partially clean up overall structure of README.md

This makes clear from the beginning that this repo also provides a CMP client\
and slightly extends the introduction.

I've started removing strong duplications from the later sections about the CMP client by integrating them (as far as needed, with minor differentiations) into the initial section that can serve for both the server and client aspects.
Please do so also for other sections as far as reasonable.

README.md

@@ -1,10 +1,11 @@
 <!--- License: Apache 2.0 -->
 
-# Features of the generic CMP RA component
+# generic CMP RA and CMP client component
 
-The generic CMP RA component supports the implementation of applications
-that provide CMP Registration Authority (RA) functions.
-It implements the RA features specified in the
+The generic CMP component supports the implementation of Java applications
+that provide CMP Registration Authority (RA) and/or CMP client functions.
+
+It implements the CMP features specified in the
 [Lightweight Certificate Management Protocol (CMP) Profile](
 https://datatracker.ietf.org/doc/draft-ietf-lamps-lightweight-cmp-profile/),
 reflecting the updates to CMP (RFC 4210) and CRMF (RFC 4211) given in
@@ -13,9 +14,20 @@ https://datatracker.ietf.org/doc/draft-ietf-lamps-cmp-updates/)
 and [Certificate Management Protocol (CMP) Algorithms](
 https://datatracker.ietf.org/doc/draft-ietf-lamps-cmp-algorithms/).
 
+It has been used as a reference implementation for the standardization of 
+CMP Updates, CMP Algorithms, and the Lightweight CMP Profile (LCMPP)
+and is being used for PoC developments for the standardization of
+[RFC4210bis](https://datatracker.ietf.org/doc/html/draft-ietf-lamps-rfc4210bis).
+
+It serves as the core of productive Java-based CMP developments.\
+It is also used in the
+[Lightweight CMP RA and CMP Client](https://github.com/siemens/LightweightCmpRa/)
+Java application for demonstration and test purposes.
+
+
 ## Basic features for use in PoCs, reference implementations, and in production
 
-* The generic RA component implements the following CMP functions and features:
+* The generic RA and CMP client component implements the following CMP functions and features:
     * Build, parse, and process CMP messages and validate their contents.
     * Validate, modify, and add CMP message protection,
       based on signatures or shared secrets (MAC).
@@ -30,7 +42,7 @@ https://datatracker.ietf.org/doc/draft-ietf-lamps-cmp-algorithms/).
 * The component supports very flexible configuration,
   allowing to set all relevant options, with reasonable defaults.
 * The component provides error reporting and logging
-  towards embedding application or execution environment.
+  towards the embedding application or execution environment.
 * All messages are ASN.1 DER-encoded for maximal interoperability.
 * The component allows using any type of message transfer, such as HTTP(S).
 * Message transfer supports also asynchronous delivery.
@@ -41,44 +53,55 @@ https://datatracker.ietf.org/doc/draft-ietf-lamps-cmp-algorithms/).
 ## Advanced features, in particular for productive use
 
 * The generic CMP RA component is usable as servlet
-  in typical web server frameworks, such as Tomcat.
-* The Configuration interface of the generic CMP RA component supports
+  in typical web server frameworks, such as Apache Tomcat.
+* The configuration interface of the generic CMP component supports
   setting options also dynamically and dependent on certificate profiles.
-* The upstream message transfer interface of the component
-    * provides optional routing information dependent on the certificate profile
-    * supports legacy servers by using PKCS#10 requests
-      and X.509 responses as alternative to CMP.
-* The component has an interface for authorizing and optionally
+* The upstream message transfer interface of the RA component and
+  the message transfer interface of the CMP client component
+  provides optional routing information dependent
+  on the CMP operation (message body type) and the certificate profile.
+* The upstream message transfer interface of the RA component
+  supports legacy servers by using PKCS#10 requests
+  and X.509 responses as alternative to CMP.
+* The RA component has an interface for authorizing and optionally
   modifying certificate requests (e.g., using an external inventory).
-* The component has an interface for reporting (also intermediate)
+* The RA component has an interface for reporting (also intermediate)
   enrollment state to external entities (e.g., inventory).
-* The component has an interface for persisting internal state
+* The RA component has an interface for persisting internal state
   (e.g., using a database) supporting long-lasting transactions with
   application recovery, to support restart on failure and load balancing.
+
+## Advanced features, in particular for productive use
 
-# Structure of the generic CMP RA component
-
-The picture below shows the overall design and relation to JAVA base components:
-
-![Structure of the generic CMP RA component](doc/CmpRaComponentDesign.png)
-
+* The Configuration interface of the generic CMP client component supports
+  setting options also dynamically and dependent on certificate profiles in a
+  similar way as for the CMP RA component.
+* The message transfer interface of the component provides
+  optional routing information dependent on the certificate profile
 
 ## Overall software design
 
-* The API for instantiating an CMP RA component is specified as Java interfaces.
-* The API to access the generic CMP RA component is based just on common
+* The API for instantiating an CMP RA component is specified as Java interfaces.\
+  For the CMP client component it is specified as a Java class.
+* The API to access the generic CMP component is based just on common
   Java libraries and runtime environment, including Java crypto provider (JCE).
 * Errors, warnings and information on internal message processing are logged
   using the framework [SLF4J](http://www.slf4j.org/).
 * The implementation uses internally the
   [Bouncy Castle library](https://www.bouncycastle.org/),
-  which providesd a low-level CMP implementation.
-* As far as possible, errors are reported at application level
-  as CMP error messages.
-  Otherwise Java exceptions are thrown,
+  which provides a low-level CMP implementation.
+* As far as possible,
+  the RA component reports errors at application level using CMP error messages.
+  For all other errors Java exceptions are thrown,
   also in case of invalid configuration and on other fatal errors.
 
