From ffa955a21b91a11a517dc0c0ef3b4567fea3541e Mon Sep 17 00:00:00 2001
From: Tom Wilkie <tom.wilkie@gmail.com>
Date: Mon, 4 Jan 2016 19:09:34 +0000
Subject: [PATCH] Split and move xfer package.

---
 app/controls.go                               |  2 +-
 app/controls_test.go                          |  7 +++--
 app/pipes.go                                  |  2 +-
 app/pipes_internal_test.go                    |  9 +++---
 app/router.go                                 |  2 +-
 common/xfer/constants.go                      | 19 +++++++++++++
 {xfer => common/xfer}/controls.go             |  0
 {xfer => common/xfer}/pipes.go                |  0
 experimental/demoprobe/main.go                |  7 +++--
 experimental/fixprobe/main.go                 |  7 +++--
 {xfer => probe/appclient}/app_client.go       | 28 ++++++++-----------
 .../appclient}/app_client_internal_test.go    |  7 +++--
 {xfer => probe/appclient}/multi_client.go     | 16 ++++++++---
 .../appclient}/multi_client_internal_test.go  |  2 +-
 .../appclient}/multi_client_test.go           | 11 ++++----
 {xfer => probe/appclient}/probe_config.go     |  9 ++----
 {xfer => probe/appclient}/report_publisher.go |  2 +-
 {xfer => probe/appclient}/resolver.go         |  6 ++--
 .../appclient}/resolver_internal_test.go      | 12 ++++----
 probe/controls/controls.go                    |  2 +-
 probe/controls/controls_test.go               |  2 +-
 probe/controls/pipes.go                       |  2 +-
 probe/docker/controls.go                      |  2 +-
 probe/docker/controls_test.go                 |  2 +-
 probe/probe.go                                |  8 +++---
 prog/app.go                                   |  2 +-
 prog/probe.go                                 | 11 ++++----
 xfer/ports.go                                 |  8 ------
 xfer/publisher.go                             | 10 -------
 29 files changed, 104 insertions(+), 93 deletions(-)
 create mode 100644 common/xfer/constants.go
 rename {xfer => common/xfer}/controls.go (100%)
 rename {xfer => common/xfer}/pipes.go (100%)
 rename {xfer => probe/appclient}/app_client.go (92%)
 rename {xfer => probe/appclient}/app_client_internal_test.go (95%)
 rename {xfer => probe/appclient}/multi_client.go (92%)
 rename {xfer => probe/appclient}/multi_client_internal_test.go (97%)
 rename {xfer => probe/appclient}/multi_client_test.go (88%)
 rename {xfer => probe/appclient}/probe_config.go (82%)
 rename {xfer => probe/appclient}/report_publisher.go (97%)
 rename {xfer => probe/appclient}/resolver.go (95%)
 rename {xfer => probe/appclient}/resolver_internal_test.go (89%)
 delete mode 100644 xfer/ports.go
 delete mode 100644 xfer/publisher.go

diff --git a/app/controls.go b/app/controls.go
index 0a77b2e1d..354afd703 100644
--- a/app/controls.go
+++ b/app/controls.go
@@ -9,7 +9,7 @@ import (
 
 	"github.com/gorilla/mux"
 
-	"github.com/weaveworks/scope/xfer"
+	"github.com/weaveworks/scope/common/xfer"
 )
 
 // RegisterControlRoutes registers the various control routes with a http mux.
diff --git a/app/controls_test.go b/app/controls_test.go
index 82e51bf64..679f73a22 100644
--- a/app/controls_test.go
+++ b/app/controls_test.go
@@ -12,7 +12,8 @@ import (
 	"github.com/gorilla/mux"
 
