Paho-C for OpenVMS Alpha and Integrity

This document serves as the guide for installing and configuring the Paho-C MQTT client API on OpenVMS (Alpha and Integrity platforms). It covers:

• Introduction: Describes the Paho-C MQTT client API and its publish-subscribe messaging model.
• Requirements: Lists necessary software versions, including OpenVMS 8.4-1H1 or above, supported TCP/IP stacks, and VSI C compiler.
• Installation: Provides the PCSI installation command (PRODUCT INSTALL PAHO_C) and post-installation steps for system-wide configuration.
• Post-Installation: Details logical name definitions, privileges, and alternative installation locations.
• Usage: Provides guidance on linking applications (synchronous/asynchronous APIs with or without SSL/TLS) and points to provided example programs.

The release includes a bug fix for network write operations when using high maxInflightMessages values and utilizes OpenSSL 1.1.1g.