# TSHttpTxnParentSelectionUrlSet¶

Traffic Server Parent Selection consistent hash URL manipulation API.

## Synopsis¶

#include <ts/ts.h>

TSReturnCode TSHttpTxnParentSelectionUrlSet(TSHttpTxn txnp, TSMBuffer bufp, TSMLoc offset)
TSReturnCode TSHttpTxnParentSelectionUrlGet(TSHttpTxn txnp, TSMBuffer bufp, TSMLoc offset)

## Description¶

The Parent Selection consistent hash feature selects among multiple parent caches based on hashing a URL (the HTTP request header URL).

These API functions allow an over-ride URL to be defined such that the over-ride URL is hashed instead of the normal (header request) URL. In addition, any filtering options that may be applied to the normal URL (such as qstring) are NOT applied to the over-ride URL since it is assumed that custom filtering has already been performed prior to explicitly setting the over-ride URL.

Note that the normal URL is only hashed on the path and query string portion (optionally excluded with the qstring option). However, the over-ride URL is hashed on the entire URL string as returned by URL::string_get_ref(). This includes the scheme and hostname such as “http://hostname” which occur prior to the path.

If the non-path URL elements should not be hashed in a meaningful manner, then they should be normalized to some value (if they are required in a valid URL) or excluded (if they are optional) when generating the over-ride URL. For example, since the over-ride URL is arbitrary, the URL scheme and hostname can simply be set to “fake://fake.fake” when creating the over-ride URL.

TSHttpTxnParentSelectionUrlSet() will set the over-ride URL.

TSHttpTxnParentSelectionUrlGet() will get the over-ride URL.

## Return Values¶

All these APIs returns a TSReturnCode, indicating success (TS_SUCCESS) or failure (TS_ERROR) of the operation.