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Developing Web Services from Scratch - For DBAs and Database Developers

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WSDL. XSD. SOAP. Namespaces. Port types. If these terms make little sense, this presentation is for you. By the end of this presentation, you will completely understand how to dissect and decipher a web service interface, understand key design patterns, and learn how to develop top-down and bottom-up web services in technologies such as Java and Oracle SOA Suite. Want to know how to expose a PL/SQL package as a web service? This technical presentation, one of my most popular, is intended for DBAs and database developers who want to know what it takes to design and create web services.

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Developing Web Services from Scratch - For DBAs and Database Developers

  1. 1. Raastech, Inc. 2201 Cooperative Way, Suite 600 Herndon, VA 20171 +1-703-884-2223 info@raastech.com Developing Web Services from Scratch For DBAs and Database Developers BGOUG Spring 2017 Conference Hotel RIU Pravets Resort Saturday, June 3, 2017 16:00 - 17:00 Hall B
  2. 2. © Raastech, Inc. 2017 | All rights reserved. Slide 2 of 61@Raastech Agenda 1. Introduction 2. Introducing Web Services 3. Accessing a Web Service 4. Anatomy of a WSDL 5. Getting Started: Concepts 6. Live Development Demo  Java Web Service: Top-Down Development  Java Web Service: Bottom-Up Development  BPEL Web Service 7. Recap & Summary
  3. 3. © Raastech, Inc. 2017 | All rights reserved. Slide 3 of 61@Raastech
  4. 4. © Raastech, Inc. 2017 | All rights reserved. Slide 4 of 61@Raastech About Me  Ahmed Aboulnaga @Ahmed_Aboulnaga  18+ years Oracle experience  Author of “Oracle SOA Suite 11g Administrator’s Handbook”  Author of “Oracle SOA Suite 12c Administrator’s Guide”  OCE (SOA Foundation Practitioner)  Oracle ACE
  5. 5. © Raastech, Inc. 2017 | All rights reserved. Slide 5 of 61@Raastech About Raastech  Small systems integrator founded in 2009  Headquartered in the Washington DC area  Specializes in Oracle Fusion Middleware  Oracle Gold Partner  Oracle SOA Specialized
  6. 6. © Raastech, Inc. 2017 | All rights reserved. Slide 6 of 61@Raastech Why This Presentation  Learn to develop a web service from scratch  Lot of PL/SQL developers are intimidated by SOA development  Presentation is specific to SOAP, but concepts are similar for REST
  7. 7. © Raastech, Inc. 2017 | All rights reserved. Slide 7 of 61@Raastech
  8. 8. © Raastech, Inc. 2017 | All rights reserved. Slide 8 of 61@Raastech  How application access was previously developed PL/SQL ProcedurePL/SQL Procedure SQL Developer Java Application .NET Application ODBC driver JDBC driver SQL*NET (internal) Custom Drivers
  9. 9. © Raastech, Inc. 2017 | All rights reserved. Slide 9 of 61@Raastech  ProC anyone?  Must be aware of the technology of the target system implementation and import the necessary libraries and drivers compatible with that technology PL/SQL ApplicationJava Application AS/400 Mainframe .NET Application .NET drivers IBM JARs JDBC driver Specific Target Implementation
  10. 10. © Raastech, Inc. 2017 | All rights reserved. Slide 10 of 61@Raastech  Standardization on SOAP over HTTP Web ServiceAny Application Java Application .NET Application SOAP over HTTP SOAP over HTTP SOAP over HTTP SOAP over HTTP
  11. 11. © Raastech, Inc. 2017 | All rights reserved. Slide 11 of 61@Raastech  No need to worry about implementation technology of target applications AWS Java Application SalesForce Paypal SOAP over HTTP SOAP over HTTP SOAP over HTTP Agnostic Target Implementation
  12. 12. © Raastech, Inc. 2017 | All rights reserved. Slide 12 of 61@Raastech CREATE PROCEDURE getWeather ( zipcode IN VARCHAR2, temperature OUT NUMBER) IS BEGIN temperature := '35'; END; CREATE PROCEDURE setWeather ( zipcode IN VARCHAR2, temperature IN NUMBER) IS BEGIN INSERT INTO temperature VALUES (zipcode, temperature); END; Request-Response Synchronous 1-way Asynchronous PL/SQL Samples
