Drv::TcpServer Tcp Server Component

The TCP server component bridges the byte stream driver model interface to a remote TCP client to which this tcp server connects and sends/receives bytes. It implements the callback formation (shown below) using a thread to receive data and producing the callback port call. Since it is a server, it must startup and listen for client connections. Designed for single client communication, it does not permit a queue of connecting clients.

For more information on the supporting TCP implementation see: Drv::TcpServerSocket. For more information on the ByteStreamModelDriver see: Drv::ByteStreamDriverModel.

Design

The manager component (typically the ground interface) initiates the transfer of send data by calling the "send" port. The caller will provide a Fw::Buffer containing the data to send and the port call will return a status of that send. These responses are an enumeration whose values are described in the following table:

Value	Description
Drv::SEND_OK	Send functioned normally.
Drv::SEND_RETRY	Send should be retried, but a subsequent send should return SEND_OK.
Drv::SEND_ERROR	Send produced an error, future sends likely to fail.

This data is immediately sent out to the remote tcp server with a configured send timeout. See Usage described below.

Callback Formation

In the callback formation, the byte stream driver component initiates the transfer of received data by calling the "readCallback" output port. This port transfers any read data in a Fw::Buffer along with a status for the receive. This status is an enumeration whose values are described in the following table:

Value	Description
Drv::RECV_OK	Receive functioned normally buffer contains valid data.
Drv::RECV_ERROR	Receive produced an error and buffer contains no valid data.

Usage

The Drv::TcpClientComponentImpl must be configured with the address of the remote connection using the configure method. The configure method will also start the TCP server listening for remote connections. However, clients will not be accepted until the connection is opened. Sockets are opened using open. When the component is set to automatically open, open is called done via the first send or receive. Users declining to use automatic opening or who wish to control when open initially happens should call open before any send or receive.

Automatic opening is the default. Call setAutomaticOpen(false); to disable this behavior.

Users desiring to receive via TCP should start the receive thread using start, may stop the thread using stop and may wait for the thread to exit using join.

The Drv::TcpServerComponentImpl must be configured with the address of the remote connection, and the socket must be open to begin. When the user calls configure the listening port of the TCP server is automatically connected and begins listening for incoming connections.

When configured to automatically connect as is the default, the single queued client will be accepted on the first send data call, or when the receive thread is started. Usually, the user runs the Drv::TcpServerComponentImpl's read thread with automatic connection enabled, which will automatically accept the client connection.

configure must be called before any data is sent or received. start must be called for the component to receive data.

Users should call stop to stop the receive task and join to wait for it to exit.

Users turning off automatic connection must call open to open the connection.

Drv::TcpServerComponentImpl comm = Drv::TcpServerComponentImpl("TCP Server");

bool constructApp(bool dump, U32 port_number, char* hostname) {
    ... configure 
    comm.configure(hostname, port_number);
    ...
    Os::TaskString name("ReceiveTask");
    comm.start(name);
}

void exitTasks() {
    ...
    comm.stop();
    (void) comm.join();
}

Class Diagram

Requirements

Name	Description	Validation
TCP-SERVER-COMP-001	The tcp server component shall implement the ByteStreamDriverModel	inspection
TCP-SERVER-COMP-002	The tcp server component shall provide a read thread	unit test
TCP-SERVER-COMP-003	The tcp server component shall provide bidirectional communication with a tcp client	unit test