Transcript Constat 2001

Proof of Concept (POC) Proposal
3-Tier PFC extensions (3TX) using Java EJBs
presented by Garfield Allen
3TX
Proof of Concept (POC) Proposal
3-Tier PFC extensions (3TX) using Java EJBs
Contents:
Part 1: DESCRIPTION: What is 3 Tier ?
Part 2: Motives for 3-Tier Migration
Part 3: 3-Tier PowerBuilder
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Proof of Concept Proposal
Proposal
Proof of which concept?
The concept to be proven is that 3-Tier PowerBuilder using the PFC and Java EJB technology
provides a highly effective and relatively simple way to solve the following problems:
 Poor client-server application security.
 Poorly coded business rules in DB Stored Procedures.
 Single application with multiple front ends.
 Inaccessible (or poorly accessible) enterprise data.
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Proof of Concept (POC) Proposal
3-Tier PFC extensions (3TX) using Java EJBs
Part 1: DESCRIPTION: What is 3 Tier ?
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Proof of Concept Proposal
Description
What is 3-Tier Architecture?
3-tier architecture implies a system that is “distributed” across client application, database server
and a “middle tier” application server.
 Middle Tier
Traditional Client-server architecture involves 2 tiers (client and server)
3-tier architecture introduces a middle tier (an application server such as Weblogic or EAServer) for hosting a portion
of the application’s functionality.
 Partitioning: Full
True 3-tier architecture involves application partitioning.
Display logic (screens) is separated from business logic (code for non-visual features).
 Partitioning: Partial
Partial 3-tier architecture means only the Database Access logic is implemented and deployed to the middle-tier
server.
Business logic remains where it is (in the client or in the database).
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Proof of Concept Proposal
What is 3-Tier Architecture?
Description: 2-Tier Architecture (Client-Server)
DB
GUI
PB Client Business
Logic
2-tier
Data
Access
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Proof of Concept Proposal
What is 3-Tier Architecture?
Description: 3-Tier Architecture
Middle Tier:
Application Server
Business
Logic
Data
Access
Any Database
Server
DB
PB Client GUI
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Proof of Concept (POC) Proposal
3-Tier PFC extensions (3TX) using Java EJBs
Part 2: Motives for 3-Tier Migration
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Proof of Concept Proposal
Motives for 3-tier migration ?
3-TIER MIGRATION
There is a growing desire to migrate 2-tier (PowerBuilder) systems to 3-tier technology. This is for the
following reasons:
 Security
 Business Rules
 Multiple Front Ends
 Enterprise Data
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Proof of Concept Proposal
Motives for 3-tier migration ?
3-TIER MIGRATION
Security
 A single generic login id is considered more secure than having large numbers of direct
database connections and user-specific userids.
 The client application NEVER connects directly to the database (this is the principle of the
database De-Militarized Zone - the DMZ).
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Proof of Concept Proposal
Motives for 3-tier migration
3-TIER MIGRATION
Business Rules
 Currently, all business rules for PowerBuilder applications reside either in the client application itself or
in the database (as Stored Procedures).
 Client-side business logic is not recommended.
 The Stored procedure programming language is considered insufficiently robust as a means of coding
complex business logic (there is no inheritance, no encapsulation, etc).
 Java-based business logic is currently the recommended alternative. Hence the demand for a Java-based
application server upon which to deploy this Java-based business logic.
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Proof of Concept Proposal
Motives for 3-tier migration
3-TIER MIGRATION
Multiple Front Ends
 Currently there are several business applications that have multiple front-ends, but a single database (for
example, the application is split between a PowerBuilder front-end AND a web front-end).
 Each front-end uses its own duplicate of some or all of the application business rules.
 Such applications would very much like to unify their code into one single enterprise-level layer that is
accessible from both front-ends. EJBs provide the means to do so.
 The same enterprise-level Java POJOs could be accessed via Java Servlets for web apps, and via EJBs for
PowerBuilder apps).
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Proof of Concept Proposal
Motives for 3-tier migration
3-TIER MIGRATION
Enterprise Data
 Enterprise data may exist in several different database systems – often from different database vendors
(eg: an Oracle DB, a Sybase DB, a mainframe DB).
 An application may sometimes requires enterprise data from all of these systems.
 3-Tier technology enables an application to easily use several different databases at once – even if the
DBMSs are from different vendors.
 For the application, database access is generic – no vendor–specific code is required
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Proof of Concept Proposal
Motives for 3-tier migration
3-TIER MIGRATION
Additional motives for migrating to 3-tier technology:
 Incorporation of new technology (Web Services, JAVA, HTML, .NET)
 Reduced Database load through Database connection caching.
 Higher performance, scalability, and High Availability through clustering.
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Proof of Concept (POC) Proposal
3-Tier PFC extensions (3TX) using Java EJBs
Part 3: 3TX – The 3-Tier PFC Extensions
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
3-Tier PowerBuilder
 PowerBuilder is fully capable of creating 3-tier applications (since version 7).
 PowerBuilder uses the Sybase application server (Sybase EASERVER).
 However PowerBuilder can also use any generic JAVA-based (J2EE compliant) application server (e.g.
WebLogic, WebSphere, JBOSS).
 Now, 3TX introduces new PFC objects to enable 2-tier PFC applications to become 3-tier
applications using EJBs.
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
New PFC Client-Side Objects and Events
 Three New PFC client-side objects have been created:
The Client Interface Manager (CIM) – Datawindow version
The Client Interface Manager (CIM) – Datastore version
EJBCA (the connection manager for EJB objects)
 Three New PFC Datawindow/Datastore events have been created:
