bef813a feat(brokerwire): carry build identity in registration · vev

M internal/adapters/brokerwire/codec.go +16 -4


@@ -102,7 +102,10 @@ func encodeClientEnvelope(message ClientMessage, maxChunkBytes uint64) (*wire.Br
102	102		}
103	103		switch m := message.(type) {
104	104		case Register:
105		-	return &wire.BrokerClientEnvelope{Payload: &wire.BrokerClientEnvelope_Register{Register: &wire.Register{}}}, nil
	105	+	if len(m.Build) > 128 {
	106	+	return nil, ErrInvalidMessage
	107	+	}
	108	+	return &wire.BrokerClientEnvelope{Payload: &wire.BrokerClientEnvelope_Register{Register: &wire.Register{Build: m.Build}}}, nil
106	109		case *Register:
107	110		if m == nil {
108	111		return nil, ErrInvalidMessage

@@ -273,7 +276,10 @@ func decodeClientEnvelope(envelope *wire.BrokerClientEnvelope, maxChunkBytes uin
273	276		if payload.Register == nil {
274	277		return nil, ErrInvalidMessage
275	278		}
276		-	return Register{}, nil
	279	+	if len(payload.Register.GetBuild()) > 128 {
	280	+	return nil, ErrInvalidMessage
	281	+	}
	282	+	return Register{Build: payload.Register.GetBuild()}, nil
277	283		case *wire.BrokerClientEnvelope_Subscribe:
278	284		return subscribeFromWire(payload.Subscribe)
279	285		case *wire.BrokerClientEnvelope_Resync:

@@ -777,6 +783,9 @@ func encodeServerEnvelope(message ServerMessage, maxChunkBytes uint64) (*wire.Br
777	783		}
778	784		switch m := message.(type) {
779	785		case Registered:
	786	+	if len(m.Build) > 128 {
	787	+	return nil, ErrInvalidMessage
	788	+	}
780	789		if m.Epoch == 0 {
781	790		return nil, ErrInvalidMessage
782	791		}

@@ -784,7 +793,7 @@ func encodeServerEnvelope(message ServerMessage, maxChunkBytes uint64) (*wire.Br
784	793		return nil, ErrInvalidMessage
785	794		}
786	795		return &wire.BrokerServerEnvelope{Payload: &wire.BrokerServerEnvelope_Registered{Registered: &wire.Registered{
787		-	Scope: scopeToWire(m.Epoch, m.Connection),
	796	+	Scope: scopeToWire(m.Epoch, m.Connection), Build: m.Build, Retiring: m.Retiring,
788	797		}}}, nil
789	798		case *Registered:
790	799		if m == nil {

@@ -922,7 +931,10 @@ func decodeServerEnvelope(envelope *wire.BrokerServerEnvelope, maxChunkBytes uin
922	931		if err != nil {
923	932		return nil, ErrInvalidMessage
924	933		}
925		-	return Registered{Epoch: epoch, Connection: connection}, nil
	934	+	if len(payload.Registered.GetBuild()) > 128 {
	935	+	return nil, ErrInvalidMessage
	936	+	}
	937	+	return Registered{Epoch: epoch, Connection: connection, Build: payload.Registered.GetBuild(), Retiring: payload.Registered.GetRetiring()}, nil
926	938		case *wire.BrokerServerEnvelope_SnapshotPart:
927	939		return snapshotPartFromWire(payload.SnapshotPart)
928	940		case *wire.BrokerServerEnvelope_OperationResult:

