We are working on an application that will be offered both as a web-based and as a cross-platform desktop solution by means of Electron.
Due to customer requirements, the desktop client cannot make use of "the cloud" to store data; all data should be stored in the local machine or, even better, the user should have the option to keep the database/data file on an external HDD so that another user on the same local network can use the same data file.
We've been looking at NeDB, PouchDB, etc, but all these use either Web SQL or IndexedDB on the browser itself to store the data.
NeDB can theoretically use the file system but that seems only possible for Node Webkit apps.
Another option is of course MongoDB, but it requires setting up a site on a web server. Seeing as how our users will set that up in on their own machines, that will work for one user only but would make it very hard for them to share the data (note: assume users with little technical know-how).
Is there a way to force NeDB to persist data in a file instead of the in-browser database?
Alternatively, does any one know of a file-based, compact database that plays well with electron/node?
We'd preferably like to use a NoSQL database, but options of file-based SQL databases will be considered as well.
I have some experience with NeDB in an Electron app and I can say it will definitely work on the filesystem.
How are you initializing NeDB (or whatever your database choice is)? Also, are you initializing it in the main or renderer process? If you can share that, I think we could trace the issue to a configuration issue.
This is how you start NeDB with a persistent data-store that saves to disk.
var Datastore = require('nedb')
, db = new Datastore({ filename: 'path/to/datafile', autoload: true });
I think MongoDB is going to be overkill for an Electron app (it's meant to be really a high performance, distributed database running in the cloud).
Another option you could consider is LevelDB (a key/value store that can persist to the filesystem) which is popular in the node community. (EDIT 4/17/17 IndexedDB uses LevelDB underneath the hood, so if you go that route, may as well just use that)
One aspect I would definitely evaluate carefully is: How difficult is this database going to be to package and distribute? How do I integrate it into my build system? Level and NeDB can be included simply via npm install and any native code compiling is handled seamlessly with node-gyp, which is as simple as it gets. However, bundling Mongo, for example, will require some work to get a working build for each different platform.
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THE PROBLEM
I'm writing a mobile app which will allow a user to log in, save some preferences that must be stored in a database, and display congressional bills to the user.
I've only written simple RESTful services with PHP and MySQL in the past. I'd like to take advantage of newer technologies, and am a little lost on general direction.
The bill data (formatted as JSON) can be gathered by running the scrapers found here. Using docker, I managed to set a working directory and download the files on my local machine.
I've designed a MySQL database for holding the relevant bill and user data.
I started to mess around in Google Cloud Platform, and read the doc that describes different models. I'm thinking of a few different ideas, but aren't familiar with GCP or what I can actually accomplish.
QUESTIONS
1) What are App Engine, Compute Engine, and Container Engine each for? I get the gist that Container Engine holds different instances of stuff you load up with docker, and that Compute Engine sets up a VM, but I don't really understand the relationships. How should I think of them?
2) When I run those scrapers from the shell, where are the files being stored, and how can I check on them? On my computer, I set a working directory, but how do directories work in GCP? Is it just a directory in the currently selected VM, or is this what Buckets are for?
IDEAS
1) Since my bill data already comes as JSON, should I skip the entire process of building a database for the bills and insert them into Firebase somehow? Is this even possible? If so, am I stuck using Firebase's NoSQL, or can I still set up a relational database?
2) I could schedule the scrapers to run periodically, detect new files, and run a script to parse the JSON and insert new bill data into my a database (PostgrSQL?/MySQL?). Then I would write an API.
3) Download the JSON files to a bucket, and write an API that reads from them. Not sure how the performance would compare to using a DB.
I'm open to other suggestions as well.
For your use case (stateless web application), App Engine is probably your best choice. The Google documentation has severalcomparisons of your computing options
You can use App Engine with PHP and cloud-hosted MySQL if you want, which could be a good way to get your toes wet without going in over your head.
I am writing a Chrome Packaged App that uses the IndexedDB for data storage. Chrome allows me to view the contents of the database, but I can't find any way to manually change the data. I need to update this data from time to time because, you know, I'm still writing the app. Any idea how to manually change the data in the database?
Any changes to the IndexedDB database have to be performed via the IndexedDB API. There are no utilities, data editors, query apps, loaders, importers, or any other kind of external utility, such as there is for MySQL, SQLite, Oracle, or any other such database.
Furthermore, it's not even theoretically possible to write such a utility, because an IndexedDB database is sandboxed inside a single app, and no other app can access it.
What I do is incorporate the needed update forms and commands (delete database, create database, count rows, etc.) as modules inside the app, perhaps accessible from a Maintenance or Admin menu item. Obviously, this is a lot of work, but there is no other way if you're using IndexedDB.
In addition, I have a "load database" menu item that loads it from JSON in an external file. I do that from time to time when I want the app to have some initial data, or test data. But, this is just an example of what I said in the first sentence, above.
HTML5 Storage Manager All in One folks promise they'll have indexedDB support soon.
They use some tricks to open extension window inside the same domain as debugged page, thus making indexedDb accessible.
Doesn't work successfully at the time of this writing, though.
I would like to give a web app with a PostgreSQL database 100% offline functionality. In an ideal case the database should be completely replicated in the browser per user, and synchronized when online. So that the same code can be used to talk to both the offline and online database. I know this is possible with PouchDB and CouchDB, but have not found a solution that works with PostgreSQL. Is this at all possible?
