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0.15.0 • Public • Published

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A YottaDB and GT.M database driver and language binding for Node.js

Version 0.15.0 - 2019 Jul 9

Copyright and License

Addon Module written and maintained by David Wicksell
Copyright © 2012-2019 Fourth Watch Software LC

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License (AGPL) as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License along with this program. If not, see

Full license text: AGPL-3.0

Contact me if you are interested in using Nodem with a different license.

Summary and Info

Nodem is an open source addon module that integrates Node.js with the YottaDB and GT.M implementations of MUMPS, providing in-process access to their database systems and some language features, as well as networked access to their core database functionality. Nodem provides access to the basic global database handling operations, as well as providing the ability to invoke M language functions and procedures. It also supports full local symbol table management. Although designed for use with YottaDB and GT.M, Nodem aims to be API-compatible (while in 'strict' mode) with the in-process Node.js interface for Caché.

All of Nodem's APIs support synchronous operation and accept arguments passed via a single JavaScript object, containing a few specific properties. The APIs that currently support both synchronous and asynchronous operation, as well as accepting arguments passed by-position, are: data, function, get, kill, nextNode, order, previous, previousNode, procedure, and set. In order to use the asynchronous versions of those APIs, you must pass a JavaScript function, taking two arguments - error and result, as the last argument to the normal synchronous APIs. When passing arguments to those APIs by-position, the first argument would be the global, local, or intrinsic special variable (only supported in the get and set APIs) string, and the next set of arguments would be each subscript (or function/procedure argument), separated as a different argument. In order to specify an intrinsic special variable when passing arguments inside of a JavaScript object, use the local property, and preface the name with a $. For the set API, the last non-function argument would be treated as the data to set in to the node. Asynchronous, and call by-position, support for the rest of the API is coming soon.

Nodem uses the YottaDB and GT.M C call-in interface. YottaDB has released a new, faster, low-level database access API, with version r1.20, called the SimpleAPI. Nodem uses YottaDB's SimpleAPI for the data, get, kill, nextNode, order, previous, previousNode, and set APIs, when it is available, and falls back to the call-in interface when it is not. SimpleAPI support for the rest of the API is coming soon.

NOTE: Nodem Developer API and User Guide coming soon. In the meantime, please refer to the Caché Node.js API documentation for further details.

Example Usage

Using Nodem with YottaDB, in the Node.js REPL:

> const ydb = require('nodem').Ydb(); // Create YottaDB connection instance - use Gtm() when connecting to GT.M
>; // Open connection to YottaDB
{ ok: true, pid: 15975 }
> ydb.version();
'Node.js Adaptor for YottaDB: Version: 0.15.0 (FWS); YottaDB Version: 1.26'
> ydb.get({global: 'test', subscripts: [0, 2, 0]}); // write ^test(0,2,0)
{ ok: true,
  global: 'test',
  subscripts: [ 0, 2, 0 ],
  data: '2 bags of wheat',
  defined: 1 }
> ydb.get('^test', 0, 2, 0); // write ^test(0,2,0)
'2 bags of wheat'
> ydb.get({global: 'test', subscripts: [0, 2, 0]}, (error, result) => {if (!error) {console.log('result:', result);}});
> result: { ok: true,
  global: 'test',
  subscripts: [ 0, 2, 0 ],
  data: '2 bags of wheat',
  defined: 1 }
> ydb.get('^test', 0, 2, 0, (error, result) => {if (!error) {console.log('result:', result);}});
> result: 2 bags of wheat
> ydb.set('^test', 0, 2, 0, '3 bags of wheat'); // set ^test(0,2,0)="3 bags of wheat"
> ydb.get({global: 'test', subscripts: [0, 2, 0]});
{ ok: true,
  global: 'test',
  subscripts: [ 0, 2, 0 ],
  data: '3 bags of wheat',
  defined: 1 }
> ydb.get({global: 'test', subscripts: ['']});
{ ok: false,
  errorCode: 150373498,
   '(SimpleAPI),%YDB-E-NULSUBSC, DB access failed because Null subscripts are not allowed for current region,%YDB-I-GVIS, \t\tGlobal variable: ^test("")' }
> ydb.close(); // Close connection to YottaDB, releasing resources and restoring terminal settings


Nodem should run on every version of Node.js starting with version 0.12.0, through the current release (v12.4.0 at this time), as well as every version of IO.js. However, in the future, both Node.js and the V8 JavaScript engine at its core, could change their APIs in a non-backwards compatible way, which might break Nodem for that version.

