Custom Development of Enterprise Services


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

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Custom Development of Enterprise Services

  1. 1. CustomCustom DevelopmentDevelopment of Enterprise Servicesof Enterprise Services -- WhatWhat doesdoes an Softwarean Software ArchitectArchitect needneed toto knowknow?? Tobias Trapp
  2. 2. © Tobias Trapp 2010 2 Table ofTable of ContentContent Implementation Details Standardization of Web Services Summary Component Architecture
  3. 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. 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
  5. 5. © Tobias Trapp 2010 5 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. 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. 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. 8. © Tobias Trapp 2010 8 Table ofTable of ContentContent Implementation Details Standardization of Web Services Summary Component Architecture
  9. 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 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. 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 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. 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: create packages that contain only ABAP proxies } } CUSTBP CUSTCRM SCs in an ABAP system
  12. 12. © Tobias Trapp 2010 12 Table ofTable of ContentContent Implementation Details Standardization of Web Services Summary Component Architecture
  13. 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.
  14. 14. © Tobias Trapp 2010 14 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. 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. 16. © Tobias Trapp 2010 16 Table ofTable of ContentContent Implementation Details Standardization of Web Services Summary Component Architecture
  17. 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.