I have host A and guest B. Node B also can be a host of guest C. So the tier is A - B - C.
At host A, I set sync.url is IP of PC A. At host B, I set sync.url is IP of PC B and register.url is IP of PC A. At host C, I set register.url is IP of PC B.
Is that correct with that properties configuration?
And also I'm using MySQL, because of node B is a host and a guest, it needs 2 trigger. But, MySQL can only use 1 trigger. How?
Thank you.
yes, that's correct. no need for two triggers. one is enough. then have two routers. for example, at the node B have one router sending data to the node A and another that will send data to node C
Related
I don't know ip address and host name of a system on internet.I only know database name, how do i connect with that database using internet and without using any third part tool.
Basically... you can't.
Every Database-Server can provide databases with any name, so you can have Database foo on server x and at the same time on server y with different data.
So without any additional info you can't get the adress of the server.
Edit:
Q: Actually server does not have static IP it generates dynamic IP.
A: You can use a DDNS prvider, to create a hostname, which changes automatically the IP adress depending on your current server IP, but without a 3rd party app it seems difficult.
I have an application built on Erlang/cowboy, the database is mnesia. The node name is webserver#127.0.0.1.
Since there is no GUI in remote server, I want to use local observer to access to the remote mnesia.
I tried many times, but still failed. Can anyone help me out? (Assume the IP of remote server is 10.123.45.67)
Your remote Erlang node name should be webserver#10.123.45.67 instead of webserver#127.0.0.1.
Also you need to set the same cookie for both nodes as well as the same node naming convention. By naming convention I mean short name (-sname flag) or long name (-name flag), becuase a node with a long node name cannot communicate with a node with a short node name.
Note that if your real remote IP is not in a trusted network, it is not good practice to do it in case of security.
I am working on udp server/client applicataion. Since for communicating with the server, all the clients must know the ip address and port number of the server. For this purpose, I have hard coded the ip and port number of my server to the clients so that everytime, the client connects to same ip and port number. (found the ip address of the server machine using ipconfig command.)
But now, the problem is that I am working on DHCP network, and there is a chance that everytime sever machine is restarted, a new ip address may be assigned to it (different from the ip address known by the clients at which they will connect.)
So, I always want the ip address hard coded at client side to be assigned to the server machine, everytime it logs in.
Is there any way to do it? I have no idea about it. Searched internet but couldn't find anything relevant.
Looking forward to help :(
Assuming that your clients are local to the server, why not abandon the hard-coded server IP address, and borrow a page from DHCP and use some kind of service discovery method:
Your clients broadcast "where is the server" message when they first come online. The server responds with "I am at IP address X.X.X.X"
When the server comes up, it broadcasts "Server is now at IP address Y.Y.Y.Y" so that if the server crashed, the clients start using the new server.
Presuming you are working on a LAN, that's how I'd do it.
Presuming your DHCP server is configurable enough:
Assign a static map MAC address/IP address in the dhcp server, so
that the same machine always get the same IP (just for the server,
not for every client).
Most entry level all in one devices with DHCP have this functionality, if not it should be quite cheap to buy a new one that has it.
If your DHCP server is a real computer, you can surely configure it to do so.
Additionally you might want to tell your clients to use a local DNS and in this local DNS server define a name for your server, so you won't have to hardcode an IP address in your clients. But the address should be located in some configuration file rather than hardcoded in any case.
I have used dnsmasq to serve as both DNS server with local names, and as DHCP server, giving the servers always the same address and pointing all the DNS requests towards itself.
This questions could be useful to find a windows alternative for dnsmasq: https://stackoverflow.com/questions/7709744/is-there-something-like-dnsmasq-for-windows
By adding a reservation field in the DHCP server we can attain this. If you are using Windows DHCP server, there is a section named 'Reservations', there we can give the MAC address of your pc and the desired IP address. Then the server will provide the mentioned IP for you.
With the narrow focus of a developer a DHCP reservation might be the logical step. But using a nameserver is far better. If the network itself changes or maybe the server is moved to another subnet or maybe even into anoher zone, using an IP address from a DHCP reservation fails, because the server's address changes.
You don't have any of these problems if you use a nameserver. That is what DNS is meant to be doing. Think of it as a "serviceprovider finding service" that detaches your service from the host it is running on.
And, like already suggested, you should never hardcode an IP address or DNS name or anything else that might change (even if you think it will not change) unless it is a design goal that things aren't working anymore if something changes (=not configurable).
I am unable to get the DNS Server IP address using C. I have tried using IP_ADAPTER_INFO however it only gets the Primary and Secondary WINS Server IP address using pAdapter->PrimaryWinsServer and pAdapter->SecondaryWinsServer.
And based on my knowledge the WINS server and the DNS server are two different types of servers.
Use GetAdaptersAddresses(), and see the IP_ADAPTER_ADDRESS structure.
I'm doing some socket programming in C where I have one server and many clients on the local network. I want the client to find (search for) the server on the network by itself (i.e.not having to specify the server's address) and connect to it. The protocol between the clients and server should be TCP.
I've been searching the web for some time to find a good solution to this, but haven't found one yet.
Any suggestion to how I would tackle this problem would be greatly appreciated.
An IP and port number is necessary for a client to connect to the game server. However, if the IP address of the server is not available, a 'compromise' could be reached by:
Using a hostname to connect to the server, you can use gethostbyname() to resolve a hostname and obtain the IP address. This should solve the issue if the server's IP is not known or is not static.
Having a process running on a known IP which can give you a list of active servers.
Having the clients scan a particular range of IP addresses instead of trying to connect to a single IP (not a very good idea, but should be doable on a LAN).
Havinh your server broadcast packets (say UDP datagrams) at fixed intervals to all hosts on the current subnet (again not really a good idea, will lead to unnecessary network traffic).
A hybrid approach with more than one of the above could also employed, for example, try connecting via a hostname and if that fails, fallback to connecting to a known IP with list of active servers etc.
If you have control over the network layout and such, I would use a solution involving DHCP and DNS.
Basically, you want to connect your DHCP server to your DNS server so that it would automatically create entries for new computers on the network. This is a feature that most DHCP servers and DNS servers support, including BIND and named and Microsoft's solution.
Then you'll set the server hostname to some known value, and have the clients find the server using DNS. That is, gethostbyname() would work properly so you could use the first bullet point offered in Bhargav's answer.