I have an app build with electron and on startup it does a large amount of API calls to setup the UI. This seems to render my UI unusable until it has all finished. I've read adding this code to the main process will have similar issues (lock up entire window). All the functions that make these API calls and save data to a vuex store return promises.
I've looked into creating child processes require('child_process').fork('/worker.js')); however I can't include my helper modules or classes from within those workers (SyntaxError: Unexpected token import).
What is the best way to do asynchronous work without blocking the UI, while still having access to my renderer classes and singletons?
This is the boilerplate I'm using if it helps https://github.com/SimulatedGREG/electron-vue/tree/master/template
Turns out I was calling vuex commit very fast which is a synchronous action and was causing the rest of the application to lock up as a result
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I'm just getting started with Meteor and I have a REST API hooked up with publish / subscribe that can periodically update per client. How do I run this behavior once globally and only refresh as long as a client is connected?
My first use case is periodically refreshing content while clients are active. My second use case is having some kind of global lock to make sure a task is only happening once at a time. I'm trying to use Meteor to make a deployment UI and I only want 1 deployment to happen at once.
publish/subscribe will work automatically only when clients are connected. However, do not put any functionality that you want to control amount of execution times in publish or subscribe functions. They might run arbitrary amount of times.
If you want some command to be executed by any client use Meteor.methodss on server side, and call it explicitly with Meteor.call from client template event.
To make sure that only one deployment happens at any given time, simplest way would be to create another collection, called for example, CurrentDeployments.And any time deployment script function in Meteor.methods is executed, check with CurrentDeployments.findOne if there are ongoing deployment or not, and only call new one if none is running.
As a side bonus, subscribe to CurrentDeployments in client, to disable 'deploy' button in case one is already running.
How does a meteor application deal with server-side methods for inserting and updating? especially:
if an application is temporarily offline (available through appCache-package) and a call to a server-side
method happens: is optimistic-ui possible? how does it work?
do i
need to define the (usually server-side) methods in /libs
directory instead of /server?
Thank you
You should put your collections under libs and use Collection.allowand Collection.deny to control the permission on both server and client side.
In meteor, most of the time you're dealing with client side data, Meteor will save them to the Minimongo and synchronize your update to server when available.
Regarding to method definition, it really depends on where you want to use it, only a few things you'll put on server, e,g, authentication logic, encryption salt
So I'm integrating SignalR and HotTowel, although really I think this is a matter of how to integrate with Durandal itself.
The issue is I have obviously multiple views. Some of these views I want to respond to SignalR messages. The question is how to do this integration considering that SignalR events have to be started before I call SignalR's hub start method.
So take the example I have view1 and view2. I want each to do something when a SignalR message is received and in the context of that view (so let's say update the DOM somehow). It's an SPA obviously so calling the SignalR start method for each view seems like a bad idea, so starting SignalR once at boot sounds like the right plan, but at that point my views may not have been loaded, and still how would I ensure that my events have the right context for the page.
This is based on my understanding that all events for SignalR have to be registered before I call start. Any thoughts clever people of StackOverflow?
Edit to expand on the problem
Part of the website involves uploading files for parsing and processing to import into a database. I have created a view where the file is selected and uploaded (using FineUploader) to a WebApiController. The controller does the basic steps of checking the uploaded file and then starts an async task to actually do the parsing and processing, while immediately returning the basic "Yep that uploaded fine" message.
This causes the list of 'in progress' files to refresh and the file appears with an 'Uploaded' status. As the async task occurs, the file is parsed, then processed against a rules system, and then finally imported into another back end data store. As each of these status changes occur, SignalR sends messages to the client to notify them of these changes, and thus update the status against the filename. In order for this to occur I must attach a function to the event as it received in SignalR. That even needs some kind of reference to my view (actually viewmodel) so it can update the correct value.
As SignalR should be started once with a call to hub.Start(), I am trying to do it during the 'boot' phase. However when my SPA starts, that view has not been loaded, and therefore neither has that viewmodel, and therefore my function that is responsible for initialising SignalR can have no understanding of the view/viewmodel it must update.
Examples I've seen on using SignalR show it being used in one view, but that doesn't really work surely if you need it in multiple views (you can't just keep calling hub.start() can you)?
Sorry, if this still doesn't make sense I'll post some code or something.
If you use
$.connection.myHub.on("myMethod", function (/* ... */) { /* ... */ });
instead of
$.connection.myHub.client.myMethod = function (/* ... */) { /* ... */ };
you can add client-side hub methods after calling $.connection.hub.start();
Meteor's documentation states:
In Meteor, your server code runs in a single thread per request, not in the asynchronous callback style typical of Node
Do they actually mean?
A) the server is running multiple threads in parallel (which seems unusual within the Node.js ecosystem)
or
B) There is still only a single thread within an evented server and each request is processed sequentially, at least until it makes calls to resources outside the server - like the datastore, at which point the server itself is handling the callbacks while it processes with other requests, so you don't have to write/administer the callbacks yourself.
Brad, your B is correct.
Meteor uses fibers internally. As you said, there's only one thread inside an evented server, but when you do (eg) a database read, Fibers yields and control quickly gets back to the event loop. So your code looks like:
doc = MyCollection.findOne(id);
(with a hidden "yield to the event loop, come back when the doc is here") rather than
MyCollection.findOne(id, function (err, doc) {
if (err)
handle(err);
process(doc);
});
Error handling in the fiber version also just uses standard JavaScript exceptions instead of needing to check an argument every time.
I think this leads to an easier style of code to read for business logic which wants to take a bunch of actions which depend on each other in series. However, most of Meteor's synchronous APIs optionally take callbacks and become asynchronous, if you'd like to use the async style.
I have a vb.net 4.0 UI that basically allows users to search for data on a SQL Server 2008 database and update/manipulate it. All of the communication with the database is done through stored procs. One of the update procs may take up to 6 minutes to process - currently the users just see the "processing..." message until the update has completed, and then they are shown the results.
I think this is a good candidate for a background task. I would like the users to be able to invoke the request, and then continue to do other work in the UI. When the task finishes it would notify them of the results. Can I accomplish this with threading? I'm new to threading but given some literature and an example or 2 I could be on my way. I've done some Googling but it's not apparent in the examples whether the user can continue working in the UI while the task executes. Are there other options to accomplish what I have described?
thanks.
There a number of options for running a background task, but in .net 4.0, the neatest is probably to make use of the TPL (Task Parallel Library). You can execute a background task as follows:
Task.Factory.StartNew(()=>SomeMethod());
Detail info can be found here.
http://msdn.microsoft.com/en-us/library/dd460717.aspx
Remember though, that if you need to perform any UI updates when returning from this call, you will need to dispatch that back on to the UI thread.
The TPL also has mechanism for running a continuation on the Dispatcher thread.
Whilst the background task is running, the UI thread will not be blocked.