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Closed 10 years ago.
I hope there is someone that can help me.
I am writing a software that users can fill in information into a database, but I want to install that same software that I created on multiple computers. When a other user is inserting new information into the software and click save then it must show on his/her computer and at the same time on the other PC's in the network.
I think this is a difficult one to crack, but I hope some one can help me.
Greetings
There are many ways to solve this. I recommend to use a server-side application (installed on the database server system for example) which receives a notification from the inserting app. Then, the server side app will send either a UDP broadcast or use a TCP connection to the clients to notify them.
The clients then just need to listen for server messages in a background thread. The messages will be 'pushed' from the server to the client.
An example which can be used as a starting point is the Indy Telnet client component which has a listener thread for server messages. You do not have to open the client firewall for incoming connections to work this way.
There are also complete messaging solutions available, but maybe they would be to heavyweight for your requirements. If you like, I can provide some links.
I would not recommend
database polling (too expensive and unflexible)
database events (run in the server process, could block operation or crash)
A standard which can be used for this messaging system is WebSocket. There are commercial and open source Delphi implementations for the client and server side.
Related
It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.
Closed 10 years ago.
I want to write a program for transferring files and documents between a network computers. Many files may have been transferring at moment. every computer can receive and send files, it means system have to be ready to send files and listening to receive files.
I can configure program on each system as i want (for example give a list of connected computers' ip to program to choose target system for transfer file into)
Do i have to make Server-Client type applications or i can have JUST one program running on computers? I know question is vast but helping me to choose the best way will be appreciated.
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I want to write this program by Delphi 2010 and network computers os is Windows 7.
You can do it peer-to-peer. The very same program can both listen for requests to transfer or receive files from other computers and issue its own requests to transfer or receive files to other computers.
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Closed 10 years ago.
What options do we have to enable a user of an app to share a file with another user on another device ?
My application is a task management app, I want to enable my users to share lists, notes, etc.
I haven't found a way to do this with iCloud.
Depending on how you want to implement the work-flow, there are a number of ways to accomplish this.
Spotify allows users to sync files between computers and mobile devices, if both are on the same local network. You could use Bonjour to discover if there are any valid endpoints on the local network, and then sync directly over a TCP/IP socket.
If you're looking for cloud sync, Parse provides a cloud-app-api service that lets you easily store objects, including files and binary data on the cloud. You'll have to write your own user management layer, but they provide API's for storing and retrieving data.
From the comments, there are other companies that provide similar services to parse: Buddy, Stackmob, Kinvey, and applicasa to name a few. The idea is to leverage an API-as-a-Service provider for all backend needs.
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Closed 10 years ago.
How to publish or deploy .NET website without delays?
I have look for websites that are build over .NET technologies, like StackOverflow, and I never saw them down because an update is being made. For my web sites, I got down time in minors updates, like correcting some bugs on my Controllers (I use MVC), not by doing something bigger like database or server movements.
So how can I prevent site loading delays due to ASP.NET Startup?
I know that it require "ASP.NET worker process" to compile the code, but how can I prevent the traffic issues.
The typical way of doing this is creating a farm of multiple web servers and, when you want to update the site, take each server offline and update them one at a time. Investigate How to create an ASP.NET web farm?.
It's all about the server setup. Most companies have at least 2-3 server: 2 Frontend servers and a backend server. Then you can take one of the frontend servers down, point all traffic to the other one, upgrade the server which is down, and then take that server up, and continue the process with the other.
In some cases you would use load balancing to make sure the two servers are synchronized.
You will notice that sometimes you cannot post here on Stackoverflow because of updates. That's because the database is a shared server, which "can be down", if you need an upgrade. Yes, there are also options against this, but it can gives problems if everyone writes to the database while the site is up, hence the "readonly mode" from time to time.
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Closed 11 years ago.
How do I track a program Internet Request? Like Windows Live Messenger, in order to make a bot that does the same thing.
Because I'm making a application that verifies the number of users online, and chat with these people, but I would like to know, where does it connect to do that.
In Web I use the LiveHTTPHeader or FireBug to see where is the page sending GET/Post DATA too and which parameters are being sent. What about desktop applications? how do I do?
You should use a library, for instance in csharp:
http://code.google.com/p/msnp-sharp/
Because tracking web request is irrelevant. if you want to make a bot, you should work with an Api.
Applications like Live Messenger, Skype etc do not normally use the http protocol to communicate with their servers or peers. Instead they mostly use their own, sometimes proprietary protocols over TCP/IP, over ports other than the default http port. In order to "listen" to what these programs are sending/receiving you would need a program that "sniffs" TCP data. I imagine however that these eavesdropping attempts will mostly prove futile, since many of the programs you are trying to understand also use encryption.
Use Wireshark to dump all your network traffic, then use filters so you keep only the data that Messenger sends.
http://www.wireshark.org/
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Closed 9 years ago.
I want to implement a Web Service that will allow users to store arbitrary data in my home computer and execute arbitrary batch programs to manipulate said data. In order to keep things simple, so I will not deal with priority queues and concurrent processes yet. My process request queue will be a simple FIFO queue.
So, I know how to implement Web Services, and obviously I know how to implement a FIFO queue, but I do not know how to implement a system service that runs in the background, waiting for requests. Where could I find learning resources on how to develop a Windows service?
I already know Windows development using the Windows API, MFC and even some ATL/WTL. (I also know .NET, but I do not like it very much, because it gets in the way how I design programs.) But I would rather not have to deal with COM.
Since you're developing a service on Windows and you want to use web services chances are that you will want to host your solution in IIS which is already the type of always-on, background application that you want. E.g. runs all the time regardless of login or UI.
If you use the .NET framework then your implementation will become especially easy due to all the project templates available in Visual Studio.
Here's some CodeProject tutorials:
http://www.codeproject.com/KB/WCF/WCFPart1.aspx
http://www.codeproject.com/KB/WCF/WCFWebService.aspx