I understood Firebase Storage not to have offline capability (because of open git requests for the feature and no mention of it in documentation) but I appear to observe it. When the client is offline and I attempt to get data from Storage, the return closure is expectedly not called. However, when the client comes back online, that closure is immediately called (returning the file from Storage), which appears to suggest that the request to get data was cached when the client was offline. Is this indeed the case?
There is no caching, but the SDK will retry with the hopes that a future request will succeed.
Related
I have a single page web application and I have NOT enabled offline persistence.
A component in this application has subscribed to a document using the onSnapshot function and recieves updates.
An other component in the same application instance reads the same document using the get function. Will firebase provide the same instance of the document, which is already loaded in the subscription? Or will it do a new request to the server?
A third component in the same application instance subscribes to the same document. Will this trigger new requests to the server?
What about reading and subscribing collections?
What about subscribing to a collection which is already subscribed, but the second subscription is called after narrowing results with the where function? Will Firestore reuse the already loaded complete collection and filter in my client instance? Or will it make server requests?
As a rule, Firestore does maintain a local cache, mostly for latency/response, not for cost savings. That said, if a document can be read from the cache, it will be, saving the read. I wouldn't try to "design" it in, however; memory limits and other considerations mean you don't really know what's in the cache or not, and shouldn't know.
IF this performance/cost is important to you, it's better to combine Firestore with something like Redux (which I do) to maintain local "sets" of documents to reduce round-trip calls, and Listeners to keep Redux current.
yes. Firebase stores documents and collections in cache memory. when you are offline you can access cache copy of data. also you can manage cache copy of documents and collections.
read this offical docs for more info
https://firebase.google.com/docs/firestore/manage-data/enable-offline
Using
FirebaseDatabase.getInstance().setPersistenceEnabled(true);
Is this guarantee to download the data only one time across the App life/App restarts even if the user has good connection?
N.B: The official docs isn't clear ( at least for me) at this point.
By enabling persistence, any data that the Firebase Realtime Database client would sync while online persists to disk and is available offline, even when the user or operating system restarts the app. This means your app works as it would online by using the local data stored in the cache. Listener callbacks will continue to fire for local updates.
The sole goal of enabling persistence is to ensure that the app continues to work, even when the user starts it when they don't have a connection to the Firebase servers.
The client does send tree of hash values of its restored local state to the server when it connects, which the server then uses to only send the modified segments back. But there is no guarantee on how much data this sends or saves.
If you want to learn more about what Firebase actually does under the hood, I highly recommend enabling debug logging and studying its output on logcat.
For more on the topic, see these questions on Firebase's synchronization strategy.
I am building some internal API for my apps/website with Firebase Functions. Internal API as in to let my apps/website to process something on server side, its doesn't mean to open to public use.
My Apps is built with ionic and website is built with angular.
I noticed the one of Firebase Functions Pricing calculation include "Invocations". Is that Invocations means every time when I call the API equal to 1 Invocation? If yes, then the API might be abused by end user, since they able to view the website source and found the API.
I been searching solution in google, some of them suggest to enable authentication and cors, to avoid abuse of the usage. But authentication and cors still counting the Invocations right?
My code structure:
client call API by get/post method, pass user TOKEN that get from Firebase Authentication
request reach the Firebase Functions
server will check the preflight info by using CORS, as well as validate the TOKEN.
Return error if didn't pass on the (3), else proceed to execute the function.
So I assume if end user inspect my web source code and get the API URL, they can simply spam my API right? Then my bill will burst because of the load of Invocations.
If you suspect that your project is being abused, which is always possible, contact Firebase support to work towards a resolution.
I am attempting do the following
write a document to server.
wait for the success event and check for metadata to confirm if its written to server
if it is not written to server even after the time out (using a timer) undo the write operation.
this is for WEBRTC calls so if a user attempts a call but was offline and closes the app since it did not succeed. after a long time the receiver would receive a call and would be weird.
There are no undo operations in Firestore. The client SDK tries doesn't really give any way to discern if the app is online or offline - it simply tries its best to service the requests that you give it via the API.
If you want to perform some operation while only online, then use Cloud Functions to make an HTTP request to backend code that performs the actions you want. If the app is offline, the HTTP request will obviously fail, and you can decide what you want to do from there.
In an interesting blogpost about 'Firebase Authentication with the Firebase 3.0 SDK and Auth0 Integration', it is stated that:
You can even have Firebase communicate with Webtask!
Now I can imagine the (web)client triggering a Firebase operation and subsequently a Webtask, but not the other way around. Or am I missing something?
Firebase can run as a serverless app, but it can also run on the server. You can even have Firebase communicate with Webtask! (sic!)
I think that paragraph is misleadingly phrased, perhaps it was just added at the last minute to spark interest. You can have a webtask communicate with Firebase, not the other way around. You don't "run Firebase" on your server either.
TL;DR: A client application may call a webtask with an HTTP request, and that task can read/write the database, but not in any other order.
Here's a quick and dirty reality check as of Nov. 2016:
The Realtime Database by itself does not provide you with a way of executing code. This includes responding to database changes and user requests, handling fan-in and fan-out operations, etc. There is no support for webhooks either.
Which means you have to provide your own execution environment for such logic on a custom server, or you can try to cram as much as possible into the client code. This is a pretty exhaustive topic by itself.
Webtasks are short-lived functions that respond to HTTP requests. Their lifecycle always starts with a request, so they are not fit for continuously watching the database for changes. But they are perfectly valid for handling requests coming in from your client application.
As you can store "secrets" for the webtasks, you can authenticate the task on an admin access level. This gives you the possibility to verify client tokens – which should be sent along with the request –; perform complex authorization and validation, and perform RTDB write operations you wouldn't trust the clients with.
Or trigger external services securely. The possibilities are close to endless.