ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie Web Services & BPEL Design of Distributed Software

Objectives After this lab session you should be able to Create a Web Service Create composite applications using BPEL Use the following technologies: WSDL, BPEL, SOAP, Web Service annotations, Jax-WS Web Service A service is a self-contained software module that performs a predetermined task Web Services are services accessible on the web BPEL (Business Process Execution Language) provides a relatively easy way to compose several Web Services into new composite services called business processes ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 2

 What you should know for Exercise1  ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 3

Jax-WS: name="CatalogService", targetNamespace=” ) This annotation makes clear that this class is a Web Service Default behavior The targetNamespace for the generated WSDL definition is generated from the package name The name of the PortType corresponds to the name of your class-file The operation name in the portType has the same name as the method in your class. All public methods in your class are now available in the web service annotation can also be customized Name: Change the name of the PortType targetNamespace: Change the targetNamespace ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 4

Jax-WS: Public CDLookupOperation(String track){ return null; } Will declare a method in your class as being a web method Default behavior annotations: all public methods exposed as web service operations One or annotations: only those methods exposed as web service operations Relates to an operation in a portType in the WSDL Gives the WSDL operation the same name as the java method This annotation can off course also be customized operationName: Change the name of the operation in the portType. ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 5

ion”,header=true) String track){ return null; } Gives control over how the arguments of the methods are mapped onto the Web Service operation Default behavior Names for the parameters is the WSDL file are arg0, arg1,… The namespace where these parameters are defined is also derived from the package name of the class file This annotation can off course also be customized Name: the name of the parameter targetNamespace: the namespace the parameter will be defined in Header: declares that the xml of this parameter should be transmitted in the SOAPHeader instead of the SOAPBody. This is recommended for transmitting metadata. ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 6

Invoking a Web Service Code generated by Netbeans When creating the Web Service client: fill in the URL of the WSDL of the Web Service In the methods of your client Right-click and select Web Service Client Resource  call Web Service operation The operations of the Web Service will be shown  choose one Netbeans generates the skeleton code! The method on the port object executes the web service operation for you and hides all its complexity Prepare the input for the operation Write some code to process and display the result (output) ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 7

public static void main(String[] args) { try { // Call Web Service Operation be.ugent.intec.ods.catalog.MyCDCatalogServiceService service = new be.ugent.intec.ods.catalog.MyCDCatalogServiceService(); be.ugent.intec.ods.catalog.CatalogService port = service.getCatalogServicePort(); // initialize WS operation arguments be.ugent.intec.ods.catalog.SearchMyCatalogForSong parameters = new be.ugent.intec.ods.catalog.SearchMyCatalogForSong(); java.lang.String song = "Believe"; // process result be.ugent.intec.ods.catalog.SearchMyCatalogForSongResponse result = port.searchMyCatalogForSong(parameters, song); System.out.println("Result = "+result); } catch (Exception ex) { ex.getStackTrace(); } ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 8

 What you should know for Exercise 2  ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 9

BPEL BPEL stands for Business Process Execution Language for Web Services It provides a relatively easy way to compose several Web Services into new composite services called business processes The NetBeans BPEL designer allows you to graphically construct BPEL processes On the right you will a palette with all the BPEL Activities you can use to construct the process A BPEL file is an XML file and you can take a look at the XML source by clicking on the Source button in the BPEL Designer ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 10

Structure of a BPEL Process Generally it looks something like this: < process name="QuotationProcess" targetNamespace= QuotationProcess/QuotationProcess xmlns= xmlns:xsd= xmlns:tns= The Process element is the root of the process. Here you can name the process and declare prefixes for namespaces used in the process definition. ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 11

Partner Links A BPEL-file consists of a series of activities describing the execution flow of the process Some of these activities handle the communication between the process and external services  called the external services Partners includes the Web services the BPEL process invokes Includes the client that invokes the BPEL process The Partner links define the parties that interact with the BPEL Process is linked to a PartnerLinkType which is defined in the WSDL of the partner service Partner link types represent the interaction between a BPEL Process and the involved parties (input/output) ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 12

Invoke The invoke activity can be used to invoke one of the partner links involved in the process How to? Drag an invoke activity on the BPEL designer Connect this activity to the operation of the partner link you want to invoke Create input and output variables for this invoke operation ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 13

Assign An activity that can be used to assign data to a variable This data can be copied from another variable or be the result of a series of XPath expressions How to? Drag an assign activity on the BPEL designer The BPEL Mapper is used to copy data from one variable to another  You copy data from left to right  In the center column you can place operations that perform transformations on the data ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 14

Reply Used to return the result to the client partner link How to? Drag a reply activity on the BPEL designer Connect this activity to the operation of the client partner link Create an output variable for this reply activity Use an assign activity to assign data to this output variable ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 15

Predicates and Xpath The mapper tool can easily be used to provide mappings between source and target variables When you look at the source view you’ll see that this mapping is done using an Xpath expression Predicates are used when the selection is not as trivial as the previous examples ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 16

Predicates and Xpath: Example A variable named “parameters” This variable is defined in XMLSchema to represent a table It exists of a collection of rows (maxOccurs=”unbounded”) with each row an unbounded number of cells ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 17

Predicates and Xpath: Example We are interested in the value of the cell where the name attribute equals the string ‘unit’ To get this you must add a predicate Editing the predicate is similar to defining for example an IF condition  using the mappertool You can see in the screenshot below that the focus is set to a cell, and a filter on those cells is defined using a predicate ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 18

Predicates and Xpath: Example You want to select the first row in an array of rows Assign in the predicate editor a number literal to the predicate The resulting code is an Xpath expression According to the Xpath specification the first element in an array of elements has index 1! ODS – Introduction to Web Services and BPEL Vakgroep Informatietechnologie p. 19