1. SOA Part1 Lecture 1 PSE GSC 1.10.2005
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Dr. Withalm 21-Apr-17
PSE Bereichspräsentation

2. Lectures at the University of Bratislava/Autumn 2010
PSE GSC
Lectures at the University of Bratislava/Autumn 2010
Lecture 1 Evolution Of Architectures- The long Way from OO to SOA
Lecture 2 WEB-Services& Semantic WEB
Lecture 3 SOA-Technological Basis
Lecture 4 SOA-Basing on J2EE
Lecture 5 SOA-Focus on Business Processes
Lecture 6 B2B Frameworks and related Standards
Lecture 7 WEB 2.0 & GRID
Dr.Withalm
PSE Bereichspräsentation

3. Lectures at the University of Bratislava/Autumn 2011
PSE GSC
Lectures at the University of Bratislava/Autumn 2011
Lecture 1 The long Way from OO to SOA & WEB- Services
Lecture 2 Semantic WEB & SOA-Technological Basis
Lecture 3 SOA-Basing on J2EE & SOA-Focus on Business Processes
Lecture 4 B2B Frameworks and related Standards
Lecture 5 WEB 2.0 & GRID & Cloud Computing
Dr.Withalm
PSE Bereichspräsentation

4. Software Architecture Programming Paradigm CORBA Application Server
Today’s Agenda
Software Architecture
Programming Paradigm
CORBA
Application Server
TP Monitor
EJB
J2EE
Dr.Withalm

5. Software Architecture
PSE GSC
Software Architecture
Software architecture is a coherent set of abstract patterns guiding the design of each aspect of a larger software system.
Software architecture underlies the practice of building computer software. In the same way as a building architect sets the principles and goals of a building project as the basis for the draftsman's plans, so too, a software architect or systems architect sets out the software architecture as a basis for actual system design specifications, per the requirements of the client.
Dr.Withalm
PSE Bereichspräsentation

6. Software Architecture Examples
PSE GSC
Software Architecture Examples
There are many common ways of designing computer software modules and their communications, among them:
Distributed computing
Client-server
Peer-to-peer system
Three-tier model
Service-oriented architecture
Dr.Withalm
PSE Bereichspräsentation

7. Distributed Computing
PSE GSC
Distributed Computing
There are many different types of distributed computing systems and many challenges to overcome in successfully architecting one. The main goal of a distributed computing system is to connect users and resources in a transparent, open, and scalable way.
This includes simple client-server system and extends up to grid computing. Grid computing uses the resources of many separate computers connected by a network (usually the internet) to solve large-scale computation problems.
Dr.Withalm
PSE Bereichspräsentation

8. PSE GSC
Scalability
A scalable system is one that can easily be altered to accommodate changes in the amount of users, resources and computing entities affected to it. Scalability can be measured in three different dimensions:
Load scalability — A distributed system should make it easy to expand to accommodate heavier or lighter loads.
Geographic scalability — A geographically scalable system is one that maintains its usefulness and usability, regardless of how far apart its users or resources are.
Administrative scalability — No matter how many different organizations need to share a single distributed system, it should still be easy to use and manage.
Some loss of performance may occur in a system that allows itself to scale in one or more of these dimensions.
Dr.Withalm
PSE Bereichspräsentation

9. PSE GSC
Client-Server
Client/Server is a scalable architecture, whereby each computer or process on the network is either a client or a server. Server software generally, but not always, runs on powerful computers dedicated for exclusive use to running the business application.
Client software on the other hand generally runs on common PCs or workstations. Clients get all or most of their information and rely on the application server for things such as configuration files, stock quotes, business application programs, or to offload compute-intensive application tasks back to the server.
Dr.Withalm
PSE Bereichspräsentation

10. Properties of a server: Passive (Slave) Waiting for requests
PSE GSC
Client-Server (cont.)
Properties of a server:
Passive (Slave)
Waiting for requests
On requests serves them and send a reply
Properties of a client:
Active (Master)
Sending requests
Waits until reply arrives
Dr.Withalm
PSE Bereichspräsentation

11. Client-Server (cont.) Web Server Print Directory Database File Mail
PSE GSC
Client-Server (cont.)
Web
Server
Print
Directory
Database
File
Mail
Dr.Withalm
PSE Bereichspräsentation

