(Engine-Level Function)
| Description: |
Instantiates a message using default values. This is useful where a non-trivial message type is used as it allows the script code developer to create an instance of a message suitable for encoding without re-defining the message structure. |
| Returns: | |
Usage:  |
Script Only. |
| Function Groups: | Protobuf |
| Related to: | ProtobufDecode | ProtobufEncode | ProtobufParse |
| Format: |
ProtobufInstantiate(ProtobufHandle, MessageTypeName[, optionalsAsInvalid]) |
| Parameters: |
| ProtobufHandle |
| A Protobuf handle returned from ProtobufParse. |
| MessageTypeName |
| The message type to use for decoding. This is the full name, that is, if the .proto file includes a package name "com.trihedral.protobufexample" and the message name is "AMessage", this would be "com.trihedral.protobufexample.AMessage". For nested messages this also includes all ancestor messages |
| OptionalsAsInvalid |
| Optional Boolean. Defaults to FALSE when unspecified or invalid. When TRUE, fields in a Protobuf specification file that are defined as optional are not given a default value when instantiated. |
| Comments: |
Generates a VTScada data structure based on the loaded proto file, so that the structure can be populated with data from script code before being used in a call to ProtobufEncode. |
Example:
Given a Protobuf specification file held in "example.proto" in a sub-folder protobuf of an application:
syntax = "proto2";
package com.trihedral.protobuf.example;
message VersionInformation {
required string name = 1;
required double version = 2;
}
The following code parses, instantiates, encodes and then decodes a message:
<
{============================= ProtobufExample ===============================}
{ Demonstration of parsing, encoding, decoding and instantiating Protobuf }
{ messages. }
{=============================================================================}
ProtobufExample
[
Protected ProtobufHandle;
Protected MessageInstance;
Protected EncodedMessage;
Protected DecodedMessage;
]
ProtobufExample [
If TRUE;
[
ProtobufHandle = ProtobufParse(Concat(Layer.GetWCPath(), "protobuf\example.proto"));
MessageInstance = ProtobufInstantiate(ProtobufHandle, "com.trihedral.protobuf.example.VersionInformation");
MessageInstance.name = "VTScada";
MessageInstance.version = 12;
EncodedMessage = ProtobufEncode(ProtobufHandle, "com.trihedral.protobuf.example.VersionInformation", MessageInstance);
DecodedMessage = ProtobufDecode(ProtobufHandle, "com.trihedral.protobuf.example.VersionInformation", EncodedMessage);
Return();
]
]
{ End of ProtobufExample }
>
