The LDPL Socket Library allows you to open, close, write to, and read from network sockets in LDPL.

It's mostly made for clients - if you want to write a server, please see the library that this one is heavily based on: Lartu's https://www.github.com/lartu/ldpl-net-server

Requires LDPL 4.3 or greater.

You can install this library by hand or using LPM.

Open a terminal and write lpm install ldpl_socket. Once downloaded, include it in your LDPL project by adding the line:

using package ldpl_socket

before the data and procedure sections of your source file. The library is ready to be used.

Include the library into your LDPL project by copying the folder ldpl_socket to your project directory and then adding the line:

include "ldpl_socket/ldpl_socket.ldpl"

before the data and procedure sections of your source file. The library is ready to be used.

This library adds a few new statements to the language:

• SOCKET CONNECT TO <hostname> AT <port> IN <number variable>
  • Use this statement to open a new socket connection. Currently only TCP connections are supported. If the connection is successfully opened, your <number var> will be set to a "socket number" that's >= 0. Otherwise, ERRORCODE will be set to a negative number.
• SOCKET CLOSE <socket number>
  • Once a socket has been opened, use this statement to close it.
• SOCKET SEND <text> TO <socket number>
  • Use this to send messages to an open connection. ERRORCODE will be set to a negative number if the send call failed.
• SOCKET SEND <text> TO <socket number> BYTES IN <number var>
  • Same as SOCKET SEND but stores the number of bytes sent in <number var>.
• SOCKET READ FROM <socket number> IN <text variable>
  • This statement should be used to check for messages on a socket connection opened with SOCKET CONNECT TO <hostname> PORT <port>. <text variable> will be set to anything received from the socket, which may not be an entire "message" in whatever protocol you're using. ERRORCODE will be set to 1 if the connection is closed. Note: By default this is a blocking call. Use the next statements to change that.
• SOCKET READ FROM <socket number> IN <text variable> BYTES IN <number var>
  • Same as SOCKET READ but stores the number of bytes received in <number var>.
• SOCKET SET BLOCKING <socket number>
• SOCKET SET NONBLOCKING <socket number>
  • By default all socket reads are blocking, but if you want to do a nonblocking call (or ensure you're using a blocking one) then these statements are for you. Basically they set/unset O_NONBLOCK on the underlying socket. In LDPL, ERRORCODE will be set to < 0 if there is an error or (most common in nonblocking mode) no data was available to be read. So, check for that.

There's an example echo client in examples/echo-client.ldpl. Use it with Lartu's demo echo server by cloning that project and running the template:

git clone https://github.com/lartu/ldpl-net-server
cd ldpl-net-server
ldpl net_template.ldpl
./net_template-bin

Then, back in ldpl-socket land, build and run the client:

make echo
./echo-client 

You should now be in a little echo repl:

~ Connected to localhost:8888 (socket:3)
< Hello there!
> Well, I never!
< Well, I never!
> ...or have I?
< ...or have I?

This library is released under the MIT License.