mjsonrpc schema

mjsonrpc_call("al_reset_alarm", {"alarms": ["Alarm A", "Alarm B"]}).then(function(rpc) {
   let result = rpc.result; // The method's results
}).catch(function(error) {
   mjsonrpc_error_alert(error);
});

Array indices in ODB paths

db_get_values and db_paste accept array indices at the end of an ODB path, to read or write some of the elements of an array. So do the midas.js functions that call them, such as mjsonrpc_db_get_values(), mjsonrpc_db_paste() and mjsonrpc_db_set_value(). Indices start at 0, and can be listed and combined with ranges:

When reading, a path with one index gives a single value. A path with several indices gives a list of their values, in the order of the indices, and its status is a list with one status for each element.

When writing with db_paste:

• One index ([2]): give a single value. A list, even of one value, is an error.
• Several indices: give a list with one value for each index, in the same order, or a single value to write to all of them. A list of a different length is an error (DB_TYPE_MISMATCH, 315), and nothing is written. The status is a list with one status for each element.
• An index past the end of the array: the array is made longer. Any new elements before it are set to 0.
• No index: the list replaces the whole array, which is resized to the length of the list. To change only some elements, give their indices.

For example, this sets /Example/Count to 9, and elements 3, 2 and 1 of /Example/Thresholds to 30, 20 and 10:

mjsonrpc_db_paste(["/Example/Count", "/Example/Thresholds[3-1]"], [9, [30, 20, 10]]).then(function(rpc) {
   let status = rpc.result.status; // [1, [1, 1, 1]]
}).catch(function(error) {
   mjsonrpc_error_alert(error);
});

How values are encoded

Most ODB values are sent as the matching JSON numbers, strings and booleans. The exceptions are:

In JavaScript, Number("0x55b96181") converts the hexadecimal string of a UINT16 or UINT32 value. For INT64 and UINT64 values, use BigInt instead (see below). When writing, you can give these values as numbers or as strings in the same format (e.g. "0x10" or "NaN").

64-bit integers in JavaScript

Midas returns INT64 and UINT64 values as strings. If you convert them with Number() or parseInt(), they will get rounded! This is particularly problematic if you have a 64-bit number that you're using as a bitmask. You should instead use BigInt() to parse the strings:

Usage of BigInt():

• BigInt() converts both decimal strings (used for INT64 values) and hexadecimal strings (used for UINT64 values).
• In calculations, use BigInt values for every number, e.g. 1n rather than 1. Otherwise you will get errors of the form TypeError: Cannot mix BigInt and other types, use explicit conversions.
• To write a value back, either convert it to a string with toString(), or let JSON encode BigInt values directly (see below). Midas accepts both decimal strings and JSON numbers for INT64/UINT64 keys.

These examples read a 64-bit counter, add one to it and write it back. They show different approaches for how to send the 64-bit number to midas:

mjsonrpc_db_get_value("/Example/Event count").then(function(rpc) {
   let count = BigInt(rpc.result.data[0]); // e.g. "9007199254740993" (INT64) or "0x0020000000000001" (UINT64)
   count += 1n;
   return mjsonrpc_db_set_value("/Example/Event count", count.toString()); // "9007199254740994"
}).catch(function(error) {
   mjsonrpc_error_alert(error);
});

// Once, at the start of the page: write BigInt values in JSON as exact numbers
BigInt.prototype.toJSON = function () {
   return JSON.rawJSON(this.toString());
};

mjsonrpc_db_get_value("/Example/Event count").then(function(rpc) {
   let count = BigInt(rpc.result.data[0]);
   count += 1n;
   return mjsonrpc_db_set_value("/Example/Event count", count); // no need for toString()
}).catch(function(error) {
   mjsonrpc_error_alert(error);
});

Key names in db_get_values results

When you read an ODB directory with db_get_values (or mjsonrpc_db_get_values()), the key names in the result are in lower case. ODB key names aren't case sensitive, but JavaScript property names are, so this means you don't need to know how a name is capitalised in the ODB:

mjsonrpc_db_get_values(["/Runinfo"]).then(function(rpc) {
   let runinfo = rpc.result.data[0];
   let run_number = runinfo["run number"]; // "Run number" in the ODB
   let state = runinfo.state;
}).catch(function(error) {
   mjsonrpc_error_alert(error);
});

Each key also has two extra entries: <name>/name, with the name as it is in the ODB, and <name>/last_written, with the time it was last written. Symlinks are followed, so you get the values they point to. To leave out the extra entries and send less data, call db_get_values with mjsonrpc_call() and set omit_names and omit_last_written. To keep the original capitalisation, set preserve_case, but then you have to use the names exactly as they are in the ODB.

