LibMISB - Examples - Library basic usage

LibMISB
Introduction
What is LibMISB What does the library do Functionalities supported
Supported Standards
MISB 0601.17 MISB 0903
Getting Started
How to get the library How to compile
Examples
Library basic usage GStreamer Application Example Application
Evaluating
Evaluating the library
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Testing library

This library has an example that you can execute. This example is a metadata converter that can encode or decode metadata. If you want to encode, the input file must respect one of the supported formats and will return a binary file with metadata encoded. On the other hand, if you want to decode the program receives a binary file and converts it to the format file selected. Currently JSON format is supported for the input and output encoding files.

The executable is located on /misb-library/examples/misb/ or if you want to compile and execute the example file out of the project. The path of the example is located on /misb-library/examples/misb/misb-converter.cpp. To compile the example we suggest you follow the next Makefile:

FLAGS:=`pkg-config --cflags --libs misb-0.0`
misb-converter: misb-converter.cpp
	g++ -o misb-converter misb-converter.cpp $(FLAGS)

The input JSON file that is going to be used is as follows:

{ 
  "key": "060E2B34020B01010E01030101000000",
  "items": [
    {
      "tag": "2",
      "value": "Oct. 24, 2008. 00:13:29.913"
    },
    {
      "tag": "3",
      "value": "MISSION01"
    },
    {
      "tag": "4",
      "value": "AF-101"
    },
    {
      "tag": "5",
      "value": "159.97436"
    },
    {
      "tag": "15",
      "value": "14190.7195"
    }
  ]
}

To perform the encoding, the following command is executed. Where the --encode flag indicates that encoding is to be performed. The -i flag indicates the input file, where the metadata must be raw without encoding. On the other hand, the -o flag indicates the output file, which contains the encoded bytes in a binary file. The --verbose flag shows the KLV bytes encoded on the terminal.

./misb-converter --verbose --encode -i misb_ST0601_sample.json -o klv.bin

Once the command is executed (with the --verbose flag), the KLV bytes are displayed. The klv.bin file contains the encoded bytes.

INFO    6 14 43 52 2 11 1 1 14 1 3 1 1 0 0 0 44 2 8 0 4 89 249 174 32 34 168 3 9 77 73 83 83 73 79 78 48 49 4 6 65 70 45 49 48 49 5 2 113 194 15 2 194 33 65 1 17 1 2 164 125

Decode command

The following command is executed to perform the decoding. The --decode flag indicates that decoding is to be performed. The -i flag indicates the input file, where the metadata must be encoded. The -o flag indicates the output file, which contains the metadata decoded.

The encoded bytes found inside the klv.bin file are:

6 14 43 52 2 11 1 1 14 1 3 1 1 0 0 0 44 2 8 0 
4 89 249 174 32 34 168 3 9 77 73 83 83 73 79 
78 48 49 4 6 65 70 45 49 48 49 5 2 113 194 15 
2 194 33 65 1 17 1 2 164 125

./misb-converter --decode -i klv.bin -o output.json

Once the command is executed, it reports that a decoded file was generated. The content of the output.json file is

{
  "key": "060E2B34020B01010E01030101000000",
  "items": [
    {
      "tag": "2",
      "value": "Oct. 24, 2008. 00:13:29.913"
    },
    {
      "tag": "3",
      "value": "MISSION01"
    },
    {
      "tag": "4",
      "value": "AF-101"
    },
    {
      "tag": "5",
      "value": "159.974365"
    },
    {
      "tag": "15",
      "value": "14190.719463"
    },
    {
      "tag": "65",
      "value": "17"
    }
  ]
}

As seen here some extra flags can be present after the decoding process since the encoding might add required tags to the encoding.

Logging

You can enable the debugging using SetLogLevel in your application with the LibMISB. For example:

  libmisb::LibMisb libmisb;
  libmisb.SetLogLevel(LIBMISB_DEBUG);