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Mobile Sound Tracker Application Architecture

I have an assignment, but I can't seem to get my head around it. I've been tasked to create a mobile app on Android Studio using the microphone sensor to record audio (Parameters: Duration & frequency). The data/sample is then stored locally, perhaps using SQLite to store the id, date, time, location and sample. Let's say after 10 samples (this is where it starts to get confusing for me), the samples are bundled up and sent to the communication server which I believe OkHttp client is used in this case. The data gets sent to a local server (Apache?) and a website (Springboot) is used to retrieve the information and show the samples on Google Maps.
https://imgur.com/a/3cXzCQl
Link to application architecture is above. I have no doubt it is wrong, but would love some insight on it please. Also, I very new to all of this so I'm sure there are a lot of gaps in my message above. If you have any questions please feel free to ask!
Technologies I've been recommended to use:
Local Server: Apache
Website: SpringBoot
Communication tool: OkHttp
Android application: Android Studio

how to create instant messaging app in android

I want to implement an instant messaging feature in my android app which will show the chat list of the current user and the conversation with each of them. I want to know which is the best option for doing so because i have heard about various feature like pusher,gcm,xmpp,etc.
I am using retrofit 2.0,php and mysql now in my app to create messaging feature,everything is working out great but but i cant figure out how to show the message received or send in the conversation instantly because for that network request call has to called every time the received or send and i have a feeling i might not be good idea as it will slow down app or something.
Any help will be appreciated
Thanks in advance

If I were you I would look at https://socket.io/. There is also a demo project for Android chat app

What is the established way to request data from an android device

I currently have an small application that I have been using to learn java/android programming. Right now I have a setup were the app on one phone sends a request (via sms) to another phone running the same app. The remote phone receives the request and sends back some info. Next I would like to try this from the web. Is there an established "best" way to to this?
I was thinking I would have a web server send requests to the device via google cloud messaging and then have the device return the data directly to the web server. (Not that I really know how to do any of that just yet).
I see that there is a google cloud messaging return path (send messages from the device to the google cloud server, but it seems very new, do I need something like that? The main thing I want is to be able to ask the phone to do something when I want, not have it poll to see if there is a request, or just periodically update some status.
UPDATE:
Thanks to the answers below for confirming to me that I was on the right track.
I now have some basic functionality.
I started out using this gcm android demo code
https://code.google.com/p/gcm/source/browse/#git%2Fgcm-client%2Fsrc%2Fcom%2Fgoogle%2Fandroid%2Fgcm%2Fdemo%2Fapp%253Fstate%253Dclosed
and this ruby gem
https://github.com/spacialdb/gcm/blob/master/README.md
between the above two I was able to send a message to my phone pretty easily.
To get the round trip working, I setup a very simple rails app on heroku.
I included a modified version of the sample code in the gcm gem in a controller and then used
HttpPatch (needed for rails 4) to send a post/patch from my phone to my web app, the controller then echoes the message back to my phone.
I guess it would be nice to get the two way gcm stuff to work, but I am not sure there are any gems that handle that, and I am not qualified to handle a task like that :)

I would say it's the right call: Google Cloud Messaging for Android
From the site Android Developer:
This could be a lightweight message telling your app there is new data
to be fetched from the server (for instance, a movie uploaded by a
friend), or it could be a message containing up to 4kb of payload data
(so apps like instant messaging can consume the message directly).
In this case you don't want to fetch data from the server but you want to send them.
You can send them in different ways. I would suggest, since you are learning, to try a RESTful solution using one of the implementation of JAX-RS.

As a short and direct answer for beginner : GCM (Google Cloud Messaging) would solve your issue. However, if your app turned out to be something bigger, other more technical and complicated solutions are present too.
see this link.

Android with google app engine (java)

I'm trying to connect my android application to the Google App Engine. I followed this google tutorial for a standard example.
My problem is that when I follow the tutorial correctly and I try to execute it, my server doesn't give me back a hello message. In debug mode I discovered that my Async thread that contacts the server just doesn't execute. Any thoughts?
I get a Threadpoolexecutor.runworker popup with source not found.

I'm not sure if this helps, but I noticed I get the same problem only when I have many of the same thread running concurrently.

Syncing Android and Server

I don't know what this is called, but it is something like syncing android application and a Web server. Examples are RSS Feeds and Weather Forecast
Does anyone know the concept behind developing application? I mean how do you sync the Android phone with a web server. Is there any programming needed in the server side and the client side(Android)
Are there any programming books that tackles this subject? Thanks.

What should I do to connect to Server from eclipse - Android?
check the whole conversation here

The server should make the data available in a meaningfull parsable format (for machines). For example RSS/XML feeds, etc. Your application should poll frequently and updates the status/screen.