Hooks and Transactions

This chapter contains the following sections:

• Adding Hooks
• Intercepting HTTP Transactions
• HTTP Alternate Selection
• • TLS Hooks
  • TS_SSL_SERVERNAME_HOOK
  • TS_SSL_VERIFY_CLIENT_HOOK
  • TLS Hook State Diagram
• Utility Functions

To understand hooks and transactions, you should be familiar with the following terminology:

Traffic Server uses HTTP state machines to process transactions. The state machines follow a complex set of states involved in sophisticated caching and document retrieval (taking into account, for example, alternate selection, freshness criteria, and hierarchical caching). The Traffic Server API provides hooks to a subset of these states, as illustrated in the below.

The two transform hooks, and TS_HTTP_RESPONSE_TRANSFORM_HOOK, are called in the course of an HTTP transform. To see where in the HTTP transaction they are called, look for the “set up transform” ovals in the HTTP Transaction State Diagram below.

For an overview of HTTP transaction timers, refer to the transaction timer diagram below.