Presentation

Recap

• A multi layer architecture powered by Spring Framework, ExtJS, Spring Security and Hibernate.

• Taken advantage of Spring’s multi layer injection and loose coupled approach of having an MVC architecture.

• Rich UI achieved using ExtJS 4.0 Framework at UI layer.

• Communication achieved using AJAX calls (XMLHttpRequest) from Client to Server using JSON objects.

Recap

Architectural view of ECMS

Development Approach

• A reference model developed for an important use case (Air Job) including UI widgets, controllers, services and DAOs.

• After full requirement analysis Entities and DAO layer interfaces are finalized.

• Individual was assigned use cases to construct UI and Services .

Flow of Development Activities

RequirementGathering and

Analysis

Reference application

development

Design andDevelopmentOf Use Cases

Entity and DAO

Implementation

Improvement And updates in Reference App

ContinuousIntegration and

Test

Development ActivitiesRequirement Analysis

Experimental Development of Reference Application

Entity Model & DAO Construction

Design, Development & testing of Use Cases

Improvement and Add-On

Continuous Integration and Testing

Hibernate (DAO Layer)

Grid View Search (Filter Approach)

• All use cases has their entry point at Grid Panels, Form panels are the second step of user interaction.

• Grid Panels are made much powerful to provide functionalities such as– Filter/Search Records – Refresh the Grid without navigating away from the page.– Embedded Pagination.– Add, Remove and Update records, all in one request to

server (which enhance usability and makes less server calls)

Transaction Management and Concurrency Control

• Optimistic Concurrency control mechanism is used.

• This is achieved by version checking against session and retrieved objects, upon any update and delete.

Versioning to control Concurrent updates

RequestContextHolder

Request

SessionVersion

VersionDAO

ECMS DB

Spring Security

• Plug and play way of apply security to the web application.• More configuration less of coding to maintain the security

aspects of the application.• Aspect Oriented Programming model (AOP)• Spring Security 3.0 release is experimented and successfully

plugged into Spring Framework 3.x.• Secure and extremely secure folders are created to secure

static and dynamic contents of server.• Access level of such folders are described in security

configuration xml.• Cryptography is used to protect password from exposure.

Security Context

Security Context Authentication Object

WebAuthenticationDetails Object

User

Authority

Security Schema

User

-user_name-password-enabled

Authority

-user_name-authority

*1

Event Based UI programming model

• Following important events are used to make server calls upon events trigger when User interacts with the system.– beforeShow (to assemble different forms and their data before it

shown to the user.)– afterRequest (to fetch the records to sync UI store with database

asynchronously and avoid any race conditions)– beforeRequest (to set parameters to the request)– beforeDestroy (to avoid destroying the pop-up windows and forms to

enhance the performance of the system)– expand (upon expanding the accordion layout’s panels)– Collapse( upon colapsing the accordion layout’s panels)

Race Conditions• During the coding, many race conditions are

discovered, because of asynchronous nature of the requests.

• Among such scenarios the most encountered one is, when a code segment is in under UPDATE or CREATE operation, during this time sending a SELECT request for the same record within the same session is found to be a race condition.

• Above race condition identified, and resolved by using afterRequest event handle the SELECT request to update the UI Store.

Race Conditions-Problem

UIController DespatcherServlet UserCaseController UserCaseService DAO

1 : updateRecord()2 : delegate update request()

3 : getRecord()4 : delegate select request()

5 : marshal and update to database()6 : saveOrUpdate()7 : getRecord()

8 : getRecord()

9 : result()

10 : execute update()

11 : return()

Race condition hereResult with no updates

Race Conditions-SolutionUIController DespatcherServlet UserCaseController UserCaseService DAO

1 : updateRecord()2 : delegate update request()

3 : marshal and update to database()

4 : saveOrUpdate()

5 : execute update()

6 : return()7 : fire afterRequest event()

8 : getRecord()9 : delegate select request()

10 : getRecord()11 : getRecord()

12 : result()

After request event fired

Example of the code

Technical Challenges

• Novelty of technology at UI layer.– ExtJS documentation studied and referenced.

• JSON Parser couldn't able to parse if object properties contains null.– Work around

• Null values are replaced with empty string before it transmitted from server to UI layer.

– Long term fix strategy• JSON Parser to be fixed.

Technical Challenges

• Handling complex objects at UI Layer (ExtJS)– mapping between objects

Future aspects and improvements

• Refreshing the stale records by estimating user’s operation Rest Time.– UI layer can be enhanced to have capability to

refresh the data grids by estimating user’s rest time, and if it reaches a particular threshold value, the system would refresh the data grid by using beforeActivate event of the RowEditor.

– Above would avoid user to get into a situation of updating a stale record on grid.

Future aspects and improvements

• UI Update for Mobility in work– Proposing client for an update of UI version for Tablets and

Smart Phones. – ExtTouch( A mobile javascript framework) shall be used to

built tablet and smart phone applications.– HTML 5 standards.– Only User Interface shall required to update and service

shall remain as it is.• This is to have an advantage of mobility and instant

access to the application with greater performance.

Future aspects and improvements

• Integration Requirement– Understand from client that operations are not

integrated to the Accounts system.– Proposal for an integration between both of the

systems can be consider.

Future aspects and improvements

• Concurrent updates acknowledgement-– Grid Panel records can be highlighted in red color

of text to notify users that the local copy of the record is stale or no more fresh, and any updates to the stale data will not be persist in database.

– The above can be achieve by Observer Design Pattern and Push model of communication from server.

Doing It Again• After getting full understanding of the domain (cargo

management), we would like to go for more generalized and multi-tenancy approach of building this application.

• Metadata entity model can be used instead of rigid domain model, by which we can achieve customization requirements of data grids, forms and any other view panels for different customer.

• Spring’s web service framework can be used to expose server side operation as web services, if necessary.

• Releasing it as a software as a service (SaaS).