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protobuf.format.txt
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protobuf.format.txt
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PROTOBUF
ALTERNATIVES ==> #See serialization formats summary
VERSION ==> #21.9
#Serialization format:
# - optimized for low size
# - separate text definition and binary serialization
# - fairly schemaful
#Generates code stub to parse/serialize data.
FILE EXTENSION ==> #.proto
MIME TYPE ==> #application/protobuf
#As extension: +proto
/=+===============================+=\
/ : : \
)==: TYPES :==(
\ :_______________________________: /
\=+===============================+=/
TYPE #Data type
VAL #VARR|BOOL|INT|NUM|STR
VAR #Must use [a-zA-Z0-9_] and start with [a-zA-Z]
VARR #Dot-delimited VAR
CASE ==> #Convention:
# - CamelCase for aggregates|types (service|rpc|message|enum type)
# - snake_case for fields (normal|oneof|map|option), package, files, builtin types
# - SNAKE_CASE for enum values
BOOL #true|false
bool #TYPE
INT #Can be:
# - N... (decimal)
# - 0N... (octal)
# - 0xN... 0X... (hex)
#Can be prefixed with +|-
[s|u]int32|64 #TYPE. 32|64 bits, signed|unsigned
#sint* is like int*, except how is is encoded (see below for difference)
ID #INT32 used as identifier in the binary format
#Max 2**29. Cannot use 19000-19999
NUM #Can be:
# - [N...][.N...][e|E[+|-]N...]
# - inf
# - nan
#Can be prefixed with +|-
float|double #TYPE. Floating point NUM 32|64 bits
[s]fixed32|64 #TYPE. Fixed point NUM 32|64 bits, signed|both
STR #"..." or '...' (same behavior, but " preferred)
#Can use:
# - any Unicode characters as is, except \0 \n \ and (depending on quote) ' "
# - \a \b \f \n \r \t \v \\ \' \"
# - \NNN (codepoint as octal)
# - \xNN or \XNN (codepoint as hex)
string #TYPE for human STR
bytes #TYPE for machine STR
TRANSTYPING ==> #The following TYPEs are automatically transtyped:
# - when server|client are using different *.proto
# - i.e. allows backward compatibility
#List of transtyping groups:
# - [u]int32|64|bool
# - sint32|64
# - string|bytes, providing valid UTF-8
# - [s]fixed32
# - [s]fixed64
/=+===============================+=\
/ : : \
)==: STATEMENTS :==(
\ :_______________________________: /
\=+===============================+=/
STATEMENT; #Always ; at end, for each line except ones ending with {}
; #Empty statement. Can be placed mostly anywhere.
// COMMENT
/* COMMENT */ #
syntax = STR #Declare protobuf version
#Must be "proto2|proto3"
# - only proto3 documented here
# - proto2 can be imported from proto3, but not other way around
#Required. Must be first statement.
package "VARR" #When imported, this file's TYPEs must be namespaced by VARR
#Implementation is language-dependent.
#VARR can be overridden for specific language using top-level OPTs:
# - go_package STR (e.g. 'google.golang.org/protobuf/types/known/anypb')
# - java_package STR (e.g. 'com.google.protobuf')
# - csharp_namespace STR (e.g. 'Google.Protobuf.WellKnownTypes')
#By convention:
# - before imports
# - if VARR instead of VAR, each part should be same as directory name
import [weak|public] "PATH.proto" #Include another *.proto file
#Can use TYPEs of PATH.proto, but not ones imported by it
# - unless "public" (only for one depth level)
#If "weak", does not fail if "PATH.proto" does not exist
service VAR { ... } #A client|server.
rpc VAR MTYPE returns MTYPE2 #An endpoint. Child of service
[{ ... }] #MTYPE is ([stream] MESSAGE_TYPE)
message VAR { ... } #Like an OBJ. Can be nested.
#VAR is the TYPE
#If a TYPE is declared inside message and used outside of it:
# - must namespace it: VAR.TYPE
# - for TYPEs of: nested message, enum
#Unknown fields allowed, but might be skipped during serialization|parsing
option OPT_VARR = VAL #Top-level or child of service|rpc|message|enum|oneof
#Declare options for a specific file|service|rpc|message|enum|oneof
#It is possible to define custom options, but hard.
#Core OPTs documented here.
#OPT_VARR can be (OPT_VARR)
OPTS #[OPT_VARR=VAL],... (uses [] brackets)
#Same but for fields|map|enum values
enum VAR { ... } #Enum type. Top-level or child of message
#VAR is the TYPE
#By convention: prefer top-level, with a prefix.
VAR = ID [OPTS] #Enum field declaration. Child of enum.
#There must be at least one enum field with ID 0
# - used as default value
# - by convention named *_UNSPECIFIED
#Two fields cannot have same ID unless ENUM_OPT.allow_alias true
oneof VAR { ... } #Child of message
#Declares that at most one of several fields is declared at once.