Reading only values that have changed

To update a page without reading everything again, call db_get_values with omit_old_timestamp set to a time (in seconds since 1970). Only the keys written since that time are returned. The time a key was last written is in its /last_written entry. The filtering has some limits:

• An array is returned whole if any of its elements was written.
• Subdirectories are always included, and appear empty ({}) if nothing in them has changed.
• Keys that have never been written (whose last-written time is 0) are always included.

Sending several requests at once

Each call to an mjsonrpc_xxx function sends a separate HTTP request to mhttpd. To send several JSON-RPC requests in one HTTP request, which is much faster, build the requests with mjsonrpc_make_request() and send them together as a list with mjsonrpc_send_request(). The result is a list with one entry for each request, in the same order. Each entry has result if the request worked, or error if it didn't, so check each one:

let requests = [
   mjsonrpc_make_request("db_get_values", {"paths": ["/Runinfo"]}),
   mjsonrpc_make_request("cm_msg_retrieve", {"min_messages": 10})
];
mjsonrpc_send_request(requests).then(function(batch) {
   for (let rpc of batch) {
      if (rpc.error)
         console.log("Request " + rpc.request.method + " failed: " + rpc.error.message);
   }
   let runinfo = batch[0].result.data[0];
   let messages = batch[1].result.messages;
}).catch(function(error) {
   mjsonrpc_error_alert(error);
});

From other languages (see below), send a JSON array of requests in the body of one POST, and the reply is a JSON array of replies.

Calling these methods from other languages

If you want, you can also call these methods from scripts and programs written in other languages: any language that can send an HTTP request will work. Send a JSON-RPC 2.0 request as an HTTP POST to mhttpd's ?mjsonrpc URL, with the Content-Type: application/json header. Put the method's parameters in params, and read its results from result.

For C++ and Python, the midas libraries are usually a better choice, as they talk to the experiment directly rather than through mhttpd. See Hello world! Writing programs in midas.

These examples read /Runinfo/Run number from mhttpd on the same machine, which by default listens on port 8080 without a password. To connect from another machine, see Web security.

curl -s -X POST -H "Content-Type: application/json" \
      -d '{"jsonrpc": "2.0", "method": "db_get_values", "params": {"paths": ["/Runinfo/Run number"]}, "id": 1}' \
      "http://localhost:8080/?mjsonrpc"

The reply looks like:

{"result":{"data":[123],"status":[1],"tid":[7],"last_written":[1792014728]},"jsonrpc":"2.0","id":1}

This example needs Java 15 or later, and only uses the standard library.

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class RunNumber {
   public static void main(String[] args) throws Exception {
         String request = """
               {"jsonrpc": "2.0", "method": "db_get_values",
                  "params": {"paths": ["/Runinfo/Run number"]}, "id": 1}
               """;

         HttpRequest httpRequest = HttpRequest.newBuilder(URI.create("http://localhost:8080/?mjsonrpc"))
               .header("Content-Type", "application/json")
               .POST(HttpRequest.BodyPublishers.ofString(request))
               .build();

         HttpResponse<String> response = HttpClient.newHttpClient()
               .send(httpRequest, HttpResponse.BodyHandlers.ofString());

         // Parse the reply with a JSON library, such as Jackson or Gson
         System.out.println(response.body());
   }
}

This example needs .NET 6 or later, and only uses the standard library.

