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This repo hosts the distributable production version of the A2J Document Assembly Tool (DAT). The document assembly tool is an optional piece of software used for producing pdf documents at the end of A2J Author Guided Interviews.



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This repo is part of the A2J Author Project which consists of four repos...
1. A2JViewer -
2. A2J Author -
3. A2J Document Automation Tool -
4. A2J Dependencies -

This repo hosts the distributable production version of the A2J Document Assembly Tool (DAT). The document assembly tool is an optional piece of software used for producing pdf documents at the end of interviews. It requires the A2Jviewer, wkhtmltopdf and nodejs 12+ to run properly. The recommended additional tools for windows are volta and pm2-windows-service and volta for *nix.

Within this repo and releases you'll find a .zip file containing the minified JavaScript source for the DAT and sample configuration files

NOTE: By downloading this application, you are agreeing to the terms included in the user license


The DAT requires nodejs 16.17.0+. Any system supporting nodejs 16.17.0+ is supported. It has been tested on ubuntu 18, centos, and Windows Server 2016 on Azure with apache and IIS

While other server environments may work, they have not been tested. Should you get another hosting environment working, please do a Pull Request at the hosted A2J DAT repo to let us know any steps taken so that we may share with others.

Current release

if installing through git, the current release version is always in the production branch. This is identical to the zipped source package in the releases page.

Upgrade notes/summary from node A2JDAT v2

The folder structure has changed. It is recommended that your current setup is backed up. This means at a minimum, config.json and ecosystem.config.js. Alternatively you may checkout/unzip this repo into a new folder.

The folder structure has changed such that the DAT is no longer a sub folder.

Old structure

Containing Folder

Current required structure:

Containing Folder
-A2JDAT (this DAT repo)

The WKHTMLTOPDF_ZOOM settings have changed. YOU MUST SET THIS CORRECTLY TO MATCH PDFs GENERATED ON A2JAUTHOR.ORG On most *nix systems this should be 1.6711 and on most windows systems this should be 1.5709.

Assuming you have all up-to-date dependencies (wkhtmltopdf, node, npm, pm2, volta) you can run npm run deploy and skip to step 13 of installation instructions for calibration. Otherwise you must start from step 0.

General Installation instructions

All Platforms + common solutions to common problems

For all platforms this document should work as written. You can skip to step 4 of Installation Instructions for systems with working DAT setup. Starting from step 1 may upgrade those DAT subdependencies which is expected to cause no issues.

This document should work as written but some components will likely need to be recompiled for the current node 16.

if the DAT does not properly start after using these instructions, the likely culprit is muhammara. This will be indicated by running pm2 logs and seeing a node version error. To confirm this, run pm2 logs which will yield something like

2|dev-hydr | was compiled against a different Node.js version using
2|dev-hydr | NODE_MODULE_VERSION 72. This version of Node.js requires
2|dev-hydr | NODE_MODULE_VERSION 93. Please try re-compiling or re-installing
2|dev-hydr | the module (for instance, using `npm rebuild` or `npm install`).
2|dev-hydr |     at Object.Module._extensions..node (node:internal/modules/cjs/loader:1183:18)
2|dev-hydr |     at Module.load (node:internal/modules/cjs/loader:981:32)
2|dev-hydr |     at Function.Module._load (node:internal/modules/cjs/loader:822:12)
2|dev-hydr |     at Module.require (node:internal/modules/cjs/loader:1005:19)
2|dev-hydr |     at Module.Hook._require.Module.require (/home/a2jprod/.volta/tools/image/packages/pm2/lib/node_modules/pm2/node_modules/require-in-the-middle/index.js:80:39)
2|dev-hydr |     at require (node:internal/modules/cjs/helpers:102:18)
2|dev-hydr |     at Object.<anonymous> (/vol/data/sites/
2|dev-hydr |     at Module._compile (node:internal/modules/cjs/loader:1101:14)
2|dev-hydr |     at Object.Module._extensions..js (node:internal/modules/cjs/loader:1153:10)
2|dev-hydr |     at Module.load (node:internal/modules/cjs/loader:981:32)

To rectify follow the instructions below:

1.) go to the a2jdat folder

2.) run npm install muhammara in a command line

3.) restart DAT process and test

if that doesn't work try below:

1.) cd node_modules/muhammara

2.) node-pre-gyp rebuild

3.) restart DAT process and test

Installation instructions

0.) NVM is no longer supported and should be uninstalled and replced with voltajs. For *nix users uninstall nvm if installed

rm -rf #NVM_HOME

1.) Install voltajs ( The DAT is a simple restful API that requires nodejs to serve endpoints. Though, you are free to install the node version that the DAT targets and manage it manually, the recommended method is to use a node version manager which will allow the simultaneous installation of multiple versions of node and mitigates several administration issues.

