle: 0x0242 Value: 8a4302f1debc9a785634127856341278563412 Handle: 0x0247 Value: 8a4802f3debc9a785634127856341278563412 Handle: 0x024c Value: 8a4d02f5debc9a785634127856341278563412 > ACL Data RX: Handle 65 flags 0x02 dlen 11 #16 [hci0] 7.244526 ATT: Read By Type Request (0x08) len 6 Handle range: 0x024e-0x0250 Attribute type: Characteristic (0x2803) < ACL Data TX: Handle 65 flags 0x00 dlen 9 #17 [hci0] 7.246144 ATT: Error Response (0x01) len 4 Read By Type Request (0x08) Handle: 0x024e Error: Attribute Not Found (0x0a) > HCI Event: Number of Completed Packets (0x13) plen 5 #18 [hci0] 7.246564 Num handles: 1 Handle: 65 Count: 2 > ACL Data RX: Handle 65 flags 0x02 dlen 9 #19 [hci0] 7.304500 ATT: Find Information Request (0x04) len 4 Handle range: 0x0237-0x0237 < ACL Data TX: Handle 65 flags 0x00 dlen 10 #20 [hci0] 7.305951 ATT: Find Information Response (0x05) len 5 Format: UUID-16 (0x01) Handle: 0x0237 UUID: Client Characteristic Configuration (0x2902) > ACL Data RX: Handle 65 flags 0x02 dlen 9 #21 [hci0] 7.364540 ATT: Find Information Request (0x04) len 4 Handle range: 0x023a-0x023a < ACL Data TX: Handle 65 flags 0x00 dlen 10 #22 [hci0] 7.366242 ATT: Find Information Response (0x05) len 5 Format: UUID-16 (0x01) Handle: 0x023a UUID: Client Characteristic Configuration (0x2902) > HCI Event: Number of Completed Packets (0x13) plen 5 #23 [hci0] 7.366660 Num handles: 1 Handle: 65 Count: 2 > ACL Data RX: Handle 65 flags 0x02 dlen 9 #24 [hci0] 7.424617 ATT: Find Information Request (0x04) len 4 Handle range: 0x0240-0x0240 < ACL Data TX: Handle 65 flags 0x00 dlen 10 #25 [hci0] 7.426085 ATT: Find Information Response (0x05) len 5 Format: UUID-16 (0x01) Handle: 0x0240 UUID: Client Characteristic Configuration (0x2902) > ACL Data RX: Handle 65 flags 0x02 dlen 9 #26 [hci0] 7.484523 ATT: Find Information Request (0x04) len 4 Handle range: 0x0244-0x0246 < ACL Data TX: Handle 65 flags 0x00 dlen 10 #27 [hci0] 7.486104 ATT: Find Information Response (0x05) len 5 Format: UUID-16 (0x01) Handle: 0x0244 UUID: Characteristic Extended Properties (0x2900) > HCI Event: Number of Completed Packets (0x13) plen 5 #28 [hci0] 7.486520 Num handles: 1 Handle: 65 Count: 2 > ACL Data RX: Handle 65 flags 0x02 dlen 9 #29 [hci0] 7.544546 ATT: Find Information Request (0x04) len 4 Handle range: 0x0245-0x0246 < ACL Data TX: Handle 65 flags 0x00 dlen 24 #30 [hci0] 7.546011 ATT: Find Information Response (0x05) len 19 Format: UUID-128 (0x02) Handle: 0x0245 UUID: Vendor specific (12345678-1234-5678-1234-56789abcdef2) > ACL Data RX: Handle 65 flags 0x02 dlen 9 #31 [hci0] 7.604713 ATT: Find Information Request (0x04) len 4 Handle range: 0x0246-0x0246 < ACL Data TX: Handle 65 flags 0x00 dlen 10 #32 [hci0] 7.606323 ATT: Find Information Response (0x05) len 5 Format: UUID-16 (0x01) Handle: 0x0246 UUID: Characteristic User Description (0x2901) > HCI Event: Number of Completed Packets (0x13) plen 5 #33 [hci0] 7.606747 Num handles: 1 Handle: 65 Count: 2 > ACL Data RX: Handle 65 flags 0x02 dlen 9 #34 [hci0] 7.664243 ATT: Find Information Request (0x04) len 4 Handle range: 0x0249-0x024b < ACL Data TX: Handle 65 flags 0x00 dlen 10 #35 [hci0] 7.665862 ATT: Find Information Response (0x05) len 5 Format: UUID-16 (0x01) Handle: 0x0249 UUID: Characteristic Extended Properties (0x2900) > ACL Data RX: Handle 65 flags 0x02 dlen 9 #36 [hci0] 7.724603 ATT: Find Information Request (0x04) len 4 Handle range: 0x024a-0x024b < ACL Data TX: Handle 65 flags 0x00 dlen 24 #37 [hci0] 7.726315 ATT: Find Information Response (0x05) len 19 Format: UUID-128 (0x02) Handle: 0x024a UUID: Vendor specific (12345678-1234-5678-1234-56789abcdef4) > HCI Event: Number of Completed Packets (0x13) plen 5 #38 [hci0] 7.726625 Num handles: 1 Handle: 65 Count: 2 > ACL Data RX: Handle 65 flags 0x02 dlen 9 #39 [hci0] 7.784545 ATT: Find Information Request (0x04) len 4 Handle range: 0x024b-0x024b < ACL Data TX: Handle 65 flags 0x00 dlen 10 #40 [hci0] 7.785996 ATT: Find Information Response (0x05) len 5 Format: UUID-16 (0x01) Handle: 0x024b UUID: Characteristic User Description (0x2901) > ACL Data RX: Handle 65 flags 0x02 dlen 9 #41 [hci0] 7.844187 ATT: Find Information Request (0x04) len 4 Handle range: 0x024e-0x0250 < ACL Data TX: Handle 65 flags 0x00 dlen 10 #42 [hci0] 7.845777 ATT: Find Information Response (0x05) len 5 Format: UUID-16 (0x01) Handle: 0x024e UUID: Characteristic Extended Properties (0x2900) > HCI Event: Number of Completed Packets (0x13) plen 5 #43 [hci0] 7.846215 Num handles: 1 Handle: 65 Count: 2 > ACL Data RX: Handle 65 flags 0x02 dlen 9 #44 [hci0] 7.904466 ATT: Find Information Request (0x04) len 4 Handle range: 0x024f-0x0250 < ACL Data TX: Handle 65 flags 0x00 dlen 24 #45 [hci0] 7.906160 ATT: Find Information Response (0x05) len 19 Format: UUID-128 (0x02) Handle: 0x024f UUID: Vendor specific (12345678-1234-5678-1234-56789abcdef6) > ACL Data RX: Handle 65 flags 0x02 dlen 9 #46 [hci0] 7.964493 ATT: Find Information Request (0x04) len 4 Handle range: 0x0250-0x0250 < ACL Data TX: Handle 65 flags 0x00 dlen 10 #47 [hci0] 7.966067 ATT: Find Information Response (0x05) len 5 Format: UUID-16 (0x01) Handle: 0x0250 UUID: Characteristic User Description (0x2901) > HCI Event: Number of Completed Packets (0x13) plen 5 #48 [hci0] 7.966489 Num handles: 1 Handle: 65 Count: 2 > HCI Event: Number of Completed Packets (0x13) plen 5 #49 [hci0] 8.203559 Num handles: 1 Handle: 65 Count: 1 > ACL Data RX: Handle 65 flags 0x02 dlen 7 #50 [hci0] 11.833674 ATT: Read Request (0x0a) len 2 Handle: 0x0236 < ACL Data TX: Handle 65 flags 0x00 dlen 7 #51 [hci0] 11.840770 ATT: Read Response (0x0b) len 2 Value: 0663 > HCI Event: Number of Completed Packets (0x13) plen 5 #52 [hci0] 12.078687 Num handles: 1 Handle: 65 Count: 1 > ACL Data RX: Handle 65 flags 0x02 dlen 9 #53 [hci0] 14.055212 ATT: Write Request (0x12) len 4 Handle: 0x0237 Data: 0100 < ACL Data TX: Handle 65 flags 0x00 dlen 5 #54 [hci0] 14.056230 ATT: Write Response (0x13) len 0 > HCI Event: Number of Completed Packets (0x13) plen 5 #55 [hci0] 14.329045 Num handles: 1 Handle: 65 Count: 1 < ACL Data TX: Handle 65 flags 0x00 dlen 11 #56 [hci0] 15.078671 ATT: Handle Value Notification (0x1b) len 6 Handle: 0x0236 Data: 0e750000 > HCI Event: Number of Completed Packets (0x13) plen 5 #57 [hci0] 15.330353 Num handles: 1 Handle: 65 Count: 1 < ACL Data TX: Handle 65 flags 0x00 dlen 9 #58 [hci0] 16.071839 ATT: Handle Value Notification (0x1b) len 4 Handle: 0x0236 Data: 066e > ACL Data RX: H On Mon, Jan 25, 2021 at 9:59 AM Luiz Augusto von Dentz <luiz.dentz@xxxxxxxxx> wrote: > > Hi Kenny, > > On Sun, Jan 24, 2021 at 10:42 PM Kenny Bian <kennybian@xxxxxxxxx> wrote: > > > > Hi Luiz, > > > > Thank you so much for your reply. I appreciate it. > > > > By "registering the services", do you mean "RegisterApplication()" in > > https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/test/example-gatt-server#n656? > > If that is the case, I believe I already registered the services. > > I checked the files in /var/lib/bluetooth. According to > > https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/settings-storage.txt#n321, > > there should be a "[ServiceChanged]" section in the "info" file. But I > > don't see it in the "info" file. Is there a way to tell the "Service > > Changed Indication" is actually working? > > Let's suppose the "Service Changed Indication" is already enabled, is > > there a way for the mobile app to check on their side to tell which > > service(s) got changed? > > HCI traces (btmon) should be able to tell you if it has been > subscribed or not, if there is an Indication in it it probably means > the remote has subscribed. > > > Thanks again for your help. > > > > On Sun, Jan 24, 2021 at 7:35 PM Luiz Augusto von Dentz > > <luiz.dentz@xxxxxxxxx> wrote: > > > > > > Hi Kenny, > > > > > > On Sun, Jan 24, 2021 at 12:45 AM Kenny Bian <kennybian@xxxxxxxxx> wrote: > > > > > > > > Hello, > > > > > > > > We implemented a GATT server on Linux in Python. The code is based on > > > > the code sample(https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/test/example-gatt-server). > > > > The BlueZ version is 5.48. But we found a problem. The cached data in > > > > /var/lib/bluetooth caused the mobile app to crash if some > > > > characteristics are changed. After some research, we found "Under BLE > > > > standard 'Generic Attribute'(0x1801), there is a Characteristic > > > > 'Service Changed' (0x2A05) with 'indicate' property", see > > > > https://github.com/espressif/esp-idf/issues/1777. > > > > > > > > The questions we have: > > > > How to enable the "Service Changed Indication"(0x2A05) in the > > > > bluetooth? Is there any code example in Python? > > > > > > If you are registering the services with Bluetoothd then it should > > > generate the service change automatically: > > > > > > https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/src/gatt-database.c#n1185 > > > > > > When a new service is registered it is indicated here: > > > > > > https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/src/gatt-database.c#n1452 > > > > > > > > > -- > > > Luiz Augusto von Dentz > > > > -- > Luiz Augusto von Dentz