using System.Net.Http.Json;
using System.Text.Json;

var request = new
{
   jsonrpc = "2.0",
   method = "db_get_values",
   @params = new { paths = new[] { "/Runinfo/Run number" } },
   id = 1
};

using var client = new HttpClient();
var response = await client.PostAsJsonAsync("http://localhost:8080/?mjsonrpc", request);
response.EnsureSuccessStatusCode();

using var reply = JsonDocument.Parse(await response.Content.ReadAsStringAsync());
if (reply.RootElement.TryGetProperty("error", out var error))
   throw new Exception($"RPC error: {error.GetProperty("message")}");

var result = reply.RootElement.GetProperty("result");
var status = result.GetProperty("status")[0].GetInt32();
if (status != 1)
   throw new Exception($"db_get_values status {status}");

Console.WriteLine($"Run number: {result.GetProperty("data")[0]}");

All methods

al_reset_alarm

reset alarms

This method accepts an object with keys:

• alarms (array of string) REQUIRED - array of alarm names

The rpc.result member contains an object with keys:

• status (array of integer) - return status of al_reset_alarm() for each alarm

al_trigger_alarm

trigger an alarm

This method accepts an object with keys:

• name (string) REQUIRED - alarm name
• message (string) REQUIRED - alarm message
• class (string) REQUIRED - alarm class
• condition (string) REQUIRED - alarm condition
• type (integer) REQUIRED - alarm type (AT_xxx)

The rpc.result member contains an object with keys:

• status (integer) - return status of al_trigger_alarm()

al_trigger_class

trigger an alarm

This method accepts an object with keys:

• class (string) REQUIRED - alarm class
• message (string) REQUIRED - alarm message
• first (bool) - see al_trigger_class() in midas.c

The rpc.result member contains an object with keys:

• status (integer) - return status of al_trigger_class()

bm_receive_event

read event buffers

This method accepts an object with keys:

• buffer_name (string) REQUIRED - name of event buffer
• event_id (integer) - requested event id, -1 means any event id
• trigger_mask (integer) - requested trigger mask, -1 means any trigger mask
• get_recent (bool) - get last available event that matches this event request
• last_event_header (array of integer) - do not resend an event we already received: event header of last received event [event_id,trigger_mask,serial_number,time_stamp]
• timeout_millisec (number) - how long to wait for an event

The rpc.result member contains an object with keys:

• binary data (arraybuffer) - binary event data
• status (integer) - return status of bm_open_buffer(), bm_request_event(), bm_set_cache_size(), bm_receive_alloc()

brpc

make RPC call into frontend program via RPC_BRPC

This method accepts an object with keys:

• client_name (string) REQUIRED - Connect to this MIDAS client, see cm_connect_client()
• cmd (string) REQUIRED - Command passed to client
• args (string) REQUIRED - Parameters passed to client as a string, could be JSON encoded
• max_reply_length (integer) - Optional maximum length of client reply. MIDAS RPC does not support returning data of arbitrary length, maximum length has to be known ahead of time.

The rpc.result member contains an object with keys:

• reply (string) - Reply from client as a string, could be JSON encoded
• status (integer) - return status of cm_connect_client() and rpc_client_call()

brpc_cxx

make RPC call into frontend program via RPC_BRPC_CXX

This method accepts an object with keys:

• client_name (string) REQUIRED - Connect to this MIDAS client, see cm_connect_client()
• cmd (string) REQUIRED - Command passed to client
• args (string) REQUIRED - Parameters passed to client as a string, could be JSON encoded

The rpc.result member contains an object with keys:

• reply (string) - Reply from client as a string, could be JSON encoded
• status (integer) - return status of cm_connect_client() and rpc_client_call()

brpc_old

make RPC call into frontend program via RPC_BRPC

This method accepts an object with keys:

• client_name (string) REQUIRED - Connect to this MIDAS client, see cm_connect_client()
• cmd (string) REQUIRED - Command passed to client
• args (string) REQUIRED - Parameters passed to client as a string, could be JSON encoded
• max_reply_length (integer) - Optional maximum length of client reply. MIDAS RPC does not support returning data of arbitrary length, maximum length has to be known ahead of time.

