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architecture_styles [2015/02/26 16:42]
apaschke
architecture_styles [2015/02/28 11:37]
apaschke [Direct Strongly-Coupled API4KB Access]
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 Both CORBA and Java RMI serialize messages in compliance with the Internet Inter-ORB Protocol (IIOP) standard. This is a comprehensive standard, which is usually implemented with support from automated tools. On the other hand, web services only specifies the use of XML and leaves up to the software developer(s) to ensure that the source and the destination have the same understanding of the XML content. There are many tools to support this understanding. WSDL specifies that messages will comply to an XML schema. If WSDL is not being used and no XML schema has been specified; the source and destination must at lease have some sort of mutual understanding of an implied schema or else they run the risk that parts of their messages will be lost or misunderstood. Both CORBA and Java RMI serialize messages in compliance with the Internet Inter-ORB Protocol (IIOP) standard. This is a comprehensive standard, which is usually implemented with support from automated tools. On the other hand, web services only specifies the use of XML and leaves up to the software developer(s) to ensure that the source and the destination have the same understanding of the XML content. There are many tools to support this understanding. WSDL specifies that messages will comply to an XML schema. If WSDL is not being used and no XML schema has been specified; the source and destination must at lease have some sort of mutual understanding of an implied schema or else they run the risk that parts of their messages will be lost or misunderstood.
  
-In the following+In the following ​three categories of communication paradigms are distinguish according to their decreasing strength of API4KB coupling.
  
 ===== Direct Strongly-Coupled API4KB Access ​ ===== ===== Direct Strongly-Coupled API4KB Access ​ =====
  
-Strong coupling with the local API4KB ​requiring direct knowledge of the (downloaded) API4KB ​libraries and knowledge artifacts ​or direct knowledge about how the inter-process interaction with the remote API4KB works in ad-hoc network programming (e.g. via socket programming).+Strong coupling with the local client ​requiring direct knowledge of the (downloaded) API4KB ​**Artifacts** ​or direct knowledge about how the inter-process interaction ​and access ​with the remote API4KB works in ad-hoc network programming (e.g. via socket programming).
  
-Example: OntoMaven and RuleMaven.+Example: ​[[http://​www.corporate-semantic-web.de/​ontomaven.html|OntoMaven and RuleMaven]].
  
  
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 A unit of composition with contractually specified interfaces and explicit content dependencies only. Component is specified in terms of a contract which includes a set of provided interfaces (interfaces that the component offers as a service to other components) and required interfaces (dependencies that this component has on other components). Container provides managed server-side hosting environment for components and deals with the distributed systems and middleware issues. ​ A unit of composition with contractually specified interfaces and explicit content dependencies only. Component is specified in terms of a contract which includes a set of provided interfaces (interfaces that the component offers as a service to other components) and required interfaces (dependencies that this component has on other components). Container provides managed server-side hosting environment for components and deals with the distributed systems and middleware issues. ​
  
-Examples, e.g. Java Beans, Corba Component Model, ​API4KB ​OntoMaven Aspect-Oriented Component Model, ...+Examples, e.g. Java Beans, Corba Component Model, ​[[http://​www.corporate-semantic-web.de/​ontomaven.html|OntoMaven Aspect-Oriented Component Model]], ...
  
 ===== Decoupled Indirect Communication ===== ===== Decoupled Indirect Communication =====
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 Publish-subscribe with event-based communication through propagation of events (via an underlying overlay network, e.g. structured and unstructured peer-to-peer or other broker overlay). Publishers publish structured events to an event service (responsible for event routing and matching) and subscribers express interest in particular events through subscriptions. Publish-subscribe with event-based communication through propagation of events (via an underlying overlay network, e.g. structured and unstructured peer-to-peer or other broker overlay). Publishers publish structured events to an event service (responsible for event routing and matching) and subscribers express interest in particular events through subscriptions.
  
-Distributed Event Based Systems with Complex Event Processing (CEP) in Event Processing Agents (EPAs) deployed in Event Processing Networks (EPNs). ​+Distributed Event Based Systems ​and Event Streaming ​with Complex Event Processing (CEP) in Event Processing Agents (EPAs) deployed in Event Processing Networks (EPNs). ​
  
 ==== Group communication ==== ==== Group communication ====
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 Examples, e.g. Tuple Spaces, Distributed Shared Memory, Message Queues (e.g., JMS, Active MQ, ...) Examples, e.g. Tuple Spaces, Distributed Shared Memory, Message Queues (e.g., JMS, Active MQ, ...)
  
-==== Asynchronous Messaging Libraries ====+====  Asynchronous Messaging Libraries ====
  
-Libraries exist which can be used according to a number of different messaging patterns.+Libraries exist which combine and can be used according to a number of the different, above mentioned ​messaging patterns, e.g.
  
-  * [[http://​en.wikipedia.org/​wiki/​%C3%98MQ|0MQ]] (ZeroMQ) provides "​sockets"​ (a many-to-many connection generalizing the concept of network socket) which each operate according to a specific messaging pattern (e.g. RPC, pub-sub, ...)+  * [[http://​en.wikipedia.org/​wiki/​%C3%98MQ|0MQ]] (ZeroMQ) ​is a lightweight messaging system specially designed for high throughput and low latency scenarios as in IoT, low-level event streaming etc. It  ​provides "​sockets"​ (a many-to-many connection generalizing the concept of network socket) which each operate according to a specific messaging pattern (e.g. RPC, pub-sub, ...), which (in contrast to e.g. more advanced messaging queue servers and enterprise service bus middlewares) need to be manually implement by combining various pieces of the framework (see ad-hoc network programming with sockets and devices in strong coupling category). 
 +  * higher-level message queue middleware such as Erlang (RabbitMQ), C (beanstalkd),​ Ruby (Starling or Sparrow), Scala (Kestrel, Kafka) or Java (ActiveMQ), and Enterprise Service Bus middleware such as OpenESB, Mule ESB, ... 
 + 
 +Examples, e.g. [[http://​responder.ruleml.org|RuleML RuleResponder]] is implemented as a Staged Event-Driven Architecture (SEDA) using the Mule ESB and ActiveMQ or RabbitMQ. It can use all kinds of synchronous and asynchronous transport protocols including e.g. AMQP, JMS, HTTP Rest, SOAP, etc..
  
 ===== Summary of Dimensions ===== ===== Summary of Dimensions =====
architecture_styles.txt · Last modified: 2015/04/24 10:11 by rmbell