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The Zotonic task queue lets applications perform tasks asynchronously.<\/p>\n

Let’s say you have some external HTTP API that you want to update whenever\na resource in Zotonic is changed. You can so by queuing an task after each\nresource update. The HTTP request to the external API will be executed\nasynchronously, so you application and its users do not have have to wait for\nit.<\/p>\n

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Add a task to the queue<\/h2>\n

To add a task to the queue, provide a module and function that should be called\nwhen the task is popped from the queue. So to add a task that will call the\nexternal_api_client:update_external_rsc()<\/span><\/code> as a callback function:<\/p>\n

<\/span>z_pivot_rsc<\/span>:<\/span>insert_task<\/span>(<\/span>\n    external_api_client<\/span>,<\/span>\n    update_external_rsc<\/span>,<\/span>\n    Context<\/span>\n).<\/span>\n<\/pre><\/div>\n<\/div>\n
You can also supply arguments that will be passed to the function. So to have\nexternal_api_client:update_external_rsc(RscId)<\/span><\/code> called:<\/p>\n
<\/span>RscId<\/span> =<\/span> 123<\/span>,<\/span>\nz_pivot_rsc<\/span>:<\/span>insert_task<\/span>(<\/span>\n    external_api_client<\/span>,<\/span>\n    update_external_rsc<\/span>,<\/span>\n    undefined<\/span>,<\/span>\n    [<\/span>RscId<\/span>]<\/span>\n    Context<\/span>\n).<\/span>\n<\/pre><\/div>\n<\/div>\n
If you want to queue the task whenever a resource is changed, add this code\nto an rsc_update_done<\/span><\/a> observer in your site module<\/span><\/a>:<\/p>\n
<\/span>%% yoursite.erl<\/span>\nmodule<\/span>(<\/span>yoursite<\/span>).<\/span>\n\n-<\/span>export<\/span>([<\/span>\n    observe_rsc_update_done<\/span>\/<\/span>2<\/span>\n]).<\/span>\n\nobserve_rsc_update_done<\/span>(<\/span>#rsc_update_done<\/span>{<\/span>id<\/span> =<\/span> RscId<\/span>},<\/span> Context<\/span>)<\/span> -><\/span>\n    z_pivot_rsc<\/span>:<\/span>insert_task<\/span>(<\/span>\n        external_api_client<\/span>,<\/span>\n        update_external_rsc<\/span>,<\/span>\n        undefined<\/span>,<\/span>\n        [<\/span>RscId<\/span>]<\/span>\n        Context<\/span>\n    ).<\/span>\n<\/pre><\/div>\n<\/div>\n<\/div>\n
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Execute queued tasks<\/h2>\n