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View all FAQs about Project Deployment and End-user Installation

What does the Dynamic Web TWAIN Service do on the end-user machine?

Dynamic Web TWAIN Service (also called “Dynamsoft Service”) is required for the Desktop Service Edition of Dynamic Web TWAIN. It’s a background system service that handles the communication between connected physical devices and the browser, as well as image processing, encoding, decoding, etc.

v19.0+
Versions below 19.0

Three processes

By default, there are three Dynamic Web TWAIN Service processes running which use the same file DynamicWebTWAINService.exe but initiated with different arguments:

The main process starts without any argument as follows:

C:\Program Files (x86)\Dynamsoft\Dynamic Web TWAIN Service {version number}\DynamicWebTWAINService.exe

Then there is a monitor process which is meant to monitor the main process and automatically start it in case it crashes. The monitor process starts like this:

C:\Program Files (x86)\Dynamsoft\Dynamic Web TWAIN Service {version number}\DynamicWebTWAINService.exe -asmonitor Global\Dynamsoft_1.5.0_352325843_stop_service_event   Global\Dynamsoft_1.5.0_352325828_certcheck_event

The last always-running process is meant to support the SSL certificate specifically for the Firefox browser:

"-scan" "\\.\pipe\dynamsoftscan_15.0_70056_60" "0" "Global\ss352604281_61_70056" "0" "C:\Program Files (x86)\Dynamsoft\Dynamic Web TWAIN Service 19\dwt_19.0.0.0318.dll"

Note: you may find another process named ‘Dynamsoft Scanning New Module’, which is a scan module. This process will start when you access an application integrated with Dynamic Web TWAIN, and will automatically stop when you close the application.

On Windows, the service runs under the Local System account

On macOS, the service runs under the current user account

On Linux, the service runs under the root account

Files and folders in the service directory

There are multiple files and folders in the service directory. Taking Windows service (located at C:\Program Files (x86)\Dynamsoft\Dynamic Web TWAIN Service {version number}) as an example, the content is as follows:

For the Service

\cache\ : Data cached on the disk. Check out Disk Caching.
\cert\ : The certificates used for SSL connection. Check out How to change the certificates.
\dump\ : Dump files in case the service crashes.
\log\ : Log files for debugging purposes.
\upload\ : Temporary location for image data to be uploaded by the file uploader.
DSConfiguration.ini : Service configuration file.
DWASManager_19000318.dll : The service manager. The name of the file may vary among different versions.
DynamicWebTWAINService.exe : The service.
service.ini : Define service name.
user_config.ini : User configuration file.
welcome.htm : The home page for the service (present when you visit http://127.0.0.1:18625)

Components

These files are named with their version number. The following uses v16.1.1 as an example.

Core scanning module
- dwt_16.1.0.0728.dll
- DSSCN2.exe
- DSSCN2x64.exe
- TWAINDSM.dll
- TWAINDSMx64.dll
Barcode Reader Addon
- \x64\
- \x86\
- dbr_7.4.0.0428.dll
- dbrx64_7.4.0.0428.dll
PDF Addon
- DynamicPdfCore_11.0.0.0428.dll
- DynamicPdfCorex64_11.0.0.0428.dll
- DynamicPdfR_11.0.0.0428.dll (for the PDF Rasterizer)
- DynamicPdfRx64_11.0.0.0428.dll (for the PDF Rasterizer)
Webcam Addon
- DynamicWebcam_15.0.0.0625.dll
- DynamicWebcamx64_15.0.0.0625.dll
File Uploader
- UploadModule_1.6.0.0428.dll
Imaging features
- DynamicImage.dll
- DynamicImagex64.dll

Supporting files

favicon.ico : The favicon.
legal.txt : Legal notice.
libcurl.dll : The file transfer library.
For OpenSSL
- libeay32.dll
- ssleay32.dll
port.lock

HTTP Requests and Responses

Dynamic Web TWAIN Service sets up a local HTTP service that accepts requests from JavaScript code running in the browser and performs operations accordingly. The following are a few examples.

NOTE

These requests are handled by the JavaScript client of the library. Please do not try to make similar requests in your own code without consulting Dynamsoft Support.

Return availability

Request

https://127.0.0.1:18623/fa/VersionInfo?ts=1603161807908

Response in case of success

{
  "id": "1",
  "method": "VersionInfo",
  "result": ["16, 1, 0, 0728", "", "64"],
  "cmdId": ""
}

Perform image removal

Request

https://127.0.0.1:18623/f/RemoveAllImages?753350643

Response in case of success

{
  "id": "414778098",
  "method": "RemoveAllImages",
  "result": [true],
  "cmdId": ""
}

Return an image

Request

https://127.0.0.1:18623/dwt/dwt_16100728/img?id=414778098&index=5&width=585&height=513&ticks=1603162807999

Response in case of success

The image data.

By default, there are three Dynamsoft Service processes running which use the same file DynamsoftService.exe but initiated with different arguments:

There are multiple files and folders in the service directory. Taking Windows service (located at C:\Windows\SysWOW64\Dynamsoft\DynamsoftServicex64_16) as an example, the content is as follows:

https://127.0.0.1:18623/fa/VersionInfo?ts=1603161807908

{
  "id": "1",
  "method": "VersionInfo",
  "result": ["16, 1, 0, 0728", "", "64"],
  "cmdId": ""
}

https://127.0.0.1:18623/f/RemoveAllImages?753350643

{
  "id": "414778098",
  "method": "RemoveAllImages",
  "result": [true],
  "cmdId": ""
}

https://127.0.0.1:18623/dwt/dwt_16100728/img?id=414778098&index=5&width=585&height=513&ticks=1603162807999

For more information, please refer to Dynamic Web TWAIN Deployment - Dynamic Web TWAIN Service.