Dynamic partner in server mode

In server mode, standard Transfer CFT operations consist of accepting a transfer request only if the partner is pre-defined in the parameter settings. This topic describes a mode where Transfer CFT can accept a connection from a partner that is not already defined. This type of partner is referred to as a dynamic partner.

Transfer CFT can accept connections from a correspondent not defined in advance by:

  • Using the mechanism for dynamic creation of a partner from a model partner
  • Generating the partner’s characteristics in a directory type EXIT task
  • Combining the 2 mechanisms described above

Creating a partner from a model

For incoming calls of unknown origin, where no local partner description corresponds to the network name, the user defines a partner CFTPART by default, in association with the definition of the protocol used CFTPROT.

This feature can be used by all protocols, but is not compatible with the routing and switching mechanism.

Note For security reasons, the DYNAM = mechanism is rarely used without also executing additional checks in a directory EXIT task.

Parameter settings

As far as parameter settings are concerned, the user sets up the mechanism by:

  • Adding the DYNAM parameter to the corresponding to the CFTPROT object
  • Creating the definition of the model partner CFTPART
  • Creating a network resource (CFTxxx) associated with the model partner

The DYNAM parameter gives the identifier of the model partner and, by extension, the identifier of its network description.

The parameters associated with the partner description trigger the usual checks. It is possible to define several dynamic partners associated with as many protocols (CFTPROT).

Restrictions

A new dynamic partner cannot be created without stopping Transfer CFT, as the latter is linked to a protocol definition that cannot be modified. However, modifications to the parameters of a model partner are immediate.

Checks

CFTPART Partner Parameters

The password given is checked in relation to the (NRPASSW) password of the model dynamic partner; these two passwords must bear the same value. As this parameter is optional, it may happen that only one of them is defined, in which case it is rejected.

The parameters IMINTIME and IMAXTIME, which define the call range to the Transfer CFT are also checked.

Partner network description

The normal check is performed on the resource class when the connection is requested.

The connections of each partner are counted in respect of the network name they give and are checked in relation to the CNXIN and CNXINOUT parameters of the network description (CFTxxx command). Thus, if CNXIN is equal to 1, 2 partners giving the same network name cannot transfer simultaneously; conversely, 2 partners giving different network names can transfer simultaneously.

When TCP type network resources (CFTTCP) are defined, the partner’s number (host) may be checked if the VERIFY parameter is set. It is nevertheless a good idea to set it to 0 (default value) so that the same model can be used for several partners.

The parameters IMINTIME and IMAXTIME are also checked.

Note Apart from checking the resource class, the above checks can be made (or remade) in the directory type EXIT task, if the latter is defined in the protocol description (EXIT parameter of the CFTPROT command).

Putting a file at disposal on hold

A file is put at disposal, which means on hold, for a partner by a transfer request of the type:

SEND PART = part, IDF = idf, STATE = HOLD

Or an equivalent request via CFTAPI ...

As the dynamic partner is not known to Transfer CFT, the request is not taken into account in "H" status, transfer postponed, unless the parameter settings authorize the use of the dynamic partner and/or the directory type EXIT task, CFTPROT object DYNAM and EXIT parameters. If this is not the case, the request is set to "K" state as in all cases of attempting to make a transfer to a partner that does not exist.

The dynamic partner can receive the file put on hold, either by:

  • Presenting itself under this name, or this network identifier
  • Using an identifier conversion (network, local) provided by a directory type EXIT task

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