I have an application where I want two users to communicate with eachother.. This has to happen every second - and I have been considering a lot of solutions.
I had a thread some time ago, which gave some really good ideas. Problem is I don't want to get into reverse-AJAX yet as I am waiting for HTML 5 sockets.
Anyway, I "just" need to create a variety of features: Chat, 1 on 1 fight, people on a map and alike. For this, I see two obvious solutions:
Database updates (read from DB every second)
Using the global Application state
Which of these solutions are the best? Or do you have some even more magic neat solution?
I would look at MemCached. You can run it on a separate server and have multiple servers share if you need it to be. If you need it to be persistent -- there is MemCachedDB
There is a really great comet framework for that, it's dead easy to use and it also supports html 5 sockets (as well as normal reverse-AJAX). If persistence is not a requirement than I don't see any reasons not to use it. There are other free alternatives too, but none of them are using C# as far as I know.
Related
A friend likes to limit his applications to a use a certain bandwidth-limit. Seen as he doesn't have the widest connection and - for example - not every application that downloads/uploads has the ability to throttle/limit their downloads/uploads (Like Steam or a torrent downloader.). So he was wondering if I could maybe put something together since I fiddle around with WinForms often. I recommended NetLimiter and NetBalancer, but I was curious as to whether I could make this in C# myself.
I have searched the web and found some decent solutions as to throttling in an application itself but as to throttling applications outside of the current application you have the source code of, I haven't been able to find anything that would help me understand how to program this from scratch.
Do any of you know how I'd go about throttling other applications? Would I have to write my own network interface and have Windows reroute traffic through that?
Thank you for your time.
EDIT: Seen as the first comment tells me I'm at the wrong address with C#, I rephrased my question in the hopes of a better way to get an answer.
Looking for suggestions regarding an upcoming project that I am involved in which revolves around adding certain functionality to an existing ASP.NET application running on IIS 6.0 programmed in VB.NET.
To aid in future development the client wants the additional functionality to be as future proof as possible. Ideally I have said that I would like to push for a solution using ASP.NET MVC3, running off IIs 7.5 and .NET 4, written in C#. This solution would act as a seamless addition to the current web-portal appearing probably just as an extra tabbed page.
But they will be completely separate web-apps. Which is crucial.
The main problems I can foresee are firstly sharing session particulars between the asp.net web app and the new application. Particularly with regard to maintaining session state (and not having IIS timing out on one of the apps). Also, conjoining the two "apps" appears problematic in my head, although this may be far simpler than I fear.
I'm asking for suggestions for these two problems if anyone has any ideas please say!
So far I've come up with the following solutions be they terrible or not:
1) Embed the new functionality into the existing codebase (not a great option). This would mean losing any potential future upgrade-ability and also means not following better OO conventions by utilising the MVC framework.
2) Using an iFrame to link to the razor pages of a seperate MVC3 app (the one I'm favouring currently). Allows uses of all new technologies, however downside is sharing session data. Either through iFrame "attributes" (is this possible?) through persisting a session state to a db? (slow?) or even some kind of web service interaction between the applications to push/pull user/session data?
Any advice/suggestions greatly appreciated!
I agree with you that C# and MVC is the "way to go", but unfortunately mixing two applications together is going to give you a whole bunch of headaches, not least the different session IDs. You'd probably have to have a shared database table to map them together and, as you can probably imagine already this reeks of "Band-aid".
What are the ramifications in rebuilding what is existing, in to C#? Perhaps you could suggest a complete upgrade. The client themselves seem to extol the virtues of future-proofing and therefore this would be the way to go. And no, I wouldn't promote the use of a "code-converter", but it really shouldn't be that difficult.
The next thing to consider, I guess, is "future-proof". Is the client worried that VB.NET is going to disappear any-time soon or that it cannot handle anything in the future? I find that a very unlikely scenario, honestly.
I think I've waffled on a bit, but essentially combining two applications, one with old and one with new functionality will cause a headaches. This could be solved by migrating the old site to C#/MVC, and then adding the extra functionality. True, this may seem like a large commitment today - but further on down the road, it will pay dividends.
If the current site can be upgrade to .NET 4.0 there's no reason why you wouldn't extend the existing application.
There's nothing to stop you mixing MVC and web forms (indeed there are several articles on how to do just this). There's nothing to stop you mixing VB.NET and C# (or, so far as I'm aware, to stop you doing MVC in VB.NET).
You'd have to work very hard to convince me of the merits of using iFrames. Very hard. You might be able to persuade me of the merits of running two applications side by side - with the functionality split by folder - but to be honest I'd be much happier upgrading the existing site and then building from there.
I am looking into the possibility of Distributing a data structure across multiple machines. I would like it to run in a process on each machine, and using (Multicast?) replicate a copy of the full data structure on all of the machines.
Does anyone have any experience in this that could point me in the right direction?
Distributed locking is hard -- and you might well need to lock, unless you're reading only. I suggest you take a look at a distributed caching framework like Microsoft's Velocity (which may be renamed as part of Azure now), or the free, open source and very good memcached.
There are other, pay-for options too -- notably GemFire and Coherence.
I'd give memcache a go, it works pretty well.
