Add initial draft of StoreComposr

cmd/tusd/main.go

@@ -12,6 +12,7 @@ import (
 	"github.com/tus/tusd"
 	"github.com/tus/tusd/filestore"
 	"github.com/tus/tusd/limitedstore"
+	"github.com/tus/tusd/memorylocker"
 	"github.com/tus/tusd/s3store"
 
 	"github.com/aws/aws-sdk-go/aws"
@@ -58,25 +59,30 @@ func main() {
 		return
 	}
 
-	var store tusd.TerminaterDataStore
+	composer := tusd.NewStoreComposer()
 	if s3Bucket == "" {
 		stdout.Printf("Using '%s' as directory storage.\n", dir)
 		if err := os.MkdirAll(dir, os.FileMode(0775)); err != nil {
 			stderr.Fatalf("Unable to ensure directory exists: %s", err)
 		}
 
-		store = filestore.New(dir)
+		store := filestore.New(dir)
+		store.UseIn(composer)
 	} else {
 		stdout.Printf("Using 's3://%s' as S3 bucket for storage.\n", s3Bucket)
 
 		// Derive credentials from AWS_SECRET_ACCESS_KEY, AWS_ACCESS_KEY_ID and
 		// AWS_REGION environment variables.
 		credentials := aws.NewConfig().WithCredentials(credentials.NewEnvCredentials())
-		store = s3store.New(s3Bucket, s3.New(session.New(), credentials))
+		store := s3store.New(s3Bucket, s3.New(session.New(), credentials))
+		store.UseIn(composer)
+
+		locker := memorylocker.New()
+		locker.UseIn(composer)
 	}
 
 	if storeSize > 0 {
-		store = limitedstore.New(storeSize, store)
+		limitedstore.New(storeSize, composer.Core, composer.Terminater).UseIn(composer)
 		stdout.Printf("Using %.2fMB as storage size.\n", float64(storeSize)/1024/1024)
 
 		// We need to ensure that a single upload can fit into the storage size
@@ -90,7 +96,7 @@ func main() {
 	handler, err := tusd.NewHandler(tusd.Config{
 		MaxSize:               maxSize,
 		BasePath:              "files/",
-		DataStore:             store,
+		StoreComposer:         composer,
 		NotifyCompleteUploads: true,
 	})
 	if err != nil {

composer.go

@@ -0,0 +1,68 @@
+package tusd
+
+type StoreComposer struct {
+	Core DataStore
+
+	UsesTerminater bool
+	Terminater     TerminaterDataStore
+	UsesFinisher   bool
+	Finisher       FinisherDataStore
+	UsesLocker     bool
+	Locker         LockerDataStore
+	UsesGetReader  bool
+	GetReader      GetReaderDataStore
+	UsesConcater   bool
+	Concater       ConcaterDataStore
+}
+
+func NewStoreComposer() *StoreComposer {
+	return &StoreComposer{}
+}
+
+func NewStoreComposerFromDataStore(store DataStore) *StoreComposer {
+	composer := NewStoreComposer()
+	composer.UseCore(store)
+
+	if mod, ok := store.(TerminaterDataStore); ok {
+		composer.UseTerminater(mod)
+	}
+	if mod, ok := store.(FinisherDataStore); ok {
+		composer.UseFinisher(mod)
+	}
+	if mod, ok := store.(LockerDataStore); ok {
+		composer.UseLocker(mod)
+	}
+	if mod, ok := store.(GetReaderDataStore); ok {
+		composer.UseGetReader(mod)
+	}
+	if mod, ok := store.(ConcaterDataStore); ok {
+		composer.UseConcater(mod)
+	}
+
+	return composer
+}
+
+func (store *StoreComposer) UseCore(core DataStore) {
+	store.Core = core
+}
+
+func (store *StoreComposer) UseTerminater(x TerminaterDataStore) {
+	store.UsesTerminater = x != nil
+	store.Terminater = x
+}
+func (store *StoreComposer) UseFinisher(x FinisherDataStore) {
+	store.UsesFinisher = x != nil
+	store.Finisher = x
+}
+func (store *StoreComposer) UseLocker(x LockerDataStore) {
+	store.UsesLocker = x != nil
+	store.Locker = x
+}
+func (store *StoreComposer) UseGetReader(x GetReaderDataStore) {
+	store.UsesGetReader = x != nil
+	store.GetReader = x
+}
+func (store *StoreComposer) UseConcater(x ConcaterDataStore) {
+	store.UsesConcater = x != nil
+	store.Concater = x
+}

