Web Services – An Introduction IBM Software Group Leigh Compton –

®
IBM Software Group
Web Services – An Introduction
Leigh Compton – Certified IT Specialist – CICS, Web Services and Java
David Myers – RDz PLM
© 2009 IBM Corporation
IBM Trademarks and Copyrights
 © Copyright IBM Corporation 2007, 2008, 2009, 2010. All rights reserved.
 The information contained in these materials is provided for informational purposes
only, and is provided AS IS without warranty of any kind, express or implied. IBM
shall not be responsible for any damages arising out of the use of, or otherwise
related to, these materials. Nothing contained in these materials is intended to, nor
shall have the effect of, creating any warranties or representations from IBM or its
suppliers or licensors, or altering the terms and conditions of the applicable license
agreement governing the use of IBM software. References in these materials to IBM
products, programs, or services do not imply that they will be available in all countries
in which IBM operates.
 This information is based on current IBM product plans and strategy, which are
subject to change by IBM without notice. Product release dates and/or capabilities
referenced in these materials may change at any time at IBM’s sole discretion based
on market opportunities or other factors, and are not intended to be a commitment to
future product or feature availability in any way.
 IBM, the IBM logo, the on-demand business logo, Rational, the Rational logo, and
other IBM Rational products and services are trademarks or registered trademarks of
the International Business Machines Corporation, in the United States, other
countries or both. Other company, product, or service names may be trademarks or
service marks of others.
2
The Promise of Services and SOA (Service Oriented Architecture)
Services are the driving business system design paradigm of the day.
Services – Generated by RDz provide a cross platform language for business oriented development
Services and SOA are based on the concept of “Service Oriented Design”
At development time…
Leverage external web services…
 Service Interfaces
 Represent external web services
 Are created via import from WSDL
 Allow the RDz developer to stay within the
context of the RDz programming model
 Focus on the business logic
 Implement SOA design elements: services and interfaces
 Leverage existing business developers for new SOA
development
 Ignore deployment targets/technology while coding/testing
RDz SOA for WAS, CICS, System i
Deploy Web Services…
To any platform
RDz
Service
 Java to WAS/Tomcat/etc.
 COBOL to CICS, iSeries
RDz
Interface
RDz
Records
As…
 A Web Service (uses SOAP)
 A private service (uses CICS ECI, J2C, or TCP)
 Other SOA runtimes when they reach critical mass
RDz
Service
Deploy Services as Web Services
WSDL
External Applications
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Consume external services
W
S
D
L
External
Web
Service
At a Very High Level
What we’re ultimately getting at here is a decoupling of application requester
from the application provider. And the placement of an intermediary function
to make things more flexible and dynamic:
Passing of an agreedto request in
message format
Intermediary Function
Simple forwarding
or
Complex message
transformation and
protocol remapping
Return of information in the
form of an agreed-to
message response
© 2008 IBM Corporation
4
What’s Behind This … Why Are We Talking About This
Over the years our application systems have become very complicated, with
tightly-coupled relationships that are often little understood.
Actual application architecture
map from real-life customer
Changes to any part of
this are …
Two basic problems:
1. Inflexible connectivity definitions
(hard-coded, deeply imbedded in
code)
• Difficult to determine what
impact there is on other
components
2. Knowledge of relationships lost
over time
• Expensive to analyze, often
expensive to implement
Possible third: duplication of
resources because reuse
difficult in this environment
• Delays often result in missed
opportunities
Two objectives: eliminate tight (hard-coded) interconnections, and create a
way for one program to dynamically seek, find, and bind to another.