  13. 13. © Raastech, Inc. 2017 | All rights reserved. Slide 13 of 61@Raastech PL/SQL Procedure PL/SQL Procedure PL/SQL Procedure PL/SQL Procedure Synchronous vs. Asynchronous
  14. 14. © Raastech, Inc. 2017 | All rights reserved. Slide 14 of 61@Raastech
  15. 15. © Raastech, Inc. 2017 | All rights reserved. Slide 15 of 61@Raastech  Now that business functionality is exposed as web services, these services need to be consumed somehow.  Since web services are standards based, they can be invoked via the majority of programming languages or through other services. Web Service Clients
  16. 16. © Raastech, Inc. 2017 | All rights reserved. Slide 16 of 61@Raastech soapUI
  17. 17. © Raastech, Inc. 2017 | All rights reserved. Slide 17 of 61@Raastech  The web service interface is accessible via an HTTP URL: http://admin.raastech.com:7001/GetWeather/WeatherPort?WSDL  The web service implementation may or may not reside on the same service: <soap:address location="http://srv.raastech.com:8888/GetWeather/WeatherPort"/>  Often impossible to tell what underlying language was used to create the web service. Accessing a WSDL
  18. 18. © Raastech, Inc. 2017 | All rights reserved. Slide 18 of 61@Raastech
  19. 19. © Raastech, Inc. 2017 | All rights reserved. Slide 19 of 61@Raastech <definitions name="Weather"> <types> <schema> <element name="zip" type="string"/> <element name="temp" type="string"/> </schema> </types> <message name="zipReq"><part name="parameters" element="zip"/></message> <message name="tempResp"><part name="parameters" element="temp"/></message> <portType name="WeatherPort"> <operation name="getWeather"> <input message="zipReq"/> <output message="tempResp"/> </operation> </portType> <binding name="WeatherBinding" type="WeatherPort"> <operation name="getWeather"> <input name="zipReq"/> <output name="tempResp"/> </operation> </binding> <service name="WeatherService"> <port name="WeatherPort" binding="WeatherBinding"> <soap:address location="http://localhost/wc/weather"/> </port> </service> </definitions> The WSDL is the interface to the web service. Implementation details of the web service is unknown. Dissecting a WSDL: Interface
  20. 20. © Raastech, Inc. 2017 | All rights reserved. Slide 20 of 61@Raastech <definitions name="Weather"> <types> <schema> <element name="zip" type="string"/> <element name="temp" type="string"/> </schema> </types> <message name="zipReq"><part name="parameters" element="zip"/></message> <message name="tempResp"><part name="parameters" element="temp"/></message> <portType name="WeatherPort"> <operation name="getWeather"> <input message="zipReq"/> <output message="tempResp"/> </operation> </portType> <binding name="WeatherBinding" type="WeatherPort"> <operation name="getWeather"> <input name="zipReq"/> <output name="tempResp"/> </operation> </binding> <service name="WeatherService"> <port name="WeatherPort" binding="WeatherBinding"> <soap:address location="http://localhost/wc/weather"/> </port> </service> </definitions> Location is referred to as the “endpoint”. Identifies where the actual code resides. Dissecting a WSDL: Endpoints
  21. 21. © Raastech, Inc. 2017 | All rights reserved. Slide 21 of 61@Raastech <definitions name="Weather"> <types> <schema> <element name="zip" type="string"/> <element name="temp" type="string"/> </schema> </types> <message name="zipReq"><part name="parameters" element="zip"/></message> <message name="tempResp"><part name="parameters" element="temp"/></message> <portType name="WeatherPort"> <operation name="getWeather"> <input message="zipReq"/> <output message="tempResp"/> </operation> </portType> <binding name="WeatherBinding" type="WeatherPort"> <operation name="getWeather"> <input name="zipReq"/> <output name="tempResp"/> </operation> </binding> <service name="WeatherService"> <port name="WeatherPort" binding="WeatherBinding"> <soap:address location="http://localhost/wc/weather"/> </port> </service> </definitions> This web service has a single operation, with an input and an output (i.e., synchronous). Dissecting a WSDL: Operations