composer.mgo

@@ -0,0 +1,50 @@
+package tusd
+
+#define USE_FUNC(TYPE) func (store *StoreComposer) Use ## TYPE(x TYPE ## DataStore) { \
+  store.Uses ## TYPE = x != nil; \
+  store.TYPE = x; \
+}
+
+#define USE_FIELD(TYPE) Uses ## TYPE bool; \
+  TYPE TYPE ## DataStore
+
+#define USE_FROM(TYPE) if mod, ok := store.(TYPE ## DataStore); ok { \
+  composer.Use ## TYPE (mod) \
+}
+
+type StoreComposer struct {
+  Core DataStore
+
+  USE_FIELD(Terminater)
+  USE_FIELD(Finisher)
+  USE_FIELD(Locker)
+  USE_FIELD(GetReader)
+  USE_FIELD(Concater)
+}
+
+func NewStoreComposer() *StoreComposer {
+  return &StoreComposer{}
+}
+
+func NewStoreComposerFromDataStore(store DataStore) *StoreComposer {
+  composer := NewStoreComposer()
+  composer.UseCore(store)
+
+  USE_FROM(Terminater)
+  USE_FROM(Finisher)
+  USE_FROM(Locker)
+  USE_FROM(GetReader)
+  USE_FROM(Concater)
+
+  return composer
+}
+
+func (store *StoreComposer) UseCore(core DataStore) {
+  store.Core = core
+}
+
+USE_FUNC(Terminater)
+USE_FUNC(Finisher)
+USE_FUNC(Locker)
+USE_FUNC(GetReader)
+USE_FUNC(Concater)

config.go

@@ -0,0 +1,64 @@
+package tusd
+
+import (
+	"log"
+	"net/url"
+	"os"
+)
+
+// Config provides a way to configure the Handler depending on your needs.
+type Config struct {
+	// DataStore implementation used to store and retrieve the single uploads.
+	// Must no be nil.
+	DataStore     DataStore
+	StoreComposer *StoreComposer
+	// MaxSize defines how many bytes may be stored in one single upload. If its
+	// value is is 0 or smaller no limit will be enforced.
+	MaxSize int64
+	// BasePath defines the URL path used for handling uploads, e.g. "/files/".
+	// If no trailing slash is presented it will be added. You may specify an
+	// absolute URL containing a scheme, e.g. "http://tus.io"
+	BasePath string
+	isAbs    bool
+	// Initiate the CompleteUploads channel in the Handler struct in order to
+	// be notified about complete uploads
+	NotifyCompleteUploads bool
+	// Logger the logger to use internally
+	Logger *log.Logger
+	// Respect the X-Forwarded-Host, X-Forwarded-Proto and Forwarded headers
+	// potentially set by proxies when generating an absolute URL in the
+	// reponse to POST requests.
+	RespectForwardedHeaders bool
+}
+
+func (config *Config) validate() error {
+	if config.Logger == nil {
+		config.Logger = log.New(os.Stdout, "[tusd] ", 0)
+	}
+
+	base := config.BasePath
+	uri, err := url.Parse(base)
+	if err != nil {
+		return err
+	}
+
+	// Ensure base path ends with slash to remove logic from absFileURL
+	if base != "" && string(base[len(base)-1]) != "/" {
+		base += "/"
+	}
+
+	// Ensure base path begins with slash if not absolute (starts with scheme)
+	if !uri.IsAbs() && len(base) > 0 && string(base[0]) != "/" {
+		base = "/" + base
+	}
+	config.BasePath = base
+	config.isAbs = uri.IsAbs()
+
+	if config.StoreComposer == nil {
+		config.StoreComposer = NewStoreComposerFromDataStore(config.DataStore)
+	} else if config.DataStore != nil {
+		// TODO: consider returning an error
+	}
+
+	return nil
+}