Short answer: I don't know of anything like this that currently exists.
However, in theory, this could be made to work...(long answer:)
Write a PostgreSQL backend for levelup (one exists for MySQL: https://github.com/kesla/mysqldown)
Wire up pouch-server to read/write from your PostgreSQL db using pouchdb's existing leveldb adapter (which in turn will have to be configured to use your postgres backend). Congrats, you can now sync data using PouchDB!
Whether an approach like this is practical in reality for your application is a different question you'll have to answer.
You may be wondering, for example, "will I be able to sync an existing complex schema with multiple tables to the client with this approach?" The answer is probably not - the mysqldown implementation of leveldown uses a single MySQL table with three fields: id, key, and value (source), and I imagine any general-purpose PostgreSQL adapter would be similar (nothing says you can't do a special-purpose adapter just for your app though!).
On the other hand, if you were to implement a couchdb-compatible API (or a subset- you may not need attachments, for example) over your existing database schema, there's nothing stopping you from using PouchDB on the client to talk directly to that as if it were an actual CouchDB - just pop in the URL and call replicate()! Implementing the replication protocol might be a fair bit of work, since you'd need to track revisions and so on somewhere - but again, technically not impossible!
There are also implementations of levelup's backend storage that are designed for browsers. See level.js, which could be another way to sync between a server-side Postgres levelup backend and the browser.
TL;DR: There's tons of work being done around Javascript databases right now. Is syncing with Postgres impossible? probably not. Would it be a lot of work? Definitely. Worth it? Who knows, but it would be cool.
Without installing PostgreSQL on the client? No. Obviously you can cache data for offline use, but an entire RDBMS+procedural languages in Javscript, no.
I have a rather simple idea for an iPhone app. What I need to accomplish:
Allow login of users (which means I'll have to store usernames, passwords, and other account info).
Allow users to submit strings that other users can view.
Attributes attached to each string that must be tracked (i.e. "votes, views, comments, etc.).
As such, I assume I'll need to start learning about databases and working between a server and client. I've gotten my feet wet in OSX/iOS programming (specifically Objective-C) before. I want to learn how one can accomplish a data-based application and the needs I listed above.
I've done some light research and discovered something called SQLite (free and open-source is always good). Is this the right path to achieve what I want to do? I'm a total "noob" when it comes to this field of server/client/data "stuff".
Your help is greatly appreciated.
SQLLite is more like a local database. Really, the database that you will use is unimportant. It sounds like a project with webservices. Inside your webservices, you might connect to a Microsoft SQL Server or anything you want.
I think you should study how to setup a webservice that can be accessed in your code. Webservices is not an Objective-C topic, it applies to any platform. Your project is more like a web development project.
You can save user's credentials in keychain.
#Kinderchocolate is right about introducing database into your project.
It hears about a app which need transmitting data among clients.It means your need server database and local database.
For server database,I recommend you to use Parse.Parse is a platform which provide a convenient way to use their server database with Objective-c in your app.This tool will save many times and energy(it's not necessary to learn PHP,Apache,Mysql).Parse is not free of course,but it has a free period and enough for you to examine your idea.
Here's Parse!.
For local database,I recommend you to use Core Data,Which is provided by XCode.Core data is so strong to meet your need.You can find a way to use Core Data in many books.
Go try Firebase for database in the cloud. (On the server). In Swift 4 there is complete support for Firebase and SQLite
I'd like to be able to have an admin app and a client app for my project. Ideally, I'd like to be able to have a shared MongoDB collection. How would I be able to accomplish this?
I tried creating collections with the same name in two different apps, but found that Meteor will keep the data separate. Any idea what I can do? Thanks.
export MONGO_URL=mongodb://localhost:3002/meteor
Then run meteor app, it will change the default database meteor uses. So share databases or collections won't be a problem!
For administrative reason, I would use a individual MongoDB server managed by myself other than using meteor's internal MongoDB.
A reasonable question and probably worth a discussion in excess of this answer:
The MongoDB connection is handled by the Meteor application process itself and this is - as far as I read and understood - part of Meteors philosophy targeting an approach that might be described like: One data source serves one application belonging to it but many clients subscribing to it.
This in mind, combining "admin" and "client" clients in one application (i.e. your Meteor app) is probably the preferred way.
From a server administrative view, however, connections are handled by Meteor in that way that there is always the default local data source which resides in your project directory (.meteor/local/db, try meteor mongo --url to obtain the mongo connection string while the meteor application process is running). But nevertheless one may specify an optional data source string for deployment purposes like described in these deployment instructions.
So you would need to choose a somewhat creepy way of "local development deployment" for your intended setup to get working. Or you go and hack the sources and... no, forget it. You probably want your application and clients to take advantage of e.g. realtime UI updates (publish) and that is why the Meteor application is tied to an "application data source" and vice-versa by now. When connecting from another app, events that trigger changes in the model would not be transported across those applications. The mongoDB instance itself of course isn't aware of that.
I'm sure the core team won't expose the data source connection to a configuration section for considered reasons unless they extend their architecture with some kind of module concept which provides a common service layer of core Model/Collections abstraction across Meteor instances - at least supporting awareness of publish/subscribe events.
Try this DDP test I hacked together for a way to bridge two apps (server A and B).
Both servers can manipulate data, but data is only stored in one collection on server A.
See this link as well