  22. 22. © Raastech, Inc. 2017 | All rights reserved. Slide 22 of 61@Raastech <definitions name="Weather"> <types> <schema> <element name="zip" type="string"/> <element name="temp" type="string"/> </schema> </types> <message name="zipReq"><part name="parameters" element="zip"/></message> <message name="tempResp"><part name="parameters" element="temp"/></message> <portType name="WeatherPort"> <operation name="getWeather"> <input message="zipReq"/> <output message="tempResp"/> </operation> </portType> <binding name="WeatherBinding" type="WeatherPort"> <operation name="getWeather"> <input name="zipReq"/> <output name="tempResp"/> </operation> </binding> <service name="WeatherService"> <port name="WeatherPort" binding="WeatherBinding"> <soap:address location="http://localhost/wc/weather"/> </port> </service> </definitions> The type of the message is defined in the “schema”. Dissecting a WSDL: Messages
  23. 23. © Raastech, Inc. 2017 | All rights reserved. Slide 23 of 61@Raastech JavaBPEL getCustomerSoapUI getCustomerSoapUI Today’s Live Development Demo
  24. 24. © Raastech, Inc. 2017 | All rights reserved. Slide 24 of 61@Raastech
  25. 25. © Raastech, Inc. 2017 | All rights reserved. Slide 25 of 61@Raastech  http://www.w3schools.com/xml/default.asp  http://www.w3schools.com/schema/default.asp  http://www.w3schools.com/xpath/default.asp  http://www.w3schools.com/xsl/default.asp  http://www.w3schools.com/xquery/default.asp  http://www.w3schools.com/webservices/default.asp  http://www.w3schools.com/webservices/ws_wsdl_intro.asp  http://www.w3schools.com/webservices/ws_soap_intro.asp  http://blog.raastech.com/2009/01/creating-top-down-java-web-service-for.html  http://blog.raastech.com/2009/03/creating-bottom-up-java-web-service-for.html w3schools References
  26. 26. © Raastech, Inc. 2017 | All rights reserved. Slide 26 of 61@Raastech  XML stands for “EXtensible Markup Language”.  XML was designed to transport and store data.  XML is designed to be self-descriptive.  XML was originally designed to transport and store data.  XML does not contain any logic. Introduction to XML
  27. 27. © Raastech, Inc. 2017 | All rights reserved. Slide 27 of 61@Raastech  XML documents follow a tree structure.  Every XML document must have 1 root element.  The root element is the parent of all other elements. <Customer> <Name>John Doe</Name> <OrderNumber>61237</OrderNumber> <Items> <Item quantity="2">Book</Item> </Items> </Customer> XML Structure – Root Element
  28. 28. © Raastech, Inc. 2017 | All rights reserved. Slide 28 of 61@Raastech  Comments <Customer> <!-- this is a comment --> <Name>John Doe</Name> <OrderNumber>61237</OrderNumber> <Items> <Item quantity="2">Book</Item> </Items> </Customer> XML Structure – Comments
  29. 29. © Raastech, Inc. 2017 | All rights reserved. Slide 29 of 61@Raastech  XML documents must have open and close tags.  Valid HTML, but invalid XML: <li> XML is easy XML Structure – Tags
  30. 30. © Raastech, Inc. 2017 | All rights reserved. Slide 30 of 61@Raastech  Open and close tags must have matching case  Valid HTML, but invalid XML: <Customer>John Doe</customer> XML Structure – Tags
  31. 31. © Raastech, Inc. 2017 | All rights reserved. Slide 31 of 61@Raastech  XML elements must be properly nested  Valid HTML, but invalid XML: <b><u>Hello World</b><u> XML Structure – Tags
  32. 32. © Raastech, Inc. 2017 | All rights reserved. Slide 32 of 61@Raastech  Entity reference. &lt; < less than &gt; > greater than &amp; & ampersand &apos; ' apostrophe &quot; " quotation mark XML Structure – Entity Reference
  33. 33. © Raastech, Inc. 2017 | All rights reserved. Slide 33 of 61@Raastech  Unlike HTML, whitespace is preserved in XML. <Customer> <Name>John Doe is a person. His age is 20.</Name> </Customer> XML Structure – Whitespace
  34. 34. © Raastech, Inc. 2017 | All rights reserved. Slide 34 of 61@Raastech  Attributes <Customer OrderNumber="61237"> <Items> <Item quantity="2">Book</Item> <Item quantity="1">Binder</Item> </Items> </Customer> XML Structure – Attributes