The rpc.result member contains an object with keys:

• reply (string) - Reply from client as a string, could be JSON encoded
• status (integer) - return status of cm_connect_client() and rpc_client_call()

cm_exist

calls MIDAS cm_exist() to check if given MIDAS program is running

This method accepts an object with keys:

• name (string) REQUIRED - name of the program, corresponding to ODB /Programs/name
• unique (bool) - bUnique argument to cm_exist()

The rpc.result member contains an object with keys:

• status (integer) - return status of cm_exist()

cm_msg1

Generate a midas message using cm_msg1()

This method accepts an object with keys:

• facility (string) - message facility, default is "midas"
• user (string) - message user, default is "javascript_commands"
• type (integer) - message type, MT_xxx from midas.h, default is MT_INFO
• message (string) REQUIRED - message text

The rpc.result member contains an object with keys:

• status (integer) - return status of cm_msg1()

cm_msg_facilities

get message facilities using cm_msg_facilities()

There are no parameters for this method.

The rpc.result member contains an object with keys:

• status (integer) - return status of cm_msg_facilities()
• facilities (array of string) - array of facility names

cm_msg_retrieve

Retrieve midas messages using cm_msg_retrieve2()

This method accepts an object with keys:

• facility (string) - message facility, default is "midas"
• min_messages (integer) - get at least this many messages, default is 1
• time (number) - start from given timestamp, value 0 means give me newest messages, default is 0

The rpc.result member contains an object with keys:

• num_messages (integer) - number of messages returned
• messages (string) - messages separated by \n
• status (integer) - return status of cm_msg_retrieve2()

cm_shutdown

calls MIDAS cm_shutdown() to stop given MIDAS program

This method accepts an object with keys:

• name (string) REQUIRED - name of the program, corresponding to ODB /Programs/name

The rpc.result member contains an object with keys:

• status (integer) - return status of cm_shutdown()

cm_transition

start and stop runs

This method accepts an object with keys:

• transition (string) REQUIRED - requested transition: TR_START, TR_STOP, TR_PAUSE, TR_RESUME
• run_number (integer) - New run number, value 0 means /runinfo/run_number + 1, default is 0
• async_flag (integer) - Transition type. Default is multithreaded transition TR_MTHREAD
• debug_flag (integer) - See cm_transition(), value 1: trace to stdout, value 2: trace to midas.log

The rpc.result member contains an object with keys:

• status (integer) - return status of cm_transition()
• error_string (string) - return error string from cm_transition()

db_copy

get complete ODB data in the "save" json encoding, suitable for reloading with odbedit command "load"

This method accepts an object with keys:

• paths (array of string) REQUIRED - array of ODB subtree paths

The rpc.result member contains an object with keys:

• data (array of object) - keys and values of ODB data for each path
• status (array of integer) - return status of db_copy_json_save() for each path

db_create

Create new ODB entries

This method accepts a single parameter (not an object):

• (object) - {desc}

The rpc.result member contains an object with keys:

• status (array of integer) - return status of db_create_key(), db_set_num_values() and db_set_data() (for TID_STRING) for each path

db_delete

delete ODB keys

This method accepts an object with keys:

• paths (array of string) REQUIRED - array of ODB paths to delete

The rpc.result member contains an object with keys:

• status (array of integer) - return status of db_delete() for each path

db_get_values

get values of ODB data from given subtrees

This method accepts an object with keys:

• paths (array of string) REQUIRED - array of ODB subtree paths, see note on array indices
• omit_names (bool) - omit the /name entries
• omit_last_written (bool) - omit the /last_written entries and the last_written[] result
• omit_tid (bool) - omit the tid[] result
• omit_old_timestamp (number) - omit data older than given ODB timestamp
• preserve_case (bool) - preserve the capitalization of ODB key names (WARNING: ODB is not case sensitive); note that this will also have side effect of setting the omit_names option

The rpc.result member contains an object with keys:

• data (array of anything) - values of ODB data for each path, all key names are in lower case, all symlinks are followed
• status (array of integer) - return status of db_copy_json_values() or db_copy_json_index() for each path
• tid (array of integer) - odb type id for each path, absent if omit_tid is true
• last_written (array of number) - last_written value of the ODB subtree for each path, absent if omit_last_written is true

db_key

get ODB keys

This method accepts an object with keys:

• paths (array of string) REQUIRED - array of ODB paths

The rpc.result member contains an object with keys:

• status (array of integer) - return status of db_key() for each path
• keys (array of integer) - timestamp when data was last updated

db_link

Create ODB symlinks

This method accepts an object with keys:

• new_links (array of string) REQUIRED - array of new symlinks to be created
• target_paths (array of string) REQUIRED - array of existing ODB paths for each link

The rpc.result member contains an object with keys:

• status (array of integer) - return status of db_create_link() for each path

db_ls

get contents of given ODB subdirectory in the "ls" json encoding - similar to odbedit command "ls -l"

This method accepts an object with keys:

• paths (array of string) REQUIRED - array of ODB subtree paths

The rpc.result member contains an object with keys:

• data (array of object) - keys and values of ODB data for each path
• status (array of integer) - return status of db_copy_json_ls() for each path

db_paste

write data into ODB

This method accepts an object with keys:

• paths (array of string) REQUIRED - array of ODB subtree paths, see note on array indices
• values (array of anything) REQUIRED - array of data values written to ODB via db_paste_json() for each path

The rpc.result member contains an object with keys:

• status (array of integer) - array of return status of db_paste_json() for each path

db_rename

Change size of ODB arrays

This method accepts an object with keys:

• paths (array of string) REQUIRED - array of ODB paths to rename
• new_names (array of string) REQUIRED - array of new names for each ODB path

The rpc.result member contains an object with keys:

• status (array of integer) - return status of db_rename_key() for each path

db_reorder

Change order of ODB keys in a subdirectory

This method accepts an object with keys:

• paths (array of string) REQUIRED - array of new symlinks to be created
• indices (array of integer) REQUIRED - array of existing ODB paths for each link

The rpc.result member contains an object with keys:

• status (array of integer) - return status of db_reorder_key() for each path

db_resize

Change size of ODB arrays

This method accepts an object with keys:

• paths (array of string) REQUIRED - array of ODB paths to resize
• new_lengths (array of integer) REQUIRED - array of new lengths for each ODB path

The rpc.result member contains an object with keys:

• status (array of integer) - return status of db_set_num_values() for each path

db_resize_string

Change size of ODB string arrays

This method accepts an object with keys:

• paths (array of string) REQUIRED - array of ODB paths to resize
• new_lengths (array of integer) REQUIRED - array of new lengths for each ODB path
• new_string_lengths (array of integer) REQUIRED - array of new string lengths for each ODB path

The rpc.result member contains an object with keys:

• status (array of integer) - return status of db_resize_string() for each path

db_scl

Show ODB clients

There are no parameters for this method.

The rpc.result member contains an object with keys:

• scl (json) - return value of db_scl()

db_set_mode

set access modes for ODB keys

This method accepts an object with keys:

• paths (array of string) REQUIRED - array of ODB paths
• modes (array of integer) REQUIRED - array of access mode bitmaps
• recursive (bool) - also set modes of directory contents recursively (default false)

The rpc.result member contains an object with keys:

• status (array of integer) - return status of db_set_mode() for each path

db_sor

Show ODB open records starting from given ODB path

This method accepts an object with keys:

• path (string) - ODB path

The rpc.result member contains an object with keys:

• sor (json) - return value of db_sor()

el_delete

Delete elog message

This method accepts an object with keys:

• tag (string) REQUIRED - tag of message to delete

The rpc.result member contains an object with keys:

• status (integer) - return status of el_delete

el_query

Query elog messages

This method accepts an object with keys:

• last_n_hours (integer) - return messages from the last N hours

The rpc.result member contains an object with keys:

• status (integer) - return status of el_retrieve
• msg (array of string) - message tag

el_retrieve

Get an elog message

This method accepts an object with keys:

• tag (string) REQUIRED - elog message tag

The rpc.result member contains an object with keys:

• status (integer) - return status of el_retrieve
• msg.tag (string) - message tag

exec_script

execute custom script defined in ODB /Script (scripts show in the menu) or /CustomScript (scripts from custom pages)

This method accepts an object with keys:

• script (string) - Execute ODB /Script/xxx
• customscript (string) - Execute ODB /CustomScript/xxx

The rpc.result member contains an object with keys:

• status (integer) - return status of cm_exec_script()

ext_delete_file

Delete a file or empty directory within userfiles

This method accepts an object with keys:

• filename (string) REQUIRED - Path relative to userfiles; symlinks and root are not allowed

The rpc.result member contains an object with keys:

• status (integer) - SUCCESS on success
• error (string) - Failure description

ext_list_files

js_ext_list_files

This method accepts an object with keys:

• subdir (string) REQUIRED - List files in experiment_directory/userfiles/subdir
• fileext (string) REQUIRED - Filename extension

The rpc.result member contains an object with keys:

• status (integer) - return status of midas library calls
• path (string) - Search path
• subdirs (array of string) - list of subdirectories
• files (array of string) - script description

ext_read_file

js_ext_read_script

This method accepts an object with keys:

• filename (string) REQUIRED - File name, read from experiment_directory/userfiles/filename

The rpc.result member contains an object with keys:

• content (string) - ASCII file content
• status (integer) - return status of midas library calls
• error (string) - error text

ext_rename_file

Rename a file or directory within userfiles without overwriting an existing entry

This method accepts an object with keys:

• filename (string) REQUIRED - Existing path relative to userfiles
• new_name (string) REQUIRED - New base name in the same directory

The rpc.result member contains an object with keys:

• status (integer) - SUCCESS on success
• error (string) - Failure description

ext_save_file

js_ext_save_file

This method accepts an object with keys:

• filename (string) REQUIRED - File name, save in experiment_directory/userfiles/filename
• script (string) REQUIRED - ASCII content

The rpc.result member contains an object with keys:

• status (integer) - return status of midas library calls
• error (string) - error text

get_alarms

get alarm data

This method accepts an object with keys:

• get_all (bool) - get all alarms, even in alarm system not active and alarms not triggered

The rpc.result member contains an object with keys:

• status (integer) - return status of midas library calls
• alarm_system_active (bool) - value of ODB "/Alarms/alarm system active"
• alarms (array of string) - final alarm text shown to user by mhttpd

get_debug

get current value of mjsonrpc_debug

There are no parameters for this method.

The rpc.result member contains a single value:

• (integer) - current value of mjsonrpc_debug

get_schema

Get the MIDAS JSON-RPC schema JSON object

There are no parameters for this method.

The rpc.result member contains a single value:

• (object) - returns the MIDAS JSON-RPC schema JSON object

get_sleep

get current value of mjsonrpc_sleep

There are no parameters for this method.

The rpc.result member contains a single value:

• (integer) - current value of mjsonrpc_sleep

get_time

get current value of mjsonrpc_time

There are no parameters for this method.

The rpc.result member contains a single value:

• (integer) - current value of mjsonrpc_time

get_timezone

get current server timezone offset in seconds

There are no parameters for this method.

The rpc.result member contains a single value:

• (integer) - offset in seconds

hs_get_active_events

get list of active history events using hs_read_event_list()

There are no parameters for this method.

The rpc.result member contains an object with keys:

• status (integer) - return status of hs_read_event_list()
• events (array of string) - array of history event names

hs_get_channels

get list of history channels in /Logger/History

There are no parameters for this method.

The rpc.result member contains an object with keys:

• status (integer) - return success or failure status
• default_channel (string) - name of the default logger history channel
• channels (array of string) - all logger history channel names
• active_channels (array of string) - active logger history channel names

hs_get_events

get list of history events that existed at give time using hs_get_events()

This method accepts an object with keys:

• channel (string) - midas history channel, default is the default reader channel
• time (number) - timestamp, value 0 means current time, default is 0

The rpc.result member contains an object with keys:

• status (integer) - return status of hs_get_events()
• channel (string) - logger history channel name
• events (array of string) - array of history event names

hs_get_last_written

get list of history tags for given history events that existed at give time using hs_get_last_written()

This method accepts an object with keys:

• channel (string) - midas history channel, default is the default reader channel
• time (number) - timestamp, value 0 means current time, default is 0
• events (array of string) REQUIRED - array of history event names
• tags (array of string) REQUIRED - array of history event tag names
• index (array of string) REQUIRED - array of history event tag array indices

The rpc.result member contains an object with keys:

• status (integer) - return status
• channel (string) - logger history channel name
• last_written (array of number) - array of last-written times for each history event

hs_get_tags

get list of history tags for given history events that existed at give time using hs_get_tags()