 	"github.com/weaveworks/scope/app"
-	"github.com/weaveworks/scope/xfer"
+	"github.com/weaveworks/scope/common/xfer"
+	"github.com/weaveworks/scope/probe/appclient"
 )
 
 func TestControl(t *testing.T) {
@@ -26,7 +27,7 @@ func TestControl(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	probeConfig := xfer.ProbeConfig{
+	probeConfig := appclient.ProbeConfig{
 		ProbeID: "foo",
 	}
 	controlHandler := xfer.ControlHandlerFunc(func(req xfer.Request) xfer.Response {
@@ -42,7 +43,7 @@ func TestControl(t *testing.T) {
 			Value: "foo",
 		}
 	})
-	client, err := xfer.NewAppClient(probeConfig, ip+":"+port, ip+":"+port, controlHandler)
+	client, err := appclient.NewAppClient(probeConfig, ip+":"+port, ip+":"+port, controlHandler)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/app/pipes.go b/app/pipes.go
index dc6a1b69e..f3dcadbd8 100644
--- a/app/pipes.go
+++ b/app/pipes.go
@@ -10,7 +10,7 @@ import (
 	"github.com/gorilla/mux"
 
 	"github.com/weaveworks/scope/common/mtime"
-	"github.com/weaveworks/scope/xfer"
+	"github.com/weaveworks/scope/common/xfer"
 )
 
 const (
diff --git a/app/pipes_internal_test.go b/app/pipes_internal_test.go
index 312e02bbe..69615c5ac 100644
--- a/app/pipes_internal_test.go
+++ b/app/pipes_internal_test.go
@@ -14,9 +14,10 @@ import (
 	"github.com/gorilla/websocket"
 
 	"github.com/weaveworks/scope/common/mtime"
+	"github.com/weaveworks/scope/common/xfer"
+	"github.com/weaveworks/scope/probe/appclient"
 	"github.com/weaveworks/scope/probe/controls"
 	"github.com/weaveworks/scope/test"
-	"github.com/weaveworks/scope/xfer"
 )
 
 func TestPipeTimeout(t *testing.T) {
@@ -50,7 +51,7 @@ func TestPipeTimeout(t *testing.T) {
 }
 
 type adapter struct {
-	c xfer.AppClient
+	c appclient.AppClient
 }
 
 func (a adapter) PipeConnection(_, pipeID string, pipe xfer.Pipe) error {
@@ -75,10 +76,10 @@ func TestPipeClose(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	probeConfig := xfer.ProbeConfig{
+	probeConfig := appclient.ProbeConfig{
 		ProbeID: "foo",
 	}
-	client, err := xfer.NewAppClient(probeConfig, ip+":"+port, ip+":"+port, nil)
+	client, err := appclient.NewAppClient(probeConfig, ip+":"+port, ip+":"+port, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/app/router.go b/app/router.go
index 36dd835fd..31456ea40 100644
--- a/app/router.go
+++ b/app/router.go
@@ -12,8 +12,8 @@ import (
 	"github.com/gorilla/mux"
 
 	"github.com/weaveworks/scope/common/hostname"
+	"github.com/weaveworks/scope/common/xfer"
 	"github.com/weaveworks/scope/report"
-	"github.com/weaveworks/scope/xfer"
 )
 
 var (
diff --git a/common/xfer/constants.go b/common/xfer/constants.go
new file mode 100644
index 000000000..6bbc0d7c6
--- /dev/null
+++ b/common/xfer/constants.go
@@ -0,0 +1,19 @@
+package xfer
+
+const (
+	// AppPort is the default port that the app will use for its HTTP server.
+	// The app publishes the API and user interface, and receives reports from
+	// probes, on this port.
+	AppPort = 4040
+
+	// ScopeProbeIDHeader is the header we use to carry the probe's unique ID. The
+	// ID is currently set to the a random string on probe startup.
+	ScopeProbeIDHeader = "X-Scope-Probe-ID"
+)
+
+// Details are some generic details that can be fetched from /api
+type Details struct {
+	ID       string `json:"id"`
+	Version  string `json:"version"`
+	Hostname string `json:"hostname"`
+}
diff --git a/xfer/controls.go b/common/xfer/controls.go
similarity index 100%
rename from xfer/controls.go
rename to common/xfer/controls.go
diff --git a/xfer/pipes.go b/common/xfer/pipes.go
similarity index 100%
rename from xfer/pipes.go
rename to common/xfer/pipes.go
diff --git a/experimental/demoprobe/main.go b/experimental/demoprobe/main.go
index 57dbc8e4c..792b5df89 100644
--- a/experimental/demoprobe/main.go
+++ b/experimental/demoprobe/main.go
@@ -9,10 +9,11 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/weaveworks/scope/common/xfer"
+	"github.com/weaveworks/scope/probe/appclient"
 	"github.com/weaveworks/scope/probe/docker"
 	"github.com/weaveworks/scope/probe/process"
 	"github.com/weaveworks/scope/report"
-	"github.com/weaveworks/scope/xfer"
 )
 
