WebDynPro for Java Common Error v5

WebDynPro for Java:
Common Error
Prevention and Fixes

© SAP AG 2006, SAP TechEd ’06 / Session ID / CD110
Agenda
Jodi Johnson
Developer, CLOROX

Learning Objectives
As a result of this workshop, you will be able to:
 Avoid some common but nasty errors in WebDynPro
 Correct the errors you couldn’t avoid
 Understand the impact of the errors
 Use practical tips to create an easier to maintain and more robust
application

SETUP Issues (Development Configuration
and Multiple Tracks)

Glossary
Development Configuration (DC):
the framework of a WebDynPro application
TRACK:
individual instance of WebDynPro
BUSINESS PACKAGE:
grouping of DCs that are treated as a unit(SCA)
SCA:
Software Deployment Archives, used by BASIS to import
WebDynPro Code between portals
SYSTEM:
HR ESS/MSS ECC5.0 PORTAL 6.2 SP 13

DC – Tips - Multiple Tracks
Make sure correct portal is selected

Ensure host matches selected portal host

REASON: Can use separate tracks and portals to support
Production, code for a project and
check Service Packs.

DC – Tip – Use correct prefix for DCs
Business Package (ESS)
No Business Package

DC – Tip – Use correct prefix for DCs
REASON: All DCs are grouped by business package and
transported to portals as a SCA.

DCs - Problem – Creating DC on server
Wrong place to add dc
Right place to add dc

DCs - Problem – Creating DC on server
EFFECT: Cannot remove DC from server.
The SCA will not build correctly, BASIS must manually
exclude the bad DC before the build will succeed
SOLUTION: Only upgrading to the next Service Pack
will remove the DC from the server.

DCs – Problem - Changing SAP vanilla DCs
Importing Vanilla SAP Configuration to
make changes

DCs – Problem - Changing SAP vanilla DCs
EFFECT: Everything works until a Service Pack is applied.
SAP DC will revert back to vanilla.
SOLUTIONS: Rewrite any changes made to SAP DC.
OR
Copy the SAP DC and make changes to
that DC.

DCs – Tip – Service Packs
PROBLEM: Service Packs will revert any SAP DCs to vanilla
and drop any new NON-SAP DCs.
EFFECT: Only vanilla SAP DCs will exist.
SOLUTION: Keep a list of all DCs created for a project,
BASIS can load them on the track after the
Service Pack is applied.

CONTEXT Overview
RFC - Remote Function Calls
(passes data from backend to WebDynPro)
Model
One to one relationship with RFC
Used Model
Allows access to Model by Custom Controller and Views
Custom Controller
(Value Nodes and Attributes)
Views

CONTEXT Inheritance from Custom Controller to View
Views can inherit context Value Node and Attributes from Custom Controller
but Custom Controller cannot inherit from Views

RFCs – Tip – Maximize coding in backend
REASON: Code runs quicker. Backend (ECC 5.0) is where data is
maintained and validated. WebDynPro should
be used for display, parsing and enforcing field
requirements.

RFC/Models – Tips – Use Input and Rename Output
Use the RFC Input
Rename the output in the
RFC input

RFC/Model – Tip – Coding for reading models
try{
Z_Rfc_Read_Sample_Input readInput = new
Z_Rfc_Read_Sample_Input ();
wdContext.nodeSampleReadModel().bind(readInput);
wdContext.nodeReadOutput().invalidate();
}
catch (Exception e) {
}

TIP: Use a try {} when reading the model
REASON: Sometimes a null record is returned as the first record.
If this happens then the framework will go fetch the
correct record only if a try{} is coded.

TIP: Always read the input
TIP: Always invalidate the output
REASON: Won’t work properly otherwise.
NOTE: Same rules apply to saving models
- move data to input
- invalidate the output
- save input

RFC – Problem - Adding new fields to RFC
Must Reimport the RFC(Model)

RFC – Problem - Adding new fields to RFC
EFFECT: Need to reimport model and restart Portal
whenever the RFC structure is changed.
SOLUTION: Upfront analysis, put all fields that will likely
be needed for future upgrades in the RFC.
Better too many fields than too few.

RFC/Model – Problem - Data structure differences
PROBLEM: WebDYnPro contains different data types than ABAP
Specifically, WebDynPro can translate a char(1)
as Boolean. If a Boolean field is changed to a
different data type, reimporting the RFC will not remove
the reference to the Boolean field in the context.
SOLUTION: Delete the context by hand and reattach

DEMO

Summary
 Do the analysis/design upfront
 Don’t modify SAP DCs – create new ones
 Work on only one track at a time
 Code data verification on the backend
 Include all possible fields in the RFCs

Further Information
 Public Web:
www.sap.com
www.sdn.sap.com
 Related Workshops/Lectures at SAP TechEd ’05
Session ID, Title, Session Type
 Americas’ SAP Users’ Group (ASUG)
www.asug.com

THANK YOU FOR YOUR
ATTENTION !
QUESTIONS – SUGGESTIONS – DISCUSSION

Please complete your session evaluation.
Be courteous — deposit your trash,
and do not take the handouts for the following session.
Feedback
Thank You !

WebDynPro for Java Common Error v5

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