In order to use the Nodem addon, you will need to have YottaDB or GT.M installed and configured correctly, including setting up your environment with the required YottaDB/GT.M environment variables. Make sure you have either $ydb_dist (only applicable for YottaDB) or $gtm_dist set to the root of the YottaDB/GT.M instance before you compile Nodem. You will also need to have Node.js installed and working.

ATTENTION: These instructions assume that the nodem repository has been installed in your home directory. The paths will likely be different if you have installed this with npm.

NOTE: If you have installed Nodem using npm, it will attempt to build mumps.node during installation. If there is a file in the nodem directory called builderror.log, and if that file contains no build errors for mumps.node, it built without issue. It also attempts to pre-compile the v4wNode.m integration routine, and there might be warnings from that, which won't affect the building of mumps.node itself. If you downloaded Nodem any other way, including cloning it from its github repository, then you'll have to build it from source. Remember to make sure that either $ydb_dist or $gtm_dist is set to the root of the YottaDB/GT.M instance before building Nodem. In order to build it, while in the root of the Nodem repository, run the 'npm install' command, e.g.

cd ~/nodem
$ npm install


$ node-gyp rebuild 2> builderror.log

In addition you will need to set a few environment variables in order for YottaDB/GT.M to find the call-in table and the M routine that it maps to. The Nodem package supplies a sample environment file, called environ. It has a commented out command to set $LD_LIBRARY_PATH to $gtm_dist, which you will need to uncomment if you need it. It is located in ~/nodem/resources and can be sourced into your working environment, either directly, or from your own environment scripts or profile/login script, e.g.

cd ~/nodem/resources
source environ


echo "source ~/nodem/resources/environ" >> ~/.profile

If you don't source the environ file, then you will need to put a copy of v4wNode.m into a directory that is specified in your $ydb_routines (only applicable for YottaDB) or $gtmroutines routines path, or in the routinesPath property in your call to the open API, so that YottaDB/GT.M can find it. It is located in the ~/nodem/src directory. Again, if you don't source the environ file, then you will also need to define the $ydb_ci (only applicable for YottaDB) or $GTMCI environment variable, or set the callinTable property in your call to the open API, and point it at the file, located in the ~/nodem/resources directory, e.g.

export ydb_ci=~/nodem/resources/
$ cp ~/nodem/src/v4wNode.m ~/p


> const callinTable = process.env.HOME + '/nodem/resources/';
> const routinesPath = process.env.HOME + '/nodem/src .'; // Make sure to include your routine directories
>{callinTable: callinTable, routinesPath: routinesPath});

You can clone the repository with this command..

$ git clone

You can also install it via npm with this command..

$ npm install nodem

You can update to the latest version with this command..

$ npm update nodem

Important Notes

The open() call works a bit differently than the Caché version; it does not require any arguments, and will connect with the database specified in the environment variable $ydb_gbldir (only applicable for YottaDB) or $gtmgbldir. If you have more than one database and would like to connect to a different one than what is defined in your environment, you can pass an object, with a property called either globalDirectory or namespace, defined as the path to your global directory file for that database, e.g.

>{globalDirectory: process.env.HOME + '/g/db_utf.gld'});

Nodem supports setting up a custom routines path, for resolving calls to other M functions and procedures, via the routinesPath property. Make sure that one of the directories in the routinesPath contains the v4wNode.m routine, located in the Nodem src directory, or its compiled object, v4wNode.o, otherwise Nodem will not be fully functional. This could be used to provide a certain level of security, by giving access only to certain routines, within a Nodem process, within an environment that contains routines with unfettered access to the system in its default environment configuration, e.g.

> const HOME = process.env.HOME;
>{routinesPath: `${HOME}/p/r124(${HOME}/p)`});

Nodem supports setting the call-in path directly in the open call, via the callinTable property. This can be handy if you are running Nodem in an environment that has other software that uses the YottaDB/GT.M call-in interface, and you don't want to worry about namespace issues. Nor would you need to set the $ydb_ci/$GTMCI environment variable, in order for NodeM to be fully functional, e.g.