 func main() {
@@ -23,7 +24,7 @@ func main() {
 	)
 	flag.Parse()
 
-	client, err := xfer.NewAppClient(xfer.ProbeConfig{
+	client, err := appclient.NewAppClient(appclient.ProbeConfig{
 		Token:    "demoprobe",
 		ProbeID:  "demoprobe",
 		Insecure: false,
@@ -31,7 +32,7 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
-	rp := xfer.NewReportPublisher(client)
+	rp := appclient.NewReportPublisher(client)
 
 	rand.Seed(time.Now().UnixNano())
 	for range time.Tick(*publishInterval) {
diff --git a/experimental/fixprobe/main.go b/experimental/fixprobe/main.go
index d19eb99b4..d5c29b2ad 100644
--- a/experimental/fixprobe/main.go
+++ b/experimental/fixprobe/main.go
@@ -9,8 +9,9 @@ import (
 	"os"
 	"time"
 
+	"github.com/weaveworks/scope/common/xfer"
+	"github.com/weaveworks/scope/probe/appclient"
 	"github.com/weaveworks/scope/report"
-	"github.com/weaveworks/scope/xfer"
 )
 
 func main() {
@@ -34,7 +35,7 @@ func main() {
 	}
 	f.Close()
 
-	client, err := xfer.NewAppClient(xfer.ProbeConfig{
+	client, err := appclient.NewAppClient(appclient.ProbeConfig{
 		Token:    "fixprobe",
 		ProbeID:  "fixprobe",
 		Insecure: false,
@@ -43,7 +44,7 @@ func main() {
 		log.Fatal(err)
 	}
 
-	rp := xfer.NewReportPublisher(client)
+	rp := appclient.NewReportPublisher(client)
 	for range time.Tick(*publishInterval) {
 		rp.Publish(fixedReport)
 	}
diff --git a/xfer/app_client.go b/probe/appclient/app_client.go
similarity index 92%
rename from xfer/app_client.go
rename to probe/appclient/app_client.go
index 379b93604..43cac073d 100644
--- a/xfer/app_client.go
+++ b/probe/appclient/app_client.go
@@ -1,4 +1,4 @@
-package xfer
+package appclient
 
 import (
 	"encoding/json"
@@ -13,6 +13,7 @@ import (
 	"github.com/gorilla/websocket"
 
 	"github.com/weaveworks/scope/common/sanitize"
+	"github.com/weaveworks/scope/common/xfer"
 )
 
 const (
@@ -20,18 +21,11 @@ const (
 	maxBackoff     = 60 * time.Second
 )
 
-// Details are some generic details that can be fetched from /api
-type Details struct {
-	ID       string `json:"id"`
-	Version  string `json:"version"`
-	Hostname string `json:"hostname"`
-}
-
 // AppClient is a client to an app for dealing with controls.
 type AppClient interface {
-	Details() (Details, error)
+	Details() (xfer.Details, error)
 	ControlConnection()
-	PipeConnection(string, Pipe)
+	PipeConnection(string, xfer.Pipe)
 	PipeClose(string) error
 	Publish(r io.Reader) error
 	Stop()
@@ -58,11 +52,11 @@ type appClient struct {
 	readers     chan io.Reader
 
