Sticky site masters ------------------- Key: JGRP-2112 URL: https://issues.jboss.org/browse/JGRP-2112 Project: JGroups Issue Type: Feature Request Reporter: Bela Ban Assignee: Bela Ban Fix For: 3.6.12, 4.0 If members in one site send messages to site masters of other sites, if we have multiple site masters, then reordering can occur. Example: * Member C in site LON sends messages C1 and C2 to site NYC * C1 picks SM1 and C2 picks SM2 * Although site masters process messages in delivery order, because C1 and C2 travel through different site masters, C2 could pass C1, leading to ordering issues h4. Design * When sending a message to the one of the site masters of the current site, or from a site master to a remote site master, we invoke a callback to pick the site master based on the original caller * Note that this only applies when we have more than one site master. * The callback passes the address of the original caller and the list of available site masters, and needs to return a site master h5. Transactions * Transactions by different originators with overlapping key sets cannot be reliably ordered * Transactional support therefore requires single site masters * This should not be an issue as transactions bundle multiple updates, so the number of messages sent is less than non-transactional updates