#Allows serializing only one of them, i.e. more memory efficient.
#Cannot use ARRs nor MAPs
#Backward compatible changes:
# - creating new oneof
# - removing oneof fields
# - but not adding oneof fields to existing oneof
[repeated] [optional] #Field declaration. Child of message|oneof.
TYPE VAR = ID [OPTS] #"repeated" is for ordered ARR
#If both "optional" and not:
# - the default value is always assigned
# - the default value is the empty value (0, false, "", [], enum value with ID 0)
#If not "optional":
# - the default value is not serialized, whether assigned implicitly or not
# - this takes less space
#If "optional":
# - the default value is serialized, whether assigned implicitly or not
# - this allows using *has|clear*() methods
#By convention, VAR plural.
FIELD_OPT.deprecated #BOOL (def: false). Document as deprecated and|or print warnings.
map<KEY_TYPE, VAL_TYPE> VAR = ID #Key/value unordered map. Child of message
[OPTS] #KEY_TYPE cannot be float|double|bytes|message|map|enum
#VAL_TYPE cannot be map nor ARR
reserved ID [to ID2|max],... #Child of message|enum
reserved VAR,... #List of previously defined ID|VAR that have been deleted.
#Forbids re-using those, to keep backward compatibility.
/=+===============================+=\
/ : : \
)==: GOOGLE.PROTOBUF :==(
\ :_______________________________: /
\=+===============================+=/
package "google.protobuf" #MESSAGE_TYPEs and ENUM_TYPEs always available.
#Mostly for reflection, i.e. protobuf to represent protobuf itself.
#Also define:
# - null|timestamp|duration
# - service versions, mixins
import #NAME is:
"google/protobuf/NAME.proto" # - wrappers (*Value)
# - struct (NullValue|ListValue|Struct|Value)
# - empty
# - any
# - type (Field.*|Syntax|Type|Option|Enum|EnumValue)
# - source_context
# - api (Api|Method|Mixin)
# - field_mask
# - duration
# - timestamp
BoolValue|[U]Int32|64Value|
FloatValue|DoubleValue| #Protobuf builtin type
StringValue|BytesValue #Has a single field: value BOOL|[U]INT32|64|FLOAT|DOUBLE|STR|BYTES
NullValue #null (not present in protobuf). ENUM_TYPE with single value: NULL_VALUE
ListValue #Protobuf ARR
LIST_VALUE.values #VALUE_ARR
Empty #MESSAGE with no fields.
Struct #Protobuf OBJ (service|message|map)
STRUCT.fields #MAP<STR,VALUE>
Value #Protobuf VAL (i.e. any type).
#If a union of one of the following.
VALUE.bool_value #BOOL
VALUE.number_value #DOUBLE, excluding inf|nan
VALUE.string_value #STR
VALUE.null_value #NULL_VALUE
VALUE.list_value #LIST_VALUE
VALUE.struct_value #STRUCT
Any #Protobuf VAL (i.e. any type)
ANY.value #BYTES
ANY.type_url #"URL" to a Type
Field.Kind #Protobuf type. ENUM_TYPE
#Can be: TYPE_BOOL|[S|U]INT32|64|DOUBLE|FLOAT|[S]FIXED32|64|STRING|BYTES|MESSAGE|ENUM|UNKNOWN
Field.Cardinality #Protobuf type optionality|repeatedness. ENUM_TYPE
#Can be: CARDINALITY_OPTIONAL|REPEATED|UNKNOWN
Syntax #Protobuf syntax. ENUM_TYPE
#Can be: SYNTAX_PROTO2|3
SourceContext #Information about the *.proto file
SOURCE_CONTEXT.file_name #"*.proto"
Api #Protobuf service
API.name #"VAR"
API.methods #METHOD_ARR
API.options #OPTION_ARR
API.source_context #SOURCE_CONTEXT
API.syntax #SYNTAX
API.version #Semver "MAJOR[.MINOR]"
API.mixins #MIXIN_ARR
Mixin #Protobuf service within another service
MIXIN.name #"VAR" of the other service
MIXIN.root #"PATH" where service is embedded
Method #Protobuf rpc
METHOD.request|response_streaming #BOOL
METHOD.request|response_type_url #"URL" to a Type
METHOD.options #OPTION_ARR
METHOD.syntax #SYNTAX
Type #Protobuf message
TYPE.name #"MESSAGE_TYPE"
TYPE.fields #FIELD_ARR
TYPE.options #OPTION_ARR
TYPE.oneofs #"VAR"_ARR of fields in oneofs
TYPE.source_context #SOURCE_CONTEXT
TYPE.syntax #SYNTAX
Field #Protobuf field
FIELD.name #"VAR"
FIELD.json_name #OPT.json_name
FIELD.number #ID
FIELD.kind #KIND representing the type
FIELD.type_url #"URL" to a Type
FIELD.cardinality #CARDINALITY
FIELD.oneof_index #INT32. 0 if in oneof. Otherwise 1-based index.
