I'm using Atmosphere 1.0.12 to push data from a server to my clients in a Grails 2.2.1 application.
The application is an auction Web site, and I'm pushing updates such as prices, bidder information, and status messages. The goal is to change information dynamically on the page without requiring a page reload. Some of the information is very easy to update, such as a price change after a bid. But other things require some logic, such as telling a user they are the high bidder, or have been outbid.
Currently I've implemented an Atmosphere service (LotPushService) to push the information.
However, after these updates, certain information is missing, such as user information and locale, because this isn't sent along with the updates and isn't being handled by the service.
Is it possible to use the service to render page templates when it sends the push update, so that session and state information is preserved?
Are there any best practices for this situation?
Have you configured the BroadcasterCache? At least you should in order to not lose messages.
Related
I'm in the process of planning the development of a mail-server to hand the sending of email across our multiple websites. Below is a description of what we are planning to implement and I'd like your opinion/suggestions.
We use ASP.NET MVC and have many web-sites hosted on Azure. We currently send mail internally within each of the web applications using SMTPServer.Send(). Obviously this is not the ideal way to send emails when you have a decently busy set of websites because the send mail call is blocking and cannot guarantee mails are sent. With this I'm worried out getting an influx of mail requests when we launch our next website (we think it'll get a decent amount of traffic and lots of emails will be sent).
My plan of action : to build a centralised mail-server that runs in the background (we use azure and this will be simply another web-application). When each one of our web applications wants to send a mail, instead of doing this internally, it'll call a web method on the mail-server called sendMail() this function will accept certain parameters and insert the mail parameters, content etc. into a database. The mail server will then poll the database at fixed time intervals, select a set of unsent emails and attempt to send them using the same SMTPServer.Send() function. If an email fails for some reason we won't flag it as sent and in the next poll interval the email will be selected again and another send attempt will be made. (we will cap the number of send attempts to say 20).
This will allow each of the websites to run smoothly without having loads of blocking send mail calls internally and the mail server will handle all the sending sequentially and in a controlled environment as a separate standalone web-application.
Thanks in advance!
Looks like a good design, Don't know the entire scenario which let to you building something like an email server. The problem has been solved well by using a service that already exist like Office 365.
Your design is good, My suggestions would be the following,
You can use Azure WebJobs to build the polling agent. You can make the web job run as a scheduled web job that does the polling and sending the mail and it can be written very clean as a simple console app.
You can use Azure API App to build the SendMail() call and you can use the Azure AD Auth on the API to authenticate the caller of the API using the Authentication and Authorization feature to easily secure your email server. You can also enable CORS easily as well to make sure you receive requests from other websites and process it.
Some issues I foresee for you,
Volume and Scaling : You can only process so much email between each polling. If you cannot then you will need to create another polling agent which will making things complicated as they need to know they are picking different sets of emails to send. If you volume is going to be low you should be fine.
Challenge : Why can't the websites send the mail them selves ? And then record it on the database for tracking. All you have to do build module or a component that they use on their web page to create and send the mail. Polymer 1.0 works well for this scenario.
Hope this helps to get you started.
With my rails application, I'm supposed to provide following features:
There a limited number of users interacting with my system (in order of 10 to 20)
Like any normal mail client users should be able to have an inbox page showing received message, response to individual email and etc....
The mail client part cannot be an external application, they want everything packaged into a single application!
Normally These emails should be stored for future use
In order to send a receive email, we do not need to setup a mail server. They will provide the server and we will fetch the message with POP3 or something else. Same goes for sending emails.
The application itself often needs to look into these message as well, so it should be able to access corresponding email objects.
Separate part of these applications can be handled with individual gems such as Mailman, ActionMailer, and etc...
But what would be your suggestions to get this done?
I suggestion customizing an open source solution according to your needs. This is a gem/project that you should look at https://github.com/mailboxer/mailboxer It has all the features that you mentioned and its straightforward in its customizations.
I am working in a Rails application and below is the scenario requiring a solution.
I'm doing some time consuming processes in the background using Sidekiq and saves the related information in the database. Now when each of the process gets completed, we would like to show notifications in a separate area saying that the process has been completed.
So, the notifications area really need to pull things from the back-end (This notification area will be available in every page) and show it dynamically. So, I thought Ajax must be an option. But, I don't know how to trigger it for a particular area only. Or is there any other option by which Client can fetch dynamic content from the server efficiently without creating much traffic.
I know it would be a broad topic to say about. But any relevant info would be greatly appreciated. Thanks :)
You're looking at a perpetual connection (either using SSE's or Websockets), something Rails has started to look at with ActionController::Live
Live
You're looking for "live" connectivity:
"Live" functionality works by keeping a connection open
between your app and the server. Rails is an HTTP request-based
framework, meaning it only sends responses to requests. The way to
send live data is to keep the response open (using a perpetual connection), which allows you to send updated data to your page on its
own timescale
The way to do this is to use a front-end method to keep the connection "live", and a back-end stack to serve the updates. The front-end will need either SSE's or a websocket, which you'll connect with use of JS
The SEE's and websockets basically give you access to the server out of the scope of "normal" requests (they use text/event-stream content / mime type)
Recommendation
We use a service called pusher
This basically creates a third-party websocket service, to which you can push updates. Once the service receives the updates, it will send it to any channels which are connected to it. You can split the channels it broadcasts to using the pub/sub pattern
I'd recommend using this service directly (they have a Rails gem) (I'm not affiliated with them), as well as providing a super simple API
Other than that, you should look at the ActionController::Live functionality of Rails
The answer suggested in the comment by #h0lyalg0rithm is an option to go.
