Summary
1 software architecture and design process
2 DBAS overall design
3 DBAS outline design features
4 DBAS detailed design
5 DBAS security framework design
6 DBAS embodiment of the process and the content
DBAS functional design include application software transactional database design and application design
functional design process is generally divided into the overall design, preliminary design and detailed design. And specific to the design part of the database transaction, the transaction can be divided into the outline design and detailed design matters
Upon completion of system design, system implementation and on into the deployment phase
Software Architecture Design Process
Software Architecture: software architecture, software architecture = components, connectors, constraints}
software architecture is the West Wing of the most essential software stuff, good architecture must be universal, efficient and stable
software architecture how Bell styles and types, such as layered structure, model - view - controller (MVC) client, server architecture, etc.
Software design
software design process: design; implement; test
design include: outline design and detailed design
summary of the design: the overall structure of software design; software can be used to establish a hierarchy diagram the overall structure. Detailed design data is design tasks, design and process design man-machine interface
design principles: modularity, information hiding, abstract and stepwise refinement
software design: the choice of a design method; object oriented programming or data-oriented design methodology
DBAS overall design
Tasks are: to determine the overall framework of the system
main contents include:
DBAS architecture design
software architecture design
software and hardware selection and configuration design
preliminary design business rules
DBAS overall design:
Software Architecture:
the system from a functional; hierarchical / structural, geographical distribution angle-resolved, divided into multiple subsystems, each subsystem defined function; global control system design, and interaction between the various subsystems clear Interface relationship
common DBAS architecture: operating systems; database management system; development environment; middleware; application software; (database transactions and applications)
Starting down into subsystems, a respective distribution function, defined mutual interaction mechanism, to complete the design subsystems, each subsystem into the transaction database module (senior transaction processing logic) from the large particle size of the functional application module (demand from business rules), to determine the relationship between the global control may invoke
the available module configuration diagram (block + + + control call forwarding) and the overall structure of a system hierarchical modular structure
Software, hardware selection and configuration design:
planning analysis phase proposed system functionality, performance and implementation constraints on the hardware and software evaluation and selection recommendations made; the demand for functional performance system put forward specific requirements. To ensure the smooth realization of DBAS functional performance, overall design stage need to make a reasonable choice of software and hardware equipment, and preliminary configuration design.
And network equipment selection: data storage and backup solutions; server selection
terminal software environment: software development platform and language, tools;
systems and third-party middleware software selection.
Business rules preliminary design:
from the perspective of system planning DBAS business processes to conform to the customer's actual = the actual business needs of
various business activities DBAS has precedence relationship logically, they can be represented as a sequence of operations, and with business processes figure shows
DBAS function outline design
On the basis of the results of the overall design, application software will DBAS further refine the module sub-system modules - design data in three areas - subsystems - modules - sub-module hierarchy, and from the structure - conduct
From a functional perspective, the DBAS system is usually divided into four levels to achieve: the presentation layer, the business logic, data access layer, data persistence layer
Summary business logic design:
design principles: the high cohesion and low coupling, i.e. the principle of a single member, member function independently; interface is simple, too complicated, to refine the decomposition
design content: structure, behavior, data interfaces, troubleshooting, safe design, system maintenance and security, etc.
Data Access Layer summary of the design
task: all kinds of transaction data processing needs for DBAS designed for operation of the database
transaction level design core is designed to identify and deal with their own affairs logic, pay attention to the process, regardless of platform, specific methods of operation and the implementation mechanism of the transaction
A complete transaction summary of the design include: transaction name, access to relational tables and data entry, business logic (transaction description), transaction user (using, start calling software modules and system of the transaction)
Glossary:
Services: access may update a program execution unit various data items in the database
characteristics of transaction: atomicity, consistency, isolation, persistent, referred to the ACID properties
of atomicity: an indivisible work unit
consistency: change from one consistent state to another consistent state
isolation: its transaction execution can not be interference
Durability: Once a transaction is committed, it changed data in the data should be permanent
Summary data persistence layer design:
part of the design content data organization and storage areas
DBAS detailed design features
Detailed presentation layer design:
Suitable man-machine step three iterative method
(1) Preliminary Design: Design and optimization interactive command system (overall design)
(2) details of the design user interface
(3) Design and improvement of prototypes
Business logic design detail
design module internal processes and algorithms, specific data structures, the external interface details
Application Security Architecture Design
1 Data Security design
five areas:
security protection: to prevent illegal use of illegal users of the database to avoid data disclosure, alteration or destruction of
the integrity of protection: to ensure the accuracy, consistency and compatibility of data sources.