  35. 35. © Raastech, Inc. 2017 | All rights reserved. Slide 35 of 61@Raastech  Should you use elements or attributes when designing XML documents? <Customer> <OrderNumber>61237</OrderNumber> <Items> <Item quantity="1">Binder</Item> </Items> </Customer> <Customer OrderNumber="61237"> <Items> <Item quantity="1">Binder</Item> </Items> </Customer> XML Structure – Attributes vs. Elements
  36. 36. © Raastech, Inc. 2017 | All rights reserved. Slide 36 of 61@Raastech  Namespaces are identifiers. <Customers> <e:Customer xmlns:e="http://raastech.com/Employees"> <e:Name>John Doe</e:Name> </e:Customer> <p:Customer xmlns:p="http://raastech.com/Partners"> <p:Name>Jane Doe</p:Name> </p:Customer> <Customers> XML Structure – Namespaces
  37. 37. © Raastech, Inc. 2017 | All rights reserved. Slide 37 of 61@Raastech  Default namespace; no need to prefix all child elements. <Customer xmlns="http://raastech.com/Employees"> <Name>John Doe</Name> </Customer> XML Structure – Default Namespace
  38. 38. © Raastech, Inc. 2017 | All rights reserved. Slide 38 of 61@Raastech  XML Schema defines elements in an XML document.  XML Schema defines attributes in an XML document.  XML Schema defines child elements, and optionally their number and order.  XML Schema defines data types for both elements and attributes.  XML Schema defines default and fixed values for elements and attributes. Introduction to XML Schema
  39. 39. © Raastech, Inc. 2017 | All rights reserved. Slide 39 of 61@Raastech  XML Schemas are well-formed XML documents and are extensible.  They are typically saved as .xsd files.  The root element of every XML Schema is the <schema> element.  The <schema> element may include attributes such as the XML namespace. Introduction to XML Schema
  40. 40. © Raastech, Inc. 2017 | All rights reserved. Slide 40 of 61@Raastech <?xml version="1.0"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified"> <xs:element name="Customer"> <xs:complexType> <xs:sequence> <xs:element name="OrderNumber" type="xs:string"/> <xs:element name="Name" type="xs:string"/> </xs:sequence> </xs:complexType> </xs:element> </xs:schema> Example of an XML Schema
  41. 41. © Raastech, Inc. 2017 | All rights reserved. Slide 41 of 61@Raastech  A simple element contains only plain text that can be defined in one of several predefined data types (or custom types).  The predefined data types in XML Schema include:  string  decimal  integer  boolean  date  time Simple Element
  42. 42. © Raastech, Inc. 2017 | All rights reserved. Slide 42 of 61@Raastech  String <someelement>Hello World</someelement>  Decimal <someelement>12.50</someelement>  Integer <someelement>12</someelement>  Boolean <someelement>true</someelement> Data Types
  43. 43. © Raastech, Inc. 2017 | All rights reserved. Slide 43 of 61@Raastech  Date <someelement>2002-09-24Z</someelement> <someelement>2008-07-24-06:00</someelement>  Time <someelement>08:00:00</someelement>  DateTime <someelement>2008-07-24T08:00:00</someelement> Data Types
  44. 44. © Raastech, Inc. 2017 | All rights reserved. Slide 44 of 61@Raastech  Restrictions are also referred to as facets.  Examples include:  minInclusive  maxInclusive  Enumeration  fractionDigits  Length  maxInclusive  maxExclusive  maxLength  minLength  totalDigits Restrictions
  45. 45. © Raastech, Inc. 2017 | All rights reserved. Slide 45 of 61@Raastech  Complex elements are XML elements that contains other elements or attributes. <xs:element name="Customer"> <xs:complexType> <xs:sequence> <xs:element name="Name" type="xs:string"/> <xs:element name="Item" type="xs:ItemType" minOccurs="1" maxOccurs="5"/> </xs:sequence> </xs:complexType> </xs:element> <xs:complexType name="ItemType"> <xs:sequence> <xs:element name="Item" type="xs:string"/> <xs:element name="Price" type="xs:decimal"/> </xs:sequence> </xs:complexType> Complex Element
  46. 46. © Raastech, Inc. 2017 | All rights reserved. Slide 46 of 61@Raastech  SOAP stands for Simple Object Access Protocol.  It is a communication protocol and allows XML documents to be exchange over HTTP.  As a result, it is platform and technology independent, and ideal for Internet-based communication.  A SOAP message is an XML document that contains the following:  Envelope  Header  Body  Fault Introduction to SOAP
