# Exchange Wire Caching


## Issue Summary

When demoing Taler to an audience, sometimes withdrawing or other operations
fail.  This can happen even with a fresh wallet.


## Root Cause

The browser caches the /keys and /wire response for a long time, even when the
wallet is re-installed.

Usually the cache expiration is set to when available denominations or signing
keys are expected to change.  This can be a rather long time.  We often have format changes
or re-deploys with different keys in-between.

## Remediation and Prevention

For demo and test, the exchange shall use shorter expiration times.
(https://bugs.gnunet.org/view.php?id=5747)

To force re-downloading of the exchange's information, we will implement
a client-version parameter to break the browser's cache.
(https://bugs.gnunet.org/view.php?id=5745)

## Discussion