You can write your data into a central database. Then each instance can access it. If you want to modify the data from an instance you shoul implement a mechanism of locking the data in the database. Is this of any help?
Publish the structure through ØMQ using PUB/SUB sockets and then you can switch between TCP or IP multicast depending on your requirements and network quality.
If your data structure is sufficiently organised you should also be able to send updates to the structure without much issue.
You can also look into Hazelcast which is a Java based solution.
Here is a direct link (1) which talks about some of the internals.
(1) http://www.hazelcast.com/documentation.jsp#Internals
And there is already a suggestion to use (repcached) memcached which should be easy to use as well.
To answer your question direction, you should probably learn about state machine replication and then look for implementations of either virtual synchrony or Paxos for your platform, to use as a building block.
Pragmatically, I would advise considering a coordination service such as ZooKeeper, that would save you a lot of trouble.
I have two C# programs and I want to send some data back and forth between them. (And check if the data arrived to the other application.)
The two programs will always run on the same computer, so no networking capability is required. I've already read some questions with similar topics here, but I'm not entirely sure which is the right method for me. (WCF, Remoting, etc.)
What I want to know, is which one is the easier to implement for a beginner in C#?
(I don't want it to get too complicated anyway, it's only a few integers and some text that I want to send.)
If there isn't a real difference in difficulty, what advantages does one have over the other?
I'd really appreciate some simple example code as well.
Thanks in advance.
You can use Pipes to send data between different instances of your application. If you just need to tell the other instance that something has happened you can send messages from one application to another by using SendMessage api.
WCF essentially packages up the various methods of communication between applications (web services, remoting, MSMQ etc) in a single package, so that they are programmatically the same in the way that they are used, and the detail of what method is used is left for configuration of the binding between. A slight simplification perhaps, but essentially what it's about.
It is worth getting into WCF if you need inter-process communication, and this would certainly be my advice as to the way to go with this. It's worth looking at IDesign, who produce a number of articles on the subject, as well as some reusable code libraries, that you may find useful. Their Juval Lowy has also written an excellent book on the subject,
Another good point about WCF is that if your requirements ever change and all of a sudden you have to move one of the application to a different machine, requiring now network capability, you will only need to change configuration on both sides, instead of having to recode.
Plus, ad David said, WCF is a good tool to have in your bag.
Cheers, Wagner.
I found MSMQ is simple to implement.
So my company stores alot of data in a foxpro database and trying to get around the performance hit of touching it directly I was thinking of messaging anything that can be done asynchronously for a snappier user experience. I started looking at ActiveMQ but don't know how well C# will hook with it. Wanting to hear what all of you guys think.
edit : It is going to be a web application. Anything touching this foxpro is kinda slow (probably because the person who set it up 10 years ago messed it all to hell, some of the table files are incredibly large). We replicate the foxpro to sql nightly and most of our data reads are ok being a day old so we are focusing on the writes. plus the write affects a critical part of the user experience (purchasing), we store it in sql and then just message to have it put into foxpro when it can. I wish we could just get rid of the foxpro, unfortunately the company doesn't want to get rid of a very old piece of software they bought that depends on it.
ActiveMQ works well with C# using the Spring.NET integrations and NMS. A post with some links to get you started in that direction is here. Also consider using MSMQ (The System.Messaging namespace) or a .NET based asynchronous messaging solution, with some options here.
MSMQ (Microsoft Message Queueing) may be a great choice. It is part of the OS and present as an optional component (can be installed via Add/Remove Programs / Windows Components), meaning it's free (as long you already paid for Windows, of course). MSMQ provides Win32/COM and System.Messaging APIs. More modern Windows Communication Foundation (aka Indigo) queued channels also use MSMQ.
Note that MSMQ is not supported on Home SKUs of Windows (XP Home and Vista Home)
Its worth mentioning that the ActiveMQ open source project defines a C# API for messaging called NMS which allows you to develop against a single C# / .Net API that can then use various messaging back ends such as
ActiveMQ
MSMQ
TibCo's EMS
any STOMP provider
any JMS provider via StompConnect
You may want to look at MSMQ. It can be used by .NET and VFP, but you'll need to rewrite to use them. Here's an article that tells you how to use MSMQ from VFP. https://learn.microsoft.com/en-us/previous-versions/visualstudio/foxpro/ms917361(v=msdn.10)
Sorry if this isn't what you are asking for...
Have you considered some sort of cache behind the scenes that acts a bit like the "bucket system" when using asynchronous sockets in c/c++ using winsock? Basicly, it works by accepting requests, and sends an immediate response back to the web app, and when it finally gets around to finding your record, it updates it on the app via AJAX or any other technology of your choice. Since I'm not a C# programmer I can't provide any specific example. Hope this helps!
Does the Fox app use .CDX indexes? If so, you might be able to improve performance by adding indexes without needing to change any program code. If it uses .IDX indexes, though, the change would have to be done in the actual app.
As the problem is with writes, I would look more towards >removing< any unneeded indexes on the tables. As is common in RDBMS, every index on a FoxPro table slows down a write operation as the indexes need to be updated, and as you aren't reading directly from (or presumably directly querying) the table you shouldn't need very many indexes. You might also want to look at any triggers or field rules on the tables as they may be slowing down the write operation. Be sure your referential integrity is still preserved, though..