How to add add, insert and remove BLE services dynamically at run time and if I have to send multiple data under one service

[Ayu7]

if I have to send multiple data under one service 

like: Service 1(Information)

Hardware Revision String

Model Number String, the

Regulatory Certification Data List 

Then what should be the proper format (like string, array, individually or something else) of sending data? 

[Hung Bui]

Hi Ayu,

Any data sending over BLE is a byte array. 

So you can either make different characteristic for each of the data you want to send. Or you can use one single characteristic and send all data via this characteristic. 
You can simply use the first byte in the array to tell which type of data containing in the array. 

[Ayu7]

Ok, but you missed first question, that 

How to add add, insert and remove BLE services dynamically at run time

[Hung Bui]

Hi again, 
If you use nRF5 SDK and softdevice, then it's not possible to remove a BLE service. You can add more service after initializing the softdevice but you can not remove. 
If you want to remove a service/characteristic you would need to disable softdevice and initialize it again. 

When you add more service/characteristic, you need to request the peer to do a new service discovery to update the new service/characteristic. 

[Ayu7]

Ok got it thanks.  Kindly clear one thing in multiple services if let's say two services have the same characteristics but have a different function then the custom UUID will be the same or different.

E.g.:-  Service 1 (Distributed System Information)

             Characteristics:  Node 1 (properties: Read) 

                                         Node 2 (properties: Read)

Service 2 (Control)

             Characteristics:  Node 1 (properties: Write) 

                                         Node 2 (properties: write)

Then Node 1 and Node 2 of both services will have the same uuid or different?

[Hung Bui]

Hi Ayu, 

There is no problem for two identical services or characteristics in the attribute table. 
The service discovery process will go through and read the handle ID (the index of them in the attribute table) to identify them, not the UUID.  Handle ID will then be used by the client to access the server. 

[Ayu7]

Hi thanks for you response. Can you provide any source from where I can refer that how to add services or characteristics dynamically?

[Hung Bui]

Hi Ayu, 
We currently don't have an example of doing so. But you can add more service by simply define the service and call sd_ble_gatts_service_add() , sd_ble_gatts_characteristic_add. The same as how you normally define a service/characteristic. 

[Ayu7]

what about service change characteristics

[Hung Bui]

Hi Ayu, 

You only need service changed indication if you update the attribute table when you are already in a connection. 

To do that, you would need to the service changed characteristic (included by default) then you need to call sd_ble_gatts_service_changed() to send the indication. 
Please take a look at this ticket: RE: I give up; how do I do a service changed? 

The example  you should have a look is ble_app_gatts

[Ayu7]

Hi Hung, thanks for last response,

1- Currently I have used two dks one for peripheral and one for client but I am not able to understand the seral monitor result. Can you explain.

2- And how to do same by  nrf connect app and dk.

3- So, what I am understanding is  when ever I am clicking button 3, a new service is getting created and client is discovering it with NRF_BLE_GATTS_C_EVT_DISCOVERY_COMPLETE and then notify that service changed received with NRF_BLE_GATTS_C_EVT_SRV_CHANGED. But let say I don't want click the Button 3 or any button and want to add services on peripheral side dynamically then how to do this. any reference or example?

[Hung Bui]

Hi Ayu, 
Sorry for late response. We are under reduced staff in the summer. 

1. Please study the code and check where the log is printed. 

2. Please verify if you can add new service by using a phone to see after you add a service would you have more service when you disconnect and then connect. 

3. I don't really understand you. If you don't want to click a button, you can change the code to do it based on something else, timer or other event. I don't see any limitation on why you can't change that.