I am new to mobile development and I undertook some freelance work. Now I am required to display a page with top N nearest places (businesses registered with us).
I am wondering what the best way of going about this is, from my experience it would seem that I would want to do this calculation in my back-end server.
I have a NodeJS server, however, it seems the server will be concurrently doing a lot of other work just verifying JWT tokens and what not, I have seen that android provides a method to easily do these calculations (Location). I have also read that there are some google API's one could use.
The idea I have is that I can pull my places with their lat, long from my database then the user sends lat,long and my server calculates top N results and sends to user.
What would you recommend and why?
Thanks!
The short answer is: Server.
But why?
The job of the server to make it so no one can use the app who is not authorized to do so. Thats one of many jobs anyway. However, you should send your location to the server, the server makes the API call, and returns the N closest locations.
You take that response, parse it, and fill in a view as you would like. With the server doing the heavy lifting, you can then also keeps track of something better, like how many calls, which calls, location of calls, etc etc.
Related
I would like to preface my query by saying that I am an absolute beginner when it comes to programming but I really want to realise this project so every little help is deeply appreciated.
I am trying to build an app that needs accurate train data for it to work and from my current research as there is not central government API for railway data , the only accurate data source for train location that I can find is in an other app that uses crowd sourcing to pinpoint the location.
I wanted to know if it is possible to fetch that train data from that app and then use it on my own as it would make my app a lot more reliable and accurate.
The issue currently is that the app only shows graphical representation of the data thats being fed to it from its servers , so I wanted to know if there is a way to access the actual data being sent to the app.
Thank you.
Let me clarify, this is a very broad question and hence will have a very broad answer too.
As far as I can understand from your question is that you want to show TRUE location on a map.
For this, you will have to understand the complete Tracking scenario. Let me explain it to you step-wise below:
There is an app, installed on a device (user) which fetches the GPS location (REAL) data and keeps sending it to a server (backend).
This GPS data is the Lattitude-Longitude coordinates of the device (user).
The server stores this information in their database for queries.
There is another user, different than the one currently sending the location data, who wants to know the location of the first user. The app which he is using will request the server (backend) to send the location data for the device. Which, in turn, will send the latest location data (LatLng coordinates) to the current app. This app will then show the location data over a map.
Now, usually, this process is followed to show one-to-one location data. However, in scenarios like Train Location etc, servers usually collect pool of location data, being received from several users, to cross-verify the actual location (average out, mean, location optimization algorithms etc.) and then display that information over a map.
As per your requirement, which I can understand, you want to get this REAL data directly from either another app or from the server. If you want to get the location data from the server, you will need an API, which serves as a Request-Response platform. However, if you are looking to get the data from another app, it would rather be simpler to get the location data directly, as your APP will also be installed on the device itself.
I would suggest you to kindly read about getting and processing location data, communication with servers over API etc for better understanding and implementation of your requirements.
I am working on an android application which can find users nearby.
I need help in design that application.
I am thinking:
1. When I start my application, I use API to find my location.
2. I send that location to my server.
3. server returns a list of other users nearby.
My question is how can the server keeps track of a list of users who are nearby?
Do I create a background service on phone who will report users location periodically?
And the server maintains a list of all users' location?
Is that approach feasible?
You're on the right track. If you are able to geocode or retrieve your current location lat/lon coordinates, there might be a library that can help you out.
My first thought was the Geocoder (https://github.com/alexreisner/geocoder) library for ruby, it offers a slick API that allows you to easily find other nearby objects:
if obj.geocoded?
obj.nearbys(30) # other objects within 30 miles
obj.distance_from([40.714,-100.234]) # distance from arbitrary point to object
obj.bearing_to("Paris, France") # direction from object to arbitrary point
end
There are other options that are easy enough too, if you're using PostgreSQL with PostGIS, you have some utility functions that I'm sure you could use to query 'nearby' users. (Found an example, "What is the best way to find all objects within a radius of another object?" http://postgis.net/docs/manual-1.3/ch03.html#id434832)
So the overall workflow would be:
Request lat/lon from device API
Send lat/lon to server/web service
Use library/database to find other users within a specified radius
Send list of users back down to device
I suspect the most difficult aspect would probably be keeping the lat/lon of other users up to date, but that's a different problem to solve.
