I'm developing a software system which receives information (which is saved to a database) and when any information is received (new insert in a specific table) an alert should be seen in the screen in the information center, so proper action can be taken.
I'm writing an application with ASPNET MVC, SQL Server 2008 Express, SQL Agent free for that version of SQL Server, Entity Framework 4, Visual Studio 2010, etc.
Right now, I've set the database and a SQL job that monitors the table each minute, if there is a new records an email is sent to same addresses. My problem is...What then? Which would be the best architecture to follow?
A couple of option I thought about are:
1) In the job connect to a web service and that web service an the web service can open a popup
2) The web page could be pooling the database table to know if there are new records
Is there any way to make push to the web page instead of the page pooling the database server?
I know maybe windows application would fit better here, but right now I must stick with ASPNET MVC as I already started and don't want to create another application.
Thanks! Daniel
Is there any way to make push to the web page instead of the page pooling the database server?
HTML5 WebSockets. Draft, pretty new, specification is still subject to change, to all browsers implement it. You will need a WebSocket Server. If you go that route make sure you read this guy's blog. He is behind Laharsub which is a must try server.
I'm pretty sure you are able to use Silverlight to push data down to the client. Here is a pretty good overview that I read a while back. HTML5 might be a better way to go. But with such limited support it's almost not worth it at this point. Granted the Silverlight application might be out of reach to, but it's still a possibility.
I would suggest that you look into (complex) event processing, or stream processing -- at least to get the feeling for architecture of these systems.
The idea is to capture a stream of events before they reach database, route them (process) within the event processor and put them in the DB from there -- treating the DB as only one of event destinations (subscribers).
Take a look at Streambase, ruleCore, and many others.
These were all developed for the type of scenario you described.
Try to see the problem from the other angle. Develop a web client that reads the database every minute and compare to last pull ...
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I'm designing a database monitoring application. Basically, the database will be hosted in the cloud and record-level access to it will be provided via custom written clients for Windows, iOS, Android etc. The basic scenario can be implemented via web services (ASP.NET WebAPI). For example, the client will make a GET request to the web service to fetch an entry. However, one of the requirements is that the client should automatically refresh UI, in case another user (using a different instance of the client) updates the same record AND the auto-refresh needs to happen under a second of record being updated - so that info is always up-to-date.
Polling could be an option but the active clients could number in hundreds of thousands, so I'm looking for a more robust and lightweight (on server) solution. I'm versed in .NET and C++/Windows and I could roll-out a complete solution in C++/Windows using IO Completion Ports but feel like that would be an overkill and require too much development time. Looked into ASP.NET WebAPI but not being able to send out notifications is its limitation. Are there any frameworks/technologies in Windows ecosystem that can address this scenario and scale easily as well? Any good options outside windows ecosystem e.g. node.js?
You did not specify a database that can be used so if you are able to use MSSQL Server, you may want to lookup SQL Dependency feature. IF configured and used correctly, you will be notified if there are any changes in the database.
Pair this with SignalR or any real-time front-end framework of your choice and you'll have real-time updates as you described.
One catch though is that SQL Dependency only tells you that something changed. Whatever it was, you are responsible to track which record it is. That adds an extra layer of difficulty but is much better than polling.
You may want to search through the sqldependency tag here at SO to go from here to where you want your app to be.
My first thought was to have webservice call that "stays alive" or the html5 protocol called WebSockets. You can maintain lots of connections but hundreds of thousands seems too large. Therefore the webservice needs to have a way to contact the clients with stateless connections. So build a webservice in the client that the webservices server can communicate with. This may be an issue due to firewall issues.
If firewalls are not an issue then you may not need a webservice in the client. You can instead implement a server socket on the client.
For mobile clients, if implementing a server socket is not a possibility then use push notifications. Perhaps look at https://stackoverflow.com/a/6676586/4350148 for a similar issue.
Finally you may want to consider a content delivery network.
One last point is that hopefully you don't need to contact all 100000 users within 1 second. I am assuming that with so many users you have quite a few servers.