© 2008 IBM Corporation
5
A “Service” – Conceptual Definition
A discrete set of business or technical functionality that can be identified, has
a defined set of input and outputs, and is reusable
Discrete – can be contained within a definite and known “fence”
Identified -- it’s recognized as a service and people acknowledge it as a service
Defined – the input and the outputs are known and understood
Reusable – is not just a one-time thing
Service
Input
Interface
“Producer”
User
“Consumer”
Implementation
Output
Exactly how the service
is implemented behind
the interface doesn’t
really matter to the
consumer of the service
There’s nothing revolutionary about this. What’s different is that we’re coming to a point
where improvements in technology have allowed us to do this better than before:
•
•
•
•
Settled on a universal and common networking protocol -- TCP/IP
Networking bandwidth is increasingly available, cheap and reliable
The idea of “industry standards” has matured and is embraced rather than resisted
Java as a platform-unaware language has opened up a new world of interoperability
© 2008 IBM Corporation
6
An Example - Currency Exchange
IBM’s Travel Expense Reimbursement application does not do its own foreign
currency conversions … it uses an external service for that:
No
[ £100,$US,15-June ]
Internet
Yes
$US
Interface
Currency = $US?
[ $196.00 ]
Implementation
Could IBM have coded an internal subroutine to do currency conversions? Sure. But very good
converters exist on the web and in this case IBM took advantage of them.
For this to work, several things need to be in place:
• IBM application needs to know about the service and where it is located
• IBM application needs to know the interface requirements: parameters, sequence, format
Understanding what services are available, where they’re located and what
interface requirements they have is a key aspect of SOA.
© 2008 IBM Corporation
7
Another Example - CICS Web Service
We’ve not really defined what a “web service” is … but for now be aware that
CICS has the ability to front-end existing CICS programs with a web service
interface … “exposing” the CICS program as a service:
Traditional
access
unaffected
Appl
EXCI
3270
CICS V3.1
Interface
SOAP/HTTP
Web Service
Client
Program
Network
CICS Web
Service
Front-End
Existing
CICS
Program
CICS program
unchanged
New front-end
allows service
oriented
invocation
Key point is that a traditional CICS program can be turned into a message based
“service” which can then be used by “service consumers” in your network
© 2008 IBM Corporation
8
Service Oriented Architecture
From www.ibm.com
Service oriented architecture
(SOA) is a business-driven IT
architectural approach that
supports integrating the
business as linked, repeatable
business tasks, or services.
An exact definition is probably not all that important. It's more
important to understand:
• The concept of a “service”
• The implied value of a loosely coupled “service” rather than a tightly coupled connection to
another application’s interface … flexibility
• That “SOA” is a path towards the use of more and more services in your I/T architecture …
not a “thing” or an “all-at-once” proposition
• That there’s more to it than just services.
© 2008 IBM Corporation
9
CICS is an Application Server
CICS is a system that hosts applications, and provides a rich set of “services”
which the applications may make use of:
CICS
“CICS Programs”
COBOL
Program
Access
PL/I
Assembler
“EXEC CICS” API
EJBs
Java
C++ classes for CICS
C/C++
These are the
“existing assets”
we’re looking to
“expose” as
services
JVMs
JCICS classes for Java
CICS EJB Support
(transparent mapping)
External Data
Resources
CICS Services
There are many ways to access programs running in CICS -- 3270 terminal,
EXCI or EPI, RMI/IIOP, MQ, HTTP. Our focus here is going to be accessing via
Web Services.
© 2008 IBM Corporation
10
Provider vs. Requester -- CICS Can Do Both
We typically consider CICS as a provider of web services:
CICS
Web
Service
Client
Appl
The case where existing (or new)
CICS applications are exposed as
reusable services.
But it can also be a consumer (or requester) of web services:
External
Service
CICS
Appl
This web service could be
anywhere accessible to CICS -inside your company or outside
Web
Service
Client
We’ll focus on the top one for the most part. The concepts you’ll see are mostly
applicable to both environments. See “CICS Web Services Guide” (SC34-6458) for more.
CICS as a Web Service Provider …
© 2008 IBM Corporation
11
CICS as a Web Services Provider
Three basic requirements of being a Web Services provider:
Ability to receive the SOAP request
Standard ways: SOAP/HTTP or SOAP/JMS
Ability to read and understand the contents of the SOAP request
XML parser along with implementation of the “WS-basic” standards
Ability to act upon the request
This is the “behind the interface” implementation we’ve shown before
CICS
HTTP
MQ
Built-in SOAP
Handler
Custom
Program
CICS
Transaction
This is defined within something called a “Pipeline,” which is a structure
within CICS that invokes your customized program(s).