Edit:
Just to clarify, you'll definitely want to store all the logged in users' lat/lon inside of some sort of database on the server. It's a very feasible approach, but you'll have to keep it up to date and be able to determine somehow if the data is stale (if that's important to your application). Whether you use a background service to keep that information up to date is kind of up to you and the constraints of the problem you're trying to solve.
So basically I have made a few small apps in the past, but this is my first 'proper' app.
One of the main features of the app, and the bit that I am struggling with is that I need to be able to populate a ListView with all of the other users logged into the app, however I only want to display users that are within a set distance, for example 10 meters.
I tried using Bluetooth to achieve this, however that didn't work. I would now like to use location services to do this.
My idea is to have to app send the location of the device to an external server every few minutes and then all other devices can run a function that compare their location to others found on this server.
Does anybody know how I could go about achieving this, or know of any tutorials that cover a simpler topic. Thank you
Disclaimer: I'm not an android developer, but this seems like a design issue not a implementation issue so hopefully my comments below might be of some use...
I don't think there's an API that you can just set to "true" to get this functionality, so I think you're going to have to custom craft all the moving parts (and there are a couple). I would think the general process would be something like:
On the client:
User on client logs in to server with some sort of identity (i.e. "user#gmail.com")
Every X minutes the client app gets the current location (i.e. "100N 90E") and sends it up to a server
Every X minutes the client polls the server to see who is within 10 miles (i.e."joe#gmail.com", "mary#gmail.com")
On the server:
Needs some sort of authentication endpoints for getting a user's identity
Needs an endpoint for users to register their location ("user#gmail.com is at 100N 90E")
Needs a service to find out how far each user is from each other
Needs an endpoint to return the users within X miles (list generated from #3)
Each one of these steps shouldn't be difficult on their own and you can actually get pretty nuts with the distribution algorithm on server step #3 if you wanted to.
Some questions you can ask yourself are:
"How do I set up a server to listen for HTTP requests?" - Take a look into Node.JS for a simple solution
"How do I get a user's location in android?" - Easy google search finds plenty of documentation
"How do I write a service to continuously perform actions?" - Node.JS would again help with this
"Where will I store user's locations and their distances from each other?" - You can look into a NoSQL option like CouchBase or MongoDb. Or you could use MySQL for a more structured database.
Hope this helps...
The situation: I have many real life locations with specific information associated with them, and updated frequently. I am unsure of how to store this information for use in an android application.
My original thought was storing the data on some server/cloud source/database, reading from the server from each Activity in the app to make sure the info is up to date, and update the server with any changes that may or may not have been made.
For example: there are 200 people inside the library, one person leaves.
So we would read the number of people from the server, display this on the app, person leaves, subtract one, send the new number back to the server.
Would this be an incorrect approach? I'm fairly new to Android in general, and I really have no experience on how to approach this type of situation, what services to use, etc.
I would look into using Parse, its a pretty sweet way to power the backend, and their website is very detailed in explaining how to use it.
I have the following case: Notify (txt /sms) the recipient of a package when the courier (who has a mobile device, access to internet) is within 30min from the recipient. / using Google Fusion tables/.
Is this possible and could someone draw, in general, the process and schema? I don't need a code, just would like to understand how the elements are connected. Links to guides/articles for Google Fusion tables can be connected with SMS notification also could be useful.
Thank you.
I'm still not sure if I understand your requirements, but maybe something like that could work.
The components you need:
A software on the couriers mobile to track his position. This could be done automatically or via an explicit action of the courier (e.g. newer browsers allow to get the geolocation).
The address of your recipients, this would make sense to store in Fusion Tables. Just tell Fusion Tables to geocode the addresses of your customers.
A service to determine "30min from recipient", maybe this could be done using Google Directions Service. Otherwise you could define a distance (like 20km away) rather than a time, which makes it much easier to implement
You need a service to send text/sms
With such a setup you could regularly use the couriers position in a spatial query on your customers data in Fusion Tables. This would answer a question like: Is there a customer in 20km distance of the courier?
If this is the case, you could trigger your text / sms service to notify your customers.