FIELD.packed #BOOL.
FIELD.options #OPTION_ARR
FieldMask #Protobuf field "VARR" path.
#ARR fields can only be specified as last VAR.
#Usually used for selection.
FIELD_MASK.paths #"VARR"_ARR
Option #Protobuf options
OPTION.name #"OPT_VARR"
OPTION.value #ANY
Enum #Protobuf enum type
ENUM.name #"VAR"
ENUM.enumvalue #ENUMVALUE_ARR
ENUM.options #OPTION_ARR
ENUM.source_context #SOURCE_CONTEXT
ENUM.syntax #SYNTAX
EnumValue #Protobuf enum value
ENUMVALUE.name #"VAR"
ENUMVALUE.number #ID
ENUMVALUE.options #OPTION_ARR
Timestamp #
TIMESTAMP.seconds #INT64. Unix time.
TIMESTAMP.nanos #INT32. Min 0, max 1e9
Duration #
DURATION.seconds #INT64. Min|max +|-1e4 years
DURATION.nanos #INT32. Min|max +|-1e9
/=+===============================+=\
/ : : \
)==: BINARY FORMAT :==(
\ :_______________________________: /
\=+===============================+=/
BINARY FORMAT ==> #Created by protoc or by generated code (*Binary())
#Memory efficient:
# - only keep IDs, not VARs nor TYPEs
# - i.e. need FILE.proto to parse
# - use varint (see its doc)
# - default values are not serialized (since undefined values use default values)
# - sint* is like int*, but takes less memory for positive|negative values close to 0 (and vice-versa)
#Messages are unordered:
# - serializing the same message might give different output
/=+===============================+=\
/ : : \
)==: JSON :==(
\ :_______________________________: /
\=+===============================+=/
JSON SERIALIZATION ==> # - bool -> BOOL
# - [u]int|fixed32 -> NUM
# - [u]int|fixed64 -> "NUM"
# - float|double -> NUM|"NaN"|"[-]Infinity"
# - string -> STR
# - bytes -> standard base64 STR with padding
# - message -> OBJ
# - key is lowerCamelCase'd
# - key can be set using OPT.json_name
# - repeated -> ARR
# - enum -> "VAR"
# - map -> OBJ
# - TYPE default value -> undefined
# - *Value -> same as underlying type
# - NullValue -> null
# - EMPTY -> OBJ
# - STRUCT -> OBJ
# - ANY -> OBJ, with @type instead of type_url
# - FIELD_MASK -> "VARR,..."
# - TIMESTAMP -> "YYYY-MM-DDTHH:MM:SS[.SSS[SSS[SSS]]]Z"
# - DURATION -> "N...[.N...]s"
JSON PARSING ==> # - BOOL -> bool
# - NUM|"NUM" -> [u]int|fixed32|64
# - NUM|"NUM[e...]"|"NaN"|"[-]Infinity" -> float|double
# - STR -> string
# - standard|url-safe base64 STR with|without padding -> bytes
# - undefined|null -> TYPE default value
# - OBJ -> message
# - key is either lowerCamelCase, protobuf name or OPT.json_name
# - "VAR"|ID_NUM -> enum
# - ARR -> repeated
# - [] or null -> empty repeated
# - OBJ -> map
# - same as underlying type -> *Value
# - null -> NullValue
# - OBJ -> EMPTY
# - OBJ -> STRUCT
# - OBJ, with @type instead of type_url -> ANY
# - "VARR,..." -> FIELD_MASK
# - "YYYY-MM-DDTHH:MM:SS[.SSS[SSS[SSS]]][TZ]" -> TIMESTAMP
# - "N...[.N...]s" -> DURATION
/=+===============================+=\
/ : : \
)==: COMPILER :==(
\ :_______________________________: /
\=+===============================+=/
protoc FILE.proto... #Convert FILE.proto to generated code.
#The generated code usually needs some runtime library.
#Does not convert SERVICE|RPC.
@CONFIG_PATH #Content is CLI flags list
--js|objc|php|python|ruby|cpp|
csharp|java_out
[LANG_OPT[=STR],...]OUT_DIR #Where to output generated code, and for which language
--decode MESSAGE_TYPE #Take message in binary format in stdin and outputs it in debug text format to stdout
#Not compatible with --*_out
--encode MESSAGE_TYPE #Inverse
--decode_raw #Same as --decode but automatically guesses MESSAGE_TYPE
--descriptor_set_out FILE #Encode FILE.proto to binary ("file descriptor set")
--descriptor_set_in FILE,... #Inverse
--include_imports #With --descriptor_set_out: include imported definitions
--include_source_info #With --descriptor_set_out: include SourceContext
--dependency_out FILE #Write list of dependencies in a "make" format
-I|--proto_path DIR #To resolve "import" statements.
