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23 Data Export

General

Various protocols are made to transmit data points as they are generated. This is enough for a lot of systems (e.g. SCADA) that have their databases and devices only have to buffer fairly recent messages in case of connection or transmission errors. However, there is frequently a need to save and keep the data in files, grouped in batches, and later transmit these batches to a remote server via HTTP(S) or FTP(S). For this purpose, a dedicated protocol has been created and called Data export.

Data export functionality is available since firmware version v1.5.0, of WCC Lite.

Overview

Data export service gathers information from other protocols and puts it into files (optionally compressing them) after a timeout or when data buffers fill up; eventually periodically sending them to a server. HTTP(S) and FTP(S) servers with optional authentication are supported. A user can optionally choose between ISO8601 and UNIX timestamp time formats (the latter being the default value). More than one instance can be set up, for instance, some of the information can be sent to an FTP server, while others could be transmitted to the HTTP server which can handle POST requests.

Using WCC Lite for data export

To configure WCC Lite to use a data export server a user can fill in the needed parameters in Excel configuration. These parameters are shown in the two tables below. Default values are shown in bold font.

Data export (data-export) parameters for Devices tab table:

Parameter

 Type

 Description

 Required

Default value

(when not specified)

Range

Min

Max
name string

User-friendly device name

 Yes


device_alias string

Device alias to be used in configuration

 Yes


enable boolean

Enabling/disabling of a device

 No 1 0 1
protocol string

Selection of protocol

 Yes
Data Export
timeout integer

The time frame during which transmission to the remote server has to be completed (in seconds)

 No 5

type string

Selection of file format

 No csv-simple

cvs-periodic

csv-simple,

json-simple,

json-samples
host string

A URL of the remote server where files should be sent

 Yes


upload_rate_sec

 integer

Frequency of generated file uploads (in seconds)

 No 60

records_buffer_size

 integer

A maximum amount of data change entries to hold before initiating the logging mechanism

 No 100

logging_period_sec

 integer

Describe how frequently the data buffer of records_buffer_size is saved to the file

 No
10
 1
3600

log_folder

 string

A folder in the WCC Lite file system to save generated files (”/var/cache/data-export”)

 No


timestamp

 string

Selection of time format

 No unixtimestamp unixtimestamp, iso8601

compress

 string

Selection of file compression mechanism

 No none none, gz, tar.gz

compress_password

 string

Enable the feature of file password protection

 No
yes, true

csv_field_separator

 string

Columns separator in .csv file format 

 No "," - (comma)

"," - (comma)

";" - (semicolon)

"." - (dot)

" " - whitespace)

"|" - (pipe)

csv_decimal_separator

 string

Decimal separator in values 

 No "." - (dot)

"." - (dot) 

"," - (comma)

The same symbols cannot be selected for both csv_field_separator and csv_decimal_separator. In such case both of them will be set to default values ­ ”.” and ”,” respectively.

The data generation rate may be going to be bigger than what the data buffer can hold (controlled by records_buffer_size and logging_period_sec). To make sure that no data loss occurs there’s an additional data logging call made in case the data buffer reaches a records_buffer_size value.

Signals to be sent are configured differently than signals for most other protocols. As data export service only transmits signals and does no data processing, usual signal logic is not used for them. That means that:

• Signals for data export service are not seen in the Imported Signals tab;
• Signals for data export service are configured in a different Excel sheet called DataExport

The parameters to be filled in the DataExport sheet are shown in the table below.

Data export (data-export) parameters for the DataExport tab

Parameter

 Type

 Description

 Required

Default value

(when not specified)

Range

Min

Max

device_alias

 string

Device alias to be used in configuration Yes

 Yes


device_name

 string

User-friendly device name as in the Device sheet

 Yes


tag_name string

User-friendly signal name

 Yes


source_device_alias string

device_alias of a source device

 Yes


source_signal_alias string

source_alias of a source signal

 Yes


enable boolean

Enabling/disabling of a measurement to be transmitted and logged

 No 1 0 1
attribute string

An additional attribute to be attached to a signal

 No


Debugging data export service

If the configuration for the Data export service is set up, a handler for the protocol will start automatically. If the configuration is missing parameters or contains errors, the protocol will not start. It is done intentionally to decrease unnecessary memory usage.

Data export (data-export) command-line debugging options

The below-described parameters for debugging are accessible over the console (SSH).

-h [--help] Display help information

-c [--config] Configuration file location

-V [ –version ] Show version

-d<debug level> [ –debug ] Set debugging level

-R [ –readyfile] Ready notification file

-p [ –http ] Show HTTP messages

-r [ –redis ] Show Redis output

If the Data export service does not work properly (e.g. data is corrupted, etc.), a user can launch a debug session from the command line interface and find out why it is not functioning properly. To launch a debugging session, a user should stop data-export processes and run the data-export command with respective flags as in the table above.