Obtain volta here:

For *nix, per the instructions above run : curl | bash

For Windows Users:

Ensure Node is in PATH:

The node installer might not always set the PATH variable correctly. Check Environment variables to ensure that there is an entry for the folder containing node.exe. For this tutorial that folder is C:\Program Files\nodejs.

Configure Node Permissions:

Node.exe must be added to the IIS_IUSRS group in order to be allowed to handle requests. This must occur every time the node executable is switched through nvm or volta. Open a command prompt and run as administrator and run icacls “%programfiles%\nodejs\node.exe” /grant IIS_IUSRS:rx

For all users

2.) Install node through volta navigate to the root folder of the DAT (contains a2jdat folder) and type the following commands in the terminal to install the required node version

volta install node@16.17.0

check that the install was successful by typing

node -v

which should produce the version number of node we installed, 16.17.0

navigate to the a2jdat subdiectory and check the node version in volta Which should automatically download the right version as it is pinned in package.json by running

volta list

check that the install was successful by typing

node -v

which should produce the version number of node we installed, 16.17.0

3.) Install global DAT dependencies and subdependencies:

Git is a source control manager and required for npm. This can be obtained through most *nix package managers. For windows, install Git by downloading latest from As of this documents writing, the latest version for the system in the azure demo environment is located at:

for windows, this README will use Git Bash for terminal commands

4.) Install build tools:

The node sub-dependencies for the DAT must be built locally on the target system and requires build tools for languages other than node. Run the command below to install the necessary build tools:

For windows

use the command below to install npm --add-python-to-path='true' --debug install --global windows-build-tools

install python 3

This requires administrator access. This is a very lengthy install- it can take over an hour even on a fast machine with a fantastic connection.

For all platforms run the command below

npm install @mapbox/node-pre-gyp node-gyp babel-cli steal-tools@1 -g

5.) Install wkhtmltopdf WKHTMLTOPDF is the engine used to transform interview data into PDF from an intermediate HTML file. Download the latest stable version from and install it in the environment. Make a note of the install path.

6.) Install node process manager The node process manager handles automatic restarts, memory mangement, monitoring, and error logging.

For All platforms: The recommended process manager is pm2 ( Install it with the following command

npm install pm2 -g

Windows users, install pm2 windows service

npm i pm2-windows-service -g pm2-service-install -n PM2

Notes to Windows users about iisnode:

a.) Older versions of this project used iisnode ( iisnode is no longer supported. For migration instructions go here: To make pm2 independent of logouts follow the instructions here to install pm2-windows-service.

Notes to Windows users if pm2-windows-service fails. Run the command below (from jon-hall/pm2-windows-service#56):
npm install -g npm-check-updates
cd %USERPROFILE%\AppData\Roaming\npm\node_modules\pm2-windows-service
ncu inquirer -u
npm install

then pm2-service-install -n PM2

The correct PM2 executable path for volta must point to pm2 node_modules folder for default pm2 installs in volta this path is %USERPROFILE%\AppData\Local\Volta\tools\image\packages\pm2\node_modules\pm2. This corresponds to the PM2_SERVICE_PM2_DIR environment variable.

7.) Download the latest DAT from repo through git or from into your webroot or preferred directory on your web server.

8.) Compile from source instructions

navigate to the downloaded location in a terminal and run either the following commands in sequence

cd a2jdat
npm run deploy

or the equivalent

cd a2jdat
npm install
npm run build
npm run build:server

if you encounter an error in this step it can often be resolved by deleting the node_modules folder in the a2jdat folder and repeating the step. If that does not work, re-clone into a brand new directory and run the commands in that directory.

if you encounter EINTEGRITY errors delete package-lock.json and rerun npm run deploy

9.) Configure DAT Since the A2J software can run on many platforms, there is a small amount of platform specific configuration that is necessary. Navigate to a2jdat\samples.configs\. There are two samples for config.json (config.json.nix.sample and that will need to be edited and saved to the containing folder of the a2jdat as config.json. Edit and save the sample appropriate to your platform (config.json.nix.sample for *NIX systems and for Windows systems).