 
+# Structure of the generic CMP RA component
+
+The picture below shows the overall design and relation to the Java base components:
+
+![Structure of the generic CMP RA component](doc/CmpRaComponentDesign.png)
+
 ## Message exchange API design
 
 For simplicity, there is only one downstream interface towards clients (EEs)
@@ -207,82 +230,27 @@ and status updates, and for persistency
   [`com.siemens.pki.cmpracomponent.main.CmpRaComponent`](src/main/java/com/siemens/pki/cmpracomponent/main/CmpRaComponent.java).
 
 
-## Javadoc API documentation
-
-After the javadoc documentation has been generated locally by invoking
-`mvn javadoc:javadoc`, it can be found
-at `target/site/apidocs/com/siemens/pki/cmpracomponent/main/CmpRaComponent.html`.
 
 # Features of the generic CMP client component
 
 The client extends the
 [generic CMP RA component](#features-of-the-generic-cmp-client-component).
-It implements the End Entity features specified in the
+It implements the end-entity features specified in the
 [Lightweight Certificate Management Protocol (CMP) Profile](
-https://datatracker.ietf.org/doc/draft-ietf-lamps-lightweight-cmp-profile/)
-reflecting the updates to CMP (RFC 4210) and CRMF (RFC 4211) given in
-[Certificate Management Protocol (CMP) Updates](
-https://datatracker.ietf.org/doc/draft-ietf-lamps-cmp-updates/)
-and [Certificate Management Protocol (CMP) Algorithms](
-https://datatracker.ietf.org/doc/draft-ietf-lamps-cmp-algorithms/).
-
-## Basic feature​s for use in PoCs, reference implementations, and in production
-
-* The generic CMP client component component implements
-the following CMP functions and features:
-    * Build, parse, and process CMP messages and validate their contents.
-    * Provide and validate CMP message protection,
-      based on signatures or shared secrets (MAC).
-    * Support all CMP use cases (including ir, cr, p10cr, kur, and rr)
-      defined in the [Lightweight CMP Profile](
-      https://datatracker.ietf.org/doc/html/draft-ietf-lamps-lightweight-cmp-profile).
-    * Support all general CMP features defined in Lightweight CMP Profile,
-      including error handling within CMP, local/central key generation,
-      and delayed delivery of all message types.
-* The component is usable in client contexts and in standalone applications.
-* Use of the component is as simple as possible,
-  not requiring specific (crypto, CMP, etc.) detailed knowledge.
-* The component supports very flexible configuration,
-  allowing to set all relevant options, with reasonable defaults.
-* The component provides error reporting and logging
-  towards embedding application or execution environment.
-* All messages are ASN.1 DER-encoded for maximal interoperability.
-* The component allows using any type of message transfer, such as HTTP(S).
-* Java interface is based on Bouncy Castle (low-level CMP)
-  and the Java crypto provider (JCE).
+https://datatracker.ietf.org/doc/draft-ietf-lamps-lightweight-cmp-profile/).
 
-## Advanced features, in particular for productive use
 
-* The Configuration interface of the generic CMP client component supports
-  setting options also dynamically and dependent on certificate profiles in a
-  similar way as for the CMP RA component.
-* The message transfer interface of the component provides
-  optional routing information dependent on the certificate profile
 
 # Structure of the generic CMP client component
 
-The picture below shows the overall design and relation to JAVA base components:
+The picture below shows the overall design and relation to the Java base components:
 
 ![Structure of the generic CMP client component](doc/CmpEeComponentDesign.png)
 
 
-## Overall software design
-
-* The API for instantiating an CMP client component is specified as a Java class.
-* The API to access the generic CMP client component is based just on common
-  Java libraries and runtime environment, including Java crypto provider (JCE).
-* Errors, warnings and information on internal message processing are logged
-  using the framework [SLF4J](http://www.slf4j.org/).
-* The implementation uses internally the
-  [Bouncy Castle library](https://www.bouncycastle.org/),
-  which providesd a low-level CMP implementation.
-* Errors are reported as Java exceptions,
-  also in case of invalid configuration and on other fatal errors.
-
-
 ## Message exchange API design
 
-For simplicity, there is only one upstream interface towards server (CA).
+For simplicity, there is only one interface towards the server (RA or CA).
 In case multiple upstream interfaces are desired:
 * Differentiation in transport/routing
   can be achieved by the embedding application multiplexing channels.
@@ -347,6 +315,12 @@ The diagram describes the interaction between an "Embedding Application" and a "
 
 For configuration interface details see [RA Configuration interface design](#configuration-interface-design) which is partly reused for client configuration.
 
-## Acknowledgements
+# Javadoc API documentation
+
+After the javadoc documentation has been generated locally by invoking
+`mvn javadoc:javadoc`, it can be found
+at `target/site/apidocs/com/siemens/pki/cmpracomponent/main/CmpRaComponent.html`.
+
+# Acknowledgements
 
 This work was partly funded by the German Federal Ministry of Education and Research in the project Quoryptan through grant number **16KIS2033**.