Proper way to sync clients?

[ajmoore79]

I'm trying to make sure I'm correctly updating my client application with the latest scope setup when the application is updated. I have a xamarin app on android using an sqlite database. On the server side, an IIS web service .net core application.

Everything works fine SO FAR, but I wanted to make sure this is a recommended way to sync my clients and get them up to date.

The method I'm using -

-each time I need to update my EF model, I publish a new scope setup on the web service using the names "v1","v2", etc.
-The clients using the original scope "v1" still seem to sync with the server
-The clients updated to the new application, are only using scope "v2" using this method:

*Each time the android application starts to sync-
-First, EF migrations updates the tables on the client to the latest version when the latest app is ran.
-Next, I use the local orchestrator to get all scopes on the client. Looping through the scopes, if the name does not match the latest "v2", then it is deprovisioned locally then the scope is deleted locally.
-Next, I get the scope information for "v2" from the web service orchestrator.
-Next, I check the local orchestrator to see if "v2" exists. If it does not, then I then provision the local client with "v2".
-Next, I sync with "v2" and use the SyncSetup that was pulled from the server.
-On the next sync, the process happens again, but nothing is deprovisioned or provisioned, because "v2" exists locally.

This works, but I'm not sure what issues this will cause if any. I'm not totally understanding on how I'm supposed to provision the clients when I need to change the database so this is what I came up with.

Aaron

[Mimetis]

For clients that are updating their local database using EF migrations, you know that they should use another scope.
So far, for these clients:

• 1 EF migrations update the tables on the client to the latest version when the latest app is starting.

Just after the EF Migrations, you already know that V2 scope is not existing, as you just made the EF Migrations.
Of course, you can check it by getting all scopes:

• 2 localOrchestrator instance gets all scopes and see if a "V2" if exists

IF exists, I guess you are good to make a sync.

Otherwise:

• 3 remoteOrchestrator gets the scope information for "V2" from server side
• 4 localOrchestrator call ProvisionAsync using the remote scope retrieved on step 3
• 5 localOrchestrator now gets the ScopeInfoClient instance and update the information using the ShadowScope method to be sure we are going to synchronize from the good timestamp (and not from the begining)

See https://dotmimsync.readthedocs.io/Provision.html#client-1

• 6 You can sync
• 7 Optionnaly you can remove the old scope on the local client

Make sense ?

[ajmoore79]

Thanks, This looks very similar to what I had mentioned except for the shadowscope park. I'll check it out today and get back to you.

[ajmoore79]

If I look at the link to the docs, it says-
"// TRICKY PART
/*
The scope v1 is new.
If we sync now, since v1 is new, we are going to sync all the rows from start
What we want is to sync from the last point we sync the old v0 scope
That's why we are shadowing the metadata info from v0 into v1
*/"

In my case, I don't mind if the client gets all rows again- do I actually need to do the shadowScope part? And If I do not do the ShadowScope, will any updated rows still sync to the server?

Aaron

[ajmoore79]

ok- sorry my 2nd question might of not been clear. If I do not do a shadowScope, will I lose any of the changed rows that did not get uploaded to the server yet?

[ajmoore79]

Ignore my last question. I see what you are saying. It does loose the changes. One more question- what happens when a client skips a version and performs a shadowScope. For instance, can I perform a shadowScope from v0 to lets say v5 without issues?

[Mimetis]

Basically, ShadowScope will configure the ScopeClientInfo like:

• V5 will sync all data from last time V0 syncs, to now.

[ajmoore79]

So you are saying it is ok to skip a shadowScope for v1-4?

[Mimetis]

I see what you are saying. It does loose the changes

Indeed, if you don't ShadowScope() a previous ClientScope, DMS sees this new ClientScope as "IsNew==true" and then will make a first initialize sync from server, without trying to upload anything (the first Sync is always "kind of" Download Only)

if you ShadowScope() this new ClientScope, then DMS is making a bidirectional sync, assuming that rows are already tracked.

So you are saying it is ok to skip a shadowScope for v1-4?

Yes.
But what is the goal, in your scenario, of scope v1, v2, and v3 ?