Choreographie vs. Orchestration in relation to its layers

German Definition: (Feel free to translate it into english and post it as comment;-))

Von einer Choreographie spricht man, wenn die Koordination einzelner unabhängiger
Services durch einen Nachrichtenaustausch realisiert wird. Von einer Orchestrierung spricht man, wenn eine kontrollierende Instanz existiert und die einzelnen Services steuert.

In einer SOA (also unterhalb der Prozesssteuerungs-Sicht) werden Services durch Choreographie koordiniert.

In der Prozessteuerungs-Sicht erfolgt die Zusammenstellung von Services zu einem Geschäftsprozess durch Orchestrierung.

The Role of Taxonomies in UDDI

Read this article article

SAML Definition

(Security Assertion Markup Language) An XML-based format from OASIS for exchanging security information for single sign-on.

Security

There are differnt kind of security:

- authentication: Am I the guy I pretend to be?
- authorization: Do I have the privilges to do this operation? ( Assigning roles and permissions to perform specific operations)
- encryption:e.g. ssl
- data integrity
- non repudiation:

What are the differences between a vocabulary, a taxonomy, a thesaurus, an ontology, and a meta-model?

see: article

XMI, MOF, UML, Ecore, Ecore-Model?

As follows I try to summarize my current knowledge about the above technologies, I've discussed with some friends. Please post me any corrections if you find any errors. 

MOF vs. UML
------------------
- MOF is on Layer M(i+2) 
- UML Metamodel on Layer M(i+1) 
- UML Model  is on Layer M(i) 

MOF in comparison to EBNF 
--------------------------------
- MOF can be compared to EBNF
- The UML Metamodel to a programming language
- The UML Model to the programm

Ecore Model vs. EMF Model
--------------------------------
- Ecore Model is on Layer M(i+1)
- EMF Model is on Layer M(i)

XMI
-----
- XMI is used for serialization of models. All layers derived from MOF can be serialized by XMI (e.g. MOF itself, UML MetaModel, UML Model can be serialized by XMI)

Essential MOF:
-----------------
- Is an attempt to join MOF and the Ecore-Model

EMF: 
------
- EMF is a framework containing  XMI 2.0 serialization, Java codegenerator

WSDL vs UDDI vs WSIL

It is the goal of the proposed Web Services Description Language (WSDL) to describe services at a functional level. The Universal Description, Discovery, and Integration (UDDI) schema aims at providing a more business-centric perspective. What has not yet been provided by these proposed standards is the ability to tie together, at the point of offering for a service, these various sources of information in a manner which is both simple to create and use. the WS-Inspection specification addresses this need by defining an XML grammar which facilitates the aggregation of references to different types of service description documents, and then provides a well defined pattern of usage for instances of this grammar. By doing this, the WS-Inspection specification provides a means by which to inspect sites for service offerings.

Source: http://www-128.ibm.com/developerworks/library/specification/ws-wsilspec/

Rest Webservices

What is Rest and what are Rest-Webservices?
Representational State Transfer is intended to evoke an image of how a well-designed Web application behaves: a network of web pages (a virtual state-machine), where the user progresses through an application by selecting links (state transitions), resulting in the next page (representing the next state of the application) being transferred to the user and rendered for their use.

— Dr. Roy Fielding, Architectural Styles and the Design of Network-based Software Architectures

Recommended articles about Rest:
- Rest-Webservices (german article)
- Definiton of Rest at answers.com

Statements about Rest:
- Amazon has both SOAP and REST interfaces to their web services, and 85% of their usage is of the REST interface REST vs. SOAP at Amazon

WS-Policy
The Web Service Policy Framework (WS-Policy) specification defines a syntax and semantic for service providers and service requestors to describe their requirements, preferences, and capabilities. The syntax provides a flexible and concise way of expressing the needs of each domain in the form of policies. A domain in this context is a generic field of interest that applies to the service, such as the following:
- Security
- Privacy
- Application priorities
- User account priorities
- Traffic control

see also: http://www-128.ibm.com/developerworks/webservices/library/ws-policy.html#listing1

WS-Policy beschreibt Anforderungen, Fähigkeiten und Zusicherungen eines Web Services aus. So kann eine Policy beispielsweise anzeigen, dass ein Web Service nur eingehende Anfragen akzeptiert, wenn diese eine gültige Signatur enthält oder die Nachricht eine bestimmte Größe nicht überschreitet.

Wie eine Policy verteilt bzw. bezogen werden kann, ist außerhalb des Anwendungsgebietes der Spezifikation. Die Spezifikationen WS-PolicyAttachment und WS-MetadataExchange spezifizieren, wie eine Policy über SOAP Nachrichten oder eingeschlossen in XML und WSDL Dokumenten zugänglich gemacht werden kann. 

(see also http://www.oio.de/public/xml/web-service-specifications.htm)
(see also http://dev2dev.bea.com/pub/a/2004/01/ws_orchard.html)

Definitions: SOA Governance consists of the following parts:

- Impact Managemnt
- Change Management
- Integrity
- XQuery
- Validity
- Contract Management