Host URL format rules

The parameter host is highly configurable and might contain a considerable amount of information:

• Protocol - FTP or HTTP (encrypted and encrypted);

• URL address - both resolved and non-resolved;

• Authentication - pair of users and/or passwords;

• Port - useful when non-standard value is used;

• Endpoint - a place in the server to which a call is made

The format for the host parameter can be summarized as:

[ h t t p ( s ) / f t p ( s ) ] : / / [ [ u s e r ] : [ p a s s w o r d ]@] [ URL ] [ : p o r t ] / [ e n d p o i n t ]

Options are printed in square brackets. A protocol has to be selected, otherwise HTTP will be used as a default. The user and password pair is optional, but if the user: password pair is used, it should proceed with the @ sign.

HTTP and FTP use default or user-assigned ports. By default HTTP uses port 80, while HTTPS uses port 443, FTP sends data over port 21, FTPS - over port 990. Make sure that these ports are open in the firewall on both the server and client side, otherwise, data will not be sent successfully.

Finally, a POST request (for HTTP) or upload (for FTP) can be made to a specific place (endpoint). This endpoint should be described after a URL and port (if used).

Format of exported data

For a server to interpret data, a set of rules for a file format has to be established.

Csv-simple format applies to all files by default and is used as in this example:

###DUID:3182121xx
#device name; tag name; value; quality; timestamp; atribute
inv1;Ia;236.9,1;1599137189963;Pa

Example of additional format csv-periodic:

###DUID:318212xxx
##DEVICE:inv1
#Time;Upv1;Upv2;Upv3;Upv4;Upv5;Upv6;Ipv1;Ipv2;Ipv3;Ipv4;Ipv5;Ipv6;Status;Error;Temp;cos;fac;Pac;Qac;Eac;E-Day;E-Total;Cycle Time
2020-09-02T15:45:00Z;462.3;462.3;370.2;370.2;371.2;371.2;1.40;1.43;1.35;1.47;1.21;1.26;512;0;26.3;1.000;50.00;3.217;-0.029;0.28;17.41;54284.53;5;
2020-09-02T15:40:00Z;462.3;462.3;370.2;370.2;371.2;371.2;1.40;1.43;1.35;1.47;1.21;1.26;;512;0;26.3;1.000;50.00;3.217;-0.029;0.28;17.41;54284.53;5;
##DEVICE:meter
#Time;Uab;Ubc;Uca;P;Q;S;F;eTOT;Cycle Time
2020-09-02T15:45:00Z;421.3;421.3;421.3;15000;100;15600;50;246894;5;
2020-09-02T15:40:00Z;421.3;421.3;421.3;15000;100;15600;50;246895;5;

Example of additional format json-simple:

{
  "metadata": {
    "duid": "318xxxxx",
    "name": "hostname",
    "loggingPeriod": "15min",
    "format": "json"
  },
  "data": [
    {
      "tag_name": "Ia",
      "device_name": "inv1",
      "attribute": "Pa",
      "last": { "value": 12.2, "timestamp": 1213123 },
      "min": { "value": 12, "timestamp": 1213123 },
      "max": { "value": 12, "timestamp": 1213123 },
      "avg": { "value": 12, "timestamp": 1213123 }
    },
    {
      "tagName": "Ib",
      "deviceName": "inv1",
      "attribute": "Pb",
      "last": { "value": -12.3, "timestamp": 1213123 },
      "min": { "value": 12, "timestamp": 1213123 },
      "max": { "value": 12, "timestamp": 1213123 },
      "avg": { "value": 12, "timestamp": 1213123 }
    },
  ]
}

Example of additional format json-sample:

{
    "metadata": {
      "duid": "318xxxxx",
      "name": "hostname",
      "loggingPeriod": "15min",
      "format": "json-samples"
    },
    "data": [
      {
        "tag_name": "Ia",
        "device_name": "inv1",
        "attribute": "Pa",
        "timestamp":{
            "first": 123123,
            "last": 123236
        },
        "first": { "value": 12.2, "timestamp": 1213123 },
        "last": { "value": 12.2, "timestamp": 1213123 },
        "min": { "value": -12, "timestamp": 1213123 },
        "max": { "value": 12, "timestamp": 1213123 },
        "avg": { "value": 12, "timestamp": 1213123 },
        "samplesCount": 2,
        "samples": [
            {"value": 12, "timestamp": 1213123, "quality": true},
            {"value": -12.3, "timestamp": 1213123, "quality": true}
        ]
      }
    ]
  }
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