7.2 Transactions

The following transactions are used to provide communications between actors in accordance with one or more of the DICOM Configuration protocols.

Configure DHCP Server

This transaction changes the configuration on a DHCP server to reflect additions, deletions, and changes to the IP parameters that have been established for this network.

Find and Use DHCP Server

This transaction is a sequence of network messages that comply with the rules of the DHCP protocol. It allows a DHCP client to find available DHCP servers and select the server appropriate for that client. This transaction obtains the mandatory IP parameter information from the DHCP server and obtains additional optional parameters from the DHCP server.

Configure Client

The service staff uses this transaction to set the initial configuration for a client.

Maintain Lease

This transaction deals with how the DHCP client should behave when its IP lease is not renewed.

DDNS Coordination

This transaction documents whether the DHCP server is coordinating with a DNS server so that access to the DHCP client can be maintained using the hostname assigned to the DHCP client.

Resolve Hostname

This transaction obtains the IP address for a computer when given a hostname.

Maintain Time

These transactions are the activities needed for an NTP or SNTP client to maintain time synchronization with a master time service.

Find NTP Server

This transaction is the autodiscovery procedure defined for NTP. This may use either a broadcast method or a DHCP supported method.

Find LDAP Server

In this transaction the DNS server is queried to obtain the IP address, port, and name of the LDAP server.

Query LDAP Server

In this transaction the LDAP server is queried regarding contents of the LDAP database.

Client Update LDAP Server

This transaction updates the configuration database using LDAP update instructions from the client being configured.

Maintain LDAP Server

This transaction updates the configuration database using local services of the LDAP server.

Figure 7.1-1 shows the actors and their transactions. The usual device will have an NTP Client, DHCP Client, and LDAP client in addition to the other applications actors. The transactions “Configure DHCP Server”, “Configure Client”, and “Maintain LDAP Server” are not shown because these transactions are between a software actor and a human actor. DICOM does not specify the means or user interface. It only requires that certain capabilities be supported.


Figure 7.1- 1 Transactions and Actors