Component bmqt_messageguid [Package bmqt]

Provide a value-semantic global unique identifier for BlazingMQ. More...

Namespaces
namespace	bmqt

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Detailed Description

Outline

• Purpose
• Classes
• Description
  • Externalization
  • Efficient comparison and hash function
    • Example 1: Externalizing

Purpose:

Provide a value-semantic global unique identifier for BlazingMQ messages.

Classes:

bmqt::MessageGUID

Value-semantic global unique ID for BlazingMQ

message bmqt::MessageGUIDLess : Binary function for comparing GUIDs. bmqt::MessageGUIDHashAlgo : Provide a hashing algorithm for Message GUID.

Description:

bmqt::MessageGUID provides a value-semantic global unique identifier for BlazingMQ messages. Each bmqa::Message delivered to BlazingMQ client from BlazingMQ broker contains a unique MessageGUID. The binary function bmqt::MessageGUIDLess can be used for comparing GUIDs, and an optimized custom hash function is provided with bmqt::MessageGUIDHashAlgo.

Externalization:

For convenience, this class provides toHex method that can be used to externalize a bmqt::MessageGUID instance. Applications can persist the resultant buffer (on filesystem, in database) to keep track of last processed message ID across task instantiations. fromHex method can be used to convert a valid externalized buffer back to a message ID.

Efficient comparison and hash function:

This component also provides efficient comparison and hash functions for convenience, and thus, applications can use this component as a key in associative containers.

Example 1: Externalizing:

  // Below, 'msg' is a valid instance of 'bmqa::Message' obtained from an
  // instance of 'bmqa::Session':

  bmqt::MessageGUID g1 = msg.messageId();

  char buffer[bmqt::MessageGUID::e_SIZE_HEX];
  g1.toHex(buffer);

  BSLS_ASSERT(true == bmqt::MessageGUID::isValidHexRepresentation(buffer));

  bmqt::MessageGUID g2;
  g2.fromHex(buffer);

  BSLS_ASSERT(g1 == g2);