Home
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running QNX Neutrino 7.1.
OS Components & Operations
Persistent Publish/Subscribe Developer's Guide
Objects and Their Attributes
The QNX Neutrino PPS service is a system with objects whose properties a publisher can modify.
Object files
PPS objects are implemented as files in a special PPS filesystem. By default, PPS objects appear under /pps, but this path depends on the -m option used when you start pps. There's never more than one instance of a PPS object, so changes to that object are immediately visible to subscribers.
Object and directory sizes

QNX Momentics IDE User's Guide
This User's Guide describes version 7.1 of the Integrated Development Environment (IDE) that's part of the QNX Momentics tool suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running QNX Neutrino 7.1.
- Quickstart Guide
- OS Components & Operations
  - Adaptive Partitioning User's Guide
  - Boot Optimization Guide
    The Boot Optimization Guide describes techniques you can use to reduce the time from your board's initial power on until you have a fully functional QNX system running on the board.
  - Building Embedded Systems
    The Building Embedded Systems guide is intended for developers who are developing or building BSPs for QNX Neutrino RTOS embedded systems.
  - Core Networking Stack User's Guide
    This guide introduces you to the QNX Neutrino Core Networking stack and its manager, io-pkt.
  - Customizing a BSP
    While QNX provides Board Support Packages (BSPs) for many common platforms and their individual variants, in some cases, you need a BSP for a board that QNX does not provide. If this is the case, you can modify a QNX BSP or develop your own.
  - Device Publishers Developer's Guide
  - High Availability Framework Developer's Guide
  - High-Performance Networking Stack (io-sock) User's Guide
    This guide contains instructions for implementing and using the QNX Neutrino High-Performance Networking Stack and its manager, io-sock.
  - Instant Device Activation
  - Migrating to QNX SDP 7.1
  - PCI Server User's Guide
  - Persistent Publish/Subscribe Developer's Guide
    - QNX Neutrino PPS Service
      The QNX Neutrino Persistent Publish/Subscribe (PPS) service is a small, extensible publish and subscribe service that offers persistence across reboots. It's designed to provide a simple and easy-to-use solution for both publish/subscribe and persistence in embedded systems, answering a need for building loosely connected systems using asynchronous publications and notifications.
    - Objects and Their Attributes
      The QNX Neutrino PPS service is a system with objects whose properties a publisher can modify.
      - Object files
        PPS objects are implemented as files in a special PPS filesystem. By default, PPS objects appear under /pps, but this path depends on the -m option used when you start pps. There's never more than one instance of a PPS object, so changes to that object are immediately visible to subscribers.
        Special objects
        Object and directory sizes
      - Change notification
        PPS informs publishers and subscribers when it creates, deletes, or truncates an object.
      - Object syntax
        In listings of the PPS filesystem, PPS objects have no special identifiers. That is, they will appear just like any other file in a listing. For example, the PPS object "PlayCurrent" in the directory /pps/media will appear in a file listing as simply /pps/media/PlayCurrent.
      - Attribute syntax
        PPS objects have user-defined attributes. Attributes are listed in a PPS object after the object name.
    - Persistence
    - Publishing
    - Subscribing
      PPS clients can subscribe to multiple objects, and PPS objects can have multiple subscribers. When a publisher changes an object, all clients subscribed to that object are informed of the change.
    - Options and Qualifiers
    - Server Objects
    - PPS Encoding and Decoding API
      The PPS encoding and decoding API makes it easy to encode and decode complex data structures such as arrays and objects in PPS attributes and to ensure attributes are properly typed.
    - PPS API reference
      This chapter describes the publicly visible PPS API functions and data types.
    - Examples
  - Platform-independent Publish/Subscribe Developer's Guide
    This guide is intended for application developers who want to use the Platform-independent Publish Subscribe (PiPS) framework to exchange information with other applications. First, the overall PiPS design and data-exchange model are explained. Then, tutorials on using PiPS are given. These tutorials cover key tasks such as selecting a publish-subscribe provider to use and writing plugins that read and write custom data types.
  - QDB Developer's Guide
  - QNX Helpers Developer's Guide
    These libraries provide QNX helpers, including helpers that assist with logging, string conversion, and number and type sizes.
  - SMMUMAN User's Guide
  - System Analysis Toolkit (SAT) User's Guide
  - System Architecture
    The System Architecture guide accompanies the QNX Neutrino RTOS and is intended for both application developers and end-users.
  - Technotes
  - User's Guide
    The QNX Neutrino User's Guide is intended for all users of a QNX Neutrino RTOS system, from system administrators to end users.
- Audio & Graphics API
- Multimedia
- Networking Middleware
- Programming
- Sensor Framework
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX Neutrino RTOS system and developers who want to create a QNX Neutrino resource manager free from vulnerabilities.
- Utilities & Libraries
QNX Hypervisor
The QNX Hypervisor allows you to run multiple OSs on a target system so you can separate critical and non-critical functions, support a wide variety of applications, and reduce hardware costs.
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX software in Amazon Web Services (AWS) and Microsoft Azure (Azure).
QNX Advanced Virtualization Frameworks User's Guide
This User's Guide is aimed at all systems integrators and developers who want to design and build embedded systems using the QNX Advanced Virtualization Frameworks.
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation and explains how to obtain technical support.

Object and directory sizes

Since PPS holds its objects in memory, they are small. Each object is allocated 32 kilobytes. This doesn't mean that each object uses 32 kilobytes of memory at run time; it uses only the amount of memory needed to internally represent its current attributes.

The number of PPS directories and objects is limited only by available memory. The depth of PPS directories is limited by the fact that the full pathnames of objects are stored in the persistent directory as files; the size of these pathnames is limited by the maximum filename size supported by the persistent filesystem used.

Note:

PPS objects shouldn't be used as a dumping ground for large amounts of data. The size of most PPS objects should be measured in hundreds of bytes, not in kilobytes.
PPS has been tested with the Power-Safe filesystem (fs-qnx6.so), using the default PPS options. This configuration supports a total pathname length of 517 bytes, with no individual pathname element longer than 508 bytes. That is, a nesting depth of 50 is possible on fs-qnx6.so, provided that the total length of the path is less than 517 bytes.

Page updated: March 12, 2026