 	// For controls
-	control ControlHandler
+	control xfer.ControlHandler
 }
 
 // NewAppClient makes a new appClient.
-func NewAppClient(pc ProbeConfig, hostname, target string, control ControlHandler) (AppClient, error) {
+func NewAppClient(pc ProbeConfig, hostname, target string, control xfer.ControlHandler) (AppClient, error) {
 	httpTransport, err := pc.getHTTPTransport(hostname)
 	if err != nil {
 		return nil, err
@@ -144,8 +138,8 @@ func (c *appClient) Stop() {
 }
 
 // Details fetches the details (version, id) of the app.
-func (c *appClient) Details() (Details, error) {
-	result := Details{}
+func (c *appClient) Details() (xfer.Details, error) {
+	result := xfer.Details{}
 	req, err := c.ProbeConfig.authorizedRequest("GET", sanitize.URL("", 0, "/api")(c.target), nil)
 	if err != nil {
 		return result, err
@@ -202,7 +196,7 @@ func (c *appClient) controlConnection() (bool, error) {
 		conn.Close()
 	}()
 
-	codec := NewJSONWebsocketCodec(conn)
+	codec := xfer.NewJSONWebsocketCodec(conn)
 	server := rpc.NewServer()
 	if err := server.RegisterName("control", c.control); err != nil {
 		return false, err
@@ -271,7 +265,7 @@ func (c *appClient) Publish(r io.Reader) error {
 	return nil
 }
 
-func (c *appClient) pipeConnection(id string, pipe Pipe) (bool, error) {
+func (c *appClient) pipeConnection(id string, pipe xfer.Pipe) (bool, error) {
 	headers := http.Header{}
 	c.ProbeConfig.authorizeHeaders(headers)
 	url := sanitize.URL("ws://", 0, fmt.Sprintf("/api/pipe/%s/probe", id))(c.target)
@@ -295,7 +289,7 @@ func (c *appClient) pipeConnection(id string, pipe Pipe) (bool, error) {
 	return false, pipe.CopyToWebsocket(remote, conn)
 }
 
-func (c *appClient) PipeConnection(id string, pipe Pipe) {
+func (c *appClient) PipeConnection(id string, pipe xfer.Pipe) {
 	go func() {
 		log.Printf("Pipe %s connection to %s starting", id, c.target)
 		defer log.Printf("Pipe %s connection to %s exiting", id, c.target)
diff --git a/xfer/app_client_internal_test.go b/probe/appclient/app_client_internal_test.go
similarity index 95%
rename from xfer/app_client_internal_test.go
rename to probe/appclient/app_client_internal_test.go
index d13b1d7cc..bd316c45d 100644
--- a/xfer/app_client_internal_test.go
+++ b/probe/appclient/app_client_internal_test.go
@@ -1,4 +1,4 @@
-package xfer
+package appclient
 
 import (
 	"compress/gzip"
@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"github.com/gorilla/handlers"
+	"github.com/weaveworks/scope/common/xfer"
 	"github.com/weaveworks/scope/report"
 	"github.com/weaveworks/scope/test"
 )
@@ -33,7 +34,7 @@ func dummyServer(t *testing.T, expectedToken, expectedID string, expectedReport
 			t.Errorf("want %q, have %q", expectedToken, have)
 		}
 
-		if have := r.Header.Get(ScopeProbeIDHeader); expectedID != have {
+		if have := r.Header.Get(xfer.ScopeProbeIDHeader); expectedID != have {
 			t.Errorf("want %q, have %q", expectedID, have)
 		}
 
@@ -151,7 +152,7 @@ func TestAppClientPublish(t *testing.T) {
 	var (
 		id      = "foobarbaz"
 		version = "imalittleteapot"
-		want    = Details{ID: id, Version: version}
+		want    = xfer.Details{ID: id, Version: version}
 	)
 
 	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
diff --git a/xfer/multi_client.go b/probe/appclient/multi_client.go
similarity index 92%
rename from xfer/multi_client.go
rename to probe/appclient/multi_client.go
index d4eceb9fc..7ee020bba 100644
--- a/xfer/multi_client.go
+++ b/probe/appclient/multi_client.go
@@ -1,4 +1,4 @@
-package xfer
+package appclient
 
 import (
 	"bytes"
@@ -10,6 +10,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/weaveworks/scope/common/xfer"
 	"github.com/weaveworks/scope/report"
 )
 
