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diff --git a/src/tools/vppapigen/VPPAPI.md b/src/tools/vppapigen/VPPAPI.md deleted file mode 100644 index df211d866a0..00000000000 --- a/src/tools/vppapigen/VPPAPI.md +++ /dev/null @@ -1,346 +0,0 @@ -# VPP API Language {#api_lang_doc} - -The VPP binary API is a message passing API. -The VPP API language is used to define a RPC interface between VPP and its -control plane. The API messages supports shared memory transport and -Unix domain sockets (SOCK_STREAM). - -The wire format is essentially that of a network formatted (big-endian) packed C struct. - -The VPP API compiler is located in *src/tools/vppapigen* and can currently -compile to JSON or C (used by the VPP binary itself). - -## Language definition - -### Defining a messages - -There are 3 types of message exchanges: - -* Request/Reply -The client sends a request message and the server replies with a -single reply message. The convention is that the reply message is -named as method_name + \_reply. - -* Dump/Detail -The client sends a "bulk" request message to the server, and the -server replies with a set of detail messages. These messages may be of -different type. A dump/detail call must be enclosed in a control ping -block (Otherwise the client will not know the end of the bulk -transmission). The method name must end with method + "\_dump", the -reply message should be named method + "\_details". The exception here -is for the methods that return multiple message types -(e.g. sw_interface_dump). The Dump/Detail methods are typically used -for acquiring bulk information, like the complete FIB table. - -* Events -The client can register for getting asynchronous notifications from -the server. This is useful for getting interface state changes, and so -on. The method name for requesting notifications is conventionally -prefixed with "want_". E.g. "want_interface_events". Which -notification types results from an event registration is defined in -the service definition. - -A message from a client must include the 'client_index', an opaque -cookie identifying the sender, and a 'context' field to let the client -match request with reply. - -An example of a message definition. The client sends the show_version request, -the server replies with the show_version_reply. - -The *client_index* and *context* fields are required in all requests. -The *context* is returned by the server and is used by the client to -match up request and reply messages. - -``` -define show_version -{ - u32 client_index; - u32 context; -}; -define show_version_reply -{ - u32 context; - i32 retval; - string program [32]; - string version [32]; - string build_date [32]; - /* The final field can be a variable length argument */ - string build_directory []; -}; - -``` - -The flags are not used by the clients, but have special meaning -for some of the tracing and debugging of the API. -The *autoreply* flag is a shorthand for a reply message with just a -*retval* field. - -``` - define : DEFINE ID '{' block_statements_opt '}' ';' - define : flist DEFINE ID '{' block_statements_opt '}' ';' - flist : flag - | flist flag - flag : MANUAL_PRINT - | MANUAL_ENDIAN - | DONT_TRACE - | AUTOREPLY - - block_statements_opt : block_statements - block_statements : block_statement - | block_statements block_statement - block_statement : declaration - | option - declaration : type_specifier ID ';' - | type_specifier ID '[' ID '=' assignee ']' ';' - declaration : type_specifier ID '[' NUM ']' ';' - | type_specifier ID '[' ID ']' ';' - type_specifier : U8 - | U16 - | U32 - | U64 - | I8 - | I16 - | I32 - | I64 - | F64 - | BOOL - | STRING - type_specifier : ID -``` - - -### Options -The *option* word is used to specify meta information. -The only current use is to specify a semantic version of the .api file itself. - -Example: -``` -option version = "1.0.0"; -``` - -``` - - option : OPTION ID '=' assignee ';' - assignee : NUM - | TRUE - | FALSE - | STRING_LITERAL -``` - -### Defining new types - -New user defined types are defined just like messages. -A typedef has two forms. It can either define an alias for a -different type (or array). - -Example: - -``` -typedef u8 ip4_address[4]; -typedef u8 ip6_address[16]; -``` - -Where the above defines two new types *vl_api_ip4_address_t* and -*vl_api_ip6_address_t*. These are aliases for the underlying -u8 array. - -In the other form, it is used to specify an abstract data type. - -``` -enum address_family { - ADDRESS_IP4 = 0, - ADDRESS_IP6, -}; - -union address_union { - vl_api_ip4_address_t ip4; - vl_api_ip6_address_t ip6; -}; - -typedef address { - vl_api_address_family_t af; - vl_api_address_union_t un; -}; -``` - -Where the new type *vl_api_address_t* - -``` - typedef : TYPEDEF ID '{' block_statements_opt '}' ';' - typedef : TYPEDEF declaration -``` - - -### Importing Definitions -You can use definitions from other .api files by importing them. -To import another .api's definitions, you add an import statement -to the top of your file: - -import "vnet/ip/ip_types.api"; - -By default