datastore.go

@@ -49,8 +49,6 @@ type DataStore interface {
 // if they want to receive DELETE requests using the Handler. If this interface
 // is not implemented, no request handler for this method is attached.
 type TerminaterDataStore interface {
-	DataStore
-
 	// Terminate an upload so any further requests to the resource, both reading
 	// and writing, must return os.ErrNotExist or similar.
 	Terminate(id string) error
@@ -62,8 +60,6 @@ type TerminaterDataStore interface {
 // resources or notifying other services. For example, S3Store uses this
 // interface for removing a temporary object.
 type FinisherDataStore interface {
-	DataStore
-
 	// FinishUpload executes additional operations for the finished upload which
 	// is specified by its ID.
 	FinishUpload(id string) error
@@ -77,8 +73,6 @@ type FinisherDataStore interface {
 // data corruption, especially to ensure correct offset values and the proper
 // order of chunks inside a single upload.
 type LockerDataStore interface {
-	DataStore
-
 	// LockUpload attempts to obtain an exclusive lock for the upload specified
 	// by its id.
 	// If this operation fails because the resource is already locked, the
@@ -96,8 +90,6 @@ type LockerDataStore interface {
 // Please, be aware that this feature is not part of the official tus
 // specification. Instead it's a custom mechanism by tusd.
 type GetReaderDataStore interface {
-	DataStore
-
 	// GetReader returns a reader which allows iterating of the content of an
 	// upload specified by its ID. It should attempt to provide a reader even if
 	// the upload has not been finished yet but it's not required.
@@ -112,8 +104,6 @@ type GetReaderDataStore interface {
 // Concatenation extension should be enabled. Only in this case, the handler
 // will parse and respect the Upload-Concat header.
 type ConcaterDataStore interface {
-	DataStore
-
 	// ConcatUploads concatenations the content from the provided partial uploads
 	// and write the result in the destination upload which is specified by its
 	// ID. The caller (usually the handler) must and will ensure that this

filestore/filestore.go

@@ -46,6 +46,13 @@ func New(path string) FileStore {
 	return FileStore{path}
 }
 
+func (store FileStore) UseIn(composer *tusd.StoreComposer) {
+	composer.UseCore(store)
+	composer.UseGetReader(store)
+	composer.UseTerminater(store)
+	composer.UseLocker(store)
+}
+
 func (store FileStore) NewUpload(info tusd.FileInfo) (id string, err error) {
 	id = uid.Uid()
 	info.ID = id

handler.go

@@ -22,6 +22,10 @@ type Handler struct {
 // endpoints to be customized. These are not part of the protocol so can be
 // changed depending on your needs.
 func NewHandler(config Config) (*Handler, error) {
+	if err := config.validate(); err != nil {
+		return nil, err
+	}
+
 	handler, err := NewUnroutedHandler(config)
 	if err != nil {
 		return nil, err
@@ -41,12 +45,12 @@ func NewHandler(config Config) (*Handler, error) {
 	mux.Add("PATCH", ":id", http.HandlerFunc(handler.PatchFile))
 
 	// Only attach the DELETE handler if the Terminate() method is provided
-	if _, ok := config.DataStore.(TerminaterDataStore); ok {
+	if config.StoreComposer.UsesTerminater {
 		mux.Del(":id", http.HandlerFunc(handler.DelFile))
 	}
 