@@ -29,15 +30,22 @@ type multiClient struct {
 }
 
 type clientTuple struct {
-	Details
+	xfer.Details
 	AppClient
 }
 
+// Publisher is something which can send a stream of data somewhere, probably
+// to a remote collector.
+type Publisher interface {
+	Publish(io.Reader) error
+	Stop()
+}
+
 // MultiAppClient maintains a set of upstream apps, and ensures we have an
 // AppClient for each one.
 type MultiAppClient interface {
 	Set(hostname string, endpoints []string)
-	PipeConnection(appID, pipeID string, pipe Pipe) error
+	PipeConnection(appID, pipeID string, pipe xfer.Pipe) error
 	PipeClose(appID, pipeID string) error
 	Stop()
 	Publish(io.Reader) error
@@ -122,7 +130,7 @@ func (c *multiClient) withClient(appID string, f func(AppClient) error) error {
 	return f(client)
 }
 
-func (c *multiClient) PipeConnection(appID, pipeID string, pipe Pipe) error {
+func (c *multiClient) PipeConnection(appID, pipeID string, pipe xfer.Pipe) error {
 	return c.withClient(appID, func(client AppClient) error {
 		client.PipeConnection(pipeID, pipe)
 		return nil
diff --git a/xfer/multi_client_internal_test.go b/probe/appclient/multi_client_internal_test.go
similarity index 97%
rename from xfer/multi_client_internal_test.go
rename to probe/appclient/multi_client_internal_test.go
index 66523adc4..0b9683f91 100644
--- a/xfer/multi_client_internal_test.go
+++ b/probe/appclient/multi_client_internal_test.go
@@ -1,4 +1,4 @@
-package xfer
+package appclient
 
 import (
 	"testing"
diff --git a/xfer/multi_client_test.go b/probe/appclient/multi_client_test.go
similarity index 88%
rename from xfer/multi_client_test.go
rename to probe/appclient/multi_client_test.go
index b4e495503..98126c1cd 100644
--- a/xfer/multi_client_test.go
+++ b/probe/appclient/multi_client_test.go
@@ -1,4 +1,4 @@
-package xfer_test
+package appclient_test
 
 import (
 	"bytes"
@@ -6,7 +6,8 @@ import (
 	"runtime"
 	"testing"
 
-	"github.com/weaveworks/scope/xfer"
+	"github.com/weaveworks/scope/common/xfer"
+	"github.com/weaveworks/scope/probe/appclient"
 )
 
 type mockClient struct {
@@ -41,7 +42,7 @@ var (
 	a2      = &mockClient{id: "2"} // hostname a, app id 2
 	b2      = &mockClient{id: "2"} // hostname b, app id 2 (duplicate)
 	b3      = &mockClient{id: "3"} // hostname b, app id 3
-	factory = func(hostname, target string) (xfer.AppClient, error) {
+	factory = func(hostname, target string) (appclient.AppClient, error) {
 		switch target {
 		case "a1":
 			return a1, nil
@@ -66,7 +67,7 @@ func TestMultiClient(t *testing.T) {
 		}
 	)
 
-	mp := xfer.NewMultiAppClient(factory)
+	mp := appclient.NewMultiAppClient(factory)
 	defer mp.Stop()
 
 	// Add two hostnames with overlapping apps, check we don't add the same app twice
@@ -88,7 +89,7 @@ func TestMultiClient(t *testing.T) {
 }
 
 func TestMultiClientPublish(t *testing.T) {
-	mp := xfer.NewMultiAppClient(factory)
+	mp := appclient.NewMultiAppClient(factory)
 	defer mp.Stop()
 
 	sum := func() int { return a1.publish + a2.publish + b2.publish + b3.publish }
diff --git a/xfer/probe_config.go b/probe/appclient/probe_config.go
similarity index 82%
rename from xfer/probe_config.go
rename to probe/appclient/probe_config.go
index 58c1093d4..c0fcaf2eb 100644
--- a/xfer/probe_config.go
+++ b/probe/appclient/probe_config.go
@@ -1,4 +1,4 @@
-package xfer
+package appclient
 
 import (
 	"crypto/tls"
@@ -9,12 +9,9 @@ import (
 	"net/http"
 