12. PSE GSC
Peer-to-Peer
A peer-to-peer (or P2P) computer network is a network that relies on the computing power and bandwidth of the participants in the network rather than concentrating it in a relatively few servers.
A pure peer-to-peer file transfer network does not have the notion of clients or servers, but only equal peer nodes that simultaneously function as both "clients" and "servers" to the other nodes on the network.
A typical example for a non peer-to-peer file transfer is an FTP server. One user uploads a file to the FTP server, then many others download it, with no need for the uploader and downloader to be connected at the same time.
Dr.Withalm
PSE Bereichspräsentation

13. PSE GSC
Three-Tier Model
Three-tier is a client-server architecture in which the user interface, functional process logic ("business rules"), data storage and data access are developed and maintained as independent modules, most often on separate platforms.
User Interface
Tier
Application
Tier
Data
Tier
Dr.Withalm
PSE Bereichspräsentation

14. N-Tier Model User Interface Tier Application Tier Data Tier PSE GSC
N-Tier Model
User Interface
Tier
Application
Tier
Data
Tier
Dr.Withalm
PSE Bereichspräsentation

15. Component Orientation:
PSE GSC
Programming Paradigm
Programming Paradigm
Real World Analogy
Object Orientation:
Aligned with fine-grained business objects
Reuse of source code based on the notion of types
Increased maintainability and modifiability of the program code through encapsulation
Print Service
Service Consumer
Archiving Service
Back Office Service
Put together to build a complex device
Wire together to build a small device
Component Orientation:
Aligned with mid-grained business functions
Reuse based on prefabricated, executable code
Increased maintainability and modifiability of the application through composition
Service Orientation:
Aligned with coarse-grained business processes
Flexibility and extensibility through composition, federation, and orchestration of services
Increased interoperability and scalability through loose-coupling
It is there and running, simply connect and use.
Dr.Withalm
Archiving Service
PSE Bereichspräsentation

16. Largest SW-Consortium more than 800 members
PSE GSC
CORBA - OMG / 1
Largest SW-Consortium
more than 800 members
System providers as: Siemens, IBM, HP, DEC, Oracle...
End users as: Boeing, AT&T, Daimler Benz...
From all branches as Telecom, Health, Finance...
Dr.Withalm
PSE Bereichspräsentation

17. Distributed Objects, Corba Style / 2
Clients don’t need to know - where the distributed object resides - what operating system it executes on - how the server object is implemented
clients only know - the interface its server object publishes - this interface serves as a building contract between clients and servers
Dr.Withalm

18. it provides no implementation details
IDL / 1
it provides no implementation details
You can use IDL to define - API’s concisely - covering important issues such as error handling
IDL-specified methods can be written and invoked from any language - that provides CORBA bindings
Programs deal with CORBA objects - using native language constructs
Dr.Withalm

19. Marhalling
The process of gathering data and transforming it into a standard format
before it is transmitted over a network so that the data can transcend network boundaries.
In order for an object to be moved around a network
it must be converted into a data stream that corresponds with the packet structure of the network transfer protocol.
This conversion is known as data marshalling.
Data pieces are collected in a message buffer before they are marshaled.
When the data is transmitted, the receiving computer converts the marshaled data back into an object.
Data marshalling is required
when passing the output parameters of a program written in one language
as input to a program written in another language.
Dr.Withalm

20. IDL / 6 ORB C C++ Ada Other IDL C C++ Ada Other IDL Client Server
Java
Ada
COBOL
Other
IDL C
C++
Java
Ada
COBOL
Other
IDL
Client
Server
ORB
Dr.Withalm

21. Structure of CORBA / 3 What exactly is an ORB / 3
PSE GSC
Structure of CORBA / 3 What exactly is an ORB / 3
Object
Adapter
Dynamic
Invocation
Skeleton
Static
Skeletons
ORB
Interface
Client
IDL
Stubs
Implementation
Repository
Object Request Broker Core
Dr.Withalm
PSE Bereichspräsentation

22. Object Request Broker Core Request
PSE GSC
Structure of CORBA / 17 Method Invocations / 1
Client
Object
Implementation
Adapter
Dynamic
Invocation
Server
IDL
Stubs
Object Request Broker Core
Request
Dr.Withalm
PSE Bereichspräsentation

23. Common Object Services
PSE GSC
Naming Service / 1
Common Object Services
Naming
Externalization
Persistence
Events
Life Cycle
Transactions
Properties
Query
Concurrency
Relationships
Collections
Time
Security
Change
Management
Trader
Licensing
Object Request Broker
Dr.Withalm
PSE Bereichspräsentation

