Merge pull request #719 from dotcloud/json_stream-feature

* API: push, pull, import, insert -> Json Stream

api.go

@@ -314,16 +314,25 @@ func postImagesCreate(srv *Server, version float64, w http.ResponseWriter, r *ht
 	tag := r.Form.Get("tag")
 	repo := r.Form.Get("repo")
 
+	if version > 1.0 {
+		w.Header().Set("Content-Type", "application/json")
+	}
+	sf := utils.NewStreamFormatter(version > 1.0)
 	if image != "" { //pull
 		registry := r.Form.Get("registry")
-		if version > 1.0 {
+		if err := srv.ImagePull(image, tag, registry, w, sf); err != nil {
-			w.Header().Set("Content-Type", "application/json")
+			if sf.Used() {
-		}
+				w.Write(sf.FormatError(err))
-		if err := srv.ImagePull(image, tag, registry, w, version > 1.0); err != nil {
+				return nil
+			}
 			return err
 		}
 	} else { //import
-		if err := srv.ImageImport(src, repo, tag, r.Body, w); err != nil {
+		if err := srv.ImageImport(src, repo, tag, r.Body, w, sf); err != nil {
+			if sf.Used() {
+				w.Write(sf.FormatError(err))
+				return nil
+			}
 			return err
 		}
 	}
@@ -359,10 +368,16 @@ func postImagesInsert(srv *Server, version float64, w http.ResponseWriter, r *ht
 		return fmt.Errorf("Missing parameter")
 	}
 	name := vars["name"]
-
+	if version > 1.0 {
-	imgId, err := srv.ImageInsert(name, url, path, w)
+		w.Header().Set("Content-Type", "application/json")
+	}
+	sf := utils.NewStreamFormatter(version > 1.0)
+	imgId, err := srv.ImageInsert(name, url, path, w, sf)
 	if err != nil {
-		return err
+		if sf.Used() {
+			w.Write(sf.FormatError(err))
+			return nil
+		}
 	}
 	b, err := json.Marshal(&ApiId{Id: imgId})
 	if err != nil {
@@ -382,8 +397,15 @@ func postImagesPush(srv *Server, version float64, w http.ResponseWriter, r *http
 		return fmt.Errorf("Missing parameter")
 	}
 	name := vars["name"]
-
+	if version > 1.0 {
-	if err := srv.ImagePush(name, registry, w); err != nil {
+		w.Header().Set("Content-Type", "application/json")
+	}
+	sf := utils.NewStreamFormatter(version > 1.0)
+	if err := srv.ImagePush(name, registry, w, sf); err != nil {
+		if sf.Used() {
+			w.Write(sf.FormatError(err))
+			return nil
+		}
 		return err
 	}
 	return nil

buildfile.go

@@ -61,7 +61,7 @@ func (b *buildFile) CmdFrom(name string) error {
 				remote = name
 			}
 
-			if err := b.srv.ImagePull(remote, tag, "", b.out, false); err != nil {
+			if err := b.srv.ImagePull(remote, tag, "", b.out, utils.NewStreamFormatter(false)); err != nil {
 				return err
 			}
 

commands.go

@@ -180,7 +180,8 @@ func (cli *DockerCli) CmdBuild(args ...string) error {
 			return err
 		} else {
 			// FIXME: Find a way to have a progressbar for the upload too
-			io.Copy(wField, utils.ProgressReader(ioutil.NopCloser(context), -1, os.Stdout, "Caching Context %v/%v (%v)\r", false))
+			sf := utils.NewStreamFormatter(false)
+			io.Copy(wField, utils.ProgressReader(ioutil.NopCloser(context), -1, os.Stdout, sf.FormatProgress("Caching Context", "%v/%v (%v)"), sf))
 		}
 		multipartBody = io.MultiReader(multipartBody, boundary)
 	}
@@ -1367,13 +1368,9 @@ func (cli *DockerCli) stream(method, path string, in io.Reader, out io.Writer) e
 	}
 
 	if resp.Header.Get("Content-Type") == "application/json" {
-		type Message struct {
-			Status   string `json:"status,omitempty"`
-			Progress string `json:"progress,omitempty"`
-		}
 		dec := json.NewDecoder(resp.Body)
 		for {
-			var m Message
+			var m utils.JsonMessage
 			if err := dec.Decode(&m); err == io.EOF {
 				break
 			} else if err != nil {
@@ -1381,6 +1378,8 @@ func (cli *DockerCli) stream(method, path string, in io.Reader, out io.Writer) e
 			}
 			if m.Progress != "" {
 				fmt.Fprintf(out, "Downloading %s\r", m.Progress)
+			} else if m.Error != "" {
+				return fmt.Errorf(m.Error)
 			} else {
 				fmt.Fprintf(out, "%s\n", m.Status)
 			}

docs/sources/api/docker_remote_api.rst

@@ -15,10 +15,17 @@ Docker Remote API
 - Default port in the docker deamon is 4243 
 - The API tends to be REST, but for some complex commands, like attach or pull, the HTTP connection is hijacked to transport stdout stdin and stderr
 
