When the connection is blocking, your socket must initiate reading or writing over the connection. It cannot wait passively for a notification from the socket connection. Use a blocking socket when your end of the connection is in charge of when reading and writing takes place. 

For client or server sockets, set the BlockMode property to bmBlocking to form a blocking connection. Depending on what else your client application does, you may want to create a new execution thread for reading or writing, so that your application can continue executing code on other threads while it waits for the reading or writing over the connection to be completed. 

For server sockets, set the BlockMode property to bmBlocking or bmThreadBlocking to form a blocking connection. Because blocking connections hold up the execution of all other code while the socket waits for information to be written or read over the connection, server socket components always spawn a new execution thread for every client connection when the BlockMode is bmThreadBlocking. When the BlockMode is bmBlocking, program execution is blocked until a new connection is established.