>{callinTable: process.env.HOME + '/nodem/resources/'});

You can configure Nodem to function as a GT.CM client, allowing Nodem to connect with a remote database. In the open() method, you can set an ipAddress, and/or a tcpPort property, and Nodem will set up the environment to connect with a YottaDB/GT.M database on a remote server that already has a GT.CM server running on that address and port. If only ipAddress or tcpPort is defined, the other one will be set with a default value; for ipAddress, or 6789 for tcpPort. Nodem will then set the $ydb_cm_NODEM (only applicable for YottaDB) or $GTCM_NODEM environment variable, for that Nodem process only, with the address and port you set in the open() call, e.g.

>{ipAddress: '', tcpPort: 6789});

If you are using IPv6, you need to surround your IP address with square brackets, e.g.

>{ipAddress: '[::1]', tcpPort: 6789});

You will also need to create a global directory file that maps one or more database segments to a data file on the remote server you want to connect with, noting that the prefix to the -file argument in the example below must be NODEM, in order to match the $ydb_cm_NODEM/$GTCM_NODEM environment variable name that Nodem sets up for you, e.g.

$ydb_dist/mumps -run GDE
GDE> change -segment DEFAULT -file=NODEM:/home/dlw/g/gtcm-server.dat

Then on the server you are connecting to, make sure you have the data file set up at the same path that you set the '-file=' option to in the global directory of your GT.CM client configuration, and have started the GT.CM server on the same ipAddress and tcpPort that you configured in the open() call in Nodem, e.g.

$ydb_dist/gtcm_gnp_server -log=gtcm.log -service=6789

NOTE: GT.CM only allows remote connections for the database access APIs, not the function nor procedure APIs. So while using Nodem in a remote GT.CM configuration, any calls to the function or procedure APIs will result in local calls, not remote calls.

Nodem supports two different character encodings, UTF-8 and M (or binary). It defaults to UTF-8 mode. The character encoding you set in Nodem is decoupled from the underlying character encoding you have set up for the YottaDB/GT.M environment it is running in. So it is possible to work with UTF-8 encoded data in the database, while in Nodem, even if you haven't set up YottaDB/GT.M to work with UTF-8 directly. You can set it to UTF-8 mode directly by passing utf-8 or utf8, case insensitively, to the charset property. If you'd rather work with an older byte-encoding scheme, that stores all characters in a single byte, you can set charset to either m, ascii, or binary, case insensitively. One thing to keep in mind when you do so, is that Node.js internally stores data in UTF-16, but interprets data in UTF-8 in most cases. You can control this through the process stream encoding methods inside of your Node.js code. Call those methods to change the encoding to 'binary' or 'ascii', and it will interpret your data as a byte encoding, using the character glyphs in your current locale, e.g.

> process.stdin.setEncoding('binary');
> process.stdout.setDefaultEncoding('binary');
>{charset: 'm'});

There are currently two different data modes that Nodem supports. The mode can be set to either 'canonical' or 'strict'. The default is canonical, and interprets data using the M canonical representation. I.e. Numbers will be represented numerically, etc. Strict mode interprets all data as strings, strictly following the convention set with the Caché Node.js driver, e.g.

>{mode: 'strict'});

Nodem also has a debug tracing mode, in case something doesn't seem to be working right. It has four levels of debugging, defaulting to 'off'. The other debug levels are 'low', 'medium', and 'high'. The higher the debug level, the more verbose the debug output will be, e.g.

>{debug: 'low'});

Nodem handles several common signals by default, closing the database connection, resetting the controlling terminal configuration, and stopping the Node.js process. These signals include SIGINT, SIGTERM, and SIGQUIT. The handling of the SIGQUIT signal will also generate a core dump of the process. All three signal handlers are on by default. However, you can turn the signal handling on or off directly, via passing true or false to a signalHandler object (with properties for each of the signals) for each individual signal, or all of them at once, e.g.