#Def: "."
#Should be set to repository root.
#Can be specified several times.
--deterministic_output #Make MAP fields order serialization determinisitc
--fatal_warnings #Non-0 exit code on warnings
--error_format STR #Error format among 'gcc' (def) or 'msvs' (Visual studio)
--print_free_field_numbers #Print ID_NUMs
--plugin [NAME=]PATH #Executable plugin. By def, search in PATH
/=+===============================+=\
/ : : \
)==: NODE :==(
\ :_______________________________: /
\=+===============================+=/
google-protobuf #Runtime npm package.
#Required by the generated code.
#See protobufjs for alternative
LANG_OPT.import_style=STR #Can be:
# - 'closure' (def)
# - 'commonjs_strict':
# - filename is "FILE_pb.js"
# - --proto_path is OUT_DIR
# - 'browser': global object
# - 'commonjs': same as commonjs_strict + browser
# - 'es6': ES modules
LANG_OPT.error_on_name_conflict #BOOL (def: false). Fail if two TYPEs with same name
LANG_OPT.binary #BOOL (def: true). Enables *Binary()
EXPORT ==> #Output file exports top-level message|enum, namespaced by package
CASE ==> # - kept as is: package, message, enum
# - converted to UpperCase: fields, oneof, map
# - converted to UPPERCASE: enum fields, oneof cases
# - converted to lowercase: toObject()
VARR|PACKAGE #Just plain OBJ
new Message() #"Message" is the Message name
MESSAGE.toObject()->OBJ #
MESSAGE.cloneMessage()->MESSAGE2 #
MESSAGE.getFIELD()->VAL #
MESSAGE.setFIELD(VAL)->MESSAGE #
MESSAGE.hasFIELD(VAL)->BOOL #Only if "optional"
MESSAGE.clearFIELD(VAL)->MESSAGE #Only if "optional"
ARR_FIELD #Uses the following methods instead.
MESSAGE.getFIELDList()->ARR
MESSAGE.setFIELDList(ARR)->MESSAGE
MESSAGE.clearFIELDList(ARR)
->MESSAGE
MESSAGE.addFIELD(VAL[,INDEX])
->MESSAGE #Def INDEX: last
NESTED_MESSAGE_FIELD #undefined if not set
#Also have the following additional methods.
MESSAGE.clearFIELD()->MESSAGE
MESSAGE.hasFIELD()->BOOL #Only if nested message field
BYTES_FIELD #Use BUFFER|BASE64_STR
#Converted to BASE64_STR in toObject()
#Also have the following additional methods.
MESSAGE.getFIELD_asB64()
->'BASE64_STR'
MESSAGE.getFIELD_asU8()->UINT8_ARR#
MAP_FIELD #Uses the following methods instead.
MESSAGE.getFIELDMap()->MAP #
MESSAGE.clearFIELDMap()->MESSAGE #
MESSAGE.ONEOFCase #OBJ:
# - value is ID_INT
# - key is either:
# - field name
# - {ONEOF}_NOT_SET (value 0)
MESSAGE.getONEOFCase()->ID_INT #
ENUM #Just plain OBJ
MESSAGE.serializeBinary
()->UINT8_ARR
Message.deserializeBinary
(UINT8_ARR)->MESSAGE #Protobuf binary format
new BinaryWriter()
MESSAGE.serializeBinaryToWriter
(MESSAGE, BINARY_WRITER)
BINARY_WRITER.getResultBuffer()
->UINT8_ARR
new BinaryReader()
Message.
deserializeBinaryFromReader
(MESSAGE, BINARY_READER)->MESSAGE#Same but more advanced
/=+===============================+=\
/ : : \
)==: LANGUAGE-SPECIFIC OPTS :==(
\ :_______________________________: /
\=+===============================+=/
LANGUAGE-SPECIFIC OPTS ==> #Top-level OPTs for specific languages.
OPT.java_outer_classname #"Class". For outermost Java class name.
#Def: filename, CamelCased
OPT.java_multiple_files #BOOL (def: false). For Java. Split generated code into several files.
OPT.cc_enable_arenas #BOOL (def: false). For C++. Memory optimization.
OPT.optimize_for #For C++|Java. How to optimize generated code. Can be:
# - "SPEED" (def)
# - "LITE_RUNTIME": like SPEED but uses libprotobuf-lite instead of libprotobuf, which
# has fewer features (no reflection nor descriptors)
# - "CODE_SIZE"
OPT.objc_class_prefix #STR. Objective-C class prefix.