(Updated description)
Frontend: Android
Core requirements: I would like to write my own code and have it executed on the server. I want the whole backend to be automated (no admin creating tables in a database and inserting records). I still want to benefit from some basic BaaS functions like sending notifications to users, server maintenance, etc. to speed up the MVP development process.
Description of MVP functionality - survey app for entrepreneurs:
An entrepreneur adds the survey and information about it (questions, possible answers). It is sent to the server and saved. There are different variants of surveys (single choice, multi-choice, open questions, etc.), so a specific document has to be created automatically by the backend code. Analogically, the creation of a document for responses has to be handled by the backend. The same in the case of the document for the final results of the survey research.
The respondent receives a notification about an available survey. The mobile app retrieves information about the survey from the server and respondent completes the survey.
The application sends the respondent's responses to the server, the server saves the information.
X respondents perform points 2 and 3.
When the survey is completed (the number of respondents set by the entrepreneur is reached), the server processes the data, collected from all respondents and saves the results of the research (in the appropriate document).
The entrepreneur receives a notification about the completed research. The application downloads the results from the server.
Additional requirements:
Server has to be able to serve many entrepreneurs and respondents at the same time without any problems like data corruption.
No admin needed for creating tables or inserting records - Backend is 100% automated.
Certainly!
You could use your admin client side of the application to upload the questions, corresponding answers, answer response limit, and completion flag (Step 1).
You could then retrieve the data from your user side of the client app from Firebase Firestore, and have the users complete the surveys and upload the answers back to Firebase Firestore. (Steps 2 & 3).
Step 5 could be achieved by using Firebase cloud functions, which listen when a Firestore document variable has reached the response limit, it could then be marked as complete. Step 6 could also be activated in the cloud function, sending a notification via FCM to your admin client.
I know this answer doesn't go into any code specifics, just wanted to let you know that this is most certainly possible with Firebase :)
I would certainly recommend creating an admin client app in addition to the user client app, rather than placing them in the same app!
Related
Context: I am total Google Cloud begginer and I have just convinced my company headers to use Firestore Realtime Database for pushing transaction status to our mobile application. We have around 4 millions users that will use significantly our application for small money transfers. Now-a-days we use the concept of polling from Android/IOS to our Microservice endpoints and it will replaced by Firebase SDK imported to our Mobile app which will listen/observe to our Firestore Collection following few Firestore Rules. Since all money transfer will be confirmed/denied in short time (from few seconds to 1 or 2 minutes) the idea of replacing polling by a real reactive approach straigh from Firestore sounded and is already ongoing coding.
The issue: Firstly I don't what to compare solutions. It is just my reality: the prodution support operators must look after our internal Dashboard. Isn't allowed to them look at Google Dashboard Console (please accept this for this question). I need get on demand metrics of our FIrestore. It is nothing to do with Google pricing. It is just our demand: they want to see metrics like:
how many users listening at the same time now
how many users took some exception during connection
is there any user holding connection for more than X minute
when was the connection pick this morning
any exception of any type surrounding our Firestore database
I read Code Samples carefully follow the sample step-by-step trying to figure out some idea if there is some API providing the answers I am looking for.
So, my straight question is: is there such type of Google API providing metrics about my Firestore Database? Maybe following the same idea we found in Performance Monitor which works on Mobile side also some similar aproach on Firestore side.
*** Edited
Future readers may find worth read also about a way to get Firestore metrics info striagh from curl/postman
A couple of things: You mentioned both Firestore and Realtime Database; just wanted to make sure that you are aware that those are two different databases offered under the Firebase umbrella.
how many users listening at the same time now
is there any user holding connection for more than X minute
Yes, there's a dashboard: https://support.google.com/firebase/answer/6317517?hl=en. Including lots of options, like users active in the last 30 mins.
how many users took some exception during connection
any exception of any type surrounding our Firestore database
Yes, you can track errors and other logging via Stack Driver logging. These can give you reports on your cloud functions.
https://cloud.google.com/functions/docs/monitoring
Where can I find Stackdriver in Firebase console?
when was the connection pick this morning
For this one, I'm not sure if you mean A. when did somebody log on in the morning, or B. what was the time that there was the peak \ most usage. If B see 1. If A,
Real-time database has the concept of presence, which lets you know if a user is currently logged in or not. See examples here from the official documentation:
https://firebase.google.com/docs/firestore/solutions/presence
and this post
How to make user presence mechanism using Firebase?
Also applies to your
is there any user holding connection for more than X minute
..............
Edit in response to comments: I believe you are experiencing the XY problem https://meta.stackexchange.com/questions/66377/what-is-the-xy-problem where you are focused on a particular solution, even though your problem has other solutions. User metrics, database events, and errors are all accessible through both dashboards and cloud functions. You can cURL cloud functions if you wish, or set up cron functions to auto report, or set up database trigger functions to log errors. So, while the exact way you want this to work may not exist, you just need to connect existing tools to get the result you want.
