Maintaining persistence of a messaging system

A system, comprising:

• one or more computer processors programmed to perform operations to:
• identify a first message in a first channel of a plurality of channels corresponding to a position in the first channel,
• wherein the first message is stored in a buffer having a time-to-live that has expired;
• send a request for messages beginning at the position to one or more client devices that subscribe to the first channel;
• receive, from at least one client device, a response message comprising one or more messages of the first channel that are at or after the position;
• retrieve messages for the first channel from one or more buffers of the first channel having time-to-lives that have not expired;
• and
• combine the retrieved messages and the messages from the response message.

A non-transitory computer-readable medium having instructions stored thereon that, when executed by one or more computer processors, cause the one or more computer processors to:

• identify a first message in a first channel of a plurality of channels corresponding to a position in the first channel,
• wherein the first message is stored in a buffer having a time-to-live that has expired;
• send, by one or more computer processors, a request for messages beginning at the position to one or more client devices that subscribe to the first channel;
• receive, from at least one client device, a response message comprising one or more messages of the first channel that are at or after the position;
• retrieve messages for the first channel from one or more buffers of the first channel having time-to-lives that have not expired;
• and
• combine, by the one or more computer processors, the retrieved messages and the messages from the response message.