The document describes a three-tier architecture for mobile computing. It consists of a presentation tier, application tier, and data tier. The presentation tier handles the user interface and rendering. The application tier controls transaction processing and accommodates many users. The data tier manages database access and storage. Middleware sits between operating systems and user applications to handle functions like network management and security across tiers. This three-tier architecture provides benefits like improved performance, flexibility, maintainability and scalability.
2. The network-centric mobile computing
architecture uses three-tier architecture
1) Presentation Tiers
2) Application Tiers
3) Data Tier
4. In three tier architecture, the first layer is User
Interface or Presentation Tier.
This layer deal with user facing device handling and
rendering. this tier includes a user system interface
where user service reside.
The second tier is the Process Management or
Application Tier
This layer is capable of accommodating hundreds of
users.
The middle process management tier controls
transaction and asynchronous queuing to ensure
reliable completion of transaction
5. The third final tier is the Database Management or Data
Tier.
This Layer is for database access and management.
The three-tier architecture is better suited for an
effective networked client/server design. It provide
increased performance , flexibility , maintainability ,
reusability and scalability , while hiding the
complexity of distributed processing from user.
All these characteristic have made three-tier
architecture a popular choice for Inter application and
net-centric information system
8. This is user facing System in the first tier. This is the
layer of agent application and system.
These applications run on the client device and offer all
the user interface.
This tier is responsible for presenting the information
to the end user.
Presentation Tier include web browsers (like Mozilla,
Internet Explorer etc…)WAP browsers and customized
client programs.
9. It performs the business logic of processing user
input , obtaining data, and making decision
In certain case, this layer will do the transconding
of data for appropriate rendering in the
presentation Tier.
In mobile computing environment in addition to
the business logic there are quite a few additional
management function that need to be performed
10. These function relate to decision on renderinal ,
network manegement , security, datastore acess,
etc.
Most of these function are implemented using
different middleware software.
Middleware frame work is defined as a layer of
software,which sits in middle between the
operating system and the user facing software.
12. The Data Tier is used to store data
needed by the application and acts as a
repository for both temporary and
permanent data.
These can range from sophisticate
relational database, legacy hierarchical
database , to even simple text files.
13. Database middle ware allows the business logic to
be independent and transparent of the database
technology and the database vendor.
Database middle ware runs between the
application program and the database.
Example of such middle ware will be ODBC,JDBC,
etc.
14. Using this middle ware , the application will be
able to access data from any source.
Data source ca be text files, spreadsheets or a
network, relational , indexed, hierarchical, XML
database, object database, etc.., fro vendors like
Oracle, SQL , Sybase , etc.