>{signalHandler: {sigint: true, sigterm: false, sigquit: false}});


>{signalHandler: false});

Nodem supports a feature called auto-relink, which will automatically relink a routine object containing any function or procedure called by the function or procedure API. By default auto-relink is off. You can enable it in one of three ways. First, you can pass it as a property of the JavaScript object argument which is passed to the function or procedure API directly, with a value of true, or any non-zero number. This will turn on auto-relink just for that call. You can also disable it, by setting autoRelink to false, or 0, if it was already enabled by one of the global settings, e.g.

> ydb.function({function: 'version^v4wTest', autoRelink: true});

Second, you can enable it globally, for every call to the function (or procedure) API, by setting the same property in a JavaScript object passed to the open API, e.g.

>{autoRelink: true});

Third, you can also enable it globally, by setting the environment variable NODEM_AUTO_RELINK to 1, or any other non-zero number, e.g.

$ node function.js


$ NODEM_AUTO_RELINK=1 node function.js

YottaDB/GT.M changes some settings of its controlling terminal device, and Nodem resets them when it closes the database connection. By default, Nodem will restore the terminal device to the state it was in when the open() call was invoked. Normally this is the desired option, however, if you wish to reset the terminal to typically sane settings, the close() call allows this by setting the resetTerminal property to true, or any non-zero number, e.g.

> ydb.close({resetTerminal: true});

Nodem has a procedure or routine API, which is similar to the function API, except that it is used to call M procedures or subroutines, which do not return any values. If the procedure API is called via a JavaScript object, then the object must contain the required procedure/routine property, set to the name of the procedure/routine. It may also contain an optional property, called arguments, which is an array of arguments to pass to the procedure/routine. It can also be called by-position, just like the function API. It also supports the autoRelink option, just as described in the function API, e.g.

> ydb.procedure({procedure: 'set^v4wTest', arguments: ['dlw', 5]});


> ydb.procedure('set^v4wTest', 'dlw', 5);

The lock API takes an optional timeout argument. If you do not set a timeout, it will wait to acquire the lock indefinitely. If you wish to come back from the call right away, if the lock is not available, simply pass a timeout argument of 0, e.g.

> ydb.lock({global: 'dlw', timeout: 5});


> ydb.lock({global: 'dlw', timeout: 0});

The kill API takes an optional nodeOnly argument. It can be set to true or false, defaulting to false. If set to true, then it will only remove the node that is passed to it; if set to false, then it will remove the node passed to it, and all of its children, or the full sub-tree, e.g.

> ydb.kill({global: 'dlw', nodeOnly: true});


> ydb.kill({local: 'dlw', nodeOnly: true});

The nodeOnly option is available when calling the kill API by passing arguments in a single JavaScript object, like above, but not when passing arguments by-position.

Additional Features

Nodem provides a built-in API usage help menu. By calling the help method without an argument, Nodem will display a list of APIs and a short description of what they do. Calling the help method with an argument string of one of those APIs will display more in-depth usage information for that method.

Nodem supports full local symbol table manipulation with the current database APIs. In order to use it, instead of defining a 'global' property in your argument object, you define a 'local' property. For APIs that support passing arguments by-position, you signify that you want them to work on a global, by using a '^' as the first character of the first argument. For the get and set APIs, if the first character of the first argument is a '$', then you are signifying that you are working with an intrinsic special variable (ISV). There is also a localDirectory API, that works the same way as the globalDirectory API, except that it lists the local symbols in the symbol table, rather than the globals in the database. One caveat is that you cannot manipulate any local variable that begins with 'v4w', as Nodem internally uses that namespace to implement the v4wNode.m integration routine. You can also call the kill API with no arguments, and it will clear the local symbol table. This functionality will allow you to call legacy M functions and procedures, without having to write wrappers in M anymore, in most cases. Here is an example of using the local symbol table functionality to call a legacy API directly from Nodem. In this example, the local variable, U, needs to be set before this API is called, as it expects it to be defined already. You can also see how the local symbol table changes, after setting the required local variable, making the call, and then clearing the symbol table, e.g.