 	}
 	switch m := message.(type) {
 	case Register:
-		return &wire.BrokerClientEnvelope{Payload: &wire.BrokerClientEnvelope_Register{Register: &wire.Register{}}}, nil
+		if len(m.Build) > 128 {
+			return nil, ErrInvalidMessage
+		}
+		return &wire.BrokerClientEnvelope{Payload: &wire.BrokerClientEnvelope_Register{Register: &wire.Register{Build: m.Build}}}, nil
 	case *Register:
 		if m == nil {
 			return nil, ErrInvalidMessage
 		if payload.Register == nil {
 			return nil, ErrInvalidMessage
 		}
-		return Register{}, nil
+		if len(payload.Register.GetBuild()) > 128 {
+			return nil, ErrInvalidMessage
+		}
+		return Register{Build: payload.Register.GetBuild()}, nil
 	case *wire.BrokerClientEnvelope_Subscribe:
 		return subscribeFromWire(payload.Subscribe)
 	case *wire.BrokerClientEnvelope_Resync:
 	}
 	switch m := message.(type) {
 	case Registered:
+		if len(m.Build) > 128 {
+			return nil, ErrInvalidMessage
+		}
 		if m.Epoch == 0 {
 			return nil, ErrInvalidMessage
 		}
 			return nil, ErrInvalidMessage
 		}
 		return &wire.BrokerServerEnvelope{Payload: &wire.BrokerServerEnvelope_Registered{Registered: &wire.Registered{
-			Scope: scopeToWire(m.Epoch, m.Connection),
+			Scope: scopeToWire(m.Epoch, m.Connection), Build: m.Build, Retiring: m.Retiring,
 		}}}, nil
 	case *Registered:
 		if m == nil {
 		if err != nil {
 			return nil, ErrInvalidMessage
 		}
-		return Registered{Epoch: epoch, Connection: connection}, nil
+		if len(payload.Registered.GetBuild()) > 128 {
+			return nil, ErrInvalidMessage
+		}
+		return Registered{Epoch: epoch, Connection: connection, Build: payload.Registered.GetBuild(), Retiring: payload.Registered.GetRetiring()}, nil
 	case *wire.BrokerServerEnvelope_SnapshotPart:
 		return snapshotPartFromWire(payload.SnapshotPart)
 	case *wire.BrokerServerEnvelope_OperationResult:

M internal/adapters/brokerwire/codec_test.go +55 -0


@@ -1258,3 +1258,58 @@ func FuzzDecodeServer(f *testing.F) {
1258	1258		_, _ = DecodeServer(payload, testEnvelopeCeiling, testChunkCeiling)
1259	1259		})
1260	1260		}
	1261	+
	1262	+	func TestBuildRegistrationCodec(t *testing.T) {
	1263	+	for _, tc := range []struct {
	1264	+	name string
	1265	+	build string
	1266	+	retiring bool
	1267	+	}{
	1268	+	{"empty", "", false}, {"matching", "release+abc", false}, {"retiring", "release+def", true},
	1269	+	} {
	1270	+	t.Run(tc.name, func(t *testing.T) {
	1271	+	request := Register{Build: tc.build}
	1272	+	raw := mustEncodeClient(t, request)
	1273	+	decoded, err := DecodeClient(raw, testEnvelopeCeiling, testChunkCeiling)
	1274	+	require.NoError(t, err)
	1275	+	require.Equal(t, request, decoded)
	1276	+	want := []byte{0xaa, 0x06, 0x00}
	1277	+	if tc.build != "" {
	1278	+	want = append([]byte{0xaa, 0x06, byte(len(tc.build) + 2), 0x0a, byte(len(tc.build))}, []byte(tc.build)...)
	1279	+	}
	1280	+	require.Equal(t, want, raw)
	1281	+	response := Registered{Epoch: 7, Connection: testConnectionID(1), Build: tc.build, Retiring: tc.retiring}
	1282	+	raw = mustEncodeServer(t, response)
	1283	+	decodedServer, err := DecodeServer(raw, testEnvelopeCeiling, testChunkCeiling)
	1284	+	require.NoError(t, err)
	1285	+	require.Equal(t, response, decodedServer)
	1286	+	envelope := &wire.BrokerServerEnvelope{}
	1287	+	require.NoError(t, proto.Unmarshal(raw, envelope))
	1288	+	require.Equal(t, tc.build, envelope.GetRegistered().GetBuild())
	1289	+	require.Equal(t, tc.retiring, envelope.GetRegistered().GetRetiring())
	1290	+	})
	1291	+	}
	1292	+	for _, tc := range []struct {
	1293	+	name string
	1294	+	server bool
	1295	+	}{{"client", false}, {"server", true}} {
	1296	+	t.Run("oversize-"+tc.name, func(t *testing.T) {
	1297	+	build := strings.Repeat("x", 129)
	1298	+	if tc.server {
	1299	+	_, err := EncodeServer(Registered{Epoch: 7, Connection: testConnectionID(1), Build: build}, testEnvelopeCeiling, testChunkCeiling)
	1300	+	require.ErrorIs(t, err, ErrInvalidMessage)
	1301	+	raw, err := proto.Marshal(&wire.BrokerServerEnvelope{Payload: &wire.BrokerServerEnvelope_Registered{Registered: &wire.Registered{Scope: scopeToWire(7, testConnectionID(1)), Build: build}}})
	1302	+	require.NoError(t, err)
	1303	+	_, err = DecodeServer(raw, testEnvelopeCeiling, testChunkCeiling)
	1304	+	require.ErrorIs(t, err, ErrInvalidMessage)
	1305	+	} else {
	1306	+	_, err := EncodeClient(Register{Build: build}, testEnvelopeCeiling, testChunkCeiling)
	1307	+	require.ErrorIs(t, err, ErrInvalidMessage)
	1308	+	raw, err := proto.Marshal(&wire.BrokerClientEnvelope{Payload: &wire.BrokerClientEnvelope_Register{Register: &wire.Register{Build: build}}})
	1309	+	require.NoError(t, err)
	1310	+	_, err = DecodeClient(raw, testEnvelopeCeiling, testChunkCeiling)
	1311	+	require.ErrorIs(t, err, ErrInvalidMessage)
	1312	+	}
	1313	+	})
	1314	+	}
	1315	+	}


