QMNet Network File Access

QMNet

QMNet uses the QMClient interface to provide an extension to the QM file system allowing network access to files on another QM system. Unlike use of NFS or mapped network drives, QMNet provides locking of remote records, ensuring that data integrity can be maintained on distributed data. Where both ends of the connection support it, the network traffic is encrypted.

Use of QMNet creates a server process on the remote system for each separate QM session that has one or more files open through QMNet. This process will consume a licence. If QM's security system is enabled on the remote system, the user name of the server process as defined using SET.SERVER must be registered for access to QM (see Application Level Security)

Two steps are necessary to use QMNet. Firstly, the server must be defined, mapping the server name to a network address, user name and password. Secondly, the remote file must either be defined using a Q-type VOC record or it may be accessed using the extended filename syntax server:account:file.

Defining the Server

QMNet supports two styles of server definition; public servers and private servers.

Public server definitions are available to all users of the system. They are created by a user with administrative rights in the QMSYS account using the SET.SERVER command and persist until they are explicitly deleted.

Private server definitions are local to the QM session in which they are defined. They are created using the SET.PRIVATE.SERVER command. On a secure system, access to this command may be restricted by the system administrator. A private server definition would normally be created dynamically by the application, either supplying the authentication details internally or prompting the user.

Both commands have the same form:

SET.SERVER name ip.address user.name password

and prompt for items not provided on the command line. The remote server must have remote access enabled by setting the NETFILES configuration parameter to 2.

Defining the Remote File

Each remote file is defined by an extended form of the Q-type VOC entry where field 4 contains the name of the server.

Once the file has been defined, it may be accessed by programs in the same way as a local file. The following restrictions apply to access from QMBasic programs:

•	The OPENSEQ statement and related sequential file access operations are not supported.

•	Access to remote files inside transactions will be non-transactional.

•	The FILEINFO() function will return the file type as FL$TYPE.NET (6). Some modes of FILEINFO() are not supported.

•	A maximum of 10 servers may be accessed at one time by any one QM process. There is no practical limit to the number of files that may be open on each server.

Listing Server Definitions

A list of all defined QMNet servers can be displayed using the LIST.SERVERS command. This can only be executed by users with administrative rights.

LIST.SERVERS

Deleting a Server Definition

The definition for a remote server may be deleted using the DELETE.SERVER or DELETE.PRIVATE.SERVER command. Deletion of public server definitions is restricted to users with administrative rights in the QMSYS account.

DELETE.SERVER name