Fortran

In the previous section, you learned how to send a TCP message from the server to a remote client by calling the msend function in libdill. We tested that it worked by communicating to the server with command-line networking tools such as curl, nc, and telnet. What if you wanted to exchange data over the network between two Fortran programs? We […]

Like we did on the server, first we need to initialize a data structure to hold the IP address and port number. In this case, they’ll be the IP address and port number of the remote host to which we’ll connect. Here’s the prototype of the ipaddr_remote function in libdill: ❶ This function returns an int. ❷ Pointer to […]

As I mentioned before, to implement the client, we’ll need Fortran interfaces to a few new libdill functions (figure 11.6): Figure 11.6 The Fortran TCP client program, illustrated Having gone through the server implementation, writing these interfaces for the client should be straightforward.

There’s only one step left before we wrap up and test our little TCP server program–once we send the message, we want to close the connection gracefully. libdill provides a function to do this–tcp_close. Can you help me implement the interface to it? Try exercise 2 in the sidebar. Exercise 2: Fortran interfaces to suffix_detach and tcp_close You […]

Finally, on each accepted connection, we’ll send a message to the client to let them know the server is alive. Not so fast, though. Recall that the data is just a stream of bytes, and the TCP protocol defines messages that are specially formatted packets of binary data. Fortunately, libdill provides a convenience function, suffix_attach, to append a suffix […]

We now have our socket open to the world, and we’re listening for connections. The C code (libdill) and the operating system will do the work of making the connection happen, so we don’t have to worry about that part. Our job here is to accept an incoming connection and do something with it (send […]

We now have an IP address data structure, and we can initialize its value by calling the ipaddr_local function. Let’s now use this structure to open a socket and listen for incoming connections. To do this, we’ll use the tcp_listen function. Like before, we’ll first look at the interface of the C function from the libdill documentation: If successful, the […]

Now that you’ve got a taste of interfacing C-structs with functions from Fortran, it’s a good time to go into more detail on compatible C and Fortran data types. I mentioned earlier that C types are different from Fortran types: int is not exactly integer, and float is not exactly real. What matters, however, is that we have a reliable way […]

Testing is recommended. Having made our call to ipaddr_local, we have no clue whether it worked or not. All that we know is that the program didn’t crash with any error message. After we initialize ipaddr, we can use libdill functions to explicitly check for the IP address and port number values stored. First, let’s take a look […]

Now that we have a derived type to interface with the ipaddr struct, let’s create an instance of it. libdill provides two functions to instantiate the ipaddr struct: ipaddr _local and ipaddr_remote. The former is used on the server side, where you want to open up a socket to listen to incoming connections. The latter is used on the client side, where you want […]