How does a 3rd party (Go/Golang) app call a service?

17 

~~~After starting run `strace -s 512 -p $(pgrep -f socket)` and `strace -s 512 -p $(pgrep -f serviceDirectory)`~~~

This works now. The `binding` definition was referring to the wrong interface (printerService instead of printService).

#### $GOPATH/src/socket/main.go

```go
package main

import (
	"bytes"
	"encoding/binary"
	"fmt"
	"log"
	"os"
	"time"

	"golang.org/x/sys/unix"
)

const (
	ProtocolID          = "e2533dc76a5bf9ba6b2d3e74d8f95bd6" // /legato/apps/sample/helloIpc/printer.api
	ServiceInstanceName = "printer"
	MaxMsgSize          = 112
	msgID_printer_Print = 0
)

type OpenMsg struct {
	MaxSize  uint32
	ProtoID  [128]byte
	IntfName [128]byte
	Wait     bool
	_        [3]byte // padding
}

const sock = "/tmp/legato/serviceDirectoryClient"

func main() {
	fmt.Println("strace -s 512 -p ", os.Getpid())
	time.Sleep(10 * time.Second)

	os.MkdirAll("/data/le_fs/", 0777)

	fd, err := unix.Socket(unix.AF_UNIX, unix.SOCK_SEQPACKET, 0)
	if err != nil {
		log.Fatal(err)
	}

	sa := &unix.SockaddrUnix{Name: sock}
	if err := unix.Connect(fd, sa); err != nil {
		log.Fatal(err)
	}

	openMsg := &OpenMsg{
		MaxSize: MaxMsgSize + 4,
		Wait:    true,
	}
	copy(openMsg.ProtoID[:], []byte(ProtocolID))
	copy(openMsg.IntfName[:], []byte(ServiceInstanceName))

	var b bytes.Buffer
	if err := binary.Write(&b, binary.LittleEndian, openMsg); err != nil {
		log.Fatal(err)
	}
	_, err = unix.SendmsgN(fd, b.Bytes(), nil, nil, 0)
	if err != nil {
		log.Fatal(err)
	}

	buf := make([]byte, 4)
	n, _, _, _, err := unix.Recvmsg(fd, buf, nil, 0)
	if err != nil {
		log.Fatal(err)
	}
	buf = buf[:n]
	log.Print("resp: buf: %#v", buf)
	log.Print("Done")
}
```

#### $GOPATH/src/socket/Makefile
```
build:
	GOOS=linux GOARCH=386 go build

pkg: build
	mkapp -v -t virt socket.adef

install: build
	scp -P 10022 socket socket.*.update root@localhost:
```

#### $GOPATH/src/socket/socket.adef
```
sandboxed: true
version: 1.0.2

bundles:
{
    file:
    {
        [x] socket /bin/
    }
}

processes:
{
    run:
    {
        ( socket )
    }
}

extern:
{
    requires:
    {
        printer = $LEGATO_ROOT/apps/sample/helloIpc/printer.api
    }
}

bindings:
{
    *.printer -> printServer.printer
}
```