强制数据与Android的firebase服务器同步

Question

I'm working on an Android app which has sqlite database. I wanted to add synchronisation for the db with some cloud service and across multiple devices of the same user. There will be login mechanism and data will be different for different users. The synchronisation will be for logged in users only. For others the data will reside locally only.

I found firebase very interesting and started adding it for the synchronisation. I cannot completely replace sqlite with firebase because I need to provide offline experience for users that are not logged in.

I implemented syncadapter for the sync operation. And I'm doing the sqlite<->firebase two way synchronisation there.

I'm using firebase transactions to avoid conflict from multiple devices. But I read that firebase Android initially writes on offline database and sync with server at a later time. This may cause transactions to fail sometimes creating inconsistencies in data. And also I think transactions are not maintained across app restarts.

If there was an option to disable offline feature for firebase and each request is sent to server instantly and finish with a successful completion or a failure I may be able to implement the synchronisation correctly here.

So is there any way to force to do write and read directly to and from server? Is there a better way to do this ensuring good conflict handling across multiple devices? Is firebase not suited for this purpose?

Answer 1

If someone is still looking for the solution.

While using firebaseRef.addValueEventListener() initially it loads data from available cache, then requests updated data from server.

In order to retrieve latest server side data, We made sure user is connected to internet and also connected to firebase server database.

        DatabaseReference connectionRefrence;
        ValueEventListener connectionValueEventListener;

        connectionRefrence = FirebaseDatabase.getInstance().getReference(".info/connected");
        connectionValueEventListener = new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                boolean connected = dataSnapshot.getValue(Boolean.class);
                if (connected) {
                    printLog("connected");
                    // TODO :: Perform your operation here with live data

                } else {
                    printLog("not connected");
                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
                printLog("connection cancelled");

            }
        };

I hope it helps.