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Part 2 : Middleware architecture, => tightly connected ( developed…
Part 2 : Middleware architecture
1. Traditional C/S Architecture
:
one of the earliest distributed computing archi.
-> the client send requests
-> the server provides services and resources
Limitations of the Classical C/S Model
a) High Technical Complexity
developers manually manage several complex mechanisms:
transaction management
database synchronization
data replication
fault management and recovery
network security
client-side development
b) Strong Coupling Between C/S
low flexibility
difficult maintenance
hard evolution of the system
c) Limited Scalability
nbr of users increases :
additional servers are required
load balancing becomes more complex
=> scaling the system is expensive and difficult
d) Complex Evolution and Maintenance
large C/S app difficult to extend / maintain / upgrade
2. Transition to Middleware
Definition :
software layer positioned between : app / OS/ networks / databases / distributed resources
foundation of advanced distributed computing environments such as: cloud computing / IoT systems / pervasive Computing envir
=> hide technical complexity and simplify distributed communication.
main Roles
:
Communication Management :
applications can communicate transparently across distributed environments.
Interoperability
: allows heterogeneous systems to work together despite : PL / OS / hardware platforms
Infrastructure Services
manage technical services :
security / messaging / transaction processing / synchronization / remote communication / resource access
3. General Middleware Architecture
A. Application Layer
: contains business applications (healthcare sys / payment sys / reservation sys)
=> interact with middl instead of directly handling network complexity
B. Middleware Layer :
core layer of the arch
Business Services
: provide app-specific logic and functionalites (patient manag / billing / reservation manag)
Infrastructure Services
: provide technical functiona (communication / security / persistence / transaction manage / messaging services)
C. Backend Layer
: midd connects app to backend resources (databases / external systems / APIs / cloud services)
4. Distributed Object Middleware
Principe :
Software objects may reside on <> servers while interacting as if they were local
Middleware ensures transparent communication between distributed components.
(+):
Location Transparency :
Applications do not need to know the physical location of objects.
Heterogeneity Transparency : <> OS / PL / hardware platforms can interoperate seamlessly
Network Transparency :
The complexity of network communication is hidden from developers.
2 technologies : CORBA ET DCOM
5. Distributed Architecture Design
each organization has: specific Business requirements / IS / technical constraints
=> therefore each distributed arch must be designed specifically for its environment
the design phase is critical because developers mus define : system components / component size / provided services / network distribution
=> tightly connected ( developed together )