Take a look at Maximum concurrent Socket.IO connections regarding the max number of open websocket connections;
Also consider whether your estimate of on the order of 100000 of simultaneous users is accurate.
How to work when internet connection down in a asp.net application ?
Means Users are working on application and suddenly internet connection down then user should still be able to add/edit/ delete operation on data, but when internet connection is up then
all changes should be done at server. Is that possible, Is there any example available to achieve this?
Thanks.
HTML5 has some offline capabilities. http://www.html5rocks.com/en/features/offline
But do you really have a business case for this? It will get complicated when you need to try and update stale data etc.
This requires use of JavaScript to store local data http://code.msdn.microsoft.com/Working-with-HTML5-local-b0cbe2ef and it needs to check whether the server can be reached before doing a proper postback, or more likely just use AJAX to communicate between the JavaScript application and the server.
There are several applications like this such as Google Mail, and such solutions are more JavaScript based than ASP.NET and you need to avoid relying on the web forms mechanisms and use .NET for building the initial page, dealing with AJAX requests and managing the application data and persistence. See How to write an offline version of an AJAX/ASP.NET web application
I have experience developing software and web applications and I have decided to do some freelance work on the side. Well, I met with my first client and they are requesting a relatively simple, custom system that (without being long winded) tracks client’s paperwork as it progresses through the business’s different manual processes. It is a small business that has about 10 employees, but all of the employees will interact with the client’s paperwork, therefore everyone would need access to the new system. When I say ‘track’ I literally mean that the employees will ‘check as complete’ on a simple page the increases a progress bar at different stages for the paperwork. Now I am %110 capable of coding the custom system that meets their needs, but I am unsure about how I should go about doing it.
The information that is being tracked in the new system and stored in the DB is confidential information that they are very protective of. My main question is how should I be developing this to be as secure as I can?
-They have their own server in house, so should I develop an application (VB and SQL) for the server and require employees to log on remotely to use it? Can more than one person access/use the application at a time?
-Or should I develop a web application (ASP.Net/VB and SQL) that is only accessible on their network to their employees? They plan to expand offices, could they set up a VPN to access the site?
I’m leaning towards a web application, but I have not done too much in term of security. Basically I’m looking for pros and cons for either option or any suggestions on what I should.
PS, stackoverflow is awesome! Long time user, first time poster!
If you want to develop using vb & sql you have to consider that:
You need to have real ip
Your system will communicate threw certain port and you have to handle the security measure for letting certain port opened in your server.
You should have good knowledge in network programming
If you want to develop using asp.net you have to consider that:
in case only office employees will use the system, you can develop against users in Active Directory and for outside users with username and password with SSL connection or vpn
for preventing more than one person access the file you can simply add column 'locked' in case file is being used.
Well im not a web fan (I suck) ive seen too many security issues go with it...i.e Lulzsec, but i do very much love VB apps.
So I would definetely recommend a VB app connected to a MSSQL database (coz it's easy to configure and havent seen any security exploits yet),my Chinese friend told me there is a way to access MySQL free databases.Now, allow remote access but make sure your Windows Firewall is also configured properly do look at all angles of security.
If I remember well there is an option in MSSQL to specify the IP addresses or is it MAC addresses that can access the DB so maybe input all of the 10 employees' IP addresses assuming they are static,if they are dynamic (DHCP) don't bother. And ask them to make the IP address of the server where you will host the DB on static.
If only 10 employees use the DB then limit the connections to 10. For now develop this when it comes to VPN you can make a Remote version of the App im sure that will come later right now focus on the basics. Also use Dotfuscator when you are publishing the app I heard it is very good.N also im suggesting the document/work order is received at the reception so that user will check in the document with specifics...if they are passing on the work order to the next user they should select the user and then THAT user may enter some sort of verification code unique to the user...im sure you can envision the rest from here. Now do I also get a cut from this?lol
I've been doing the same for years now, and I always take the website side, this days I go width ASP.NET MVC 4, it's easier, everything in their place and extremely easier to test and maintain.