-2. Endpoints
+2. Version
+==========
+
+The current verson of the API is 1.1
+Calling /images/<name>/insert is the same as calling /v1.1/images/<name>/insert
+You can still call an old version of the api using /v1.0/images/<name>/insert
+
+3. Endpoints
 ============
 
-2.1 Containers
+3.1 Containers
 --------------
 
 List containers
@@ -460,7 +467,7 @@ Remove a container
         :statuscode 500: server error
 
 
-2.2 Images
+3.2 Images
 ----------
 
 List Images
@@ -549,7 +556,19 @@ Create an image
 
            POST /images/create?fromImage=base HTTP/1.1
 
-        **Example response**:
+        **Example response v1.1**:
+
+        .. sourcecode:: http
+
+           HTTP/1.1 200 OK
+	   Content-Type: application/json
+
+	   {"status":"Pulling..."}
+	   {"progress":"1/? (n/a)"}
+	   {"error":"Invalid..."}
+	   ...
+
+        **Example response v1.0**:
 
         .. sourcecode:: http
 
@@ -580,7 +599,19 @@ Insert a file in a image
 
            POST /images/test/insert?path=/usr&url=myurl HTTP/1.1
 
-	**Example response**:
+	**Example response v1.1**:
+
+        .. sourcecode:: http
+
+           HTTP/1.1 200 OK
+	   Content-Type: application/json
+
+	   {"status":"Inserting..."}
+	   {"progress":"1/? (n/a)"}
+	   {"error":"Invalid..."}
+	   ...
+
+	**Example response v1.0**:
 
         .. sourcecode:: http
 
@@ -695,7 +726,19 @@ Push an image on the registry
 
 	    POST /images/test/push HTTP/1.1
 
-	 **Example response**:
+	 **Example response v1.1**:
+
+        .. sourcecode:: http
+
+           HTTP/1.1 200 OK
+	   Content-Type: application/json
+
+	   {"status":"Pushing..."}
+	   {"progress":"1/? (n/a)"}
+	   {"error":"Invalid..."}
+	   ...
+
+	 **Example response v1.0**:
 
         .. sourcecode:: http
 
@@ -801,7 +844,7 @@ Search images
 	   :statuscode 500: server error
 
 
-2.3 Misc
+3.3 Misc
 --------
 
 Build an image from Dockerfile via stdin

graph.go

@@ -165,7 +165,8 @@ func (graph *Graph) TempLayerArchive(id string, compression Compression, output
 	if err != nil {
 		return nil, err
 	}
-	return NewTempArchive(utils.ProgressReader(ioutil.NopCloser(archive), 0, output, "Buffering to disk %v/%v (%v)", false), tmp.Root)
+	sf := utils.NewStreamFormatter(false)
+	return NewTempArchive(utils.ProgressReader(ioutil.NopCloser(archive), 0, output, sf.FormatProgress("Buffering to disk", "%v/%v (%v)"), sf), tmp.Root)
 }
 
 // Mktemp creates a temporary sub-directory inside the graph's filesystem.

runtime_test.go

@@ -68,7 +68,7 @@ func init() {
 		runtime: runtime,
 	}
 	// Retrieve the Image
-	if err := srv.ImagePull(unitTestImageName, "", "", os.Stdout, false); err != nil {
+	if err := srv.ImagePull(unitTestImageName, "", "", os.Stdout, utils.NewStreamFormatter(false)); err != nil {
 		panic(err)
 	}
 }

server.go

@@ -68,7 +68,7 @@ func (srv *Server) ImagesSearch(term string) ([]ApiSearch, error) {
 	return outs, nil
 }
 