Concurrency control: to ensure that multiple users can share a database, maintain data consistency and
data backup and recovery: data recovery after a system failure, with regular backup of the database, no data is lost
data encryption transmission: some advanced sensitive data through certain data transmission algorithm
Application Security Architecture Design
Security protection (1) databases
The main protection:
user authentication: windows provinces validation, SQL authentication
access control:
back-end database is different users different access requirements for data set different permissions for different programs is legitimate to set permissions for each user level, external users set up a limited search function
view mechanism: the mechanism by view confidential data users have no right to hide
(2) protect the integrity of the database
integrity of the database data in the database refers to the accuracy, consistency and compatibility
: Set the integrity check
on the data set some constraints (entity integrity, referential integrity, user-defined integrity)
integrity constraints target: column (type, range, accuracy, sorting), tuple (link constraint between each attribute record), the relationship (between the plurality of recording, the relationship between the set of link set ) three levels
DBAS integrity constraint function comprises checking integrity constraints and disposed Sword
Concurrently (3) control database
concurrent access: transaction performed overlapping in time.
Operation of concurrent users accessing the same data may result in inconsistent data and undermining transaction isolation, therefore DBMS must provide concurrency control mechanism, concurrency control mechanism is a measure of an important indicator of the performance of a DBMS, database concurrency control methods used to achieve technology is blocked.
The so-called block: T prior to a transaction data objects (tables, records, etc.) operation Xianxiang system issues a request to its lock, the lock, the lock transaction T before it is released, the other transactions can not update data objects
Basic types of locks:
Exclusive lock: a write lock, for the transaction if the data object A together with X lock, to read and modify only T A, no other transaction can no longer applied to any type of lock A, A on release know T lock, making him a lock to ensure that other transactions can not be read before the release of the lock on the T and a modification a
Shared lock: read lock, if the transaction data object A to T plus S lock, other transactions can only then to add S A lock can not add X lock, release S T know the lock on A, a shared lock to ensure that the other transactions can read a, but not make any changes before the a S T release lock on a
Avoid deadlocks
Deadlocks are circulated between two or more transactions wait
: design principles deadlock avoidance
(second transaction after the first transaction commit or rollback) (1) in accordance with the same order to access the resource
( 2) to avoid interaction transaction
(3) the use of small transaction mode, and shorten the length of elapsed time
(4) to make use record-level lock (row locks), less table level lock
(5) using a bonded connection of the user to open the same It is connected to two or more mutually cooperative
Data backup and recovery (4) database
database recovery Rationale:
redundant data stored on other memory using the system (data backup) to reconstruct
data backup and recovery strategy:
Hot Standby (Active / standby mode hot standby server )
data dump (data backup)
data encryption storage (data for high sensitivity)
(5) data encryption transmission
common means of transmission of data encryption
digital certificate security
keys to encrypt the symmetric
digital signature
digital envelope
implement
purchase third-party middleware product integration is a fast and effective solution
Environmental safety design:
Vulnerability and Patch: periodically find vulnerabilities patch update
computer virus protection: anti-virus software, real-time monitoring
network environment security: firewalls, intrusion detection systems; network isolation (logical isolation and physical isolation)
physical environment security: anti-theft devices; ups; temperature alarm
System security design
management level security measures
DBAS implementation
1 Create a database
considerations; initial space; database increment size; access performance (number of concurrent access assessment rate)
2 data reproduced
screening data - data format conversion - input data - check data
3 writing and debugging applications
4 database system running (functional testing and performance testing)
