[jira] [Assigned] (CAMEL-25523) camel-slack - the consumer skips messages when more than maxResults messages are posted between two polls

["shashank (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CAMEL-25523?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

shashank reassigned CAMEL-25523:
--------------------------------

    Assignee: shashank

> camel-slack - the consumer skips messages when more than maxResults messages are posted between two polls
> ---------------------------------------------------------------------------------------------------------
>
>                 Key: CAMEL-25523
>                 URL: https://issues.apache.org/jira/browse/CAMEL-25523
>             Project: Camel
>          Issue Type: Bug
>          Components: camel-slack
>            Reporter: shashank
>            Assignee: shashank
>            Priority: Major
>
> {{SlackConsumer.poll()}} (lines 75-94 at main a6979506bb1c) makes one {{conversations.history}} request with {{oldest}} set to the timestamp of the last consumed message and {{limit}} set to {{maxResults}} (default 10), routes the messages of that response and sets the timestamp to the first of them ({{createExchanges}}, lines 96-123):
> {code:java}
> ConversationsHistoryResponse response = slack.methods(token).conversationsHistory(req -> req
>         .channel(channelId)
>         .oldest(timestamp)
>         .limit(timestamp != null ? Integer.parseInt(slackEndpoint.getMaxResults()) : 1));
> ...
> Queue<Exchange> exchanges = createExchanges(response.getMessages());
> {code}
> Slack returns "the most recent messages in the time range first" and at most {{limit}} of them; when there are more, {{has_more}} is true and {{response_metadata.next_cursor}} points to the following, older, page. The consumer ignores both. So when more than {{maxResults}} messages are posted to the channel between two polls (default delay 10 seconds), it routes the {{maxResults}} most recent ones, moves the timestamp past the others, and never consumes them. Nothing is logged. With the docs example {{maxResults=1}}, any two messages posted within one poll interval lose one of them. The docs say the consumer "will consume only newer messages in the channel", i.e. all of them.
> h3. Reproduction
> New {{SlackConsumerHasMoreTest}}: a local HTTP server answers {{conversations.list}} and {{conversations.history}} as Slack does ({{oldest}} exclusive, most recent first, {{limit}} per page, {{has_more}} and {{next_cursor}}), via the {{serverUrl}} option. The route uses {{maxResults=2}}; after the first poll has routed the last message of the history, five messages are posted at once. On main both tests (default order and {{naturalOrder=true}}) fail twice:
> {noformat}
> mock://result Received message count. Expected: <5> but was: <2>
> {noformat}
> h3. Proposed fix
> When a poll that follows the first one gets {{has_more}}, the consumer reads the following pages with {{next_cursor}} (same {{limit}}) in the same poll and routes all the messages, in the same order as before (most recent first, or oldest first with {{naturalOrder}}); the timestamp is still the most recent message. A poll with no more than {{maxResults}} new messages sends the same single request as before, and the first poll (which reads the last message of the history) is unchanged. A poll can now route more than {{maxResults}} messages; the option description, the component docs (and the catalog copies) say that {{maxResults}} is the number of messages per request, and the 4.23 upgrade guide has a note (raise {{maxResults}} for a busy channel to need fewer requests). camel-slack tests with the fix: 8, 0 failures (1 skipped, needs a Slack token).
> Found with a Lean 4 model of the poll (a channel as a list of increasing timestamps, the API as "after oldest, most recent first, limit per page"): "a poll routes every message newer than the timestamp" fails for five new messages and {{limit}} 2, and with {{limit}} 1 the second of two messages is never routed by any later poll; main is proved to route at most {{limit}} messages (so it misses some whenever more are new). The fix is proved to route exactly the new messages for every channel, timestamp and {{maxResults}} >= 1, and to send the same single request as main when no more than {{maxResults}} messages are new. Confirmed with the real consumer.
> Affected: main, camel-4.22.x, camel-4.18.x, camel-4.14.x (same code, GitHub contents API).
> Duplicate check (2026-10-10): JIRA text "slack" and "consumer" (17, none about skipped messages; CAMEL-18187 is about pooled exchanges, CAMEL-12806 about an empty list), "conversations.history" (none); GitHub pull requests "SlackConsumer" (3, none related), "slack consumer" (none). No open pull request changes {{SlackConsumer}}.
> _Filed with Claude Code on behalf of allthingssecurity._



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