-func (srv *Server) ImageInsert(name, url, path string, out io.Writer) (string, error) {
+func (srv *Server) ImageInsert(name, url, path string, out io.Writer, sf *utils.StreamFormatter) (string, error) {
 	out = utils.NewWriteFlusher(out)
 	img, err := srv.runtime.repositories.LookupImage(name)
 	if err != nil {
@@ -92,7 +92,7 @@ func (srv *Server) ImageInsert(name, url, path string, out io.Writer) (string, e
 		return "", err
 	}
 
-	if err := c.Inject(utils.ProgressReader(file.Body, int(file.ContentLength), out, "Downloading %v/%v (%v)\r", false), path); err != nil {
+	if err := c.Inject(utils.ProgressReader(file.Body, int(file.ContentLength), out, sf.FormatProgress("Downloading", "%v/%v (%v)"), sf), path); err != nil {
 		return "", err
 	}
 	// FIXME: Handle custom repo, tag comment, author
@@ -100,7 +100,7 @@ func (srv *Server) ImageInsert(name, url, path string, out io.Writer) (string, e
 	if err != nil {
 		return "", err
 	}
-	fmt.Fprintf(out, "%s\n", img.Id)
+	out.Write(sf.FormatStatus(img.Id))
 	return img.ShortId(), nil
 }
 
@@ -292,7 +292,7 @@ func (srv *Server) ContainerTag(name, repo, tag string, force bool) error {
 	return nil
 }
 
-func (srv *Server) pullImage(r *registry.Registry, out io.Writer, imgId, endpoint string, token []string, json bool) error {
+func (srv *Server) pullImage(r *registry.Registry, out io.Writer, imgId, endpoint string, token []string, sf *utils.StreamFormatter) error {
 	history, err := r.GetRemoteHistory(imgId, endpoint, token)
 	if err != nil {
 		return err
@@ -302,7 +302,7 @@ func (srv *Server) pullImage(r *registry.Registry, out io.Writer, imgId, endpoin
 	// FIXME: Launch the getRemoteImage() in goroutines
 	for _, id := range history {
 		if !srv.runtime.graph.Exists(id) {
-			fmt.Fprintf(out, utils.FormatStatus("Pulling %s metadata", json), id)
+			out.Write(sf.FormatStatus("Pulling %s metadata", id))
 			imgJson, err := r.GetRemoteImageJson(id, endpoint, token)
 			if err != nil {
 				// FIXME: Keep goging in case of error?
@@ -314,12 +314,12 @@ func (srv *Server) pullImage(r *registry.Registry, out io.Writer, imgId, endpoin
 			}
 
 			// Get the layer
-			fmt.Fprintf(out, utils.FormatStatus("Pulling %s fs layer", json), id)
+			out.Write(sf.FormatStatus("Pulling %s fs layer", id))
 			layer, contentLength, err := r.GetRemoteImageLayer(img.Id, endpoint, token)
 			if err != nil {
 				return err
 			}
-			if err := srv.runtime.graph.Register(utils.ProgressReader(layer, contentLength, out, utils.FormatProgress("%v/%v (%v)", json), json), false, img); err != nil {
+			if err := srv.runtime.graph.Register(utils.ProgressReader(layer, contentLength, out, sf.FormatProgress("Downloading", "%v/%v (%v)"), sf), false, img); err != nil {
 				return err
 			}
 		}
@@ -327,8 +327,8 @@ func (srv *Server) pullImage(r *registry.Registry, out io.Writer, imgId, endpoin
 	return nil
 }
 
-func (srv *Server) pullRepository(r *registry.Registry, out io.Writer, remote, askedTag string, json bool) error {
+func (srv *Server) pullRepository(r *registry.Registry, out io.Writer, remote, askedTag string, sf *utils.StreamFormatter) error {
-	fmt.Fprintf(out, utils.FormatStatus("Pulling repository %s from %s", json), remote, auth.IndexServerAddress())
+	out.Write(sf.FormatStatus("Pulling repository %s from %s", remote, auth.IndexServerAddress()))
 	repoData, err := r.GetRepositoryData(remote)
 	if err != nil {
 		return err
@@ -365,11 +365,11 @@ func (srv *Server) pullRepository(r *registry.Registry, out io.Writer, remote, a
 			utils.Debugf("(%s) does not match %s (id: %s), skipping", img.Tag, askedTag, img.Id)
 			continue
 		}
-		fmt.Fprintf(out, utils.FormatStatus("Pulling image %s (%s) from %s", json), img.Id, img.Tag, remote)
+		out.Write(sf.FormatStatus("Pulling image %s (%s) from %s", img.Id, img.Tag, remote))
 		success := false
 		for _, ep := range repoData.Endpoints {
-			if err := srv.pullImage(r, out, img.Id, "https://"+ep+"/v1", repoData.Tokens, json); err != nil {
+			if err := srv.pullImage(r, out, img.Id, "https://"+ep+"/v1", repoData.Tokens, sf); err != nil {
-				fmt.Fprintf(out, utils.FormatStatus("Error while retrieving image for tag: %s (%s); checking next endpoint\n", json), askedTag, err)
+				out.Write(sf.FormatStatus("Error while retrieving image for tag: %s (%s); checking next endpoint", askedTag, err))
 				continue
 			}
 			success = true
@@ -394,17 +394,17 @@ func (srv *Server) pullRepository(r *registry.Registry, out io.Writer, remote, a
 	return nil
 }
 
