Zig

Azure Service Bus - Peek-Lock Message (Non-Destructive Read)

See more Azure Service Bus Examples

Shows how to atomically retrieve and lock a message from a queue or subscription for processing. The message is guaranteed not to be delivered to other receivers (on the same queue or subscription only) during the lock duration specified in the queue/subscription description.

For more information, see https://docs.microsoft.com/en-us/rest/api/servicebus/peek-lock-message-non-destructive-read

Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // Note: Requires Chilkat v9.5.0.65 or greater.

    // This requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // Make the initial connection.
    // A single REST object, once connected, can be used for many Azure Service Bus REST API calls.
    // The auto-reconnect indicates that if the already-established HTTPS connection is closed,
    // then it will be automatically re-established as needed.
    const rest = try chilkat.Rest.init();
    defer rest.deinit();
    const b_auto_reconnect = true;
    rest.connect("<yournamespace>.servicebus.windows.net", 443, true, b_auto_reconnect) catch {
        std.debug.print("{s}\n", .{try rest.getLastErrorText(alloc)});
        return;
    };

    // ----------------------------------------------------------------------------------------------
    // The code above this comment could be placed inside a function/subroutine within the application
    // because the connection does not need to be made for every request.  Once the connection is made
    // the app may send many requests..
    // ----------------------------------------------------------------------------------------------

    // Let's load a previously computed SAS token and use it.
    // See Azure Shared Access Signature for an example to genenerate an Azure SAS token.
    const sb_token = try chilkat.StringBuilder.init();
    defer sb_token.deinit();
    sb_token.loadFile("qa_data/tokens/serviceBusSas.txt", "utf-8") catch {};

    // Tell the REST object to use the Azure Shared Access Signature for authorization.
    sb_token.prepend("SharedAccessSignature ") catch {};
    rest.addHeader("Authorization", try sb_token.getAsString(alloc)) catch {};

    // ----------------------------------------------------------------------------------------------

    // Peek-lock a message from the subscription "feedings" in the topic "gilaMonster"
    const topic_name = "gilaMonster";
    const subscription_name = "feedings";

    // Build the path..
    const sb_path = try chilkat.StringBuilder.init();
    defer sb_path.deinit();
    sb_path.append("/") catch {};
    sb_path.append(topic_name) catch {};
    sb_path.append("/subscriptions/") catch {};
    sb_path.append(subscription_name) catch {};
    sb_path.append("/messages/head") catch {};

    // If peek-locking from a queue, the path would be built like this:
    const sb_queue_path = try chilkat.StringBuilder.init();
    defer sb_queue_path.deinit();
    sb_queue_path.append("/") catch {};
    sb_queue_path.append("queueName") catch {};
    sb_queue_path.append("/messages/head") catch {};
    // This example will use the sbPath..

    // Add a timeout parameter.
    rest.addQueryParam("timeout", "20") catch {};

    // Use the POST HTTP verb to peek-lock the message.
    // Note that the only difference between the destructive Read-and-Delete and the non-destructive Peek-Lock
    // is that the HTTP verb.  (POST is for peek-lock, DELETE is fore read-and-delete.)
    const sb_response_body = try chilkat.StringBuilder.init();
    defer sb_response_body.deinit();
    rest.fullRequestNoBodySb("POST", try sb_path.getAsString(alloc), sb_response_body) catch {
        std.debug.print("{s}\n", .{try rest.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("Response Status Code = {d}\n", .{rest.getResponseStatusCode()});

    // Check for a success response.
    // CAREFUL: This returns a 201 response instead of a 200 response.  In general, either 200 or 201 should always indicate success.
    if (rest.getResponseStatusCode() != 201) {
        std.debug.print("{s}\n", .{try rest.getLastRequestStartLine(alloc)});
        std.debug.print("{s}\n", .{try rest.getLastRequestHeader(alloc)});
        std.debug.print("{s}\n", .{try sb_response_body.getAsString(alloc)});
        std.debug.print("Failed.\n", .{});
        return;
    }

    // The content of the message is returned in the HTTP response body.
    // The HTTP response headers contains extra information.  For example:
    const json_broker_props = try chilkat.JsonObject.init();
    defer json_broker_props.deinit();
    json_broker_props.load(try rest.responseHdrByName(alloc, "BrokerProperties")) catch {};
    json_broker_props.setEmitCompact(false);
    std.debug.print("{s}\n", .{try json_broker_props.emit(alloc)});

    // An example of the BrokerProperties JSON that is returned:

    //     {
    //       "DeliveryCount": 2,
    //       "EnqueuedSequenceNumber": 3000003,
    //       "EnqueuedTimeUtc": "Wed, 07 Dec 2016 17:42:48 GMT",
    //       "Label": "M2",
    //       "LockToken": "0a13ee8a-be32-4458-89e0-5e1401caa6a0",
    //       "LockedUntilUtc": "Wed, 07 Dec 2016 18:13:12 GMT",
    //       "MessageId": "7bea513a6ddb49089e07bfbee26d85bd",
    //       "SequenceNumber": 3,
    //       "State": "Active",
    //       "TimeToLive": 922337203685.47754
    //     }

    // Also the "Location" response header contains the URI of the locked message.
    // This can be used to ulock or delete the message.
    std.debug.print("Location: {s}\n", .{try rest.responseHdrByName(alloc, "Location")});

    // An example of the Location URI:
    // https://chilkat.servicebus.windows.net/gilamonster/subscriptions/feedings/messages/3/0a13ee8a-be32-4458-89e0-5e1401caa6a0

    // If successful, the message is the contents of the response body.
    const message = try sb_response_body.getAsString(alloc);
    std.debug.print("Received message: {s}\n", .{message});

    std.debug.print("Success.\n", .{});
}