The Most important keys are: GUIDES_DIR- required to establish location of templates GUIDES_URL- relative web location of guides WKHTMLTOPDF_PATH- path to binary of WKHTMLTOPDF VIEWER_PATH- path to folder containing guides folder. For most standalone installs this will be the path to the extracted viewer which should enclose a guides folder. For A2JAuthor installations this will be the folder containing userfiles WKHTMLTOPDF_DPI- desired default dpi to render pdfs. CALI recommends minimum of 300 WKHTMLTOPDF_ZOOM- The correction factor used to render text pdfs. This is necessary to standardize rendering across all platforms. On most *nix systems this should be 1.6711 and on most windows systems this should be 1.5709.

All other keys must be present but the value is irrelevant.

Ensure that the value for the key WKHTMLTOPDF_PATH matches the path noted above where WKHTMLTOPDF is installed. Backslashes are special characters in json so each backslash must be typed twice to escape them and work properly.

a sample config.json for Windows is below:

  "GUIDES_DIR": "C:\\inetpub\\wwwroot\\a2j-viewer\\guides",
  "GUIDES_URL": "../a2j-viewer/guides",
  "VIEWER_PATH": "C:\\inetpub\\wwwroot\\a2j-viewer\\viewer\\",
  "WKHTMLTOPDF_PATH": "C:\\Program Files\\wkhtmltopdf\\bin\\wkhtmltopdf",

a sample config.json for Linux is below:

  "GUIDES_DIR": "/var/www/mysite.tld/a2j-viewer/guides",
  "GUIDES_URL": "../a2j-viewer/guides",
  "VIEWER_PATH": "/vol/data/sites/viewer.mysite.tld/a2jviewer/viewer",
  "WKHTMLTOPDF_PATH": "/usr/bin/local/wkhtmltopdf",

10.) Configure the server

The DAT is a simple restful interface with endpoints located at /api/. Requests must be routed through the node /bin/www target. We will setup a reverse proxy to accomplish this.

Reverse proxy for windows (IIS)

for IIS Advanced Request Routing will need to be setup. Follow the instructions here:

for IIS/Windows below is an example web.config

<?xml version="1.0" encoding="UTF-8"?>
     This is an exampe configuration file for using the DAT with pm2
                <rule name="ReverseProxyInboundRule1" stopProcessing="true">
                    <match url="(api/.*)" />
                    <action type="Rewrite" url="http://localhost:3000/{R:1}" />

IIS will need to be restarted before these changes take effect

Reverse proxy for Apache (Linux)

for apache add the following directives to your site config

ProxyPass /api http://localhost:3000/api
ProxyPassReverse /api http://localhost:3000/api
ProxyBadHeader Ignore
Reverse proxy for nginx (Linux)

for nginx add the following directives

Location /api {

11.) Edit ecosystem.config.js

we have created a script to allow pm2 to manage memory and multiple instances of the DAT. The default script will run a cluster of 4 processes and restart a process if it uses more than 768MB.

12.) Start the node process navigate to the DAT folder in a terminal

pm2 start ecosystem.config.js

Configure auto-restart of pm2

To configure pm2 to autoload on startup run the following command with the desired pm2 processes running pm2 save


13.) Testing and calibration To ensure that the documents produced are identical to a2jauthor, run and generate a pdf through the DAT calibration guide provided in /calibration folder. With the PDF viewed at actual size and captured in screenshot The letter height of the Arial text should be 68pixels. A canonical png and pdf is included in the /calibration folder for comparison.

Security Note

This software uses software with dependencies with a few known security vulnerabilities. The features required to exploit this vulnerability are not used in this software in normal production and hence it is not an issue.

More info

To find out more about A2J Viewer and A2J Author® please see our website,

Ever growing backend documentation including tutorials and examples can be found at

For questions, contact Tobias Nteireho at




This repo hosts the distributable production version of the A2J Document Assembly Tool (DAT). The document assembly tool is an optional piece of software used for producing pdf documents at the end of A2J Author Guided Interviews.








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