-func (srv *Server) ImagePull(name, tag, endpoint string, out io.Writer, json bool) error {
+func (srv *Server) ImagePull(name, tag, endpoint string, out io.Writer, sf *utils.StreamFormatter) error {
 	r := registry.NewRegistry(srv.runtime.root)
 	out = utils.NewWriteFlusher(out)
 	if endpoint != "" {
-		if err := srv.pullImage(r, out, name, endpoint, nil, json); err != nil {
+		if err := srv.pullImage(r, out, name, endpoint, nil, sf); err != nil {
 			return err
 		}
 		return nil
 	}
 
-	if err := srv.pullRepository(r, out, name, tag, json); err != nil {
+	if err := srv.pullRepository(r, out, name, tag, sf); err != nil {
 		return err
 	}
 
@@ -477,14 +477,14 @@ func (srv *Server) getImageList(localRepo map[string]string) ([]*registry.ImgDat
 	return imgList, nil
 }
 
-func (srv *Server) pushRepository(r *registry.Registry, out io.Writer, name string, localRepo map[string]string) error {
+func (srv *Server) pushRepository(r *registry.Registry, out io.Writer, name string, localRepo map[string]string, sf *utils.StreamFormatter) error {
 	out = utils.NewWriteFlusher(out)
-	fmt.Fprintf(out, "Processing checksums\n")
+	out.Write(sf.FormatStatus("Processing checksums"))
 	imgList, err := srv.getImageList(localRepo)
 	if err != nil {
 		return err
 	}
-	fmt.Fprintf(out, "Sending images list\n")
+	out.Write(sf.FormatStatus("Sending image list"))
 
 	repoData, err := r.PushImageJsonIndex(name, imgList, false)
 	if err != nil {
@@ -492,18 +492,18 @@ func (srv *Server) pushRepository(r *registry.Registry, out io.Writer, name stri
 	}
 
 	for _, ep := range repoData.Endpoints {
-		fmt.Fprintf(out, "Pushing repository %s to %s (%d tags)\r\n", name, ep, len(localRepo))
+		out.Write(sf.FormatStatus("Pushing repository %s to %s (%d tags)", name, ep, len(localRepo)))
 		// For each image within the repo, push them
 		for _, elem := range imgList {
 			if _, exists := repoData.ImgList[elem.Id]; exists {
-				fmt.Fprintf(out, "Image %s already on registry, skipping\n", name)
+				out.Write(sf.FormatStatus("Image %s already on registry, skipping", name))
 				continue
 			}
-			if err := srv.pushImage(r, out, name, elem.Id, ep, repoData.Tokens); err != nil {
+			if err := srv.pushImage(r, out, name, elem.Id, ep, repoData.Tokens, sf); err != nil {
 				// FIXME: Continue on error?
 				return err
 			}
-			fmt.Fprintf(out, "Pushing tags for rev [%s] on {%s}\n", elem.Id, ep+"/users/"+name+"/"+elem.Tag)
+			out.Write(sf.FormatStatus("Pushing tags for rev [%s] on {%s}", elem.Id, ep+"/users/"+name+"/"+elem.Tag))
 			if err := r.PushRegistryTag(name, elem.Id, elem.Tag, ep, repoData.Tokens); err != nil {
 				return err
 			}
@@ -516,13 +516,13 @@ func (srv *Server) pushRepository(r *registry.Registry, out io.Writer, name stri
 	return nil
 }
 
