Virtual application delivery chassis system

A computer program product comprising a non-transitory computer readable storage medium having a computer readable program, wherein the computer readable program when executed on one or more computers causes the computers to:

• (a) send, by each blade of a plurality of blades of a virtual application distribution chassis, a virtual application distribution chassis message to each of the other blades in the virtual application distribution chassis;
• (b) determine by each blade whether the virtual application distribution chassis message was received from a master blade within a predetermined period of time;
• (c) in response to determining that the virtual application distribution chassis message was not received from the master blade within the predetermined period of time, send a master claim message by each blade to each of the other blades in the virtual application distribution chassis, each master claim message comprising a blade priority and a blade identity for the sending blade;
• (d) determine by each blade receiving the master claim messages whether any of the blade priorities obtained from the received master claim messages is higher than the blade priority of the receiving blade, comprising:
• (d1) determine by a given receiving blade that a blade priority obtained from a given master claim message is equal to a blade priority of the given receiving blade;
• and
• (d2) in response to determining that the blade priority obtained from the given master claim message is equal to the blade priority of the given receiving blade, determine whether the blade identity obtained from the given master claim message is numerically smaller than a blade identity of the given receiving blade;
• and
• (d3) in response to determining that the blade identity obtained from the given master claim message is numerically smaller than the blade identity of the given receiving blade, repeat the determine (d1) and the determine (d2) with another received master claim message;
• (e) in response to determining that the blade identity of the given receiving blade is numerically smaller than the blade identities obtained from each of the other received master claim messages, set a status of the given receiving blade to a new master blade;
• (f) in response to setting the status of the given receiving blade to the new master blade, send by the given receiving blade a second virtual application distribution chassis message to the other blades in the virtual application distribution chassis, the second virtual application distribution chassis message indicating the status of the new master blade of the given receiving blade;
• (g) assign a first blade of the plurality of blades as an active blade to a virtual address, and assigning a second blade of the plurality of blades as a backup blade to the virtual address, wherein the plurality of blades are operatively coupled as the virtual application distribution chassis within a data network, the data network comprising a network switch, wherein service requests destined for the virtual address are sent to the first blade by the network switch;
• (h) determine by each blade that the virtual application distribution chassis message was not received from the first blade within the predetermined period of time;
• (i) in response to determining that the virtual application distribution chassis message was not received from the first blade within the predetermined period of time, change a status of the second blade to the active blade for the virtual address;
• and
• (j) send a virtual address change message to the network switch to inform the network switch to send future service requests destined for the virtual address to the second blade.

A system, comprising:

• a plurality of blades operatively coupled as a virtual application distribution chassis within a data network, wherein each blade comprises a processor and a computer readable storage medium having a computer readable program, the computer readable program when executed by the processor causes the plurality of blades to:
• (a) send by each blade a virtual application distribution chassis message to each of the other blades in the virtual application distribution chassis;
• (b) determine by each blade whether the virtual application distribution chassis message was received from a master blade within a predetermined period of time;
• (c) in response to determining that the virtual application distribution chassis message was not received from the master blade within the predetermined period of time, send a master claim message by each blade to each of the other blades in the virtual application distribution chassis, each master claim message comprising a blade priority and a blade identity for the sending blade;
• (d) determine by each blade receiving the master claim messages whether any of the blade priorities obtained from the received master claim messages is higher than the blade priority of the receiving blade, comprising:
• (d1) determine by a given receiving blade that a blade priority obtained from a given master claim message is equal to a blade priority of the given receiving blade;
• and
• (d2) in response to determining that the blade priority obtained from the given master claim message is equal to the blade priority of the given receiving blade, determine whether the blade identity obtained from the given master claim message is numerically smaller than a blade identity of the given receiving blade;
• and
• (d3) in response to determining that the blade identity obtained from the given master claim message is numerically smaller than the blade identity of the given receiving blade, repeat the determine (d1) and the determine (d2) with another received master claim message;
• (e) in response to determining that the blade identity of the given receiving blade is numerically smaller than, the blade identities obtained from each of the other received master claim messages, set a status of the given receiving blade to a new master blade;
• (f) in response to setting the status of the given receiving blade to the new master blade, send by the given receiving blade a second virtual application distribution chassis message to the other blades in the virtual application distribution chassis, the second virtual application distribution chassis message indicating the status of the new master blade of the given receiving blade;
• (g) assign a first blade of the plurality of blades as an active blade to a virtual address, and assigning a second blade of the plurality of blades as a backup blade to the virtual address, wherein the plurality of blades are operatively coupled as the virtual application distribution chassis within a data network, the data network comprising a network switch, wherein service requests destined for the virtual address are sent to the first blade by the network switch;
• (h) determine by each blade that the virtual application distribution chassis message was not received from the first blade within the predetermined period of time;
• (i) in response to determining that the virtual application distribution chassis message was not received from the first blade within the predetermined period of time, change a status of the second blade to the active blade for the virtual address;
• and
• (j) send a virtual address change message to the network switch to inform the network switch to send future service requests destined for the virtual address to the second blade.