@@ -1258,3 +1258,58 @@ func FuzzDecodeServer(f *testing.F) {
1258	_, _ = DecodeServer(payload, testEnvelopeCeiling, testChunkCeiling)	1258		_, _ = DecodeServer(payload, testEnvelopeCeiling, testChunkCeiling)
1259	})	1259		})
1260	}	1260		}
		1261	+
		1262	+	func TestBuildRegistrationCodec(t *testing.T) {
		1263	+	for _, tc := range []struct {
		1264	+	name string
		1265	+	build string
		1266	+	retiring bool
		1267	+	}{
		1268	+	{"empty", "", false}, {"matching", "release+abc", false}, {"retiring", "release+def", true},
		1269	+	} {
		1270	+	t.Run(tc.name, func(t *testing.T) {
		1271	+	request := Register{Build: tc.build}
		1272	+	raw := mustEncodeClient(t, request)
		1273	+	decoded, err := DecodeClient(raw, testEnvelopeCeiling, testChunkCeiling)
		1274	+	require.NoError(t, err)
		1275	+	require.Equal(t, request, decoded)
		1276	+	want := []byte{0xaa, 0x06, 0x00}
		1277	+	if tc.build != "" {
		1278	+	want = append([]byte{0xaa, 0x06, byte(len(tc.build) + 2), 0x0a, byte(len(tc.build))}, []byte(tc.build)...)
		1279	+	}
		1280	+	require.Equal(t, want, raw)
		1281	+	response := Registered{Epoch: 7, Connection: testConnectionID(1), Build: tc.build, Retiring: tc.retiring}
		1282	+	raw = mustEncodeServer(t, response)
		1283	+	decodedServer, err := DecodeServer(raw, testEnvelopeCeiling, testChunkCeiling)
		1284	+	require.NoError(t, err)
		1285	+	require.Equal(t, response, decodedServer)
		1286	+	envelope := &wire.BrokerServerEnvelope{}
		1287	+	require.NoError(t, proto.Unmarshal(raw, envelope))
		1288	+	require.Equal(t, tc.build, envelope.GetRegistered().GetBuild())
		1289	+	require.Equal(t, tc.retiring, envelope.GetRegistered().GetRetiring())
		1290	+	})
		1291	+	}
		1292	+	for _, tc := range []struct {
		1293	+	name string
		1294	+	server bool
		1295	+	}{{"client", false}, {"server", true}} {
		1296	+	t.Run("oversize-"+tc.name, func(t *testing.T) {
		1297	+	build := strings.Repeat("x", 129)
		1298	+	if tc.server {
		1299	+	_, err := EncodeServer(Registered{Epoch: 7, Connection: testConnectionID(1), Build: build}, testEnvelopeCeiling, testChunkCeiling)
		1300	+	require.ErrorIs(t, err, ErrInvalidMessage)
		1301	+	raw, err := proto.Marshal(&wire.BrokerServerEnvelope{Payload: &wire.BrokerServerEnvelope_Registered{Registered: &wire.Registered{Scope: scopeToWire(7, testConnectionID(1)), Build: build}}})
		1302	+	require.NoError(t, err)
		1303	+	_, err = DecodeServer(raw, testEnvelopeCeiling, testChunkCeiling)
		1304	+	require.ErrorIs(t, err, ErrInvalidMessage)
		1305	+	} else {
		1306	+	_, err := EncodeClient(Register{Build: build}, testEnvelopeCeiling, testChunkCeiling)
		1307	+	require.ErrorIs(t, err, ErrInvalidMessage)
		1308	+	raw, err := proto.Marshal(&wire.BrokerClientEnvelope{Payload: &wire.BrokerClientEnvelope_Register{Register: &wire.Register{Build: build}}})
		1309	+	require.NoError(t, err)
		1310	+	_, err = DecodeClient(raw, testEnvelopeCeiling, testChunkCeiling)
		1311	+	require.ErrorIs(t, err, ErrInvalidMessage)
		1312	+	}
		1313	+	})
		1314	+	}
		1315	+	}