 	"github.com/certifi/gocertifi"
+	"github.com/weaveworks/scope/common/xfer"
 )
 
-// ScopeProbeIDHeader is the header we use to carry the probe's unique ID. The
-// ID is currently set to the a random string on probe startup.
-const ScopeProbeIDHeader = "X-Scope-Probe-ID"
-
 var certPool *x509.CertPool
 
 func init() {
@@ -34,7 +31,7 @@ type ProbeConfig struct {
 
 func (pc ProbeConfig) authorizeHeaders(headers http.Header) {
 	headers.Set("Authorization", fmt.Sprintf("Scope-Probe token=%s", pc.Token))
-	headers.Set(ScopeProbeIDHeader, pc.ProbeID)
+	headers.Set(xfer.ScopeProbeIDHeader, pc.ProbeID)
 }
 
 func (pc ProbeConfig) authorizedRequest(method string, urlStr string, body io.Reader) (*http.Request, error) {
diff --git a/xfer/report_publisher.go b/probe/appclient/report_publisher.go
similarity index 97%
rename from xfer/report_publisher.go
rename to probe/appclient/report_publisher.go
index efde88da4..83098491a 100644
--- a/xfer/report_publisher.go
+++ b/probe/appclient/report_publisher.go
@@ -1,4 +1,4 @@
-package xfer
+package appclient
 
 import (
 	"bytes"
diff --git a/xfer/resolver.go b/probe/appclient/resolver.go
similarity index 95%
rename from xfer/resolver.go
rename to probe/appclient/resolver.go
index c2524a8f1..f37909ada 100644
--- a/xfer/resolver.go
+++ b/probe/appclient/resolver.go
@@ -1,4 +1,4 @@
-package xfer
+package appclient
 
 import (
 	"log"
@@ -6,6 +6,8 @@ import (
 	"strconv"
 	"strings"
 	"time"
+
+	"github.com/weaveworks/scope/common/xfer"
 )
 
 const (
@@ -76,7 +78,7 @@ func prepare(strs []string) []target {
 				continue
 			}
 		} else {
-			host, port = s, strconv.Itoa(AppPort)
+			host, port = s, strconv.Itoa(xfer.AppPort)
 		}
 		targets = append(targets, target{host, port})
 	}
diff --git a/xfer/resolver_internal_test.go b/probe/appclient/resolver_internal_test.go
similarity index 89%
rename from xfer/resolver_internal_test.go
rename to probe/appclient/resolver_internal_test.go
index c1d57b948..f86abfd00 100644
--- a/xfer/resolver_internal_test.go
+++ b/probe/appclient/resolver_internal_test.go
@@ -1,4 +1,4 @@
-package xfer
+package appclient
 
 import (
 	"fmt"
@@ -7,6 +7,8 @@ import (
 	"sync"
 	"testing"
 	"time"
+
+	"github.com/weaveworks/scope/common/xfer"
 )
 
 func TestResolver(t *testing.T) {
@@ -68,22 +70,22 @@ func TestResolver(t *testing.T) {
 	}
 
 	// Initial resolve should just give us IPs
-	assertAdd(ip1+port, fmt.Sprintf("%s:%d", ip2, AppPort))
+	assertAdd(ip1+port, fmt.Sprintf("%s:%d", ip2, xfer.AppPort))
 
