ATEST-302

Readme.md

@@ -60,21 +60,47 @@ POST http://<host>:<port>/channels
 #### Data
 
 ```json
-{"regex": "TRFCA|TRFCB", "dbMode": "databuffer"}
+{"regex": "TRFCA|TRFCB","backends": ["databuffer"],"ordering":"asc","reload":true}
 ```
 
 ##### Explanation
 
-- **regex**: Reqular expression used to filter channel names (default: no filtering). Filtering is done using JAVA's [Pattern](https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html), more precisely [Matcher.find()](https://docs.oracle.com/javase/8/docs/api/java/util/regex/Matcher.html#find--)). 
-- **dbMode**: Defines the database to access (values: **databuffer**|archiverappliance)
-
+- **regex**: Reqular expression used to filter channel names. In case this value is undefined, no filter will be applied. Filtering is done using JAVA's [Pattern](https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html), more precisely [Matcher.find()](https://docs.oracle.com/javase/8/docs/api/java/util/regex/Matcher.html#find--)).
+- **backends**: Array of backends to access (values: databuffer|archiverappliance|filestorage). In case this value is undefined, all backends will be queried for their channels.
+- **ordering**: The ordering of the channel names (values: **none**|asc|desc).
+- **reload**: Forces the server to reload cached channel names (values: **false**|true).
 
 ### Example
 
+#### Command
+
 ```bash
 curl -H "Content-Type: application/json" -X POST -d '{"regex": "TRFCA|TRFCB"}' http://data-api.psi.ch/sf/channels
 ```
 
+#### Response
+
+```json
+[
+   {
+      "backend":"databuffer",
+      "channels":[
+         "Channel_01",
+         "Channel_02",
+         "Channel_03"
+      ]
+   },
+   {
+      "backend":"archiverappliance",
+      "channels":[
+         "Channel_01",
+         "Channel_04",
+         "Channel_05"
+      ]
+   }
+]
+```
+
 <a name="query_range"/>
 
 ## Query Range 
@@ -127,6 +153,36 @@ Queries are applied to a range. The following types of ranges ranges are support
 - **endMillis**: The end time of the range.
 - **[endNanos]**: The optional nanosecond offset.
 
+<a name="query_channel_names"/>
+
+## Query Channel Names
+
+The simplest way to define channels is to use an array of channel name Strings.
+
+```json
+"channels":[
+	"Channel_02",
+	"Channel_04"
+]
+```
+
+The query interface will automatically select the backend which contains the channel (e.g., *databuffer* for *Channel_02* and *archiverappliance* for *Channel_04*. In case name clashes exist, the query interface will use following order of priority: *databuffer*, *archiverappliance* and *filestorage*.
+
+It is also possible to explicitly define the backend to overcome name clashes.   
+
+```json
+"channels":[
+   {
+      "name":"Channel_01",
+      "backend":"archiverappliance"
+   },
+   {
+      "name":"Channel_01",
+      "backend":"databuffer"
+   }
+]
+```
+
 
 <a name="query_data"/>
 
@@ -144,7 +200,7 @@ A request is performed by sending a valid JSON object in the HTTP request body.
 
 The following attributes can be specified:
 
-- **channels**: Array of channel names to be queried.
+- **channels**: Array of channels to be queried (see [Query Range](Readme.md#query_channel_names)).
 - **range**: The range of the query (see [Query Range](Readme.md#query_range)).
 - **ordering**: The ordering of the data (see [here](https://git.psi.ch/sf_daq/ch.psi.daq.common/blob/master/src/main/java/ch/psi/daq/common/ordering/Ordering.java) for possible values).
 - **fields**: The requested fields (see [here](https://git.psi.ch/sf_daq/ch.psi.daq.query/blob/master/src/main/java/ch/psi/daq/query/model/QueryField.java) for possible values).
@@ -152,8 +208,6 @@ The following attributes can be specified:
 - **binSize**: Activates data binning. Specifies the number of pulses per bin for pulse-range queries or the number of milliseconds per bin for time-range queries (using number of pulses and number of milliseconds makes this binning strategy consistent between channel with different update frequencies). 
 - **aggregations**: Activates data aggregation. Array of requested aggregations (see [here](https://git.psi.ch/sf_daq/ch.psi.daq.query/blob/master/src/main/java/ch/psi/daq/query/model/Aggregation.java) for possible values). These values will be added to the *data* array response.
 - **aggregationType**: Specifies the type of aggregation (see [here](https://git.psi.ch/sf_daq/ch.psi.daq.query/blob/master/src/main/java/ch/psi/daq/query/model/AggregationType.java)). The default type is *value* aggregation (e.g., sum([1,2,3])=6). Alternatively, it is possible to define *index* aggregation for multiple arrays in combination with binning (e.g., sum([1,2,3], [3,2,1]) = [4,4,4]).
-- **aggregateChannels**: Specifies whether the data of the requested channels should be combined together using the defined aggregation (values: true|**false**) 
-- **dbMode**: Defines the database to access (values: **databuffer**|archiverappliance)
 - **compression**: Defines the compression algorithm to use, default value is **none**, see all values [here](https://github.psi.ch/sf_daq/ch.psi.daq.query/blob/master/src/main/java/ch/psi/daq/query/model/Compression.java))
 - **responseFormat**: Specifies the format the response of the requested data is in, either in JSON or CSV format, default value **JSON**, see all values [here](https://github.psi.ch/sf_daq/ch.psi.daq.query/blob/master/src/main/java/ch/psi/daq/query/model/ResponseFormat.java))
 
@@ -165,7 +219,7 @@ If compression is enabled, we have to tell `curl` that the data is compressed so
 
 ### `responseFormat`: data is in JSON by default
 
-Responses can be formatted as CSV or JSON using the `responseFormat` field. The returned data is JSON-formatted per default. 
+Responses can be formatted as CSV or JSON using the `responseFormat` field. The returned data is JSON-formatted by default. 
 
 CSV export does not support `index` and `extrema` aggregations.
 
@@ -319,7 +373,7 @@ See JSON representation of the data above.
 
 ```json
 {
-   "dbMode":"archiverappliance",
+   "backend":"archiverappliance",
    "range":{
       "startMillis":0,
       "startNanos":0,