M internal/adapters/brokerwire/messages.go +3 -1


@@ -35,7 +35,7 @@ type ClientMessage interface{ brokerClientMessage() }
35	35		type ServerMessage interface{ brokerServerMessage() }
36	36
37	37		// Register opens one client connection to the broker.
38		-	type Register struct{}
	38	+	type Register struct{ Build string }
39	39
40	40		func (Register) brokerClientMessage() {}
41	41

@@ -192,6 +192,8 @@ func (CancelPreview) brokerClientMessage() {}
192	192		type Registered struct {
193	193		Epoch ports.BrokerEpoch
194	194		Connection ports.BrokerConnectionID
	195	+	Build string
	196	+	Retiring bool
195	197		}
196	198
197	199		func (Registered) brokerServerMessage() {}

 type ServerMessage interface{ brokerServerMessage() }
 // Register opens one client connection to the broker.
-type Register struct{}
+type Register struct{ Build string }
 func (Register) brokerClientMessage() {}
 type Registered struct {
 	Epoch      ports.BrokerEpoch
 	Connection ports.BrokerConnectionID
+	Build      string
+	Retiring   bool
 }
 func (Registered) brokerServerMessage() {}

M internal/protocol/wire/broker.pb.go +31 -5


@@ -846,6 +846,7 @@ func (*BrokerServerEnvelope_PreviewPublication) isBrokerServerEnvelope_Payload()
846	846		// Register opens one client connection to the broker.
847	847		type Register struct {
848	848		state protoimpl.MessageState `protogen:"open.v1"`
	849	+	Build string `protobuf:"bytes,1,opt,name=build,proto3" json:"build,omitempty"`
849	850		unknownFields protoimpl.UnknownFields
850	851		sizeCache protoimpl.SizeCache
851	852		}

@@ -880,6 +881,13 @@ func (*Register) Descriptor() ([]byte, []int) {
880	881		return file_broker_proto_rawDescGZIP(), []int{7}
881	882		}
882	883
	884	+	func (x *Register) GetBuild() string {
	885	+	if x != nil {
	886	+	return x.Build
	887	+	}
	888	+	return ""
	889	+	}
	890	+
883	891		// Subscribe asks for snapshot and lifecycle publications for one scope.
884	892		type Subscribe struct {
885	893		state protoimpl.MessageState `protogen:"open.v1"`

@@ -1557,6 +1565,8 @@ func (x CloseStream) GetRef() BrokerStreamRef {
1557	1565		type Registered struct {
1558	1566		state protoimpl.MessageState `protogen:"open.v1"`
1559	1567		Scope *BrokerScope `protobuf:"bytes,1,opt,name=scope,proto3" json:"scope,omitempty"`
	1568	+	Build string `protobuf:"bytes,2,opt,name=build,proto3" json:"build,omitempty"`
	1569	+	Retiring bool `protobuf:"varint,3,opt,name=retiring,proto3" json:"retiring,omitempty"`
1560	1570		unknownFields protoimpl.UnknownFields
1561	1571		sizeCache protoimpl.SizeCache
1562	1572		}