 	// Trigger another resolve with a tick; again,
 	// just want ips.
 	c <- time.Now()
-	assertAdd(ip1+port, fmt.Sprintf("%s:%d", ip2, AppPort))
+	assertAdd(ip1+port, fmt.Sprintf("%s:%d", ip2, xfer.AppPort))
 
 	ip3 := "1.2.3.4"
 	updateIPs("symbolic.name", makeIPs(ip3))
 	c <- time.Now() // trigger a resolve
-	assertAdd(ip3+port, ip1+port, fmt.Sprintf("%s:%d", ip2, AppPort))
+	assertAdd(ip3+port, ip1+port, fmt.Sprintf("%s:%d", ip2, xfer.AppPort))
 
 	ip4 := "10.10.10.10"
 	updateIPs("symbolic.name", makeIPs(ip3, ip4))
 	c <- time.Now() // trigger another resolve, this time with 2 adds
-	assertAdd(ip3+port, ip4+port, ip1+port, fmt.Sprintf("%s:%d", ip2, AppPort))
+	assertAdd(ip3+port, ip4+port, ip1+port, fmt.Sprintf("%s:%d", ip2, xfer.AppPort))
 
 	done := make(chan struct{})
 	go func() { r.Stop(); close(done) }()
diff --git a/probe/controls/controls.go b/probe/controls/controls.go
index ed2f61bd6..2d12daa69 100644
--- a/probe/controls/controls.go
+++ b/probe/controls/controls.go
@@ -3,7 +3,7 @@ package controls
 import (
 	"sync"
 
-	"github.com/weaveworks/scope/xfer"
+	"github.com/weaveworks/scope/common/xfer"
 )
 
 var (
diff --git a/probe/controls/controls_test.go b/probe/controls/controls_test.go
index 04bb66268..b7c153a6c 100644
--- a/probe/controls/controls_test.go
+++ b/probe/controls/controls_test.go
@@ -4,9 +4,9 @@ import (
 	"reflect"
 	"testing"
 
+	"github.com/weaveworks/scope/common/xfer"
 	"github.com/weaveworks/scope/probe/controls"
 	"github.com/weaveworks/scope/test"
-	"github.com/weaveworks/scope/xfer"
 )
 
 func TestControls(t *testing.T) {
diff --git a/probe/controls/pipes.go b/probe/controls/pipes.go
index eec4da28f..cf540419f 100644
--- a/probe/controls/pipes.go
+++ b/probe/controls/pipes.go
@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"math/rand"
 
-	"github.com/weaveworks/scope/xfer"
+	"github.com/weaveworks/scope/common/xfer"
 )
 
 // PipeClient is the type of the thing the probe uses to make pipe connections.
diff --git a/probe/docker/controls.go b/probe/docker/controls.go
index fdb63a19a..2057069e4 100644
--- a/probe/docker/controls.go
+++ b/probe/docker/controls.go
@@ -5,9 +5,9 @@ import (
 
 	docker_client "github.com/fsouza/go-dockerclient"
 
+	"github.com/weaveworks/scope/common/xfer"
 	"github.com/weaveworks/scope/probe/controls"
 	"github.com/weaveworks/scope/report"
-	"github.com/weaveworks/scope/xfer"
 )
 
 // Control IDs used by the docker intergation.
diff --git a/probe/docker/controls_test.go b/probe/docker/controls_test.go
index 67a658958..97ab285f6 100644
--- a/probe/docker/controls_test.go
+++ b/probe/docker/controls_test.go
@@ -8,11 +8,11 @@ import (
 
 	"github.com/gorilla/websocket"
 
+	"github.com/weaveworks/scope/common/xfer"
 	"github.com/weaveworks/scope/probe/controls"
 	"github.com/weaveworks/scope/probe/docker"
 	"github.com/weaveworks/scope/report"
 	"github.com/weaveworks/scope/test"
-	"github.com/weaveworks/scope/xfer"
 )
 
 func TestControls(t *testing.T) {
diff --git a/probe/probe.go b/probe/probe.go
index c28ac688b..bf244a7b0 100644
--- a/probe/probe.go
+++ b/probe/probe.go
@@ -7,8 +7,8 @@ import (
 
 	"github.com/armon/go-metrics"
 
+	"github.com/weaveworks/scope/probe/appclient"
 	"github.com/weaveworks/scope/report"
-	"github.com/weaveworks/scope/xfer"
 )
 
 const (
@@ -18,7 +18,7 @@ const (
 // Probe sits there, generating and publishing reports.
 type Probe struct {
 	spyInterval, publishInterval time.Duration
-	publisher                    *xfer.ReportPublisher
+	publisher                    *appclient.ReportPublisher
 
 	tickers   []Ticker
 	reporters []Reporter
@@ -52,11 +52,11 @@ type Ticker interface {
 }
 
