Rework Thread and Communication concept

[huebl]

The thread is currently single threaded. This is problematic in several ways.

• The processing of slow tasks blocks other tasks

• The application uses the same thread as the SDK.

• The processor is not used optimally

[huebl]

In an OPC UA application, there are several software components that can work independently of each other. For communication between the various software components, a bus communication system should be used. The bus communication system is used for the asynchronous exchange of messages. Each participant in the bus communication system has a unique name. The bus communication system should provide the following feature.

• Register and discover participants
• Sending and receiving asynchronous messages between participants
• Publish and subscribe to specific message types

In addition, the following functions should be supported.

• The message exchange should work across process boundaries.
• For creating new messages, the model based design should be supported.
• Various transport media should be supported.

[huebl]

In all Software components of the application a uniform thread concept should be used. This concept should support the following concepts.

• All operations should be performed by non-blocking tasks.
• All operations are inserted into a queue and executed by one or more threads.

The following operations are supported.

• Asynchronous tasks
• Timer tasks
• Socket Tasks
• Message Tasks

[huebl]

If an application consists of several software components, there are often dependencies between the software components during startup. A software component can go through several init states during startup. These dependencies between the software components should be able to be set using the configuration file.

[huebl]

With this issue, a concept should first be worked out.

[huebl]

In the first step, only a documentation is to be created.

[atimin]

`The thread is currently single threaded. This is problematic in several

I have a problem with the stack when an OPC UA client tries to communicate with the server by using several threads. If one of them is stuck, the session is closed by timeout. In this case, I consider the problem as a single-threaded session. Maybe there is a better word to express the problem concisely.

[huebl]

This feature is to be implemented with Issue #339. For this reason the feature is closed.