Multicast cluster servicer for communicating amongst a plurality of nodes without a dedicated local area network

An apparatus comprising:

• at least one processor;
• a memory coupled to at least one processor;
• a cluster communication servicer residing in said memory, said cluster communication servicer including:
• a group send mechanism for sending group messages to predefined groups of nodes in a cluster, wherein the group send mechanism delivers group messages to a send queue corresponding to a specified group of nodes, the message queue sending the group message to the specified group of nodes in the cluster by sending a multicast message to members of the specified group of nodes on a local subnet and sending a point to point messages to a relay node for members of the specified group of nodes in the cluster on non local subnets;
• and
• a plurality of node objects for receiving messages from other nodes in the cluster and delivering the received message to a client, and wherein the plurality of node objects include a plurality of receive next parameters, with each of the plurality of receive next parameters indicating a sequence number for a next message to be received for a corresponding message queue such that the plurality of node objects will not redeliver a received message that has been previously delivered by the node object.

A method for sending a group message from a sending node to a group of nodes in a cluster, the method comprising the steps of:

• sending a multicast message to members of the group in a local subnet, the multicast message comprising a UDP/IP multicast message specifying a UDP multicast address;
• sending a point to point message to a relay node on a non-local subnet that include members of the group;
• and
• sending a multicast message from the relay node on the non-local subnets to other members on the non-local subnet.

A method for sending a group message from a sending node to a specified group of nodes in a cluster, the method comprising the steps of:

• enqueing the group message onto a message queue for the specified group of nodes in the cluster;
• sending a multicast message to members of the specified group in a local subnet by specifying a UDP multicast address for the specified group;
• sending a point to point message to a relay node on a non-local subnet that include members of the group by specifying an IP address of the relay node;
• sending a multicast message from the relay node on the non-local subnets to other members on the non-local subnet by specifying the UDP multicast address for the specified group;
• sending an acknowledgment message to the sending node from each node in the group receiving the group message;
• and
• waiting to send a next group message from the sending queue until the acknowledgment message from each group node is received by the sending node.

A program product comprising:

• (A) a cluster communication servicer, said cluster communication servicer including:
• a group send mechanism for sending group messages to predefined groups of nodes in a cluster, wherein the group send mechanism delivers group messages to a send queue corresponding to a specified group of nodes, the message queue sending the group message to the specified group of nodes in the cluster by sending a multicast message to members of the specified group of nodes on a local subnet and sending a point to point messages to a relay node for members of the specified group of nodes in the cluster on non local subnets;
• and
• a plurality of node objects for receiving messages from other nodes in the cluster and delivering the received message to a client, and wherein the plurality of node objects include a plurality of receive next parameters, with each of the plurality of receive next parameters indicating a sequence number for a next message to be received for a corresponding message queue such that the plurality of node objects will not redeliver a received message that has been previously delivered by the node object;
• and
• (C) signal bearing media bearing said cluster communication servicer.