you can only use definitions from directly imported .api files. - -The API compiler searches for imported files in a set of directories -specified on the API compiler command line using the --includedir flag. -``` -import : IMPORT STRING_LITERAL ';' -``` - -### Comments - -The API language uses C style comments. -``` -/* */ -// -``` - -### Enumerations -Enums are similar to enums in C. - -Every enum definition must contain a constant that maps to zero -as its first element. This is because: - -There must be a zero value, so that we can use 0 as a numeric default value. -The zero value needs to be the first element. - -As in C, enums can be used as flags or just as numbers. -The on-wire, and in memory representation size of an enum can be specified. -Not all language bindings will support that. The default size is 4 (u32). - -Example -``` -enum ip_neighbor_flags -{ - IP_API_NEIGHBOR_FLAG_NONE = 0, - IP_API_NEIGHBOR_FLAG_STATIC = 0x1, - IP_API_NEIGHBOR_FLAG_NO_FIB_ENTRY = 0x2, -}; -``` - -Which generates the vl_api_ip_neighbor_flags_t in the C binding. -In Python that is represented as an IntFlag object -VppEnum.vl_api_ip_neighbor_flags_t. - -``` - enum : ENUM ID '{' enum_statements '}' ';' - enum : ENUM ID ':' enum_size '{' enum_statements '}' ';' - enum_size : U8 - | U16 - | U32 - enum_statements : enum_statement - | enum_statements enum_statement - enum_statement : ID '=' NUM ',' - | ID ',' -``` - -### Services -The service statement defines the relationship between messages. -For request/response and dump/details messages it ties the -request with the reply. For events, it specifies which events -that can be received for a given want_* call. - -Example: -``` -service { - rpc want_interface_events returns want_interface_events_reply - events sw_interface_event; -}; - -``` - -Which states that the request want_interface_events returns a -want_interface_events_reply and if enabled the client will -receive sw_interface_event messages whenever interface states changes. - -``` - service : SERVICE '{' service_statements '}' ';' - service_statements : service_statement - | service_statements service_statement - service_statement : RPC ID RETURNS NULL ';' - | RPC ID RETURNS ID ';' - | RPC ID RETURNS STREAM ID ';' - | RPC ID RETURNS ID EVENTS event_list ';' - event_list : events - | event_list events - events : ID - | ID ',' -``` - - -## Types -### Scalar Value Types - -.api type|size|C type|Python type ----------|----|------|----------- -i8 | 1|i8 |int -u8 | 1|u8 |int -i16 | 2|i16 |int -u16 | 2|u16 |int -i32 | 4|i32 |int -u32 | 4|u32 |int -i64 | 8|i64 |int -u64 | 8|u64 |int -f64 | 8|f64 |float -bool | 1|bool |boolean -string |variable|vl_api_string_t|str - -### User Defined Types -#### vnet/ip/ip_types.api - -.api type|size|C type|Python type ----------|----|------|----------- -vl_api_address_t|20|vl_api_address_t|`<class 'ipaddress.IPv4Address'> or <class 'ipaddress.IPv6Address'>` -vl_api_ip4_address_t|4|vl_api_ip4_address_t|`<class 'ipaddress.IPv4Address'>` -vl_api_ip6_address_t|16|vl_api_ip6_address_t|`<class 'ipaddress.IPv6Address'>` -vl_api_prefix_t|21|vl_api_prefix_t|`<class 'ipaddress.IPv4Network'> or <class 'ipaddress.IPv6Network'>` -vl_api_ip4_prefix_t|5|vl_api_ip4_prefix_t|`<class 'ipaddress.IPv4Network'>` -vl_api_ip6_prefix_t|17|vl_api_ip6_prefix_t|`<class 'ipaddress.IPv6Network'>` -vl_api_ip4_address_with_prefix_t|5|vl_api_ip4_address_with_prefix_t|`<class 'ipaddress.IPv4Interface'>` -vl_api_ip6_address_with_prefix_t|17|vl_api_ip6_address_with_prefix_t|`<class 'ipaddress.IPv6Interface'>` - -#### vnet/ethernet/ethernet_types.api -.api type|size|C type|Python type ----------|----|------|----------- -vl_api_mac_address_t|6|vl_api_mac_address_t|`class 'vpp_papi.MACAddress'>` - -#### vnet/interface_types.api -.api type|size|C type|Python type ----------|----|------|----------- -vl_api_interface_index_t|4|vl_api_interface_index_t|int - -### New explicit types - -#### String versus bytes -A byte string with a maximum length of 64: -``` -u8 name[64]; -``` -Before the "string" type was added, text string were defined like this. -The implications of that was the user would have to know if the field -represented a \0 ended C-string or a fixed length byte string. -The wire format of the 'string' type is a u32 length - -An IPv4 or IPv6 address was previously defined like: -``` -u8 is_ip6; -u8 address[16]; -``` - -Which made it hard for language bindings to represent the -address as anything but a byte string. -The new explicit address types are shown above. - -## Language generators - -The VPP API compiler currently has two output modules. One generating JSON -and one generating C header files that are directly used by the VPP -infrastructure and plugins. - -The C/C++, Python, Go Lua, and Java language bindings are generated based -on the JSON files. - -### Future considerations -- [ ] Generate C/C++ (vapi) client code directly from vppapigen -- [ ] Embed JSON definitions into the API server, so dynamic languages - can download them directly without going via the filesystem and JSON - files. |