The request URL for retrieving information about a single channel has the following form:
/channels/all/by-name/<channel-name>//channels/by-server/<server ID>/by-name/<channel-name>/
Both variants return the same data.
The only difference between them is that the variant that includes the
server ID in the URL will return status code 404 (not found) when the
channel exists, but belongs to a different server.
The <channel name> has to be replaced
by the encoded form of the channel name.
The <server ID> has to be replaced by
the UUID associated with the respective server.
Only use the second variant if the query shall be limited to a
specific server.
The request must use the GET method.
The response is a JSON object with the following attributes:
| Field name | Internal data type | JSON data type | Description |
|---|---|---|---|
| channelDataId | UUID | string | internal ID for the channel |
| channelName | string | string | channel’s name |
| controlSystemName | string | string | human-readable name of the control-system support used for the channel |
| controlSystemType | string | string | internal identifier for the control-system support used for the channel |
| decimationLevelToRetentionPeriod | map of int to int | object with string attribute values | decimation levels that exist for the channel and their respective retention periods (both specified in seconds) |
| enabled | boolean | boolean |
true if the channel is enabled,
false if it is disabled.
|
| errorMessage | string | string |
error message for the channel. May be null.
|
| options | map of string to string | object with string attribute values | control-system-specific configuration options that have been specified for the channel (the attribute name is the option name and the attribute value is the option value) |
| serverId | UUID | string | ID of the server that owns the channel |
| serverName | string | string | human-readable name of the server that owns the channel |
| state | string | string |
channel’s current state. One of destroyed,
disabled, disconnected,
error, initializing,
or ok.
null if status information is not
available.
|
| totalSamplesDropped | long | string |
number of samples that have been dropped for the channel
(since the last reinitialization).
null if status information is not
available.
|
| totalSamplesSkippedBack | long | string |
number of samples that were discarded because they skipped
back in time (since the last reinitialization).
null if status information is not
available.
|
| totalSamplesWritten | long | string |
number of samples that have been written for the channel
(since the last reinitialization).
null if status information is not
available.
|
If information about the channel can currently not be retrieved, HTTP error code 503 (service unavailable) is returned and the response body is invalid. If the channel does not exist or if a server ID has been specified and the channel belongs to a different server, HTTP error code 404 (not found) is returned and the response body is invalid.
Request:
GET /admin/api/1.0/channels/all/by-name/someChannel/
Response:
{
"channelDataId": "ef126a63-375b-4f28-a1d1-17e8f42271a9",
"channelName": "someChannel",
"controlSystemName": "Channel Access",
"controlSystemType": "channel_access",
"decimationLevelToRetentionPeriod": {
"0": "864000",
"30": "31536000",
"900": "0"
},
"enabled": true,
"errorMessage": null,
"options": {},
"serverId": "7cf8f393-cd00-46ae-9343-53e9cb5793fd",
"serverName": "myserver",
"state": "OK",
"totalSamplesDropped": "0",
"totalSamplesSkippedBack": "1",
"totalSamplesWritten": "42"
}