-func (srv *Server) pushImage(r *registry.Registry, out io.Writer, remote, imgId, ep string, token []string) error {
+func (srv *Server) pushImage(r *registry.Registry, out io.Writer, remote, imgId, ep string, token []string, sf *utils.StreamFormatter) error {
 	out = utils.NewWriteFlusher(out)
 	jsonRaw, err := ioutil.ReadFile(path.Join(srv.runtime.graph.Root, imgId, "json"))
 	if err != nil {
 		return fmt.Errorf("Error while retreiving the path for {%s}: %s", imgId, err)
 	}
-	fmt.Fprintf(out, "Pushing %s\r\n", imgId)
+	out.Write(sf.FormatStatus("Pushing %s", imgId))
 
 	// Make sure we have the image's checksum
 	checksum, err := srv.getChecksum(imgId)
@@ -537,7 +537,7 @@ func (srv *Server) pushImage(r *registry.Registry, out io.Writer, remote, imgId,
 	// Send the json
 	if err := r.PushImageJsonRegistry(imgData, jsonRaw, ep, token); err != nil {
 		if err == registry.ErrAlreadyExists {
-			fmt.Fprintf(out, "Image %s already uploaded ; skipping\n", imgData.Id)
+			out.Write(sf.FormatStatus("Image %s already uploaded ; skipping", imgData.Id))
 			return nil
 		}
 		return err
@@ -570,22 +570,22 @@ func (srv *Server) pushImage(r *registry.Registry, out io.Writer, remote, imgId,
 	}
 
 	// Send the layer
-	if err := r.PushImageLayerRegistry(imgData.Id, utils.ProgressReader(layerData, int(layerData.Size), out, "", false), ep, token); err != nil {
+	if err := r.PushImageLayerRegistry(imgData.Id, utils.ProgressReader(layerData, int(layerData.Size), out, sf.FormatProgress("", "%v/%v (%v)"), sf), ep, token); err != nil {
 		return err
 	}
 	return nil
 }
 
-func (srv *Server) ImagePush(name, endpoint string, out io.Writer) error {
+func (srv *Server) ImagePush(name, endpoint string, out io.Writer, sf *utils.StreamFormatter) error {
 	out = utils.NewWriteFlusher(out)
 	img, err := srv.runtime.graph.Get(name)
 	r := registry.NewRegistry(srv.runtime.root)
 
 	if err != nil {
-		fmt.Fprintf(out, "The push refers to a repository [%s] (len: %d)\n", name, len(srv.runtime.repositories.Repositories[name]))
+		out.Write(sf.FormatStatus("The push refers to a repository [%s] (len: %d)", name, len(srv.runtime.repositories.Repositories[name])))
 		// If it fails, try to get the repository
 		if localRepo, exists := srv.runtime.repositories.Repositories[name]; exists {
-			if err := srv.pushRepository(r, out, name, localRepo); err != nil {
+			if err := srv.pushRepository(r, out, name, localRepo, sf); err != nil {
 				return err
 			}
 			return nil
@@ -593,14 +593,14 @@ func (srv *Server) ImagePush(name, endpoint string, out io.Writer) error {
 
 		return err
 	}
-	fmt.Fprintf(out, "The push refers to an image: [%s]\n", name)
+	out.Write(sf.FormatStatus("The push refers to an image: [%s]", name))
-	if err := srv.pushImage(r, out, name, img.Id, endpoint, nil); err != nil {
+	if err := srv.pushImage(r, out, name, img.Id, endpoint, nil, sf); err != nil {
 		return err
 	}
 	return nil
 }
 
-func (srv *Server) ImageImport(src, repo, tag string, in io.Reader, out io.Writer) error {
+func (srv *Server) ImageImport(src, repo, tag string, in io.Reader, out io.Writer, sf *utils.StreamFormatter) error {
 	var archive io.Reader
 	var resp *http.Response
 
@@ -609,21 +609,21 @@ func (srv *Server) ImageImport(src, repo, tag string, in io.Reader, out io.Write
 	} else {
 		u, err := url.Parse(src)
 		if err != nil {
-			fmt.Fprintf(out, "Error: %s\n", err)
+			return err
 		}
 		if u.Scheme == "" {
 			u.Scheme = "http"
 			u.Host = src
 			u.Path = ""
 		}
-		fmt.Fprintf(out, "Downloading from %s\n", u)
+		out.Write(sf.FormatStatus("Downloading from %s", u))
 		// Download with curl (pretty progress bar)
 		// If curl is not available, fallback to http.Get()
 		resp, err = utils.Download(u.String(), out)
 		if err != nil {
 			return err
 		}
-		archive = utils.ProgressReader(resp.Body, int(resp.ContentLength), out, "Importing %v/%v (%v)\r", false)
+		archive = utils.ProgressReader(resp.Body, int(resp.ContentLength), out, sf.FormatProgress("Importing", "%v/%v (%v)"), sf)
 	}
 	img, err := srv.runtime.graph.Create(archive, nil, "Imported from "+src, "", nil)
 	if err != nil {
@@ -635,7 +635,7 @@ func (srv *Server) ImageImport(src, repo, tag string, in io.Reader, out io.Write
 			return err
 		}
 	}
-	fmt.Fprintf(out, "%s\n", img.ShortId())
+	out.Write(sf.FormatStatus(img.ShortId()))
 	return nil
 }
 

