4. Quickstart

Contents:

• 4.1. Process Management
  • 4.1.1. Starting the LN manager with a minimal configuration
  • 4.1.2. Configuring processes and their dependencies
  • 4.1.3. Managing Processes
  • 4.1.4. Starting and Stopping Processes in the LN manager GUI
• 4.2. Topic Communication in Python
  • 4.2.1. Creating Message Definitions
  • 4.2.2. The Publisher Python Script
  • 4.2.3. The Subscriber Python Script
  • 4.2.4. Configuring the LN Manager for Message Exchange
    • 4.2.4.1. Running Publisher and Subscriber with manual Process Management
    • 4.2.4.2. Delegating the Process Management to the LN Manager
• 4.3. Calling and handling Services from Python
  • 4.3.1. What can LN Services provide?
  • 4.3.2. Our example: Geometric heavy lifting
  • 4.3.3. Defining message definitions for service calls
  • 4.3.4. Defining a service provider in Python
    • 4.3.4.1. Initialization
    • 4.3.4.2. Handler Methods
    • 4.3.4.3. Running the Handlers
  • 4.3.5. Calling services from Python
    • 4.3.5.1. Instantiating the Client
    • 4.3.5.2. Calling the Service from Client Methods
  • 4.3.6. Configuring services support in the links and nodes manager
    • 4.3.6.1. Compatibility between Client and Provider Implementations
• 4.4. Topic Communication in C++
  • 4.4.1. Creating Message Definitions
  • 4.4.2. The Publisher Program
  • 4.4.3. The Subscriber Program
  • 4.4.4. Configuring the LN Manager for Message Exchange
    • 4.4.4.1. Running Publisher and Subscriber with manual Process Management
    • 4.4.4.2. Delegating the Process Management to the LN Manager
• 4.5. Calling and handling Services from C++
  • 4.5.1. What can LN Services provide?
  • 4.5.2. Our example: Geometric heavy lifting
  • 4.5.3. Writing message definitions for service calls
  • 4.5.4. Defining a service provider in C++
    • 4.5.4.1. Build Scripts for Client and Provider
    • 4.5.4.2. The Request Data Buffer
  • 4.5.5. Calling services from C++
    • 4.5.5.1. Instantiating the Client
    • 4.5.5.2. Calling the Service from Client Methods
    • 4.5.5.3. The Request Buffer Type
  • 4.5.6. Configuring services support in the links and nodes manager
    • 4.5.6.1. Compatibility between Client and Provider Implementations

For some people, the easiest and quickest way to understand something new is to get started with some short and sweet sample code they can read and modify. If you are like this, this chapter is for you!

Each of the next five sections show some essential code examples for the most important features of links and nodes:

1. an example how to start the LN manager and manage interdependent processes with it.

2. an example how to let processes communicate via publish/subscribe and topics.

3. an example how to integrate LN services, which are similar to remote procedure call into a program.

They assume that you have read the Introduction, specifically the sections named “Overview on the functions provided by Links and Nodes” and “Main components of Links and Nodes Applications”, and have a ready installed system, as described in the chapter “Getting Started”. All three are written in Python; we assume that you know how to create, edit and run python scripts. If you need an explanation for some specific term, you can look it up in the Glossary.

As mentioned, the examples show the necessary code, but do not try to explain all of the underlying magic. For some more explanation of the concepts which are used here, you can then go to the next chapter, the Tutorials.