pfc_ejblookup
pfc_ejbretrieve
pfc_ejbupdate
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
Client-Side Objects: Client Interface Manager (CIM)
 Automatically manages all interaction between DataWindow/DataStore and EJB server.
 Is automatically called from the DW/DS sqlpreview( ) event if CIM object is in memory.
 Has its own retrieve and update functions.
 Automatically calls ejbretrieve, ejblookup and ejbupdate events.
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
Client-Side Objects: EJBCA
 EJBCA is the run-time name for the new PFC object n_ejbconnection.
 This is the connection manager for all EJB objects.
 Represents the EJB server equivalent of SQLCA transaction object
 It is derived from the ejbconnection object found in the pbejbclientXX.pbl.
 Handles all EJB server connection duties.
 Handles connect, disconnect and lookup.
 Handles specialist database functions like begin trans, commit, rollback and sysdate.
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
Client-Side Events: pfc_ejblookup
 Represents the EJB equivalent of settransobject() function.
 Here, the system is told which EJB object will be used with this DW/DS
 Coded at the application level (not at the PFC level)
 Each DW/DS can be coded individually, or in the ancestor.
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
Client-Side Events: pfc_ejbretrieve
 Represents the EJB equivalent pfc_retrieve() event.
 Here, the system is told which EJB method is used to retrieve data into this DW/DS.
 Coded at the application level (not at the PFC level).
 Each DW/DS can be coded individually, or in the ancestor.
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
Client-Side Events: pfc_ejbupdate
 Represents the EJB equivalent of the update() DW/DS function.
 Here, the system is told which EJB method is used to update the data to the database from this
DW/DS.
 Coded at the application level (not at the PFC level).
 Each DW/DS can be coded individually, or in the ancestor.
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
Server-Side Objects and Methods
 Three Java components have been created:
Data Access Object (DAO) – Stateless Session Bean
User Session Object (UsrSession) - Stateful Session Bean
Main object – Java POJO
 Server-Side objects encompass five standard methods:
pfcRetrieve
pfcUpdate
pfcInitSession
pfcEndSession
pfcGetSysDate
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
Server-Side Objects: Data Access Object (DAO)
 Stateless Session Bean.
 Handles JDBC drivers.
 Connection cache management.
 Open and close connection
 Resultset processing
 Stored procedure calls
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
Server-Side Objects: User Session Object.
 Stateful session bean.
 Stores user specific data (information that is needed beyond each method call).
 Stores the name of the DataBase cache that is assigned to this user (for systems with multiple Database
roles).
 A serialized reference (Java Handle) to this object is stored in the client (PowerBuilder) application as a
global variable.
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
Server-Side Objects: Main object
 This is the REAL server-side object.
 EJBs have no genuine user-defined methods.
 User-defined methods of the EJB simply reference the same-name methods of the POJO.
 In this manner, the implementation of business rules is confined to the POJO only.
 No business rules are implemented in the EJB (therefore maintenance is simpler).
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
Server-Side Methods: The Five General Methods
 pfcRetrieve
For processing all retrieve statements and in-line SQL statements.
 pfcUpdate
For processing all “UPDATE”, “DELETE” and “INSERT” statements.
 pfcInitSession
Instantiation of the UsrSession stateful session bean.
The EJB’s java handle reference is given as the return value.
 pfcEndSession
Destroys the UsrSession stateful session bean.
This command is issued just before the PowerBuilder application closes.
 pfcGetSysDate
Returns the current system date of the database specified in the connection cache.
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
3TX and the PFC Framework:
 The client application (PowerBuilder) generates SQL to be sent to the database.
 Each time the client application attempts to send a SQL statement to the database it is intercepted and
re-directed to the CIM.
 The CIM (in conjunction with the EJBCA) handles all aspects of communication with the Java server:
Calling Java proxies
Formatting SQL
Processing return values
Resultsets
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3-Tier PowerBuilder
3TX and the PFC Framework:
 The CIM automatically populates the PowerBuilder DataWindow or DataStore.
 The server-side Java EJBs together handle all aspects of database communication
 For simplicity, all business methods are encapsulated in the server-side POJO. The EJBs do nothing but
call the POJO’s methods.
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Proof of Concept Proposal
How does it work within PowerBuilder ?
3TX – The 3-Tier PFC Extensions
DW1
DW2
DW3
Client
Workstation
sqlpreview
Application
Server
EJB Stateful Bean
(Session manager)
Connection Cache
CIM
Any Database
EJB Stateless
Bean (DAO)
DS1
sqlpreview
DS2
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Proof of Concept Proposal
3TX – v2.0 - What’s in the next version ?
3TX – Coming Soon v2.0
The Next Version of 3TX with the PFC Framework:
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
Support for EAServer, JBoss and Websphere (currently only Weblogic is supported).

Server-Side PowerBuilder objects (NVOs deployed on the Java server using the PowerBuilder Application Server Plug-In – available with PB 11.5).

Full 3-Tier functionality (no SQL is exchanged between client and server – only arguments and parameters).

Support for EJB v3.0 (currently only EJB 2.1 is supported).

Support for .NET – a PowerBuilder NVO that is EJB enabled (that is, can communicate with a Java server using EJBs) will be deployed directly to the
Visual Studio.Net development environment to build hybrid PB/.NET applications (a pure .NET application is currently INCAPABLE of
communicating with Java EJBs).
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Proof of Concept Proposal
For More Information: Contact Details
Contact Details:
For more information, please contact the following email address/phone number:
 EMAIL:
[email protected]
 Telephone:
+33 (0) 6 43 43 87 27
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