nce 4What this talk is about The workings of a message-handling library. How messages and the fields in them are specified. Efficiently identifying (with matchers) a message coming off the wire. The expressions https://github.com/intel/compile-time-init-build 7Part 1 Fields and messages: how they are structured and specified. 8Fields A field is: a human-readable name a type (almost always integral IP Address 4 128 Destination IP Address 5 160 Options (if IHL > 5) ⋮ ⋮ 14 448 10IPv4 Header Fields 1: using version = 2: field<"version", std::uint8_t>::located; 3:

meta_structs for fields and parameters template struct meta_structs_from_query { static constexpr auto ts = parse_type_specs(); using fields_type = typename typename meta_struct_from_type_specs< query_string, ts.fields, false, std::make_index_sequencefields.size()>>::type; using parameters_type = typename meta_struct_from_type_specs< query_string, ts.params constexpr auto ret_counts = get_type_spec_count(); combined_type_specsfields, ret_counts.params> ret = {}; … return ret; }combined_type_specs and type_specs template

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Binary, JSON, etc. 6 json serialize_struct(any any_value) { json json; for (Field f : reflect_fields(any_value)) { json[f.name]["value"] = f.value(); json[f.name]["type"] = f.type; } return json; serialize_struct(any_value); } } json serialize_struct(any any_value) { json json; for (Field f : reflect_fields(any_value)) { json[f.name]["value"] = value_to_json(f.value()); json[f.name]["type"] = f.type; Go from client API 1 0 json serialize_struct(any any_value) { json json; for (Field f : reflect_fields(any_value)) { json[f.name]["value"] = f.value(); json[f.name]["type"] = f.type; } return json;

memory data structure into a data buffer. This transformation requires traversing and encoding all fields. • Both MessagePack and Protocol Buffers follow this approach. Fanchen Su, XOffsetDatastructure data buffer back into a memory data structure. This conversion needs traversing and decoding all fields. • Both MessagePack and Protocol Buffers employ this method. Fanchen Su, XOffsetDatastructure structure, which becomes the data buffer. • This transformation requires traversing and setting fields in memory using Builders. • Examples of solutions that use this approach include FlatBuffers and

programming errors could have serious consequences • May require random access to fields • Maybe the size of some fields cannot be known until run time • Maybe read at B, modify, and pass along to C Stroustrup message descriptor knows • what message is being written/read • where the buffer is • where the fields are being mapped to Message buffer: Sequence of bytes std::string Int32_t double[12] Stroustrup Some want guarantees that some fields are always written • Some necessary types are not native in all needed languages • Some want static guarantees that only a subset of fields can be accessed • Use standard-library

see, some of the libraries end with a @ symbol followed by two strings separated by a slash. These fields are the user and channel for the Conan package, and they are useful if you want to make specific inspecting the recipe with conan get command: $ conan get poco/1.9.4@ To see only specific fields of the recipe you can use the conan inspect command instead: 6.1. Installing dependencies 39 Conan behavior in Conan v1.x) Conan will store a modified version of the conanfile.py with the values of the fields in plain text: import os from conans import ConanFile, CMake, tools class HelloConan(ConanFile):

see, some of the libraries end with a @ symbol followed by two strings separated by a slash. These fields are the user and channel for the Conan package, and they are useful if you want to make specific inspecting the recipe with conan get command: $ conan get poco/1.9.4@ To see only specific fields of the recipe you can use the conan inspect command instead: 6.1. Installing dependencies 39 Conan behavior in Conan v1.x) Conan will store a modified version of the conanfile.py with the values of the fields in plain text: import os from conans import ConanFile, CMake, tools class HelloConan(ConanFile):

see, some of the libraries end with a @ symbol followed by two strings separated by a slash. These fields are the user and channel for the Conan package, and they are useful if you want to make specific inspecting the recipe with conan get command: $ conan get poco/1.9.4@ To see only specific fields of the recipe you can use the conan inspect command instead: 6.1. Installing dependencies 39 Conan behavior in Conan v1.x) Conan will store a modified version of the conanfile.py with the values of the fields in plain text: import os from conans import ConanFile, CMake, tools class HelloConan(ConanFile):

see, some of the libraries end with a @ symbol followed by two strings separated by a slash. These fields are the user and channel for the Conan package, and they are useful if you want to make specific inspecting the recipe with conan get command: $ conan get poco/1.9.4@ To see only specific fields of the recipe you can use the conan inspect command instead: 6.1. Installing dependencies 39 Conan behavior in Conan v1.x) Conan will store a modified version of the conanfile.py with the values of the fields in plain text: import os from conans import ConanFile, CMake, tools class HelloConan(ConanFile):

see, some of the libraries end with a @ symbol followed by two strings separated by a slash. These fields are the user and channel for the Conan package, and they are useful if you want to make specific inspecting the recipe with conan get command: $ conan get poco/1.9.4@ To see only specific fields of the recipe you can use the conan inspect command instead: 6.1. Installing dependencies 39 Conan behavior in Conan v1.x) Conan will store a modified version of the conanfile.py with the values of the fields in plain text: import os from conans import ConanFile, CMake, tools class HelloConan(ConanFile):