 	// GET handler requires the GetReader() method
-	if _, ok := config.DataStore.(GetReaderDataStore); ok {
+	if config.StoreComposer.UsesGetReader {
 		mux.Get(":id", http.HandlerFunc(handler.GetFile))
 	}
 

limitedstore/limitedstore.go

@@ -12,27 +12,19 @@
 // properly. Two tusd.FileStore instances using the same directory, for example.
 // In addition the limited store will keep a list of the uploads' IDs in memory
 // which may create a growing memory leak.
-//
-// While LimitedStore implements the GetReader, LockUpload, UnlockUpload,
-// FinishUpload and ConcatUploads methods, it does not contain proper definitions
-// for them. When invoked, the call will be passed to the underlying
-// data store as long as it provides these methods. If not, either an error
-// is returned or nothing happens (see the specific methods for more
-// detailed information). The motivation behind this decision was, that this
-// allows to expose the additional extensions implemented using the
-// interfaces, such as GetReaderDataStore.
 package limitedstore
 
 import (
 	"github.com/tus/tusd"
-	"io"
 	"sort"
 	"sync"
 )
 
 type LimitedStore struct {
+	tusd.DataStore
+	terminater tusd.TerminaterDataStore
+
 	StoreSize int64
-	tusd.TerminaterDataStore
 
 	uploads  map[string]int64
 	usedSize int64
@@ -55,15 +47,21 @@ func (p pairlist) Less(i, j int) bool { return p[i].value < p[j].value }
 // New creates a new limited store with the given size as the maximum storage
 // size. The wrapped data store needs to implement the TerminaterDataStore
 // interface, in order to provide the required Terminate method.
-func New(storeSize int64, dataStore tusd.TerminaterDataStore) *LimitedStore {
+func New(storeSize int64, dataStore tusd.DataStore, terminater tusd.TerminaterDataStore) *LimitedStore {
 	return &LimitedStore{
 		StoreSize:  storeSize,
-		TerminaterDataStore: dataStore,
+		DataStore:  dataStore,
+		terminater: terminater,
 		uploads:    make(map[string]int64),
 		mutex:      new(sync.Mutex),
 	}
 }
 
+func (store *LimitedStore) UseIn(composer *tusd.StoreComposer) {
+	composer.UseCore(store)
+	composer.UseTerminater(store)
+}
+
 func (store *LimitedStore) NewUpload(info tusd.FileInfo) (string, error) {
 	store.mutex.Lock()
 	defer store.mutex.Unlock()
@@ -72,7 +70,7 @@ func (store *LimitedStore) NewUpload(info tusd.FileInfo) (string, error) {
 		return "", err
 	}
 
-	id, err := store.TerminaterDataStore.NewUpload(info)
+	id, err := store.DataStore.NewUpload(info)
 	if err != nil {
 		return "", err
 	}
@@ -91,7 +89,7 @@ func (store *LimitedStore) Terminate(id string) error {
 }
 
 func (store *LimitedStore) terminate(id string) error {
-	err := store.TerminaterDataStore.Terminate(id)
+	err := store.terminater.Terminate(id)
 	if err != nil {
 		return err
 	}
@@ -135,55 +133,3 @@ func (store *LimitedStore) ensureSpace(size int64) error {
 