24. containing applications written in different programming languages
CORBA-Strenghts/1
CORBA was designed for integrating applications in heterogeneous environments
containing applications written in different programming languages
running on different operating systems and different machines.
CORBA was designed specifically to address
the integration problems faced in a typical IT environment.
Dr.Withalm

25. CORBA achieves this level of interoperability
CORBA-Strenghts/2
CORBA achieves this level of interoperability
by specifying program interfaces in an implementation-neutral interface definition language (IDL).
IDL can be mapped to almost any required programming language
C, C++, FORTRAN, COBOL, Ada, Java,..
allowing you to develop your programs in the language of your choice.
CORBA also specifies the Internet Inter-ORB Protocol (IIOP)
as a common communications protocol for TCP/IP networks.
Just as IDL hides programming language differences
IIOP enables different applications to communicate with each other
through a standard protocol
hiding platform and network differences.
Dr.Withalm

26. There is a lack of products supporting IIOP client side.
CORBA-Weaknesses/1
There is a lack of products supporting IIOP client side.
IIOP don't reach the adoption expected by OMG consortium from the main software vendors
And there are few Programming and administrator software tools based on CORBA IIOP
Loose coupling is a difficult feature in CORBA world:
Client and Server sides are strongly coupled with static and binary IIOP messages
it is unfeasible to add some header or information dynamically in the IIOP messages between the client and the server
There is no notion of intermediary node in the CORBA model
even if a distributed object can be in client, server or both roles
So loose coupling and agility in the system are difficult or even unfeasible.
Dr.Withalm

27. IIOP is not firewall friendly and not opened on all firewalls
CORBA-Weaknesses/2
IIOP is not firewall friendly and not opened on all firewalls
Network administrators have been very reluctant to open ports on firewalls.
If the HTTP protocol has gain lot of facilities to be allowed from the beginning,
it is not the case for IIOP network protocol and CORBA had suffered this situation.
CORBA programming is quite complex
CORBA client programming is somewhere quite complex to master, with complex APIs,
The necessary skills to develop CORBA Clients or CORBA Servers are important,
even if the code is always based on template or framework that can be reused.
Dr.Withalm

28. CORBA-Competition Microsoft COM and DCOM Sun Micro System EJB
Dr.Withalm

29. Currently there are other tendencies in the market
CORBA-Conclusion
Last CORBA specification releases are from 2002 with the addition of CORBA 3.0 and CORBA CCM.
Currently there are other tendencies in the market
but since there are existing applications running with CORBA
they should be considered in order to be integrated.
Efforts on integrating CORBA IDL and Web Services WSDL are on the roadmap of some of the main CORBA players.
This will offer (thanks to idl2wsdl converters) translations from CORBA description to Web Service description
Dr.Withalm

30. Application servers/2 ORBs/1
- feature varying degrees of complexity
the simplest ones make it possible to connect
client applications and
distributed objects
make it easy to find and use objects distributed on clients
are less well suited for transaction controlled environments with high data volumes
are called ORBs
Dr.Withalm

31. Application servers/3 ORBs/2
- provide a communication backbone for distributed objects
but normally not the robust infrastructure required
to support large numbers of users and mission-critical operations
application developers must access services such as transaction, persistence, multi-threading on their own
Dr.Withalm

32. TP-monitors are managing programs (or processes) that operate on data
PSE GSC
What is a TP monitor ?
TP-monitors are managing programs (or processes) that operate on data
complex applications are broken into pieces of code called transactions
Using these transactions, a TP-monitor can get pieces of software that don’t know anything about each other to act in total unison
Dr.Withalm
PSE Bereichspräsentation

33. What does a TP Monitor do ? / 1
PSE GSC
What does a TP Monitor do ? / 1
runs classes of applications that could service thousands of clients
provides an environment that interjects itself between the remote clients and servers
manages transactions
routes them across systems
Dr.Withalm
PSE Bereichspräsentation

34. What does a TP Monitor do ? / 2
PSE GSC
What does a TP Monitor do ? / 2
load balance their execution
restart them after failures
can manage transactional resources on a single server or across multiple servers
can cooperate with other TP monitors in federated arrangements
Dr.Withalm
PSE Bereichspräsentation