This is what does the mapping of XML to application data structure and
invokes the CICS transaction.
© 2008 IBM Corporation
12
CICS Web Services Development Tools
There are two primary tools used to develop CICS web services:
1. CICS Web Service Assistant
Consists of a set of JCL batch utilities that generate program components
 DFHLS2WS – Transforms a language structure into a Web Service Binding File and a Web Service
Description (WSDL). Use this to put a web service front end on an existing application.
 DFHWS2LS - Generates a Web Service binding file from a Web Service description (WSDL). This utility also
generates a language structure that you can use in your application programs. Use this to create a new
CICS application based on a WSDL, or to enable CICS to be a web service requester
2. Rational Developer for System z (RDz)
An Eclipse-based tool for zSeries development (not just web services), it does what CICS Web
Service Assistant does with additional flexibility and capabilities.
RDz is the more powerful alternative.
CICS Web Service Assistant should only be used for basic
web services enablement and when Eclipse expertise is
lacking
© 2008 IBM Corporation
13
What’s Produced by RDz for Web Services
The process of creating and defining a Web Service to CICS
z/OS
System
RDz
Import
into RDz
COBOL source, including
COPYBOOK of existing
CICS application
Run through
the creation
wizards
More complex scenarios can
occur, of course. But this
illustrates some essential
elements of the process
COBOL source to our new
handler, which converts SOAP
XML-to-COMMAREA and viceversa
Compile this into
the CICS LOADLIB
WSBIND file, which is a binary file
that contains information about the
service, including the “URI Map” that
triggers the execution of the pipeline
and web service
Optional used to
define the CICS
pipeline entries
© 2008 IBM Corporation
14
The Importance of XML in Web Services
You will see that XML is the common mechanism to exchange information in a
web services environment. What is XML, and why is it valuable?
<SOAP-ENV:Envelope>
<SOAP-ENV:Body>
<q0:DFHCOMMAREA>
<CustNo>3</CustNo>
</q0:DFHCOMMAREA>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
A series of “tags” that mark the beginning and end of
blocks of XML
It holds both the data, as well as description of the data
<CustNo> provides an indicator of what the data is; “3” is the actual data.
It is both machine readable and human readable, which
makes things relatively easy to understand
Contrast with bit-format protocols, where bits within bytes meant certain
things. Machine readable yes; human readable less so.
Characters use “Unicode” encoding, which means it’s
universally understood
As opposed to the old EBCDIC vs. ASCII debates
Example of XML SOAP envelope
we’ll use in one of the labs
XML is “Self Describing”
XML can be “parsed”
Something called a “Schema Definition” (XSD) is
used to tell a program what XML tags to expect.
If a program knows what tags to
expect (the WSDL supplies this),
then the program can “parse”
(extract) information from the XML.
The WSDL file (more in moment) has XSD
information
15
“SOAP over HTTP”
You’ll frequently hear this phrase. What it’s referring to is the passing of an
XML document -- a SOAP “envelope” -- using the HTTP protocol
Web Service
Client
Web Service
Provider
XML File
HTTP Protocol
(TCP/IP Network)
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:q0="http://www.WBCSCUSTI.com/schemas/WBCSCUSTIInterface"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<SOAP-ENV:Body>
<q0:DFHCOMMAREA>
The SOAP input for our CICS lab
<CustNo>3</CustNo>
</q0:DFHCOMMAREA>
Knowing the layout is not that important to
</SOAP-ENV:Body>
us at this point
</SOAP-ENV:Envelope>
The key is that the client program knew what the provider expected -- what data
elements and what XML tags to use. How did it know that? It had the WSDL file.
The Web Service Description Language (WSDL) file …
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The WSDL File
WSDL contains information about the service -- where it’s located, what
parameters it takes as input, what it gives back as output, what XML tags to
use, etc. It is sometimes known as a “bindings file”.
