READ ATTRIBUTE

Initiator Conf. Reads the file attributes of the currently

selected file.

F-SELECT Initiator Conf. Selects an existing file and binds it to the

FTAM regime.

F-TERMINATE Initiator Conf. Gracefully dissolves an FTAM regime and

unbinds it from its association.

F-TRANSFER-END Initiator Conf. Confirms completion of a data transfer.

F-U-ABORT Initiator or

responder

Uncf. Dissolves unconditionally an FTAM

regime and its binding to an association.

F-WRITE Initiator Uncf. Initiates a bulk data transfer from the

initiator (in the role of sender) to the responder (in the role of receiver).

3_{For information on which services are supported, refer to the conformance statement in the Software} Product Description.

†Confirmed or unconfirmed.

When negotiating a service, FTAM entities exchange FTAM service primitives that carry FTAM PCI data as parameters. Some parameters carry association- specific information, such as the identities of the FTAM entities or action results. Other parameters carry protocol-specific information, such as the active values for file attributes and permitted filestore actions (both for the initiator and for concurrent users).

7.2.3.3 Relationship of Services to Regimes

Except for the grouping services, each service always occurs within a single type of regime. Furthermore, each constituent service of a regime occurs during a specific phase of the regime. The only other exceptions are the F-P-ABORT and F-U-ABORT services, which can occur at any time once the FTAM regime is established. Figure 7–7 shows the general relationship of services to their regimes.

7.2 Overview of FTAM Operation

Figure 7–7 Relationship of File Services to Regimes

Key:

FTAM regime File selection regime File open regime Data transfer regime

LKG−4447−90R F−INITIALIZE F−CREATE or F−SELECT F−READ−ATTRIBUTE or F−CHANGE−ATTRIBUTE F−DELETE or F−DESELECT F−OPEN F−ERASE or F−LOCATE F−CLOSE F−READ F−DATA F−DATA−END F−CANCEL F−TRANSFER−END

F−TERMINATE, F−P−ABORT, or F−U−ABORT

3 1 2 4 1 2 3 4

7.2.4 The FTAM File Protocol

The FTAM file protocol implements a series of operational rules that govern the FTAM communications and the operations of file services during an association. These rules are implemented by the FTAM protocol machine (FPM). Acting for an initiator, the FPM issues request service primitives, and acting for a responder, the FPM issues indication service primitives.

7.2 Overview of FTAM Operation

7.2.5 Summary of the FTAM Operation Overview

In summary, FTAM associations involve asymmetrical communication between two FTAM entities (an initiator and a responder). The initiator and responder implement the virtual-filestore and file-service models to communicate about and manipulate files. The basic elements of each model are as follows:

• Virtual-filestore model

The virtual-filestore model defines a hierarchical file model with its essential file structures and a set of possible filestore actions. Document types help FTAM entities communicate about file structures and filestore actions. • File-service model

The file-service model defines the available FTAM services, the service parameters carried by each service primitive, the sequencing of file services into standard regimes, and the activity attributes that dynamically describe the current conditions of a regime, a file, the virtual filestore, and the initiator.

• The file protocol

The file protocol defines the communications rules that permit the exchange of file information between open systems. These rules are implemented by software called the FTAM protocol machine (FPM).

The interplay among the elements of the virtual-filestore and file-service models and the protocol machines allows open systems to build common views of each other’s files and to act on each other’s files in controlled, mutually understood ways.

7.3 Overview of ACSE

The Association Control Service Element (ACSE) contributes to every FTAM entity. ACSE is a service provider to the FTAM service element. The ACSE protocol and services provide facilities for establishing and releasing associations between any application entities.

7.3.1 Establishing an Association

For each association, ACSE establishes an application context. An application

context is an explicitly identified set of one or more application service elements

(in this case, FTAM), related options, and any other necessary information or rules for an association.

When requesting an association, the FTAM protocol machine supplies the information that the FTAM regime requires. Using an association-establishment service (A-ASSOCIATE), ACSE passes this information down to the Presentation layer as user information in a connection request. Presentation then specifies it as user information to Session.

The resulting presentation and session connections have a one-to-one

correspondence to the association. A-ASSOCIATE also carries parameters that affect the behavior of Presentation and Session for the current connection. For example, A-ASSOCIATE negotiates which Session functional units are available during a connection.

7.3 Overview of ACSE

7.3.2 Terminating an Association

When the FTAM initiator issues an F-TERMINATE request, ACSE submits an A-RELEASE request to the Presentation release (P-RELEASE) service. This is a confirmed service. If the negotiated-release functional unit is negotiated, the acceptor can refuse the release. Data in transit is preserved.

7.3.3 ACSE Services

As a very specialized service element, ACSE has only four services, which deal exclusively with starting and stopping associations. Table 7–3 lists these services.

Table 7–3 ACSE Services

ACSE Service Type3 Explanation

A-ASSOCIATE Conf. Initiates an association by those application-service-element

(ASE) procedures identified by the application-context-name parameter; submits requests to the underlying presentation connection service (P-CONNECT).

A-RELEASE Conf. If successful, causes the completion of the use of an

association using those ASE procedures identified by the application context. Preserves the data during transit.

A-ABORT Uncf. Causes the abnormal release of the association with the

possible loss of information in transit; submits requests to the underlying presentation-user abort service (P-U- ABORT).

A-P-ABORT Uncf. Indicates the abnormal release of the association as a result

of action by the underlying presentation service with the possible loss of information in transit; receives indications from the underlying presentation-provider abort service (P-P-ABORT).

8