@@ -1598,6 +1608,20 @@ func (x Registered) GetScope() BrokerScope {
1598	1608		return nil
1599	1609		}
1600	1610
	1611	+	func (x *Registered) GetBuild() string {
	1612	+	if x != nil {
	1613	+	return x.Build
	1614	+	}
	1615	+	return ""
	1616	+	}
	1617	+
	1618	+	func (x *Registered) GetRetiring() bool {
	1619	+	if x != nil {
	1620	+	return x.Retiring
	1621	+	}
	1622	+	return false
	1623	+	}
	1624	+
1601	1625		// SnapshotPart is one fragment of a snapshot publication. Parts of one
1602	1626		// generation and revision arrive in index order and carry exactly one
1603	1627		// nested payload.

@@ -3186,9 +3210,9 @@ const file_broker_proto_rawDesc = "" +
3186	3210		"\x14broker_error_message\x18\xd0\x01 \x01(\v2\x1f.vev.wire.v1.BrokerErrorMessageH\x00R\x12brokerErrorMessage\x124\n" +
3187	3211		"\bshutdown\x18\xd1\x01 \x01(\v2\x15.vev.wire.v1.ShutdownH\x00R\bshutdown\x12S\n" +
3188	3212		"\x13preview_publication\x18\xd2\x01 \x01(\v2\x1f.vev.wire.v1.PreviewPublicationH\x00R\x12previewPublicationB\t\n" +
3189		-	"\apayload\"\n" +
3190		-	"\n" +
3191		-	"\bRegister\"u\n" +
	3213	+	"\apayload\" \n" +
	3214	+	"\bRegister\x12\x14\n" +
	3215	+	"\x05build\x18\x01 \x01(\tR\x05build\"u\n" +
3192	3216		"\tSubscribe\x12.\n" +
3193	3217		"\x05scope\x18\x01 \x01(\v2\x18.vev.wire.v1.BrokerScopeR\x05scope\x12\x1e\n" +
3194	3218		"\n" +

@@ -3242,10 +3266,12 @@ const file_broker_proto_rawDesc = "" +
3242	3266		"\x03ref\x18\x01 \x01(\v2\x1c.vev.wire.v1.BrokerStreamRefR\x03ref\x12\x12\n" +
3243	3267		"\x04data\x18\x02 \x01(\fR\x04data\"=\n" +
3244	3268		"\vCloseStream\x12.\n" +
3245		-	"\x03ref\x18\x01 \x01(\v2\x1c.vev.wire.v1.BrokerStreamRefR\x03ref\"<\n" +
	3269	+	"\x03ref\x18\x01 \x01(\v2\x1c.vev.wire.v1.BrokerStreamRefR\x03ref\"n\n" +
3246	3270		"\n" +
3247	3271		"Registered\x12.\n" +
3248		-	"\x05scope\x18\x01 \x01(\v2\x18.vev.wire.v1.BrokerScopeR\x05scope\"\xab\x03\n" +
	3272	+	"\x05scope\x18\x01 \x01(\v2\x18.vev.wire.v1.BrokerScopeR\x05scope\x12\x14\n" +
	3273	+	"\x05build\x18\x02 \x01(\tR\x05build\x12\x1a\n" +
	3274	+	"\bretiring\x18\x03 \x01(\bR\bretiring\"\xab\x03\n" +
3249	3275		"\fSnapshotPart\x12.\n" +
3250	3276		"\x05scope\x18\x01 \x01(\v2\x18.vev.wire.v1.BrokerScopeR\x05scope\x12\x1e\n" +
3251	3277		"\n" +