The web application has a very big advantage to any standalone windows application, you deploy and upgrade only one application instead to maintain all the different versions once you start deploying windows apps, and they are harder to debug once you start to having different machines with different versions and so on...
so, Web or Win app = Web app, always!
All you need is a server that run IIS and set it up for using Active Directory (Visual Studio has that project already, simply create an ASP.NET MVC and choose the "intranet" template), it will set up everything for you, and all you need later is tweak the Active Directory connection string.
I also use a self-signed SSL to protect data between client and server, as I also make the apps available outside the office without VPN needed, as long as they login with their secure AD credentials.
And... audit everything into a secondary database, every action performed by a user since they login until they logout, every view, update or creating data witch .NET makes it simple if you create your Logging method to simple log messages and Stack messages on errors.
This will greatly benefit your employer and you when something goes wrong.
I would say to go with web application. Advantage using web application is, if they want to expand bussiness .. same can you do with you WebApp. But choose .Net over VB, going with latest techonology will help you resolve current challanges.
We have an ASP.NET website where user adds items to database.
There are several sites on same server, each with its own database.
I need to implement a mechanism to check database for the state of each item.
If item is unprocessed, submit it to a third party web-service.
I see two options:
put the code in a webapp
put the code in a Windows service
The first option has the advantage that the code knows which database to connect to.
With Windows service, it has to be aware of all databases, so it's harder to maintain. Also, if I have only one Windows service, it will have to use threads to process items in each database in parallel.
Maybe there's another way beside these two?
What are the other issues, and what would you recommend?
Please explain your choice.
This sounds like a good place for a message queue to be involved. Each item would be wrapped into a message and placed in the queue. The "item processor" (a service?) would subscribe to the queue and perform some work using each item as it arrives. How the messages get placed on the queue is up to you, but for an example you could have each site publish the "new item" message to the queue.
Queues can be a bit of an intimidating concept at first, but frameworks such as MassTransit can help. Well worth learning.
I believe Windows Service is a good option compared to a web app, mainly because a web app would have to be triggered manually by someone, while a Windows Service can be running at all times, checking for updates.
There's another option, if you have access to each of the existing site's code. Why not write a Web Service that will submit data to your third party web service. Then in each of the existing web sites, modify the logic that stores changes in the database to also post the changes to your custom Web Service (or even skip the custom WS and call the third party directly).
We have an intranet system that schedules routine tasks. We also have Fogbugz for bug tracking. When an urgent bug comes in, we track that task in the bugtracker. However, I need to write back to both the Intranet and our CMS. I'm thinking Biztalk as the middle piece, but am not sure the best way to go about it. Database adapter? Web services?
I know I can use the CMS adapter for Microsoft CMS. I'd love to hear your experiences with Fogbugz.
I'm guessing that watching the database for changes would be the best way to do it. That way, you could post any changes you saw happen in the FogBugz database through other Biztalk adapters.
Please keep us updated with what you decide to do - I'd be interested to hear about it.
Version 6 of the FogBugz API is pretty well documented at http://www.fogcreek.com/FogBugz/docs/60/topics/advanced/API.html. The API is implemented as an ASP page that accepts GET or POST params and returns XML after a user has been authenticated.
So, we can use the HTTP Send Adapter to POST requests to the FogBugz system, either updating bug records or retrieving information. The response from the API call is basic Xml that will be returned in the response body that can be read by BizTalk as necessary.
Be aware that the HTTP Send Adapter can only POST data - it cannot use the GET verb (http://msdn.microsoft.com/en-us/library/aa561642.aspx)
Isn't FogBugz based on a SQL Server Database? Or do you use a hosted alternative?
If it's using a SQL Server you're controlling I'd just tie up two send ports to the process that read and handles the "FixBugMessage". One send port that uses the CMS Adapter and writes to the CMS and another that just uses the SQL Adapter and via an Stored Procedure writes to the FogBugz database.