A cassandra cluster must always use the same rpc port default 9160
On Friday, September 6, 2013, Paul LeoNerd <leon...@leonerd.org.uk> wrote: > I'm trying to work out how a client is best to maintain a list of what > nodes are available in the cluster, for maintaining connections to. > > I understand the general idea is to query the "system.peers" table, and > REGISTER an interest in TOPOLOGY_CHANGE and STATUS_CHANGE messages to > watch for nodes being added/removed or becoming unavailable/available. > So far so good. > > A few details of this seem a bit awkward though: > > * The "system.peers" table identifies peers only by their IP address, > not including the port number, whereas TOPOLOGY and STATUS_CHANGE > messages include a port. > > What happens if there is more than one copy of a node using the same > IP address? How do I know which TCP port I can use to communicate > CQL with a given peer? > > * The "system.peers" table doesn't contain any information giving the > current availability status of the nodes, so I don't know if they > are initially up or down. > > I can just presume all the known nodes are up until I try connecting > to them - in any case, it could be that Cassandra knows of the > existence of nodes that for some reason my client can't connect to, > so I'd have to handle this case anyway. But it feels like that hint > should be there somewhere. > > * The "system.peers" table doesn't include the actual node I am > querying it on. > > Most of the missing information does appear in the "system.local" > table, but not the address. The client does know /an/ address it has > connected to that node using, but how can I be sure that this > address is the one that will appear in the "peers" list on other > nodes? It's quite common for a server to have multiple addresses, so > it may be that I've connected to some address different to that > which the other nodes know it by. > > I'm quite new to Cassandra, so there stands a chance I've overlooked > something somewhere. Can anyone offer any comment or advice on these > issues, or perhaps point me in the direction of some client code that > manages to overcome them? > > Thanks, > > -- > Paul "LeoNerd" Evans > > leon...@leonerd.org.uk > ICQ# 4135350 | Registered Linux# 179460 > http://www.leonerd.org.uk/ >