This method accepts an object with keys:

• channel (string) - midas history channel, default is the default reader channel
• time (number) - timestamp, value 0 means current time, default is 0
• events (array of string) - array of history event names, default is get all events using hs_get_events()

The rpc.result member contains an object with keys:

• status (integer) - return status
• channel (string) - logger history channel name
• events (array of integer) - history tag number of array elements, omitted if 1

hs_image_retrieve

Get a list of history image files

This method accepts an object with keys:

• image (string) - image name as defined under /History/Images/<image>
• start_time (number) REQUIRED - start time of the data
• end_time (number) REQUIRED - end time of the data

The rpc.result member contains an object with keys:

• time (array of arraybuffer) - array of time stamps in seconds
• filename (array of arraybuffer) - array of file names

hs_read

get history data for given history events that existed at give time using hs_read_buffer()

This method accepts an object with keys:

• channel (string) - midas history channel, default is the default reader channel
• start_time (number) REQUIRED - start time of the data
• end_time (number) REQUIRED - end time of the data
• events (array of string) REQUIRED - array of history event names
• tags (array of string) REQUIRED - array of history event tag names
• index (array of string) REQUIRED - array of history event tag array indices

The rpc.result member contains an object with keys:

• status (integer) - return status
• channel (string) - logger history channel name
• data (array of number) - value data

hs_read_arraybuffer

get history data for given history events that existed at give time using hs_read_buffer()

This method accepts an object with keys:

• channel (string) - midas history channel, default is the default reader channel
• start_time (number) REQUIRED - start time of the data
• end_time (number) REQUIRED - end time of the data
• events (array of string) REQUIRED - array of history event names
• tags (array of string) REQUIRED - array of history event tag names
• index (array of string) REQUIRED - array of history event tag array indices

The rpc.result member contains an object with keys:

• binary data (arraybuffer) - binary data, see documentation

hs_read_binned

get history data for given history events that existed at give time using hs_read_buffer()

This method accepts an object with keys:

• channel (string) - midas history channel, default is the default reader channel
• start_time (number) REQUIRED - start time of the data
• end_time (number) REQUIRED - end time of the data
• num_bins (integer) REQUIRED - number of time bins
• events (array of string) REQUIRED - array of history event names
• tags (array of string) REQUIRED - array of history event tag names
• index (array of string) REQUIRED - array of history event tag array indices

The rpc.result member contains an object with keys:

• status (integer) - return status
• channel (string) - logger history channel name
• data (array of number) - value of last data entry

hs_read_binned_arraybuffer

get history data for given history events that existed at give time using hs_read_buffer()

This method accepts an object with keys:

• channel (string) - midas history channel, default is the default reader channel
• start_time (number) REQUIRED - start time of the data
• end_time (number) REQUIRED - end time of the data
• num_bins (integer) REQUIRED - number of time bins
• events (array of string) REQUIRED - array of history event names
• tags (array of string) REQUIRED - array of history event tag names
• index (array of string) REQUIRED - array of history event tag array indices

The rpc.result member contains an object with keys:

• binary data (arraybuffer) - binary data, see documentation

hs_reopen

reopen the history channel to make sure we see the latest list of events using hs_clear_cache()

This method accepts an object with keys:

• channel (string) - midas history channel, default is the default reader channel

The rpc.result member contains an object with keys:

• status (integer) - return status of hs_get_events()
• channel (string) - logger history channel name

jrpc

make RPC call into frontend program via RPC_JRPC

This method accepts an object with keys:

• client_name (string) REQUIRED - Connect to this MIDAS client, see cm_connect_client()
• cmd (string) REQUIRED - Command passed to client
• args (string) REQUIRED - Parameters passed to client as a string, could be JSON encoded
• max_reply_length (integer) - Optional maximum length of client reply. MIDAS RPC does not support returning strings of arbitrary length, maximum length has to be known ahead of time.