> ydb.localDirectory();
> ydb.set({local: 'U', data: '^'});
{ ok: true, local: 'U', data: '^' }
> ydb.localDirectory();
[ 'U' ]
> ydb.procedure({procedure: 'AGET^ORWORR', arguments: [, 9, '2^0', 13, 0]});
{ ok: true,
  procedure: 'AGET^ORWORR',
  arguments: [ <1 empty item>, 9, '2^0', 13, 0 ] }
> ydb.localDirectory();
[ 'DILOCKTM', 'DISYS', 'DT', 'DTIME', 'DUZ', 'IO', 'U', 'XPARSYS' ]
> ydb.kill();
> ydb.localDirectory();

Nodem supports calling functions and procedures with arguments passed by reference, or by variable, in addition to the standard passing by value. This will allow someone who needs to interface Nodem with legacy M APIs that require using local variables in this manner, the ability to do so directly in Nodem, rather than having to write an M wrapper around the API, and calling that from Nodem. In order to use this functionality, you need to pass your arguments via a specially formatted object, in order to instruct Nodem that you wish to pass arguments differently than normal. This is necessary because if you tried to pass an argument by reference or by variable directly, Node.js will try to dereference it as a local JavaScript variable, and you would never be able to refer to the right symbol in the back-end M database environment. The structure of the specially formatted object is simple. It contains a 'type' property, which can be one of three values: 'reference', 'variable', or 'value'; and it also contains a 'value' property which contains the name you want to use when the type is 'reference' or 'variable', and the actual data you want to pass if type is 'value'. The 'value' type is there for consistency, but you would normally just pass arguments by value directly, without resorting to this specially formatted argument object. Here is an example of how you could use this functionality, while calling a legacy M API, many of which require passing arguments in this fashion, e.g.

> ydb.set({local: 'U', data: '^'});
{ ok: true, local: 'U', data: '^' }
> const arg = {type: 'reference', value: 'LIST'};
> ydb.procedure({procedure: 'LISTALL^ORWPT', arguments: [arg, 'A', 1]});
{ ok: true,
  procedure: 'LISTALL^ORWPT',
  arguments: [ { type: 'reference', value: 'LIST' }, 'A', 1 ] }
> ydb.localDirectory();
[ 'LIST', 'U' ]
>{local: 'LIST'});
{ ok: true, local: 'LIST', defined: 10 }
> ydb.nextNode({local: 'LIST'});
{ ok: true,
  local: 'LIST',
  subscripts: [ 1 ],
  defined: 1 }
> ydb.nextNode({local: 'LIST', subscripts: [1]});
{ ok: true,
  local: 'LIST',
  subscripts: [ 2 ],
  defined: 1 }
> ydb.nextNode({local: 'LIST', subscripts: [2]});
{ ok: true,
  local: 'LIST',
  subscripts: [ 3 ],
  defined: 1 }
> ydb.nextNode({local: 'LIST', subscripts: [3]});
{ ok: true, local: 'LIST', defined: 0 }


API Description
close Close the database connection
data Determine whether a global or local node has data and/or children
function Call an extrinsic function
get Retrieve the value of a global, local, or intrinsic special variable node
globalDirectory List the names of the globals in the database
help Display a help menu of method usage
increment Atomically increment the value stored in a global or local node
kill Delete a global or local node, and optionally, all of its children; or delete all local variables
localDirectory List the names of the variables in the local symbol table
lock Lock a global or global node, or local or local node, incrementally
merge Merge a global or local tree/sub-tree, or data node, to a global or local tree/sub-tree, or data node
nextNode Retrieve the next global or local node, regardless of subscript level
open Open the database connection
order or next Retrieve the next global or local node, at the current subscript level
previous Same as order, only in reverse
previousNode Same as nextNode, only in reverse in YottaDB r1.10 or newer, otherwise not yet implemented
procedure or routine Call a procedure/routine/subroutine
retrieve Not yet implemented
set Set a global, local, or intrinsic special variable node, to a new value
unlock Unlock a global or global node, or local or local node, incrementally; or release all locks
update Not yet implemented
version or about Display version information; if database connection open, display its version


Fourth Watch Software endeavors not to make any breaking changes to APIs, but as Nodem is still in development, its interface may change in future versions.

Contact Info

If you have any questions or feature requests, email me at
If you want to report any issues, visit

See Also

  • The Node.js server-side JavaScript runtime.
  • The YottaDB implementation of MUMPS.
  • The GT.M implementation of MUMPS.


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