Chapter 14 - AppleTalk Transaction Protocol (ATP)
This chapter describes how Open Transport implements the AppleTalk Transaction Protocol (ATP). It explains how you can use ATP to send requests and responses between ATP endpoints, with one endpoint initiating the request and the other responding to it. You can create an endpoint that can both initiate or respond, or you can create one endpoint that only makes requests and another that only makes responses. Because ATP provides a connectionless transaction-based service, you do not incur the overhead entailed in establishing, maintaining, and breaking a connection that is associated with connection-oriented protocols, such as ADSP, but you can transfer only a limited amount of data using ATP.You should read this chapter if you want to write an application that requires reliable delivery of data but does not require the transfer of a large amount of data. This chapter explains how you
This chapter begins with a description of ATP and the services that it provides under Open Transport. The section "Using Open Transport Functions With ATP" then gives detailed information about how ATP client applications use the endpoint functions that Open Transport provides for connectionless transaction-based protocols. For a more detailed explanation of endpoints and their functions, read the chapter "Endpoints" in this book.
- open and bind an ATP endpoint
- get information about an ATP endpoint
- use Open Transport functions to initiate and respond to a transaction
- specify ATP options to control connectionless transaction-based services
For an overview of ATP and how it fits within the AppleTalk protocol stack, read the chapter "Introduction to AppleTalk" in this book, which also introduces and defines some of the terminology used in this chapter. For a complete explanation of the ATP specification, see Inside AppleTalk, second edition.
Chapter Contents
- About ATP
- Using ATP
- At-Least-Once and Exactly-Once Transactions
- Sending and Receiving ATP Data
- Specifying ATP Options
- The Retry Count and Interval Options
- The Release Timer Option
- Other ATP-Specific Options
- Using the ATP Packet Header User Bytes
- Using General Open Transport Functions with ATP
- OTSndURequest
- OTRcvURequest
- OTSndUReply
- OTRcvUReply
- ATP Reference
- Options