COMSOL 6.2 - File Schemes and File Handling

Transferring Files from Server to Client

To transfer files from a COMSOL Server to the client application, do not add any node under , and follow these steps:

Write the data to temp:///output.data, for example.

Add temp:///output.data as the argument to a downloadtoclient action.

For assistance when defining the argument for the downloadtoclient action, click the button (

) to open an dialog box (see Editing Initial Values and Arguments in Declarations and Command Sequences), where you can choose one of the file schemes below from the list. You then specify the filename (such as output.data) in the field. For the embedded:/// file scheme, choose an existing file in the application from the list under . Click to close the dialog box and fill the field with the selected file scheme and filename.

The data file can also be referenced from a Model Manager database, with the exception that this is not supported for applications running on a COMSOL Server (for which Model Manager databases are not accessible). See the dbfile:/// file scheme below and the documentation for the Model Manager.

File Schemes

Anywhere in the model or application where a file path is given that would normally refer to a file on the client file system, you can instead use a scheme syntax such as <scheme>:///... to refer to a file that should be taken from somewhere else on the server. The following table includes the available schemes and where the files exist when running from the Application Builder and COMSOL Server.

Table 4-3: File Schemes.
Scheme	Refers to	Default Path in Application Builder	Default Path on COMSOL Server
embedded:///	Files embedded in the model using file libraries (read only).	Inside the MPH-file	Inside the MPH-file
upload:///	Files that are uploaded to file declarations.	user:/// or temp:/// depending on target	user:/// or temp:/// depending on target
temp:///	Files in a random temporary directory, which is unique for each started application instance.	Random subdirectory of %TEMP% or /tmp	Random subdirectory of .comsol/v62server/service/users/[username]
common:///	Files in a directory shared by all users and applications.	In .comsol/v62/applications/files/common	In .comsol/v62server/applications/files/common
user:///	Files in a directory shared by all applications for the current user.	In .comsol/v62/applications/files/user	In .comsol/v62server/applications/files/users/[username]
dbfile:///	File versions stored in a Model Manager database.	N/A	Not supported

Files saved to the temp scheme do not persist between multiple runs of the same application, even for the same user. Files saved to the user scheme persist and can be accessed by the same user, even for other applications. Files saved to the common scheme persist and can be accessed by all users for all applications.

You can modify the default locations separately using the following preference settings.

Table 4-4: Default Location Preferences.
Scheme	Application Builder Preference	COMSOL Server Preference
temp:///	Files>Folder for temporary files	Files>Folder for temporary files
common:///	Files>Folder for common files	Files>Folder for application library files
user:///	Files>Folder for user files	Files>Folder for application user files

URI Syntax

File scheme strings are uniform resource identifiers (URIs) as defined by RFC 2396 (https://www.ietf.org/rfc/rfc2396.txt). In addition to what is allowed by RFC 2396, the file schemes allow any nonreserved Unicode characters in the path segments. This means that spaces do not need to be escaped in file and directory names. Sequences of escaped octets (for example, %20) are decoded as UTF-8. Currently, the file schemes do not use the authority component; that is, they are always on the form <scheme>:///<path> with three initial slashes.