  47. 47. © Raastech, Inc. 2017 | All rights reserved. Slide 47 of 61@Raastech  Envelope  Root element of a SOAP message.  xmlns:soap namespace should always have the value of http://www.w3.org/2001/12/soap-envelope.  Header  Optional.  Could include information such as authentication information.  First child element of the Envelope element.  Body  Required.  Contains the content of the SOAP message (i.e., the payload). SOAP Message
  48. 48. © Raastech, Inc. 2017 | All rights reserved. Slide 48 of 61@Raastech  Example: <?xml version="1.0"?> <soap:Envelope xmlns:soap="http://www.w3.org/2001/12/soap-envelope"> <soap:Header> </soap:Header> <soap:Body> <m:Customer xmlns:m="http://raastech.com/Customer"> <m:Name>John Doe</m:Name> </m:Customer> </soap:Body> </soap:Envelope> SOAP Message
  49. 49. © Raastech, Inc. 2017 | All rights reserved. Slide 49 of 61@Raastech  WSDL stands for Web Services Description Language.  It is an XML document that describes a web service (i.e., it is the interface specification for the web service).  It specifies the location of the web service, the operations it supports, and the message types. Introduction to WSDL
  50. 50. © Raastech, Inc. 2017 | All rights reserved. Slide 50 of 61@Raastech
  51. 51. © Raastech, Inc. 2017 | All rights reserved. Slide 51 of 61@Raastech  A top-down web service begins with a WSDL.  Stubs for the underlying Java classes are created.  Live Development Demo Java Web Service Development: Top-Down WSDL (interface) Java (Class) WSDL (interface) Create interface first Java class stub auto-created Webservice development (top-down)
  52. 52. © Raastech, Inc. 2017 | All rights reserved. Slide 52 of 61@Raastech
  53. 53. © Raastech, Inc. 2017 | All rights reserved. Slide 53 of 61@Raastech  A bottom-up web service begins with an already existing Java class.  Class and methods are easily exposed as a web service interface.  Live Development Demo Java Web Service Development: Bottom-Up Java (class) WSDL (interface) Java (class) WSDL auto-generated from Java class Create Java class first Webservice development (bottom-up)
  54. 54. © Raastech, Inc. 2017 | All rights reserved. Slide 54 of 61@Raastech
  55. 55. © Raastech, Inc. 2017 | All rights reserved. Slide 55 of 61@Raastech  Live Development Demo BPEL Web Service Development
  56. 56. © Raastech, Inc. 2017 | All rights reserved. Slide 56 of 61@Raastech
  57. 57. © Raastech, Inc. 2017 | All rights reserved. Slide 57 of 61@Raastech { "Customer": { "FirstName":"John", "LastName":"Doe" } } <?xml version="1.0"?> <soap:Envelope xmlns:soap="http://www.w3.org/2001/12/soap-envelope"> <soap:Body> <m:Customer xmlns:m="http://raastech.com/Customer"> <m:FirstName>John</m:FirstName> <m:LastName>Doe</m:LastName> </m:Customer> </soap:Body> SOAP/XML Message  Strong message type validation  Based on XML standard  Wide usage and adoption  Not size-friendly:  Size of data: 7 bytes  Size of message: 236 bytes REST/JSON Message  Lightweight and efficient (mobile!)  Growing usage and adoption  Most moving to REST now  Size-friendly:  Size of data: 7 bytes  Size of message: 50 bytes SOAP vs. REST
  58. 58. © Raastech, Inc. 2017 | All rights reserved. Slide 58 of 61@Raastech  http://www.ateam-oracle.com/performance-study-rest-vs-soap-for-mobile-applications/ SOAP vs. REST
  59. 59. © Raastech, Inc. 2017 | All rights reserved. Slide 59 of 61@Raastech  Why has web services become the accepted standard?  Are you more familiar with XML terminology?  What is a popular SOAP client testing tool?  What are the components of a SOAP message?  Can you understand a WSDL when you look at it now?  What is the difference between top-down and bottom-up web service development?  What is REST? Recap
  60. 60. © Raastech, Inc. 2017 | All rights reserved. Slide 60 of 61@Raastech Contact Information  Ahmed Aboulnaga  Technical Director  @Ahmed_Aboulnaga  ahmed.aboulnaga@raastech.com
  61. 61. © Raastech, Inc. 2017 | All rights reserved. Slide 61 of 61@Raastech Q&A

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