I am developing an Android app which basically does this: On the landing(home) page it shows a couple of words. These words need to be updated on daily basis. Secondly, there is an 'experiences' tab in which a list of user experiences (around 500) shows up with their profile pic, description,etc.
This basic app is expected to get around 1 million users daily who will open the app daily at least once to see those couple of words. Many may occasionally open up the experiences section.
Thirdly, the app needs to have a push notification feature.
I am planning to purchase a managed wordpress hosting, set up a website, and add a post each day with those couple of words, use the JSON-API to extract those words and display them on app's home page. Similarly for the experiences, I will add each as a wordpress post and extract them from the Wordpress database. The reason I am choosing wordpress is that it has ready made interfaces for data entry which will save my time and effort.
But I am stuck on this: will the wordpress DB be able to handle such large amount of queries ? With such a large userbase and spiky traffic, I suspect I might cross the max. concurrent connections limit.
What's the best strategy in my case ? Should I use WP, or use firebase or any other service ? I need to make sure the scheme is cost effective also.
My app is basically very similar to this one:
https://play.google.com/store/apps/details?id=com.ekaum.ekaum
For push notifications, I am planning to use third party services.
Kindly suggest the best strategy I should go with for designing the back end of this app.
Thanks to everyone out there in advance who are willing to help me in this.
I have never used Wordpress, so I don't know if or how it could handle that load.
You can still use WP for data entry, and write a scheduled function that would use WP's JSON API to copy that data into Firebase.
RTDB-vs-Firestore scalability states that RTDB can handle 200 thousand concurrent connections and Firestore 1 million concurrent connections.
However, if I get it right, your app doesn't need connections to be active (i.e. receive real-time updates). You can get your data once, then close the connection.
For RTDB, Enabling Offline Capabilities on Android states that
On Android, Firebase automatically manages connection state to reduce bandwidth and battery usage. When a client has no active listeners, no pending write or onDisconnect operations, and is not explicitly disconnected by the goOffline method, Firebase closes the connection after 60 seconds of inactivity.
So the connection should close by itself after 1 minute, if you remove your listeners, or you can force close it earlier using goOffline.
For Firestore, I don't know if it happens automatically, but you can do it manually.
In Firebase Pricing you can see that 100K Firestore document reads is $0.06. 1M reads (for the two words) should cost $0.6 plus some network traffic. In RTDB, the cost has to do with data bulk, so it requires some calculations, but it shouldn't be much. I am not familiar with the pricing small details, so you should do some more research.
In the app you mentioned, the experiences don't seem to change very often. You might want to try to build your own caching manually, and add the required versioning info in the daily data.
Edit:
It would possibly be more efficient and less costly if you used Firebase Hosting, instead of RTDB/Firestore directly. See Serve dynamic content and host microservices with Cloud Functions and Manage cache behavior.
In short, you create a HTTP function that reads your database and returns the data you need. You configure hosting to call that function, and configure the cache such that subsequent requests are served the cached result via hosting (without extra function invocations).
I'm trying to get started implementing Web Push in one of my apps. In the examples I have found, the client's endpoint URL is generally stored in memory with a comment saying something like:
In production you would store this in your database...
Since only registered users of my app can/will get push notifications, my plan was to store the endpoint URL in the user's meta data in my database. So far, so good.
The problem comes when I want to allow the same user to receive notifications on multiple devices. In theory, I will just add a new endpoint to the database for each device the user subscribes with. However, in testing I have noticed that endpoints change with each subscription/unsubscription on the same device. So, if a user subscribes/unsubscribes several times in a row on the same device, I wind up with several endpoints saved for that user (all but one of which are bad).
From what I have read, there is no reliable way to be notified when a user unsubscribes or an endpoint is otherwise invalidated. So, how can I tell if I should remove an old endpoint before adding a new one?
What's to stop a user from effectively mounting a denial of service attack by filling my db with endpoints through repeated subscription/unsubscription?
That's more meant as a joke (I can obvioulsy limit the total endpoints for a given user), but the problem I see is that when it comes time to send a notification, I will blast notification services with hundreds of notifications for invalid endpoints.
I want the subscribe logic on my server to be:
Check if we already have an endpoint saved for this user/device combo
If not add it, if yes, update it
The problem is that I can't figure out how to reliably do #1.
I will just add a new endpoint to the database for each device the user subscribes with
The best approach is to have a table like this:
endpoint | user_id
add an unique constraint (or a primary key) on the endpoint: you don't want to associate the same browser to multiple users, because it's a mess (if an endpoint is already present but it has a different user_id, just update the user_id associated to it)
user_id is a foreign key that points to your users table
if a user subscribes/unsubscribes several times in a row on the same device, I wind up with several endpoints saved for that user (all but one of which are bad).