 	return nil
 }
-
-// GetReader will pass the call to the underlying data store if it implements
-// the tusd.GetReaderDataStore interface. Else tusd.ErrNotImplemented will be
-// returned.
-func (store *LimitedStore) GetReader(id string) (io.Reader, error) {
-	if s, ok := store.TerminaterDataStore.(tusd.GetReaderDataStore); ok {
-		return s.GetReader(id)
-	} else {
-		return nil, tusd.ErrNotImplemented
-	}
-}
-
-// LockUpload will pass the call to the underlying data store if it implements
-// the tusd.LockerDataStore interface. Else this function simply returns nil.
-func (store *LimitedStore) LockUpload(id string) error {
-	if s, ok := store.TerminaterDataStore.(tusd.LockerDataStore); ok {
-		return s.LockUpload(id)
-	}
-
-	return nil
-}
-
-// UnlockUpload will pass the call to the underlying data store if it implements
-// the tusd.LockerDataStore interface. Else this function simply returns nil.
-func (store *LimitedStore) UnlockUpload(id string) error {
-	if s, ok := store.TerminaterDataStore.(tusd.LockerDataStore); ok {
-		return s.UnlockUpload(id)
-	}
-
-	return nil
-}
-
-// FinishUpload will pass the call to the underlying data store if it implements
-// the tusd.FinisherDataStore interface. Else this function simply returns nil.
-func (store *LimitedStore) FinishUpload(id string) error {
-	if s, ok := store.TerminaterDataStore.(tusd.FinisherDataStore); ok {
-		return s.FinishUpload(id)
-	}
-
-	return nil
-}
-
-// ConcatUploads will pass the call to the underlying data store if it implements
-// the tusd.ConcaterDataStore interface. Else tusd.ErrNotImplemented will be
-// returned.
-func (store *LimitedStore) ConcatUploads(dest string, src []string) error {
-	if s, ok := store.TerminaterDataStore.(tusd.ConcaterDataStore); ok {
-		return s.ConcatUploads(dest, src)
-	} else {
-		return tusd.ErrNotImplemented
-	}
-}

limitedstore/limitedstore_test.go

@@ -11,11 +11,7 @@ import (
 )
 
 var _ tusd.DataStore = &LimitedStore{}
-var _ tusd.GetReaderDataStore = &LimitedStore{}
 var _ tusd.TerminaterDataStore = &LimitedStore{}
-var _ tusd.LockerDataStore = &LimitedStore{}
-var _ tusd.ConcaterDataStore = &LimitedStore{}
-var _ tusd.FinisherDataStore = &LimitedStore{}
 
 type dataStore struct {
 	t                    *assert.Assertions
@@ -45,10 +41,6 @@ func (store *dataStore) GetInfo(id string) (tusd.FileInfo, error) {
 	return tusd.FileInfo{}, nil
 }
 
-func (store *dataStore) GetReader(id string) (io.Reader, error) {
-	return nil, tusd.ErrNotImplemented
-}
-
 func (store *dataStore) Terminate(id string) error {
 	// We expect the uploads to be terminated in a specific order (the bigger
 	// come first)
@@ -66,7 +58,7 @@ func TestLimitedStore(t *testing.T) {
 	dataStore := &dataStore{
 		t: a,
 	}
-	store := New(100, dataStore)
+	store := New(100, dataStore, dataStore)
 
 	// Create new upload (30 bytes)
 	id, err := store.NewUpload(tusd.FileInfo{

memorylocker/memorylocker.go

@@ -18,21 +18,26 @@ import (
 // cheap mechansim. Locks will only exist as long as this object is kept in
 // reference and will be erased if the program exits.
 type MemoryLocker struct {
-	tusd.DataStore
 	locks map[string]bool
 }
 
-// New creates a new lock memory wrapper around the provided storage.
+// New creates a new lock memory.
-func NewMemoryLocker(store tusd.DataStore) *MemoryLocker {
+func NewMemoryLocker(_ tusd.DataStore) *MemoryLocker {
+	return New()
+}
+
+func New() *MemoryLocker {
 	return &MemoryLocker{
-		DataStore: store,
 		locks: make(map[string]bool),
 	}
 }
 
+func (locker *MemoryLocker) UseIn(composer *tusd.StoreComposer) {
+	composer.UseLocker(locker)
+}
+
 // LockUpload tries to obtain the exclusive lock.
 func (locker *MemoryLocker) LockUpload(id string) error {
-
 	// Ensure file is not locked
 	if _, ok := locker.locks[id]; ok {
 		return tusd.ErrFileLocked

memorylocker/memorylocker_test.go

@@ -1,7 +1,6 @@
 package memorylocker
 
 import (
-	"io"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -9,28 +8,11 @@ import (
 	"github.com/tus/tusd"
 )
 
