These are the slides of my talk at SAP Mentor monday 8th november about development of Enterprise Services.

1. CustomCustom DevelopmentDevelopment of Enterprise Servicesof Enterprise Services --
WhatWhat doesdoes an Softwarean Software ArchitectArchitect needneed toto knowknow??
Tobias Trapp

2. © Tobias Trapp 2010 2
Table ofTable of ContentContent
Implementation Details
Standardization of Web Services
Summary
Component Architecture

3. © Tobias Trapp 2010 3
WhichWhich SAP technologySAP technology isis thethe mostmost appropriateappropriate forfor specificspecific purposespurposes??
lightweight interfaces: REST are very useful for integration of output and
document management systems
application integration: A2A services outside-in using PI
commerce transactions between businesses : B2B services generated
outside-in, propably using PI
integration using arbitrary clients: A2X services generated outside in
exposing BOL classes on the fly: CRM Web Service framework
mobile apps: Sybase CRM Mobile Sales and Mobility for SAP
coming soon: project Gateway
exposing function modules on thy fly: inside out generation
WelcomeWelcome to ABAP Web Serviceto ABAP Web Service JungleJungle!!

4. © Tobias Trapp 2010 4
„„InsideInside OutOut““ isis aa DeadDead End StreetEnd Street
„Inside Out“ means poor man‘s SOA
no standardized data types
we can‘t control mandatory and
non-mandatory elements
no standardized naming conventions
no standardized communication patterns
no patterns for asynchronous scenarios
no standardized change strategies: first one wins vs. last one wins
complicated & database–like because of TABLES parameters
important frameworks are missing
- idempotency
- forward error handling
- no enhancement concept for customers

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Enterprise ServicesEnterprise Services
Build your SOA on standards and best practices
use global data types according UN/CEFACT standards
develop enterprise „outside in“: generate ABAP proxies from a WSDL (file, URL,
ESR) using transaction SPROXY / SE80
follow ESR modelling guidelines and create ESR certified content
from SAP Guidelines for Best-Built Applications that Integrate with
SAP Business Suite:

6. © Tobias Trapp 2010 6
NearlyNearly everythingeverything youyou needneed toto knowknow isis writtenwritten downdown
There are lots of resources on SCN and SAP Press
many tutorials about ESR on SDN
SOA 300 training
everything about modelling & implementation is written down
in SAP Press Book „Developing Enterprise Services for SAP“
„How To… Develop, Monitor and Debug WS Consumer
and Provider“
Enterprise SOA Development Handbook 1.1
chapter about SOA & loose coupling of
applications in SAP Guidelines for
Best-Built Applications that Integrate
with SAP Business Suite

7. © Tobias Trapp 2010 7
Enterprise ServicesEnterprise Services havehave wellwell--defineddefined SemanticsSemantics
Use naming conventions and communication patterns
naming convention is: <business object view> <action> <message type>
Sales Order Create Request
actions are Create, Read, Update (first one wins), Change (last one wins),
Cancel and Check: Purchase Order Cancel Check Query Request
there are well-defined semantics described below:

8. © Tobias Trapp 2010 8
Table ofTable of ContentContent
Implementation Details
Standardization of Web Services
Summary
Component Architecture

9. © Tobias Trapp 2010 9
SOASOA byby „„ControlledControlled EvolutionEvolution““
SOA by Design vs. SOA by Evolution
SAP‘s SOMAID methodology is heavy weight – you need a list of all processes
whether they are IT-based or not
whenever you can use Enterprise Services of SAP Business Suite - you‘ll find them
on ES work place http://www.sdn.sap.com/irj/bpx/esworkplace
if necessary enhance SAP standard services as described in
Enterprise Service Enhancement Guide
create custom Enterprise Services using SAP‘s
modelling approach - construct them from business
objects of your ABAP app.

