refactor(docs): Clean up and update the README.md

README.md

@@ -45,8 +45,8 @@ open62541 is licensed under the MPLv2. That is, changes to files under MPLv2 fal
 But the library can be combined with private development from separate files, also if a static binary is produced, without the license affecting the private files.
 See the full [license document](LICENSE) for details.
 
-**Fraunhofer IOSB** maintains open62541 and provides **[official commercial support](https://www.iosb.fraunhofer.de/en/projects-and-products/open62541.html)**.
-Additional service providers are listed on [open62541.org](https://www.open62541.org/).
+**Fraunhofer IOSB** employs several of the open62541 developers and provides **[commercial support](https://www.iosb.fraunhofer.de/en/projects-and-products/open62541.html)**.
+Additional service providers in the open62541 ecosystem are listed on [open62541.org](https://www.open62541.org/).
 
 ## Official Certification
 
@@ -84,58 +84,55 @@ For individual discussion and support, use the following channels:
 
 We want to foster an open and welcoming community. Please take our [code of conduct](CODE_OF_CONDUCT.md) into regard.
 
+## Build System, Code Structure and Dependencies
+
+The build environment of open62541 is generated via CMake. See the [build documentation](https://www.open62541.org/doc/master/building.html) for details.
+To simplify the integration with existing software projects, the open62541 sources can be compressed (amalgamated) into a single-file-distribution, a pair of `open62541.c/.h` files.
+The functionality included in the single-file-distribution depends on the current CMake configuration.
+
+The source code is structured as follows:
+
+- Public API (`/include`): The public API is exposed to applications using open62541. The headers for plugin implementations are in `/plugins/include`.
+- Core Library (`/src`): The core library has no dependencies besides the C99 standard headers.
+- Architecture Support (`/arch`): Architecture support is implemented via the `EventLoop` plugin. This keeps the architecture-specific code - for example to use the POSIX APIs - out of the core library. Ports to different (embedded) architectures are provided.
+- Default Plugins Implementations (`/plugins`): The plugin interfaces allow the integration with different backend systems and libraries. For example concerning crypto primitives, storage of the information model, and so on. Default implementations are provided.
+- Dependencies (`/deps`): Some additional libraries are used via git submodules or have been internalized in the `deps/` folder. More information on the third-party libraries and their respective licenses can be found in [deps/README.md](deps/README.md)
+- Building and Code Generation: Some code is auto-generated from XML definitions that are part of the OPC UA standard. The code generation scripts use Python as part of the build process.
+
+On most systems, a bare-bones open62541 requires the C standard library only.
+Depending on the build configuration, open62541 depends on additional libraries, such as mbedTLS or OpenSSL for encryption.
+
 ## Development
 
-As an open source project, new contributors are encouraged to help improve open62541. The file [CONTRIBUTING.md](CONTRIBUTING.md) aggregates good practices that we expect for code contributions. The following are good starting points for new contributors:
+As an open source project, new contributors are encouraged to help improve open62541.
+The file [CONTRIBUTING.md](CONTRIBUTING.md) aggregates good practices that we expect for code contributions.
+The following are good starting points for new contributors:
 
 - [Report bugs](https://github.com/open62541/open62541/issues)
 - Improve the [documentation](http://open62541.org/doc/current)
 - Work on issues marked as "[good first issue](https://github.com/open62541/open62541/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22)"
 
 For custom development that shall eventually become part of the open62541 library, please keep one of the core maintainers in the loop.
 
-### Dependencies
-
-On most systems, open62541 requires the C standard library only. For dependencies during the build process, see the following list and the [build documentation](https://www.open62541.org/doc/master/building.html) for details.
-
-- Core Library: The core library has no dependencies besides the C99 standard headers.
-- Default Plugins: The default plugins use the POSIX interfaces for networking and accessing the system clock. Ports to different (embedded) architectures are achieved by customizing the plugins.
-- Building and Code Generation: The build environment is generated via CMake. Some code is auto-generated from XML definitions that are part of the OPC UA standard. The code generation scripts run with both Python 2 and 3.
-
-**Note:**
-Some (optional) features are dependent on third-party libraries. These are all listed under the `deps/` folder.
-Depending on the selected feature set, some of these libraries will be included in the resulting library.
-More information on the third-party libraries can be found in the corresponding [deps/README.md](deps/README.md)
-
 ### Code Quality
 
 We emphasize code quality. The following quality metrics are continuously checked and are ensured to hold before an official release is made:
 
 - Zero errors indicated by the Compliance Testing Tool (CTT) of the OPC Foundation for the supported features
 - Zero compiler warnings from GCC/Clang/MSVC with very strict compilation flags
-- Zero issues indicated by unit tests (more than 80% coverage)
+- Zero issues indicated by unit tests (we target more than 80% code coverage)
 - Zero issues indicated by clang-analyzer, clang-tidy, cpp-check and the Codacy static code analysis tools
 - Zero unresolved issues from fuzzing the library in Google's oss-fuzz infrastructure
 - Zero issues indicated by Valgrind (Linux), DrMemory (Windows) and Clang AddressSanitizer / MemorySanitizer for the CTT tests, unit tests and fuzzing
 
-## Installation and code usage
-
-For every release, we provide some pre-packed release packages which you can directly use in your compile infrastructure.
-
-Have a look at the [release page](https://github.com/open62541/open62541/releases) and the corresponding attached assets.
-
-A more detailed explanation on how to install the open62541 SDK is given in our [documentation](https://www.open62541.org/doc/master/building.html#building-the-library).
-In essence, clone the repository and initialize all the submodules using `git submodule update --init --recursive`. Then use CMake to configure your build.
-
-Furthermore we provide "pack branches" that are up-to-date with the corresponding base branches, and in addition have the git submodules in-place for a zip download.
-Here are some direct download links for the current pack branches:  
+### Security and Vulnerability Handling
 
-  - [pack/master.zip](https://github.com/open62541/open62541/archive/pack/master.zip)
-  - [pack/1.0.zip](https://github.com/open62541/open62541/archive/pack/1.0.zip)
+The project has established a process for handling vulnerabilities.
+See the [SECURITY.md](SECURITY.md) for details and how to responsibly disclose findings to the maintainers.
 
 ## Examples
 
-A complete list of examples can be found in the [examples directory](https://github.com/open62541/open62541/tree/master/examples).
+Code examples can be found in the [/examples](https://github.com/open62541/open62541/tree/master/examples) directory.
 To build the examples, we recommend to install open62541 as mentioned in the previous section.
 Using the GCC compiler, just run ```gcc -std=c99 <server.c> -lopen62541 -o server``` (under Windows you may need to add additionally link against the ```ws2_32``` 
 socket library).