Understanding and Developing Web Services: For DBAs and Database Developers

Raastech, Inc.
2201 Cooperative Way, Suite 600
Herndon, VA 20171
+1-703-884-2223
info@raastech.com
Understanding and Developing Web Services
For DBAs and Database Developers
Wednesday, May 20,2015
8:30 - 9:30 am
Room: Superior and Erie

© Raastech, Inc. 2015 | 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

About Us
 Ahmed Aboulnaga @Ahmed_Aboulnaga
 18+ years Oracle experience
 Author of “Oracle SOA Suite 11g Administrator’s Handbook”
 OCE (SOA Foundation Practitioner)
 Oracle ACE
.

About Raastech
 Small systems integrator founded in 2009
 Headquartered in the Washington DC area
 Specializes in Oracle Fusion Middleware
 Oracle Platinum Partner & Reseller
 Oracle SOA Specialized
 100% of consultants are Oracle certified
 100% of consultants present at major Oracle conferences
 100% of consultants have published books, whitepapers, or articles
 Oracle SOA Specialized – 1 in 1,500 worldwide
 Oracle Platinum Partner – 1 in 3,000 worldwide

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

Custom Drivers
 How application access was previously developed
PL/SQL
ProcedurePL/SQL
Procedure
SQL
Developer
Java
Application
.NET
Application
ODBC driver
JDBC driver
SQL*NET
(internal)

Specific Target Implementation
 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
Java
Application
.NET
Application
.NET JARs
Java API
JDBC drive

SOAP over HTTP
 Standardization on SOAP over HTTP
Web
ServiceAny
Application
Java
Application
.NET
Application
SOAP over HTTP
SOAP over HTTP
SOAP over HTTP

Agnostic Target Implementation
 No need to worry about
implementation technology
of target applications
AWS
Java
Application
SalesForce
Intuit
SOAP over HTTP
SOAP over HTTP
SOAP over HTTP

PL/SQL Samples
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 weather
VALUES (zipcode, temperature);
END;
Request-Response
Synchronous
1-way
Asynchronous

Synchronous vs. Asynchronous
PL/SQL
Procedure
PL/SQL
Procedure
PL/SQL
Procedure
PL/SQL
Procedure

Web Service Clients
 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.

SoapUI

Accessing a WSDL
 The web service interface is accessible via an HTTP URL:
http://admin.packt.com:7001/Packt-GetWeather-context-root/WeatherPort?WSDL
 The web service implementation may or may not reside on the same
service:
<soap:address location="http://srv.packt.com:8888/Packt-GetWeather-context-
root/WeatherPort"/>
 Often impossible to tell what underlying language was used to create
the web service.

Dissecting a WSDL: Interface
<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">
<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.

<types>
<schema>
</schema>
</types>
</operation>
</portType>
</operation>
</binding>
</port>
</service>
</definitions>
Dissecting a WSDL: Endpoints
Location is referred
to as the “endpoint”.
Identifies where the
actual code resides.

<types>
<schema>
</schema>
</types>
</operation>
</portType>
</operation>
</binding>
</port>
</service>
</definitions>
Dissecting a WSDL: Operations
This web service
has a single
operation, with an
input and an output
(i.e., synchronous).

<types>
<schema>
</schema>
</types>
</operation>
</portType>
</operation>
</binding>
</port>
</service>
</definitions>
Dissecting a WSDL: Messages
The type of the
message is defined
in the “schema”.

JavaBPEL
Today’s Live Development Demo
getWeatherSoapUI
getWeatherSoapUI

w3schools References
 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

 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

 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

 Comments
<Customer>

<Items>
</Items>
</Customer>
XML Structure – Comments

 XML documents must have open and close tags.
 Valid HTML, but invalid XML:
<li> XML is easy
XML Structure – Tags

 Open and close tags must have matching case
<Customer>John Doe</customer>

 XML elements must be properly nested
<b><u>Hello World</b><u>

 Entity reference.
< < less than
> > greater than
& & ampersand
' ' apostrophe
" " quotation mark
XML Structure – Entity Reference

 Unlike HTML, whitespace is preserved in XML.
<Customer>
<Name>John Doe
is a person. His age is 20.</Name>
</Customer>
XML Structure – Whitespace

 Attributes
<Customer OrderNumber="61237">
<Items>
<Item quantity="1">Binder</Item>
</Items>
</Customer>
XML Structure – Attributes

 Should you use elements or attributes when designing
XML documents?
<Customer>
<Items>
</Items>
</Customer>
<Customer OrderNumber="61237">
<Items>
</Items>
</Customer>
XML Structure – Attributes vs. Elements

 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

 Default namespace; no need to prefix all child elements.
<Customer xmlns="http://raastech.com/Employees">
</Customer>
XML Structure – Default Namespace

 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

 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

<?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

 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

 String
<someelement>Hello World</someelement>
 Decimal
<someelement>12.50</someelement>
 Integer
<someelement>12</someelement>
 Boolean
<someelement>true</someelement>
Data Types

 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

 Restrictions are also referred to as facets.
 Examples include:
 minInclusive
 maxInclusive
 Enumeration
 fractionDigits
 Length
 maxInclusive
 maxExclusive
 maxLength
 minLength
 totalDigits
Restrictions

 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

 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

 Example:
<soap:Envelope xmlns:soap="http://www.w3.org/2001/12/soap-envelope">
<soap:Body>
<m:Customer xmlns:m="http://raastech.com/Customer">
<m:Name>John Doe</m:Name>
</m:Customer>
</soap:Body>
SOAP Message

 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

 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

Java Web Service Development: Top-Down Approach
 A top-down web service begins with a WSDL.
 Stubs for the underlying Java classes are created.
 Live Development Demo

Java Web Service Development: Bottom-Up Approach
 A bottom-up web service begins with an already existing Java class.
 Class and methods are easily exposed as a web service interface.

BPEL Web Service Development

SOAP vs. REST
{
"Customer":
{
"FirstName":"John",
"LastName":"Doe"
}
}
<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 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
JSON Message
 Lightweight and efficient (mobile!)
 Growing usage and adoption
 Oracle will standardize on REST
 Size-friendly:
 Size of data: 7 bytes
 Size of message: 50 bytes

SOAP vs. REST
 http://www.ateam-oracle.com/performance-study-rest-vs-soap-for-mobile-applications/

Recap
 Why has web services become the accepted standard?
 Are you more familiar with XML terminology?
 What is a popular SOAP client testing tool?
 What is SOAP and 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?

Contact Information
 Ahmed Aboulnaga
 Technical Director
 @Ahmed_Aboulnaga
 ahmed.aboulnaga@raastech.com

Q&A

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