10. © Tobias Trapp 2010 10
ABAPABAP AppsApps, ESR, ESR SWCVsSWCVs and XMLand XML NamespacesNamespaces
How to structure ESR development
SWVCs in ESR correspond to ABAP SCs
an ABAP application corresponds to an repository namespace
define data types for reuse in separate namespaces
create repository namespace for each application containing business objects
this leads to a hierarchy of repository namespaces
http://tempuri.org/xi/flightmanagement/CRM
http://tempuri.org/xi/flightmanagement/CRM/Global
http://tempuri.org/xi/flightmanagement/BP
http://tempuri.org/xi/flightmanagement/BP/Global
http://tempuri.org/xi/flightmanagement/Global
hint: avoid special characters in XML names because package names of generated
classes consumers tend to get complicated – this is a problem of many non-SAP
frameworks

11. © Tobias Trapp 2010 11
ABAPABAP ComponentComponent StructureStructure
How to structure server proxies according to your ABAP component hierarchy?
in NW 7.01 there can be only one proxy element per system (and ABAP
namespace).
ESR dependencies lead to dependencies in ABAP: proxy elements will be reused -
so be careful if the proxies are in different ABAP components:
http://tempuri.org/xi/flightmanagement/CRM
http://tempuri.org/xi/flightmanagement/CRM/Global
http://tempuri.org/xi/flightmanagement/BP
http://tempuri.org/xi/flightmanagement/BP/Global
http://tempuri.org/xi/flightmanagement/Global
create packages that contain only ABAP proxies
}
}
CUSTBP
CUSTCRM
SCs in an
ABAP system

12. © Tobias Trapp 2010 12
Table ofTable of ContentContent
Implementation Details
Standardization of Web Services
Summary
Component Architecture

13. © Tobias Trapp 2010 13
BestBest PracticesPractices forfor Creating Enterprise ServicesCreating Enterprise Services
Common mistakes and how to avoid them
specify error handling: system errors, wrong input parameters, missing
authorities…
consider compensation scenarios: what happens if a web service call fails?
use forward error handling in asynchronous scenarios
consider reviews for ESR development – developers tend to break every rule
because they can do anything in XML
keep code in generated classes small – delegate to classes
containing business logic for each method
use naming conventions for data types, parameters,
message types and message data types in generated classes
develop in a test driven way: check ABAP classes using unit tests,
test Enterprise Services using ABAP test tool resp. eCATT
study best practices in SAP guidelines esp. the SAP Press book
don‘t follow guidelines for SAP Business Suite blindly: asually an ES doesn‘t
need to be XI 3.0 conform and contain more than 1 operation.

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AbsolutelyAbsolutely necessarynecessary toto knowknow:: ExtendedExtended XML HandlingXML Handling
Empty values vs. Null values
NULL values have different semantics compared to initial values:
- NULL values in an update service mean that they should not be changed
- NULL values in a query mean that a data element is not relevant in a search
Initial values can be coded as empty XML elements
NULL values can be coded using xsi:nil and missing elements
In the constructor of a server proxy switch extended XML handling on:
set_extended_xml_handling( i_switch_on = abap_true ).
Then you get the information about every data element (omitted, xsi:nil, initial) in
an structure PRXCTRLTAB

15. © Tobias Trapp 2010 15
AA hiddenhidden gemgem:: GenericGeneric Code List Provider FrameworkCode List Provider Framework
Codes can be defined an ABAP backend system
define code lists as XML schema enumeration types
only if the values are well-defined & do not change
In most cases code lists are defined in ABAP backend in
customizing tables
you can bind domain values, (text) tables to server
proxy data elements and read them using the
generic Enterprise Service QueryCodeList
the framework is extensible – think of time depended
customizing, subsets of customizing sets…

16. © Tobias Trapp 2010 16
Table ofTable of ContentContent
Implementation Details
Standardization of Web Services
Summary
Component Architecture

17. © Tobias Trapp 2010 17
ExplainExplain toto developersdevelopers thethe conceptconcept of Enterprise Servicesof Enterprise Services
As software architect now you are well prepared for a SOA project, but don‘t
forget:
keep yourself informed - ABAP frameworks are rapidly evolved by SAP
learn about eventing, service groups, forward error handling…
What do developers of Enterprise Services need to know?
a prototype implementation will help developers to understand the concepts
teach developers the transactional behaviour esp. in update/change services: SET
UPDATE TASK LOCAL, cl_soap_commit_rollback and that enterprise
services are stateless – no DB cursor!
don‘t forget to test the enterprise services with user with different authorization
profiles in the ABAP backend.