Develop Reference

how to send the updated code for the ble to the ble device using our application

I am creating an android application I want to integrate a feature in my app where I can send a zip file to the ble device to update the code of my peripheral from my application.
this is the ota part.
Using bluetooth.
Like how nrf simulator app does that by selecting from the phone storage dfu.

send data using bluetooth to android mobile without an app?

I am working on iBeacon based project to send the push notification to Android devices using Bluetooth wireless technology. Is there any way to send the push notification to Android device without any installed app over the Bluetooth? Basically, iBeacon is connected to Pi using Bluetooth and Pi (Pi 3 with inbuilt Bluetooth) will communicate with Android devices using Bluetooth. Following are the possible ways to send data/notification to Android devices:
By an installed app
Push notification through chrome using web-socket
But above both ways are not useful for my task. Kindly allow me to know if there is any way to do it.

You can use Google Nearby to send a notification to the device on beacon detection. Tapping the notification can bring up a website or open a Google Play Store page to install your app.
https://developers.google.com/nearby/

Is it possible to enable bluetooth of another android phone by my android phone

I want to develop an android app which should have functionality to enable bluetooth of another android phone.

This will only be possible if you install on both phones an app. At phone 1 you have the app where you can turn on/off bluetooth of the other phone. The app on phone 2 receives this on/off message and turns bluetooth on or off using the Bluetooth permission.
But I think your idea does not make sense since you need to communicate between those two apps that app2 knows to turn on bluetooth. So this communication would only work via internet/wlan.
Without installing an app on phone2 this is not possible due to security reasons.

Is it possible to remote android phone from a Bluetooth device?

I have a Bluetooth device which can receive a data from the android phone. When it receive a string as 'Request', the device will send a control message to the phone 'Open'. Based on the control message, the android phone can call an Intent service as open a calling. Due to security, I am not sure is it possible in android version 5.0 to 6.0? Can you give me some suggestion?

Yes, It is possible inside your app to handle messages received from other devices.

Android Bluetooth LE push notifications

I've been working with iOS ANCS BLE notifications, it works great because our BLE accessory can receive app notifications 'out of the box' without installing our own app on the Apple device.
I'm newer to the Android development environment. Is there an equivalent for Android or does an Android app need to be running to push notifications over BLE. If an app is required is there a GATT standard I should be following similar to ANCS ?

I have been working with IOS ANCS as well, and like you mentioned it works very well without the need of installing an app on the app device. But Android does not provide something similar to this. You will need to write your own app and install it on the android device.
Its good to point out that IOS does not give you access to notifications but android does, which is why it its possible to write your own app.
Cheers.

Yeap you can use ANCS for android just add service UUID and Characteristics UUID your app and add characteristic in GATT service.Than callback