This chapter defines abstract messages for the purpose of communicating various events related to the scheduling of appointments for services or for the use of resources. There are three basic types of messages defined in this transaction set: request transactions and their responses, query transactions and their responses, and unsolicited transactions and their responses. Request transactions communicate requests for the scheduling of appointments for services or for the use of resources. These transactions occur between placer (requesting) applications and filler (processing) applications. The query and unsolicited transaction sets provide for the exchange of scheduling information between systems. The exchange of this information is achieved either actively or passively. The active gathering of scheduling information is performed by issuing query transactions to a filler application from a querying application. The passive gathering of this information is performed by accepting unsolicited transactions issued by a filler application.
This chapter describes various roles under which applications might operate. The roles discussed in this chapter illustrate the underlying model used to develop this specification. They do not imply the need for a particular application model or method of implementation.
This chapter defines the transactions at the seventh level, that is, the abstract message. Various schemes are used to generate the actual characters that comprise the messages according to the communication environment. The HL7 Encoding Rules will be used where there is not a complete Presentation Layer. This is described in Chapter 1, "Relationship to Other Protocols." The examples included in this chapter were constructed using the HL7 Encoding Rules.