-type zeroStore struct{}
-
-func (store zeroStore) NewUpload(info tusd.FileInfo) (string, error) {
-	return "", nil
-}
-func (store zeroStore) WriteChunk(id string, offset int64, src io.Reader) (int64, error) {
-	return 0, nil
-}
-
-func (store zeroStore) GetInfo(id string) (tusd.FileInfo, error) {
-	return tusd.FileInfo{}, nil
-}
-
-func (store zeroStore) GetReader(id string) (io.Reader, error) {
-	return nil, tusd.ErrNotImplemented
-}
-
 func TestMemoryLocker(t *testing.T) {
 	a := assert.New(t)
 
 	var locker tusd.LockerDataStore
-	locker = NewMemoryLocker(&zeroStore{})
+	locker = New()
 
 	a.NoError(locker.LockUpload("one"))
 	a.Equal(tusd.ErrFileLocked, locker.LockUpload("one"))

s3store/s3store.go

@@ -131,6 +131,14 @@ func New(bucket string, service s3iface.S3API) S3Store {
 	}
 }
 
+func (store S3Store) UseIn(composer *tusd.StoreComposer) {
+	composer.UseCore(store)
+	composer.UseTerminater(store)
+	composer.UseFinisher(store)
+	composer.UseGetReader(store)
+	composer.UseConcater(store)
+}
+
 func (store S3Store) NewUpload(info tusd.FileInfo) (id string, err error) {
 	var uploadId string
 	if info.ID == "" {

unrouted_handler.go

@@ -6,7 +6,6 @@ import (
 	"io"
 	"log"
 	"net/http"
-	"net/url"
 	"os"
 	"regexp"
 	"strconv"
@@ -52,35 +51,12 @@ var ErrStatusCodes = map[error]int{
 	ErrModifyFinal:         http.StatusForbidden,
 }
 
-// Config provides a way to configure the Handler depending on your needs.
-type Config struct {
-	// DataStore implementation used to store and retrieve the single uploads.
-	// Must no be nil.
-	DataStore DataStore
-	// MaxSize defines how many bytes may be stored in one single upload. If its
-	// value is is 0 or smaller no limit will be enforced.
-	MaxSize int64
-	// BasePath defines the URL path used for handling uploads, e.g. "/files/".
-	// If no trailing slash is presented it will be added. You may specify an
-	// absolute URL containing a scheme, e.g. "http://tus.io"
-	BasePath string
-	// Initiate the CompleteUploads channel in the Handler struct in order to
-	// be notified about complete uploads
-	NotifyCompleteUploads bool
-	// Logger the logger to use internally
-	Logger *log.Logger
-	// Respect the X-Forwarded-Host, X-Forwarded-Proto and Forwarded headers
-	// potentially set by proxies when generating an absolute URL in the
-	// reponse to POST requests.
-	RespectForwardedHeaders bool
-}
-
 // UnroutedHandler exposes methods to handle requests as part of the tus protocol,
 // such as PostFile, HeadFile, PatchFile and DelFile. In addition the GetFile method
 // is provided which is, however, not part of the specification.
 type UnroutedHandler struct {
 	config        Config
-	dataStore     DataStore
+	composer      *StoreComposer
 	isBasePathAbs bool
 	basePath      string
 	logger        *log.Logger
@@ -97,42 +73,26 @@ type UnroutedHandler struct {
 // a router (aka mux) of your choice. If you are looking for preconfigured
 // handler see NewHandler.
 func NewUnroutedHandler(config Config) (*UnroutedHandler, error) {
-	logger := config.Logger
+	if err := config.validate(); err != nil {
-	if logger == nil {
-		logger = log.New(os.Stdout, "[tusd] ", 0)
-	}
-	base := config.BasePath
-	uri, err := url.Parse(base)
-	if err != nil {
 		return nil, err
 	}
 