The rpc.result member contains an object with keys:

• reply (string) - Reply from client as a string, could be JSON encoded
• status (integer) - return status of cm_connect_client() and rpc_client_call()

jrpc_cxx

make RPC call into frontend program via RPC_JRPC_CXX

This method accepts an object with keys:

• client_name (string) REQUIRED - Connect to this MIDAS client, see cm_connect_client()
• cmd (string) REQUIRED - Command passed to client
• args (string) REQUIRED - Parameters passed to client as a string, could be JSON encoded

The rpc.result member contains an object with keys:

• reply (string) - Reply from client as a string, could be JSON encoded
• status (integer) - return status of cm_connect_client() and rpc_client_call()

jrpc_old

make RPC call into frontend program via RPC_JRPC

This method accepts an object with keys:

• client_name (string) REQUIRED - Connect to this MIDAS client, see cm_connect_client()
• cmd (string) REQUIRED - Command passed to client
• args (string) REQUIRED - Parameters passed to client as a string, could be JSON encoded
• max_reply_length (integer) - Optional maximum length of client reply. MIDAS RPC does not support returning strings of arbitrary length, maximum length has to be known ahead of time.

The rpc.result member contains an object with keys:

• reply (string) - Reply from client as a string, could be JSON encoded
• status (integer) - return status of cm_connect_client() and rpc_client_call()

make_subdir

js_make_subdir

This method accepts an object with keys:

• subdir (string) REQUIRED - Create folder experiment_directory/userfiles/subdir

The rpc.result member contains an object with keys:

• status (integer) - return status of midas library calls
• path (string) - Search path

null

RPC method always returns null

There are no parameters for this method.

The rpc.result member contains a single value:

• (null) - always returns null

read_binary_file

js_read_binary_file

This method accepts an object with keys:

• filename (string) REQUIRED - File name, read from experiment_directory/userfiles/filename

The rpc.result member contains an object with keys:

• binary data (arraybuffer) - Binary file content
• status (integer) - Return status of midas library calls
• error (string) - Error text

seq_validate

js_seq_validate

This method accepts an object with keys:

• script (string) REQUIRED - MSL source text
• filename (string) - current file below userfiles/sequencer, used to resolve INCLUDE paths

The rpc.result member contains an object with keys:

• status (integer) - MIDAS status code
• errors (array of string) - validation diagnostic
• warnings (array of string) - non-blocking missing ODB path diagnostic

set_debug

set new value of mjsonrpc_debug

This method accepts a single parameter (not an object):

• (object) - {desc}

The rpc.result member contains a single value:

• (integer) - new value of mjsonrpc_debug

set_sleep

set new value of mjsonrpc_sleep

This method accepts a single parameter (not an object):

• (object) - {desc}

The rpc.result member contains a single value:

• (integer) - new value of mjsonrpc_sleep

set_time

set new value of mjsonrpc_time

This method accepts a single parameter (not an object):

• (object) - {desc}

The rpc.result member contains a single value:

• (integer) - new value of mjsonrpc_time

ss_millitime

get current MIDAS time using ss_millitime()

There are no parameters for this method.

The rpc.result member contains a single value:

• (integer) - current value of ss_millitime()

start_program

start MIDAS program defined in ODB /Programs/name

This method accepts an object with keys:

• name (string) REQUIRED - name of the program, corresponding to ODB /Programs/name

The rpc.result member contains an object with keys:

• status (integer) - return status of ss_system()

user_example1

example of user defined RPC method that returns up to 3 results

This method accepts an object with keys:

• arg (string) REQUIRED - example string argment
• optional_arg (integer) - optional example integer argument

The rpc.result member contains an object with keys:

• string (string) - returns the value of "arg" parameter
• integer (integer) - returns the value of "optional_arg" parameter

user_example2

example of user defined RPC method that returns more than 3 results

This method accepts an object with keys:

• arg (string) REQUIRED - example string argment
• optional_arg (integer) - optional example integer argument

The rpc.result member contains an object with keys:

• string1 (string) - returns the value of "arg" parameter
• string2 (string) - returns "hello"
• string3 (string) - returns "world!"
• value1 (integer) - returns the value of "optional_arg" parameter
• value2 (number) - returns 3.14

user_example3

example of user defined RPC method that returns an error

This method accepts an object with keys:

• arg (integer) REQUIRED - integer value, if zero, throws a JSON-RPC error

The rpc.result member contains an object with keys:

• status (integer) - returns the value of "arg" parameter