35. Why a Server Operating System needs a TP Monitor
PSE GSC
Why a Server Operating System needs a TP Monitor
Dr.Withalm
PSE Bereichspräsentation

36. Distributed Transactions / 1
Context
Object Request Broker
Transactional
Client
Recoverable
Server
Begin
End
Transaction Service
method
propagation
involvement
Dr.Withalm

37. Component transaction monitors
- are application servers that have developed from a mixture of
traditional TP monitors and
ORB technologies
- provide infrastructure able to automatically manage
transactions, object distribution, multi-threading, security, persistence, and resources (=Corba services)
Dr.Withalm

38. Server-side components /2
- Business is always moving, products, processes, and goals of a company are bound to change in the course of times
- If it is possible to encapsulate the software that models a business into a business object, the software will then be flexible, scalable, and reusable and thus be able to develop on its own in line with the business
Dr.Withalm

39. Server-side components /3
- A server-side component model defines
an architecture for developing distributed business objects
- and combines
the accessibility of distributed object systems with
the changeability of the business logic in the form of an object
- Server-side component models are used on the application servers of the middle layer
that manage the components at runtime and make them available to remote clients
Dr.Withalm

40. Server-side components /5
- Depending on the component model, the server administrator is able to set the behavior of a server-side component
with respect to transaction, security, and even persistence
by assigning certain values to these attributes
Dr.Withalm

41. Server-side components /6
- When new products are being developed and corporate processes change
it is possible to re-assemble, change, and extend server-side components in such a way
that the business system will reflect these changes
- A business system can be regarded as a collection of server-side components
that model concepts such as customers, products, reservations, warehouses, etc.
Dr.Withalm

42. Server-side components /7
- Each component is like a building block that can be combined with other components to form a business logic
Products can be stored in a warehouse or delivered to a customer
A customer can make a reservation or buy a product
- You can assemble or disassemble components, use them in other components, and change their definitions
- A business system based on server-side components is
flexible because it consists of objects, and
accessible because the components can be distributed
Dr.Withalm

43. Enterprise Bean/1 Component
- There are two different types
Entity Bean
Session Bean
Dr.Withalm

44. Enterprise Bean/2 Entity Beans
model business entities that can be expressed in the form of nouns
for example: customer, piece of equipment, entry in stock list, location,...
- thus model objects from the real world
persistent data records in some kind of database
- represent data and behavior
- constitute a system with a reusable and consistent interface to the data held in a database
- behavior typically focuses on applying business rules
directly linked to the modification of data
- moreover, Entity Beans may contain relations to other entities
- are shared by many clients
Dr.Withalm

45. Enterprise Bean/3 Session Beans/1
are an extension of the client application and are responsible for managing processes or tasks
for example: they are typically used to manage certain activities such as a reservation; in doing so, they rely on Entity Beans
All these operations are reflected in the database by actions being performed on the corresponding Entity Beans
work on behalf of the client and manage operations or tasks
- provide the right place for business logic
- are not persistent like an Entity Bean
nothing is being mapped onto a database
nothing is being saved in between sessions
Dr.Withalm

46. - work with Entity Beans, data, and other resources
Sessions Beans/2
- work with Entity Beans, data, and other resources
in order to control a business process
- the business process is the key issue in every business system
defines how entities interact with one another
in order to model the actual business
- govern tasks and resources
but do not themselves represent any data
Dr.Withalm

47. - reduce the number of network connections the client needs
Sessions Beans/3
- reduce the number of network connections the client needs
improves the system performance
- One method call in client applications results in a multitude of method calls on the server
the network registers only the traffic caused by the one method call for the Session Bean
- reduce the number of stubs used on the client side
which in turn saves memory space and CPU time at the client
Dr.Withalm

48. Stateful Session Beans/1
- manage a conversation state while being used by a client
- are not written to the database, but kept in memory
as long as a client uses a session
the client can make conversation with the bean
while the bean's individual methods are invoked
the state of the Session Bean may change
such changes may affect future method calls
Dr.Withalm

49. Stateful Session Beans/2
- The conversation state remains active only as long as
a client actively uses the bean
if the client terminates or releases the Session Bean,
the conversation state is lost for ever
are bound to a client for their entire lifetime
- manage the state between method calls
this is referred to as conversation state
representing the continuous conversation between client and stateful Session Bean
- the integrity of this conversation state must be
retrained during the whole time it takes to execute the service for the client
- do not participate in instance pooling
instead an activation is used
Dr.Withalm

