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We are planning to develop an ERP-project using ASP.NET and SQL. Client asked one feature: to be able to access and use ERP even if connection to Internet fails (using without Internet). Is it possible?
Of course you can use that without internet. You may host your web-site on some server in that company and all employers of that company may use this ERP. But nobody outside company will not be able to connect to that. Government committees usually use this way. If they scare about privacy and security, they may just take VPN access, it is secure. Another way (the worst, as I think): users from outside connect to computers inside company, and work over that computers.
Second solution: Web-based asynchronous application. You will create something like framework, you will install that to all users' computer. What is the principle of that's work? All user's will have their own database file, and they will work with their database. You just need to make a synchronization service between databases. For example, every time when user have internet, your service will synchronize data between user's database and server's database.
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Hi guys I'm creating a device that can be controlled by google assistant;
currently I created an arduino that interfaces with an esp8266 and through the service "IFTTT" I can communicate without problems. Now I would like to extend the project so as to make it public so as to find it in the "Home control" devices of google.
Is it possible to use "Arduino / esp8266"? How?
If it is not possible in this way what kind of board do you recommend?
In order for your device to work with the Google Assistant, you should consult the smart home documentation. If your device can connect to the Internet, you're good. The ESP8266, since it already connects through IFTTT, will work for a more public project as well.
You'll need to create some sort of server backend which will act as the source of truth, responding to requests from the Google Assistant and dispatching commands to devices. If you can use the ESP8266 as a web server with minimal (< 5s) latency, you'll be set. Alternatively, you can use a simple service like Firebase.
Your web server will need to respond to three primary types of intents: SYNC, QUERY, and EXECUTE. The documentation walks through all of them, but they give you the ability to provide devices for each user, return the state of these devices, and send commands to do actions.
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I am making a small project where there is a qt client application and basic server application written in c++. I am able to connect between two different computers through my application (over SSL, Socket). Now I want to connect my client application to access a sqlite database which is on server.
For example. lets say my client application is a simple login form. When user press Login button then I want my application to access the sqlite database on server, and verify whether the details are valid.
Above a just a example fr explanation. I know I can do the above thing in various other ways but I want the above functionality for something different.I searched a lot over internet but unable to find a good example or explanation. Please through some insight.
SQLite data is stored in a single file, and there's no database server running on top of it. So it does not have any network connection capability. A very simple solution is to make the SQLite database file available on a network in some way like sharing it's directory.
There are other options which use third party libraries :
netSQLite : a client/server solution running over TCP/IP with SQLite3 at its core.
Navicat : enables remote SQLite connection although it is not free.
SQLiteServer: a multithreaded TCP/IP server for SQLite
SQLiteDBMS: a database management server for SQLite. It allows an sqlite3 process to be accessed via a TCP/IP network.
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I will be moving a high load prod system over to new hardware over the next few weeks. However in the mean time I would like to validate that the new hardware will handle the expected loads. I would really like to stick some kind of 'proxy' infront of the current web server and copy all that http traffic to the new environment, i.e. run them both in parallel.
Ideally this proxy would also validate that the responses are the same.
I can then monitor the new hardware stats (cpu, mem, etc) and see if it looks ok.
What is this kind of proxy called? Any one have any suggestions? This is for a Windows .Net (asp.net) and SQL server environment.
Thanks all
Varnish comes to mind - https://www.varnish-cache.org/
Edit
I'd actually use nginx... (two years experience after answering this question).. varnish would be silly to use. nginx would definitely be the better option.
Have a look a JMeter. It's Java based but allows you to record user journeys and play them back in bulk for stress testing.
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I read about OpenBTS it's really amazing... but I was wondering if we can use it to build phone-to-phone provider-less network.
Any clues or experiments are really appreciated.
One thing to be aware of is that open BTS is 2G/GSM only - i.e. it does not support 3G/UMTS.
This may or may not be important to you depending on what you would like to achieve.
There does appear to be some discussion on adding this functionality in the future (i.e. building an open node b/RNC effectively) but it will be tricky as the authentication mechanism used in 3G requires the network owning the SIM to provide authentication data for even the most basic communication.
GSM follows a strict client-server model. Mobile phones are intended to be clients.
If you would want to build phones with phone-to-phone capability you would need to implement network functionality in the phone. With this, phone-to-phone (theoretically) could be done in an ad-hoc-network model, with one phone running the network part.
I would suspect that one has to look at impacts on the pyhsical/radio layer as well.
Rather unrealistic, IMHO.
May be of interest:
http://terranet.se/history/
So far this company (TerraNet) seem to be only offering sowftware for creating mesh networks over Wifi (I think Wifi is a big disadvantage due to the battery drain. If only we could use GSM), but they seem to share this idea.
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I was wondering where I could learn more about decentralized sharing and P2P networks. Ideally, I'd like to create something to help students share files with one another over their universities network, so they could share without fear of outside entities.
I'm not trying to build the next Napster here, just wondering if this idea is feasible. Are there any open source P2P networks out there that could be tweaked to do what I want?
Basically you need a server (well, you don't NEED a server, but it would make it much simplier) that would store user IPs between other things like file hash lists, etc.
That server can be in any enviroinment you want (which is very comfortable).
Then, each client connects to the server (it should have a dns, it can be a free one, I've used no-ip.com once) and sends basic information first (such as its IP, and a file hash list), then sends something every now and then (say each 5 minutes or less) to report that it's still reachable.
When a client searchs files/users, it just asks the server.
This is a centralized network, but the file sharing would be done in p2p client-to-client connections.
The reason to do it like this is that you can't know an IP to connect to without some reference.
Just to clear this server thing up:
- Torrents use trackers.
- eMule's ED2K uses lugdunum servers.
- eMule's "true p2p" Kademlia uses known nodes (clients) (most of the time taken from servers like this).
Tribler is what you are looking for!
It's a fully decentralized BitTorrent Client from the Delft University of Technology. It's Open Source and written in Python, so also a great starting point to learn.
Use DC++
What is wrong with Bit-Torrent?
Edit: There is also a pre-built P2P network on Microsoft operating systems that is pretty cool as the basis to build something. http://technet.microsoft.com/en-us/network/bb545868.aspx