Yes, unfortunately the push API has a wild unsubscription mechanism and you have to deal with it.
The endpoints can expire or can be invalid (or even malicious, like android.chromlum.info). You need to detect failures (using the HTTP status code, timeouts, etc.) when you try to send the push message from your application server. Then, for some kind of failures (permanent failures, like expiration) you need to delete the endpoint.
What's to stop a user from effectively mounting a denial of service attack by filling my db with endpoints through repeated subscription/unsubscription?
As I described above, you need to properly delete the invalid endpoints, once you realize that they are expired or invalid. Basically they will produce at most one invalid request. Moreover, if you have high throughput, it takes only a few seconds for your server to make requests for thousands of endpoints.
My suggestions are based on a lot of experiments and thinking done when I was developing Pushpad.
Another way is to have a keep alive field on you server and have your service worker update it whenever it receives a push notification. Then regularly purge endpoints which haven't been responded to recently.
I am about to start working on the back-end for a mobile app (initially iOS/Android, later also website) and I am thinking whether Realm could fulfill all my needs.
The basic idea is that there are two types of users - customers and service-providers. The customers send requests to the server once in a while and are subscribed (real-time) for any event that might occur in relation to this request in the future. Each service-provider is listening for specific requests from all customers and is the one who is going to trigger various events (send data) for each of those requests.
From the Realm docs, it is obvious that the real-time data sync is not going to be a problem. The thing I am concerned about is how to model the scenario (customer/service-provider) in the Realm 'world'. Based on what I read, it is preferred to have one realm per user. Therefore, I suppose the user will register and will be given a realm. Then whenever he makes a request, it is going to be stored in his realm. Now the question is how to model the service-provider. There are going to be various service-providers each responding (triggering various kinds of events up to one hour after request) to different kinds of requests. (Each user can send any request and therefore be served by any service-provider.)
I read a bit about that Realm supports data sharing among different realms which could be a partial solution for this problem, however I was not able to find if this 'sharing' could share only particular requests. (Meaning each service-provider will get only requests intended for him.)
My question is whether this scenario is doable using Realm?
This sounds like a perfect fit for Realm's server-side event-handling. Put simply, Realm offers the ability through our Node SDK to listen for changes across Realms on the server.
So in your example, where each mobile user would have their own Realm, the URL for this would be /~/myRealm in which the tilde represents the Realm user ID. The Node SDK event handling API allows you to register a JS function that will run in response to changes represented by a Regex pattern for Realm URLs. In this case you could use: ^/([0-9a-f]+)/myRealm so that any time any user's myRealm updated, the server could perform some logic.
In this manner, the server via the Node SDK is really a "super-user" or service-provider as you describe. When an event fires, the JS function that runs is provided the Realm that was updated and a list of indexes pertaining to the objects in the Realm that were inserted, deleted, or modified. You can then perform any logic in JS, such as using the changed data to call out to another API or opening the Realm in question or any other and writing changes which will get pushed back out to the respective clients.
The full server-side event handling is part of Realm Professional Edition, but we recently released another way to interact with this called Realm Functions. This provides the ability through the server's dashboard to create the same JS functions that will run in response to changes across Realms. The developer edition support 3 functions so you can try it out immediately!
I've been putting together a mechanism to sync activity data collected by the MS Band with our backend via the cloud API and getting all the boilerplate setup for the OAuth flows... The intent being to periodically run this data through our backend processes to categorise periods of meaningful walk based activity.
I've been experimenting with the data available and as far as I can tell we cannot get access to the raw step data (or at a fine grained level )? We have successfully been able to request summary info by hour/day, however this is not fit for our purpose.
What I'd like is to access step data in the form [startTimeStamp,endTimeStamp,stepsTaken,...] where each record represents a continuous period of movement by the wearer.
We would also be able to work with data summarised by minute as this would give enough context to our use case.
Is this possible via the cloud API? or are there any plans to implement the Period "Minute" on the summary API endpoint?
https://api.microsofthealth.net/v1/me/Summaries/Minute?startTime=2015-12-09T14%3A00%3A00.369Z
If this isn't possible perhaps there is another way to make this data available? (via HealthKit on iOS or Fit on Android?)
As a complete alternate perhaps it might be possible to get the accumulated step data detail from the band via bluetooth in a similar fashion to the native MS Health App?
We already use the SDK to stream realtime Heart Rate data during user cardio sessions, but there appears to be no way to extract the historical step info from the band directly.
Thanks!
the Band itself monitors and logs the steps over time. When sync'ing, that log is transferred to the Cloud via the Microsoft Health app. The app then pulls the "steps for the day" from the Health service.
These logs are not exposed to apps via the SDK. The only way to calculate steps per custom short period yourself is to have your app sample the counter in the background on a frequent enough basis in order to do the calculation.