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Short Portlet Programming Guide in P-Grade (Gridsphere) environment

Short Portlet Programming Guide in P-Grade (Gridsphere) environment. G. Hermann. Content. Main ideas Execution model Representation Part I Java – JSP collaboration Part II Definition of Portlets by portlet.xml and layout.xml Tomcat directory hierarchy. Main ideas.

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Short Portlet Programming Guide in P-Grade (Gridsphere) environment

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  1. Short Portlet Programming Guide in P-Grade (Gridsphere) environment G. Hermann

  2. Content • Main ideas • Execution model • Representation • Part I Java – JSP collaboration • Part II Definition of Portlets by portlet.xml and layout.xml • Tomcat directory hierarchy

  3. Main ideas • Layout design and business logic are separated • Response WEB pages are generated with the help of run time compiled and linked java code. • Even little parts of WEB pages can be handled independently (portlet concept)

  4. Warning ! • We restrict ourselves to the Portlet implementation of the Gridsphere • Focus on the class ActionPortlet Tasks: • Defines “states” described by Java Servlet Pages (Jsp) • Defines callback routines called • before HTML response generation (view) • after user action (update)

  5. First request from client Next requests from client Y(ActionFormEvent) X(RenderFormEvent) init(PotletConfig) Execution model - possible ways HTTML response generation

  6. First request from client Next requests from client Y(ActionFormEvent) X(RenderFormEvent) init(PotletConfig) Execution model-regime modify HTTML response generation

  7. First request from client Next requests from client X(RenderFormEvent) init(PotletConfig) Execution model-regime show HTTML response generation

  8. Representation I • java code (Action Portlet)defines the callback routines and the current (and next) state made intuitive to the client by defining the selection of the proper Jsp page in that state. The java code is responsible for the whole business logic. • Java Servlet Page (JSP) (file: xx.jsp) Composes the frame of the layout and defines communication interface between the client and java code in a given state. • The UI Tag Librarydefines the layout and the passive –data- interface between java code and JSP. The Java representation of the UI Tag Library follows the Bean concept. The JSP representation of UI Tag Library is XML. • “portlet.xml” defines the portlet and references the java code • “layout.xml” defines the menu hierarchy haw the callable portlets should appear. (layout.xml is GridSphere specific!)

  9. First request from client Next requests from client Y(ActionFormEvent) X(RenderFormEvent) init(PotletConfig) UI Tag Library objects Ani.jsp Representation II class Any extends ActionPortlet HTTML response generation

  10. Remarks(1) UI TAG LIBRARY • The UI Tag Library is not discussed in detailed in the subsequent example. • The Java side usage of it is self explaining by the Bean paradigm. • For the XML usage of it in the JSP file consult the document:http://www.gridsphere.org/gridsphere/docs/TagGuide/TagGuide.htm • What you must know is that the interface variables are identified by associated Strings

  11. Remarks(2) State Transitions Please note that the event handling interrupt routines of the Java Class ActionPortlet may terminate with the state transition instruction setNextState(PortletReqest,String), where the String parameter may refer either • a name of a routine, or • a JSP. The action defined in that JSP defines the next state.

  12. Remarks(3) other state subtilities • The String “DEFAULT_HELP_PAGE” is used to define a JSP when the client hits the “?” icon on the portlet • The String “DEFAULT_EDIT_PAGE” is used to define a JSP when client hits the “pen” edit icon.

  13. Remarks (4) Programing style • The JSP pages may contain direct java code fragments among UI tags and forms.However you are emphatically asked to avoid them: The overview of the program logic can be lost easily if the program code is fragmented, and the JSP is not used as its designated: for gathering and rendering of client data.

  14. Part I: Life Cycle of a Portlet by an example The simple Portlet “EnterName” redisplays a single string entered by the client.

  15. EnterName.java and the corresponding EnterName.jsp files

  16. First request from client Next requests from client Y(ActionFormEvent) X(RenderFormEvent) Init(PotletConfig) First Request arrives from the client HTTML response generation The routine init will be activated

  17. Java – Jsp connections-1 DEFAULT_VIEW_PAGE determines that before the elaboration of the first response the given rendering routine will be called.

  18. First request from client Next requests from client Y(ActionFormEvent) X(RenderFormEvent) Init(PotletConfig) First Rendering HTTML response generation Variables need to show to the client are prepared

  19. Java – Jsp connections-2 The jsp is referenced by the java code. After the running of the routine the HTML generation defined by the Jsp will be performed

  20. Java – Jsp connections-3 The parameter referenced by the handle “nameSessionHandle” does not exist, therefore the bean object referenced “nameOld” – wich will be created upon the first reference –receives the value “not defined”.

  21. Java – Jsp connections-4 The bean referenced as “nameOld” will be used to display the value known by the system before the user interaction.

  22. Java – Jsp connections-5 The jsp page will generate the HTML response

  23. HTML generated by the JSP as it appears for the Client The Jsp page will generate the HTML code in the response for the selected frame

  24. The internally generated bean objects are used to exchange data between Jsp defined HTML code and Java routines Java – Jsp connections-6

  25. Java – Jsp connections-7 The user hitting the button labeled as “Update” generates a Request activating the routine updateName

  26. Java – Jsp connections-8 Example: The Client fills the text field as “newValue”, and hits the Button “Update”

  27. First request from client Next requests from client Y(ActionFormEvent) X(RenderFormEvent) Init(PotletConfig) Repeated request arrives The prescribed ActionFormEvent handler will be activated. HTTML response generation

  28. Java – Jsp connections-9 In the action event handler the value defined by the client and stored in a bean referenced as “nameNew” will be read

  29. Java – Jsp connections-10 The text value will be forwarded to the subsequent rendering routine via the handle “nameSessionHandle”

  30. Java – jsp connections As a last step the routine triggers the rendering event

  31. First request from client Next requests from client Y(ActionFormEvent) X(RenderFormEvent) Init(PotletConfig) Repeated Rendering HTTML response generation

  32. Java – Jsp connections-11 As the value associated by “nameSessionHandle” is not emptythe bean referenced as “nameOld”will receive this value

  33. HTML generated by the JSP as it appears for the Client after repeated Rendering The bean referenced “nameOld” now has the value “newValue”

  34. Summary of all external Java- Jsp connections

  35. Part II Definition of a Portlet • A new portlet prepared by the java and JSP files must have an entry in the file “portlet.xml” and it • must be referenced in the file “layout.xml”, • must define an interpreter java class path, • And a title label

  36. portlet.xml The new potrlet Portlet name will be referenced in file layout.xml Path of the java class controlling the portlet Text in the title of the portlet

  37. The layout.xml • Must define the menu hierarchy • Define the appropriate labels for the user navigation • Reference the used portlets

  38. layout.xml Display name of a group of a submenu Display name of of a submenu item Referencing the name of the potled defined in portlet.xml Portlet as a submenu item Referencing the web application

  39. Summary of connectons: layout.xml, portlet.xml and HTML image

  40. webapps/ hu/ …/ …/ jsp/ WEB-INF/ …/ portal30/ …/ …/ hello/ …/ …/ hello/ portlets/ pgportal/ lpds/ sztaki/ …/ portlet.xml enterName.jsp …jsp lib/ layout.xml …/ …jsp classes/ EnterName.class Tomcat dictionary The jar files encountered here must correspond to the import references defined in EnterName.java

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