-	// Ensure base path ends with slash to remove logic from absFileURL
-	if base != "" && string(base[len(base)-1]) != "/" {
-		base += "/"
-	}
-
-	// Ensure base path begins with slash if not absolute (starts with scheme)
-	if !uri.IsAbs() && len(base) > 0 && string(base[0]) != "/" {
-		base = "/" + base
-	}
-
 	// Only promote extesions using the Tus-Extension header which are implemented
 	extensions := "creation"
-	if _, ok := config.DataStore.(TerminaterDataStore); ok {
+	if config.StoreComposer.UsesTerminater {
 		extensions += ",termination"
 	}
-	if _, ok := config.DataStore.(ConcaterDataStore); ok {
+	if config.StoreComposer.UsesConcater {
 		extensions += ",concatenation"
 	}
 
 	handler := &UnroutedHandler{
 		config:          config,
-		dataStore:       config.DataStore,
+		composer:        config.StoreComposer,
-		basePath:        base,
+		basePath:        config.BasePath,
-		isBasePathAbs:   uri.IsAbs(),
+		isBasePathAbs:   config.isAbs,
 		CompleteUploads: make(chan FileInfo),
-		logger:          logger,
+		logger:          config.Logger,
 		extensions:      extensions,
 	}
 
@@ -211,8 +171,7 @@ func (handler *UnroutedHandler) PostFile(w http.ResponseWriter, r *http.Request)
 	// Only use the proper Upload-Concat header if the concatenation extension
 	// is even supported by the data store.
 	var concatHeader string
-	concatStore, ok := handler.dataStore.(ConcaterDataStore)
+	if handler.composer.UsesConcater {
-	if ok {
 		concatHeader = r.Header.Get("Upload-Concat")
 	}
 
@@ -258,14 +217,14 @@ func (handler *UnroutedHandler) PostFile(w http.ResponseWriter, r *http.Request)
 		PartialUploads: partialUploads,
 	}
 
-	id, err := handler.dataStore.NewUpload(info)
+	id, err := handler.composer.Core.NewUpload(info)
 	if err != nil {
 		handler.sendError(w, r, err)
 		return
 	}
 
 	if isFinal {
-		if err := concatStore.ConcatUploads(id, partialUploads); err != nil {
+		if err := handler.composer.Concater.ConcatUploads(id, partialUploads); err != nil {
 			handler.sendError(w, r, err)
 			return
 		}
@@ -290,7 +249,8 @@ func (handler *UnroutedHandler) HeadFile(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	if locker, ok := handler.dataStore.(LockerDataStore); ok {
+	if handler.composer.UsesLocker {
+		locker := handler.composer.Locker
 		if err := locker.LockUpload(id); err != nil {
 			handler.sendError(w, r, err)
 			return
@@ -299,7 +259,7 @@ func (handler *UnroutedHandler) HeadFile(w http.ResponseWriter, r *http.Request)
 		defer locker.UnlockUpload(id)
 	}
 
-	info, err := handler.dataStore.GetInfo(id)
+	info, err := handler.composer.Core.GetInfo(id)
 	if err != nil {
 		handler.sendError(w, r, err)
 		return
@@ -350,7 +310,8 @@ func (handler *UnroutedHandler) PatchFile(w http.ResponseWriter, r *http.Request
 		return
 	}
 
-	if locker, ok := handler.dataStore.(LockerDataStore); ok {
+	if handler.composer.UsesLocker {
+		locker := handler.composer.Locker
 		if err := locker.LockUpload(id); err != nil {
 			handler.sendError(w, r, err)
 			return
@@ -359,7 +320,7 @@ func (handler *UnroutedHandler) PatchFile(w http.ResponseWriter, r *http.Request
 		defer locker.UnlockUpload(id)
 	}
 
-	info, err := handler.dataStore.GetInfo(id)
+	info, err := handler.composer.Core.GetInfo(id)
 	if err != nil {
 		handler.sendError(w, r, err)
 		return
@@ -393,7 +354,7 @@ func (handler *UnroutedHandler) PatchFile(w http.ResponseWriter, r *http.Request
 	// Limit the
 	reader := io.LimitReader(r.Body, maxSize)
 