50. Stateless Session Beans
- do not have a conversation state at all
- each method is completely independent of all other methods and uses only the data
passed on as parameters
- provide the best performance of all bean types
with respect to throughput and use of resources
only a few stateless Session Beans are needed
to serve hundreds, or even thousands, of clients
do not manage any state between method calls
each method call is therefore
independent of all others, and
executes its task without the use of instance variables
- any stateless Session Bean can
serve requests from any EJB object of a suitable type
allows the container
to swap bean instances in and out between the client's method calls
Dr.Withalm

51. Classes and interfaces/1
- In order to implement an Enterprise Bean it is necessary to define two interfaces and one or two classes
Remote interface
Home interface
Bean class
Primary key class
Dr.Withalm

52. - manages a multitude of interactions between a bean and its server
Containers/1
- manages a multitude of interactions between a bean and its server
- is responsible for providing a uniform interface between bean and server
- creates new instances of beans
- ensures that the server stores instances correctly
Dr.Withalm

53. Resource management and primary services
- How is it possible to manage millions of distributed objects at the same time?
resource management is extremely important
how to control
how distributed objects use memory and processing time
- Currently, 6 primary services are supported
Multi-threading
Transaction management
Persistence
Object distribution
Naming
Security
Dr.Withalm

54. and enable the developer to concentrate
J2EE/1
The J2EE platform (Java 2 Platform, Enterprise Edition) is a software framework that provides technologies for the design and development of multi-tier business applications.
It also provides services that ease the development of business applications,
and enable the developer to concentrate
on the business functions he has to implement, not on the technologies involved.
Dr.Withalm

55. J2EE/2
Dr.Withalm

56. The J2EE platform uses a multi-tiered distributed application model.
This means application logic is divided into components according to function
and the various application components that make up a J2EE application
are installed on different machines depending on which tier
in the multi-tiered J2EE environment the application component belongs.
Dr.Withalm

57. Client tier components run on the client machine
J2EE/4
The J2EE Application parts shown in above figure are presented in J2EE Application Components
Client tier components run on the client machine
Web tier components run on the J2EE server
Business tier components run on the J2EE server
Enterprise information system (EIS) tier software runs on the EIS server
Dr.Withalm

58. J2EE/5
This figure can also be used for representing the architecture of the J2EE platform
where the architecture defines a client tier, a middle tier and a back-end tier.
The client tier supports different types of clients
from applications and applets to thin web-based and mobile clients.
The middle tier provides infrastructure for the business services
and is subdivided into the web tier and the Enterprise JavaBeans (EJB) tier.
The web tier provides services related to the web and thin clients.
The EJB tier provides the environment for executing business logic components.
The back-end tier provides enterprise services such as
data persistence
but can also host other existing enterprise information systems (EIS).
Dr.Withalm

59. J2EE works on any platform with a compliant Java VM
J2EE/6 Strenghts
J2EE works on any platform with a compliant Java VM
and a compliant set of required platform services
EJB container, JMS service, etc., etc..
All of the specifications that define the J2EE platform are published and reviewed publicly
and numerous vendors offer compliant products and development environments.
The different J2EE integration technologies can be used in different integration problems
Dr.Withalm

60. There's a gap between J2EE's strength in designing applications
J2EE/7 Weakness
There's a gap between J2EE's strength in designing applications
and the need to manage the composite nature of newer programs
that have real-time requirement
you will need to use Integrated transactions, message routing, integrity, wrappers, bridges and access tools to external applications, etc.
J2EE is a single-language platform.
Calls from/to objects in other languages are possible through CORBA
but CORBA support is not a ubiquitous part of the platform
Dr.Withalm

61. Main competitor is Microsoft .Net platform
J2EE/8 Competitors
Main competitor is Microsoft .Net platform
Dr.Withalm

62. Thank you for your attention!
PSE GSC
Thank you for your attention!
PSE Bereichspräsentation

63. Farbpalette mit Farbcodes
PSE GSC
Farbpalette mit Farbcodes
Primäre Flächenfarbe:
Akzentfarben:
R 255
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B 255
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B 093
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G 083
B 105
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R 064
G 127
B 183
R 064
G 064
B 064
Sekundäre Flächenfarben:
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R 255
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B 166
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Dr.Withalm
PSE Bereichspräsentation