utils/utils.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"crypto/sha256"
 	"encoding/hex"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"index/suffixarray"
@@ -69,7 +70,7 @@ type progressReader struct {
 	readProgress int           // How much has been read so far (bytes)
 	lastUpdate   int           // How many bytes read at least update
 	template     string        // Template to print. Default "%v/%v (%v)"
-	json         bool
+	sf *StreamFormatter
 }
 
 func (r *progressReader) Read(p []byte) (n int, err error) {
@@ -93,7 +94,7 @@ func (r *progressReader) Read(p []byte) (n int, err error) {
 	}
 	// Send newline when complete
 	if err != nil {
-		fmt.Fprintf(r.output, FormatStatus("", r.json))
+		r.output.Write(r.sf.FormatStatus(""))
 	}
 
 	return read, err
@@ -101,11 +102,12 @@ func (r *progressReader) Read(p []byte) (n int, err error) {
 func (r *progressReader) Close() error {
 	return io.ReadCloser(r.reader).Close()
 }
-func ProgressReader(r io.ReadCloser, size int, output io.Writer, template string, json bool) *progressReader {
+func ProgressReader(r io.ReadCloser, size int, output io.Writer, template []byte, sf *StreamFormatter) *progressReader {
-	if template == "" {
+      	tpl := string(template)
-		template = "%v/%v (%v)\r"
+	if tpl == "" {
+		tpl = string(sf.FormatProgress("", "%v/%v (%v)"))
 	}
-	return &progressReader{r, NewWriteFlusher(output), size, 0, 0, template, json}
+	return &progressReader{r, NewWriteFlusher(output), size, 0, 0, tpl, sf}
 }
 
 // HumanDuration returns a human-readable approximation of a duration
@@ -564,16 +566,57 @@ func NewWriteFlusher(w io.Writer) *WriteFlusher {
 	return &WriteFlusher{w: w, flusher: flusher}
 }
 
-func FormatStatus(str string, json bool) string {
+type JsonMessage struct {
-	if json {
+	Status   string `json:"status,omitempty"`
-		return "{\"status\" : \"" + str + "\"}"
+	Progress string `json:"progress,omitempty"`
-	}
+	Error    string `json:"error,omitempty"`
-	return str + "\r\n"
 }
 
-func FormatProgress(str string, json bool) string {
+type StreamFormatter struct {
-	if json {
+	json bool
-		return "{\"progress\" : \"" + str + "\"}"
+	used bool
-	}
+}
-	return "Downloading " + str + "\r"
+
+func NewStreamFormatter(json bool) *StreamFormatter {
+	return &StreamFormatter{json, false}
+}
+
+func (sf *StreamFormatter) FormatStatus(format string, a ...interface{}) []byte {
+	sf.used = true
+	str := fmt.Sprintf(format, a...)
+	if sf.json {
+		b, err := json.Marshal(&JsonMessage{Status:str});
+		if err != nil {
+			return sf.FormatError(err)
+		}
+		return b
+	}
+	return []byte(str + "\r\n")
+}
+
+func (sf *StreamFormatter) FormatError(err error) []byte {
+	sf.used = true
+	if sf.json {
+		if b, err := json.Marshal(&JsonMessage{Error:err.Error()}); err == nil {
+			return b
+		}
+		return []byte("{\"error\":\"format error\"}")
+	}
+	return []byte("Error: " + err.Error() + "\r\n")
+}
+
+func (sf *StreamFormatter) FormatProgress(action, str string) []byte {
+	sf.used = true
+	if sf.json {
+		b, err := json.Marshal(&JsonMessage{Progress:str})
+		if err != nil {
+                        return nil
+                }
+		return b
+	}
+	return []byte(action + " " + str + "\r")
+}
+
+func (sf *StreamFormatter) Used() bool {
+	return sf.used
 }