-	bytesWritten, err := handler.dataStore.WriteChunk(id, offset, reader)
+	bytesWritten, err := handler.composer.Core.WriteChunk(id, offset, reader)
 	if err != nil {
 		handler.sendError(w, r, err)
 		return
@@ -406,8 +367,8 @@ func (handler *UnroutedHandler) PatchFile(w http.ResponseWriter, r *http.Request
 	// If the upload is completed, ...
 	if newOffset == info.Size {
 		// ... allow custom mechanism to finish and cleanup the upload
-		if store, ok := handler.dataStore.(FinisherDataStore); ok {
+		if handler.composer.UsesFinisher {
-			if err := store.FinishUpload(id); err != nil {
+			if err := handler.composer.Finisher.FinishUpload(id); err != nil {
 				handler.sendError(w, r, err)
 				return
 			}
@@ -426,8 +387,7 @@ func (handler *UnroutedHandler) PatchFile(w http.ResponseWriter, r *http.Request
 // GetFile handles requests to download a file using a GET request. This is not
 // part of the specification.
 func (handler *UnroutedHandler) GetFile(w http.ResponseWriter, r *http.Request) {
-	dataStore, ok := handler.dataStore.(GetReaderDataStore)
+	if !handler.composer.UsesGetReader {
-	if !ok {
 		handler.sendError(w, r, ErrNotImplemented)
 		return
 	}
@@ -438,7 +398,8 @@ func (handler *UnroutedHandler) GetFile(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	if locker, ok := handler.dataStore.(LockerDataStore); ok {
+	if handler.composer.UsesLocker {
+		locker := handler.composer.Locker
 		if err := locker.LockUpload(id); err != nil {
 			handler.sendError(w, r, err)
 			return
@@ -447,7 +408,7 @@ func (handler *UnroutedHandler) GetFile(w http.ResponseWriter, r *http.Request)
 		defer locker.UnlockUpload(id)
 	}
 
-	info, err := handler.dataStore.GetInfo(id)
+	info, err := handler.composer.Core.GetInfo(id)
 	if err != nil {
 		handler.sendError(w, r, err)
 		return
@@ -460,7 +421,7 @@ func (handler *UnroutedHandler) GetFile(w http.ResponseWriter, r *http.Request)
 	}
 
 	// Get reader
-	src, err := dataStore.GetReader(id)
+	src, err := handler.composer.GetReader.GetReader(id)
 	if err != nil {
 		handler.sendError(w, r, err)
 		return
@@ -479,8 +440,7 @@ func (handler *UnroutedHandler) GetFile(w http.ResponseWriter, r *http.Request)
 // DelFile terminates an upload permanently.
 func (handler *UnroutedHandler) DelFile(w http.ResponseWriter, r *http.Request) {
 	// Abort the request handling if the required interface is not implemented
-	tstore, ok := handler.config.DataStore.(TerminaterDataStore)
+	if !handler.composer.UsesTerminater {
-	if !ok {
 		handler.sendError(w, r, ErrNotImplemented)
 		return
 	}
@@ -491,7 +451,8 @@ func (handler *UnroutedHandler) DelFile(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	if locker, ok := handler.dataStore.(LockerDataStore); ok {
+	if handler.composer.UsesLocker {
+		locker := handler.composer.Locker
 		if err := locker.LockUpload(id); err != nil {
 			handler.sendError(w, r, err)
 			return
@@ -500,7 +461,7 @@ func (handler *UnroutedHandler) DelFile(w http.ResponseWriter, r *http.Request)
 		defer locker.UnlockUpload(id)
 	}
 
-	err = tstore.Terminate(id)
+	err = handler.composer.Terminater.Terminate(id)
 	if err != nil {
 		handler.sendError(w, r, err)
 		return
@@ -591,7 +552,7 @@ func getHostAndProtocol(r *http.Request, allowForwarded bool) (host, proto strin
 // of a final resource.
 func (handler *UnroutedHandler) sizeOfUploads(ids []string) (size int64, err error) {
 	for _, id := range ids {
-		info, err := handler.dataStore.GetInfo(id)
+		info, err := handler.composer.Core.GetInfo(id)
 		if err != nil {
 			return size, err
 		}