However, primitive options are.
Use setinterval in javascript to perform a task every x seconds. Say polling.
Use jQuery or native ajax to poll for information to a controller/action via route and have the controller push data as JSON.
Use document.getElementById or jQuery to update data on the page.
Say my user is viewing messages/index, and someone else sends him a message. I'd like the user's view to update in real-time to reflect the new message, kind of like how Twitter lets me know there are more messages on my timeline. Are there any examples of this being done in Rails?
You can either use AJAX to poll the server for updates on a regular basis (pull model), or use the Juggernaut plugin or similar to enable the server to send updates to the client (push model). Note that this requires Flash to be installed on the client.
DUI.stream from digg might be the solution you are looking for. It keeps an open xhr stream that you can keep on adding objects to to send to the user. It has a ruby client example
I am to build a web application which will accept different events from external sources and present them quickly to the user for further actions. I want to use Ruby on Rails for the web application. This project is a internal development project. I would prefer simple and easy to use solutions for rapid development over high reliable and complex systems.
What it should do
The user has the web application opened in his browser. Now an phone call comes is. The phone call is registered by a PBX monitoring daemon. In this case via the Asterisk Manager Interface. The daemon sends the available information (remote extension, local extension, call direction, channel status, start time, end time) somehow to the web application. Next the user receives a notified about the phone call event. The user now can work with this. For example by entering a summary or by matching the call to a customer profile.
The duration from the first event on the PBX (e.g. the creation of a new channel) to the popup notification in the browser should be short. Given a fast network I would like to be within two seconds. The single pieces of information about an event are created asynchronously. The local extension may be supplied separate from the remote extension. The user can enter a summary before the call has ended. The end time, new status etc. will show up on the interface as soon as one party has hung up.
The PBX monitor is just one data source. There will be more monitors like email or a request via a web form. The monitoring daemons will not necessarily run on the same host as the database or web server. I do not image the application will serve thousands of logged in users or concurrent requests soon. But from the design 200 users with maybe about the same number of events per minute should not be a scalability issue.
How should I do?
I am interested to know how you would design such an application. What technologies would you suggest? How do the daemons communicate their information? When and by whom is the data about an event stored into the main database? How does the user get notified? Should the browser receive a complete dataset on behalf of a daemon or just a short note that new data is available? Which JS library to use and how to create the necessary code on the server side?
On my research I came across a lot of possibilities: Message brokers, queue services, some rails background task solutions, HTTP Push services, XMPP and so on. Some products I am going to look into: ActiveMQ, Starling and Workling, Juggernaut and Bosh.
Maybe I am aiming too hight? If there is a simpler or easier way, like just using the XML or JSON interface of Rails, I would like to read this even more.
I hope the text is not too long :)
Thanks.
If you want to skip Java and Flash, perhaps it makes sense to use a technology in the Comet family to do the push from the server to the browser?
http://en.wikipedia.org/wiki/Comet_%28programming%29
For the sake of simplicity, for notifications from daemons to the Web browser, I'd leave Rails in the middle, create a RESTful interface to that Rails application, and have all of the daemons report to it. Then in your daemons you can do something as simple as use curl or libcurl to post the notifications. The Rails app would then be responsible for collecting the incoming notifications from the various sources and reporting them to the browser, either via JavaScript using a Comet solution or via some kind of fatter client implemented using Flash or Java.
You could approach this a number of ways but my only comment would be: Push, don't pull. For low latency it's not only quicker it's more efficient, as your server now doesn't have to handle n*clients once a second polling the db/queue. ActiveMQ is OK, but Starling will probably serve you better if you're not looking for insane levels of persistence.
You'll almost certainly end up using Flash on the client side (Juggernaut uses it last time I checked) or Java. This may be an issue for your clients (if they don't have Flash/Java installed) but for most people it's not an issue; still, a fallback mechanism onto a pull notification system might be prudent to implement.
Perhaps http://goldfishserver.com might be of some use to you. It provides a simple API to allow push notifications to your web pages. In short, when your data updates, send it (some payload data) to the Goldfish servers and your client browsers will be notified, with the same data.
Disclaimer: I am a developer working on goldfish.
The problem
There is an event - either external (or perhaps internally within your app).
Users should be notified.
One solution
I am myself facing this problem. I haven't solved it yet, but this is how I intend to do it. It may help you too:
(A) The app must learn about the event (via an exposed end point)
Expose an end point by which you app can be notified about external events.
When the end point is hit (and after authentication then users need to be notified).
(B) Notification
You can notify the user directly by changing the DOM on the current web page they are on.
You can notify users by using the Push API (but you need to make sure your browsers can target that).
All of these notification features should be able to be handled via Action Cable: (i) either by updating the DOM to notify you when a phone call comes in, or (ii) via a push notification that pops up in your browser.
Summary: use Action Cable.
(Also: why use an external service like Pusher, when you have ActionCable at your disposal? Some people say scalability, and infrastructure management. But I do not know enough to comment on these issues. )