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Lecture 5: Implementation (Synchronous DS (Distributed Communication…
Lecture 5: Implementation
Synchronous DS
Corba: Common Object Request Broker Architecture
The Object Requester Broker ORB is responsible to identify and locate objects which are considered
Interface Description Language
(IDL) instances.
The client has basically no knowledge, where an object is located, thus the ORB is required to inform about it’s IP address, port number and other specs.
an example of Distributed Object Paradigm
Distributed Communication Environment
Cell: set of DCE nodes including clients, servers
Cell Directory Server (CDS): holds names of resources
Distributed Time Server (DTS): synchronize time for all nodes in cell
Security Services: grant or forbid access to resources by ACL
Remote Procedure Calls : transaction oriented
thread
implementation
Distributed File System (DFS)
Asynchronous DS
Message Bus
identify
Sender
Publisher
Receivers
One or many subscribers
#
Communication pattern of Bus in
Von-Neumann
architecture
Addressing attached components
Message Protocol
Safe transmission among components
Interrupt handler -> deterministic access to resources
Definition: is a messaging infrastructure to allow different systems to communicate through a shared set of interfaces
Coupling application
Any components may be replaced easily on the bus, new component can be simply added
The bus acts soly as transport vehicle, it has no idea of content it carries
Message Queue
messages types(recipient)
PUT: append message to selected queue
GET: block until queue is none-empty and remove first mess
POLL: Check if queue is none-empty, remove first message
NOTIFY: invoke a call-handler in case a message is injected into specified queue
Message Broker
Def: central component, taking care of the heterogeneity of attached nodes
Common message protocol: agree on syntax (structure) and semantic (content)
Mediation nodes: application gateways for proprietary systems
Routing on the bus happens subject-base ->
Enterprise Application Integration
EAI
Messages are translated from/to the proprietary local application format to common one.