 // New makes a new Probe.
-func New(spyInterval, publishInterval time.Duration, publisher xfer.Publisher) *Probe {
+func New(spyInterval, publishInterval time.Duration, publisher appclient.Publisher) *Probe {
 	result := &Probe{
 		spyInterval:     spyInterval,
 		publishInterval: publishInterval,
-		publisher:       xfer.NewReportPublisher(publisher),
+		publisher:       appclient.NewReportPublisher(publisher),
 		quit:            make(chan struct{}),
 		spiedReports:    make(chan report.Report, reportBufferSize),
 		shortcutReports: make(chan report.Report, reportBufferSize),
diff --git a/prog/app.go b/prog/app.go
index f7986e069..8d8a15090 100644
--- a/prog/app.go
+++ b/prog/app.go
@@ -14,7 +14,7 @@ import (
 	"github.com/weaveworks/weave/common"
 
 	"github.com/weaveworks/scope/app"
-	"github.com/weaveworks/scope/xfer"
+	"github.com/weaveworks/scope/common/xfer"
 )
 
 // Router creates the mux for all the various app components.
diff --git a/prog/probe.go b/prog/probe.go
index e6f46536d..d7dba92e5 100644
--- a/prog/probe.go
+++ b/prog/probe.go
@@ -17,7 +17,9 @@ import (
 	"github.com/weaveworks/weave/common"
 
 	"github.com/weaveworks/scope/common/hostname"
+	"github.com/weaveworks/scope/common/xfer"
 	"github.com/weaveworks/scope/probe"
+	"github.com/weaveworks/scope/probe/appclient"
 	"github.com/weaveworks/scope/probe/controls"
 	"github.com/weaveworks/scope/probe/docker"
 	"github.com/weaveworks/scope/probe/endpoint"
@@ -26,7 +28,6 @@ import (
 	"github.com/weaveworks/scope/probe/overlay"
 	"github.com/weaveworks/scope/probe/process"
 	"github.com/weaveworks/scope/report"
-	"github.com/weaveworks/scope/xfer"
 )
 
 // Main runs the probe
@@ -94,20 +95,20 @@ func probeMain() {
 	}
 	log.Printf("publishing to: %s", strings.Join(targets, ", "))
 
-	probeConfig := xfer.ProbeConfig{
+	probeConfig := appclient.ProbeConfig{
 		Token:    *token,
 		ProbeID:  probeID,
 		Insecure: *insecure,
 	}
-	clients := xfer.NewMultiAppClient(func(hostname, endpoint string) (xfer.AppClient, error) {
-		return xfer.NewAppClient(
+	clients := appclient.NewMultiAppClient(func(hostname, endpoint string) (appclient.AppClient, error) {
+		return appclient.NewAppClient(
 			probeConfig, hostname, endpoint,
 			xfer.ControlHandlerFunc(controls.HandleControlRequest),
 		)
 	})
 	defer clients.Stop()
 
-	resolver := xfer.NewStaticResolver(targets, clients.Set)
+	resolver := appclient.NewStaticResolver(targets, clients.Set)
 	defer resolver.Stop()
 
 	processCache := process.NewCachingWalker(process.NewWalker(*procRoot))
diff --git a/xfer/ports.go b/xfer/ports.go
deleted file mode 100644
index 11e1e074a..000000000
--- a/xfer/ports.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package xfer
-
-var (
-	// AppPort is the default port that the app will use for its HTTP server.
-	// The app publishes the API and user interface, and receives reports from
-	// probes, on this port.
-	AppPort = 4040
-)
diff --git a/xfer/publisher.go b/xfer/publisher.go
deleted file mode 100644
index 7ac56a93e..000000000
--- a/xfer/publisher.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package xfer
-
-import "io"
-
-// Publisher is something which can send a stream of data somewhere, probably
-// to a remote collector.
-type Publisher interface {
-	Publish(io.Reader) error
-	Stop()
-}