 // Register opens one client connection to the broker.
 type Register struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
+	Build         string                 `protobuf:"bytes,1,opt,name=build,proto3" json:"build,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
 	return file_broker_proto_rawDescGZIP(), []int{7}
 }
+func (x *Register) GetBuild() string {
+	if x != nil {
+		return x.Build
+	}
+	return ""
+}
 // Subscribe asks for snapshot and lifecycle publications for one scope.
 type Subscribe struct {
 	state      protoimpl.MessageState `protogen:"open.v1"`
 type Registered struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
 	Scope         *BrokerScope           `protobuf:"bytes,1,opt,name=scope,proto3" json:"scope,omitempty"`
+	Build         string                 `protobuf:"bytes,2,opt,name=build,proto3" json:"build,omitempty"`
+	Retiring      bool                   `protobuf:"varint,3,opt,name=retiring,proto3" json:"retiring,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
 	return nil
 }
+func (x *Registered) GetBuild() string {
+	if x != nil {
+		return x.Build
+	}
+	return ""
+}
+func (x *Registered) GetRetiring() bool {
+	if x != nil {
+		return x.Retiring
+	}
+	return false
+}
 // SnapshotPart is one fragment of a snapshot publication. Parts of one
 // generation and revision arrive in index order and carry exactly one
 // nested payload.
 	"\x14broker_error_message\x18\xd0\x01 \x01(\v2\x1f.vev.wire.v1.BrokerErrorMessageH\x00R\x12brokerErrorMessage\x124\n" +
 	"\bshutdown\x18\xd1\x01 \x01(\v2\x15.vev.wire.v1.ShutdownH\x00R\bshutdown\x12S\n" +
 	"\x13preview_publication\x18\xd2\x01 \x01(\v2\x1f.vev.wire.v1.PreviewPublicationH\x00R\x12previewPublicationB\t\n" +
-	"\apayload\"\n" +
+	"\apayload\" \n" +
-	"\n" +
+	"\bRegister\x12\x14\n" +
-	"\bRegister\"u\n" +
+	"\x05build\x18\x01 \x01(\tR\x05build\"u\n" +
 	"\tSubscribe\x12.\n" +
 	"\x05scope\x18\x01 \x01(\v2\x18.vev.wire.v1.BrokerScopeR\x05scope\x12\x1e\n" +
 	"\n" +
 	"\x03ref\x18\x01 \x01(\v2\x1c.vev.wire.v1.BrokerStreamRefR\x03ref\x12\x12\n" +
 	"\x04data\x18\x02 \x01(\fR\x04data\"=\n" +
 	"\vCloseStream\x12.\n" +
-	"\x03ref\x18\x01 \x01(\v2\x1c.vev.wire.v1.BrokerStreamRefR\x03ref\"<\n" +
+	"\x03ref\x18\x01 \x01(\v2\x1c.vev.wire.v1.BrokerStreamRefR\x03ref\"n\n" +
 	"\n" +
 	"Registered\x12.\n" +
-	"\x05scope\x18\x01 \x01(\v2\x18.vev.wire.v1.BrokerScopeR\x05scope\"\xab\x03\n" +
+	"\x05scope\x18\x01 \x01(\v2\x18.vev.wire.v1.BrokerScopeR\x05scope\x12\x14\n" +
+	"\x05build\x18\x02 \x01(\tR\x05build\x12\x1a\n" +
+	"\bretiring\x18\x03 \x01(\bR\bretiring\"\xab\x03\n" +
 	"\fSnapshotPart\x12.\n" +
 	"\x05scope\x18\x01 \x01(\v2\x18.vev.wire.v1.BrokerScopeR\x05scope\x12\x1e\n" +
 	"\n" +

M internal/protocol/wire/schema/broker.proto +5 -1


@@ -110,7 +110,9 @@ message BrokerServerEnvelope {
110	110		}
111	111
112	112		// Register opens one client connection to the broker.
113		-	message Register {}
	113	+	message Register {
	114	+	string build = 1;
	115	+	}
114	116
115	117		// Subscribe asks for snapshot and lifecycle publications for one scope.
116	118		message Subscribe {

@@ -220,6 +222,8 @@ message CloseStream {
220	222		// Registered confirms one accepted client connection and its assigned scope.
221	223		message Registered {
222	224		BrokerScope scope = 1;
	225	+	string build = 2;
	226	+	bool retiring = 3;
223	227		}
224	228
225	229		// SnapshotPart is one fragment of a snapshot publication. Parts of one

 }
 // Register opens one client connection to the broker.
-message Register {}
+message Register {
+  string build = 1;
+}
 // Subscribe asks for snapshot and lifecycle publications for one scope.
 message Subscribe {
 // Registered confirms one accepted client connection and its assigned scope.
 message Registered {
   BrokerScope scope = 1;
+  string build = 2;
+  bool retiring = 3;
 }
 // SnapshotPart is one fragment of a snapshot publication. Parts of one