Understanding and Developing Web Services - For DBAs and Developers

Raastech, Inc. 2201 Cooperative Way, Suite 600 Herndon, VA 20171 +1-703-884-2223 [email protected]

Understanding and Developing Web Services For DBAs and Developers

Session 467 Wednesday April 15,2015

4:30 - 5:30 pm Room Banyan C

© 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 Procedure PL/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 Application Java

Application

Java Application

.NET Application

.NET JARs

Java API

JDBC drive


SOAP over HTTP

Standardization on SOAP over HTTP

Web Service Any

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.


<definitions name="Weather">

<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”.


Java

B

PEL

Today’s Live Development Demo

getWeather SoapUI

getWeather SoapUI



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

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




























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

Valid HTML, but invalid XML: <Customer>John Doe</customer>



XML elements must be properly nested

Valid HTML, but invalid XML: <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

REST 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

[email protected]


Q&A

Technology

Understanding and Developing Web Services - For DBAs and Developers