It can be long and complicated … what follows is a boiled-down snippet to show essence
<complexType name="DFHCOMMAREA">
<sequence>
<element name="CustNo">
<simpleType>
<restriction base="int"/>
Client knows input XML and
</simpleType>
data requirements based on this
</element>
</sequence>
Client knows where service
</complexType>
What service will return was here … removed to save space
is located based on this
<wsdl:service name="WBCSCUSService">
<wsdl:port binding="tns:WBCSCUSBinding" name="WBCSCUSPort">
<soap:address location="http://mig.null.washington.ibm.com:12301/WBCSCUST"/>
</wsdl:port>
</wsdl:service>
Web Service
Client
<SOAP-ENV:Body>
<q0:DFHCOMMAREA>
<CustNo>3</CustNo>
</q0:DFHCOMMAREA>
</SOAP-ENV:Body>
Web Service
Provider
Where does WSDL come from? …
17
WSDL File is a Product of RDz
You could hand-code the WSDL.
More likely you’ll use a development tool (in our case, RDz)
to create the web service, and RDz will also produce the
WSDL.
Service Program
Web Service
Provider
With WSDL, client
knows where service
is and how to drive it
WSDL File
• Rational Application Developer
• WebSphere Developer for zSeries
• Other Development Tools
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Web Service
Client
That's all well and good, but what about performance?
http://listserv.uga.edu/cgi-bin/wa?A2=ind0908&L=CICS-L&D=0&P=30338
That’s .1 second
1/10th of a second
Any other questions about "Why Web Services"?
19
Service Oriented Architecture Model – and IMS
Monitoring/Event Management
IMS Database
Web Services
Services
Data Services/Messaging
J2EE/JCA (EJB)
SQL/
XQuery/XML
SOAP/J2EE
J2EE/JCA
(EJB)
Data Abstraction
Data
IMS
DB
Governance
Security
Process/Orchestration
Legacy
Rep
IMS
App
Source: Linthicum Group
20
IMS On Demand Overview
Web
service
clients
Solutions
Solutions
DLI
WID
RAD
Model
Utility
Java/J2EE
Client
Java
dev
IMS
WebSphere
SAP
Client
Application
developer
Direct
SOAP
IMS SOAP
Gateway
WDz
TCP
/IP
Java
class
Library
Database
DL/I
Java
class
Library
SQL
XQuery
DL/I
CICS
Developer
DB2
SP/CICS
Java
class
Library
DLI
DLI
Model
Utility
Model
Utility
21
Java /J2EE
Developer
IMS DB
Resource
Adapter
Database
manager
IMS
APP
Java
class
Library
WebSphere
ODBA /DRA
Client
Developer
SOAP
Transaction
manager
IMS Connect
.NET
Client
Web Service
IMS TM
Resource
Adapter
MFS Web
Services
Direct
Database
access
Developers
DB2
Developer
TCP/IP Access to IMS
z/OS
CONNECT
IMS
TM
App
22
IMS
DB CTRL
Architecture Foundation - IMS Connect
 A capability that provides connectivity support between TCP/IP
applications and IMS transactions – Integrated into IMS V9
Configured on a z/OS server
 Benefits and Value
 Supports TCP/IP sockets access to IMS transactions and commands
 Provides a general purpose and structured interface
 Provides a strategic base for new connection technologies:
 Operations Manager – IMS Control Center
 IMS SOAP Gateway
 MFS Web Services
IMSB
Web Server program
COMTI
Visual Basic
PowerBuilder
Java Applet
BROWSER
...
Web
Server
Cobol
Assembler
C/C++
Java
TCP/IP
IMS Connect
VTAM
Websphere
23
IMSA
IMS TM Resource Adapter
z/OS
WebSphere
TM RA
CONNECT
App
IMS
TM
App
24
IMS
DB CTRL
J2EE/JCA Architecture
J2EE Application Server
Container-Component
Contract
Application
Component
Application Contract
CCI (common client
Interface)
Connection
Management
System Contracts
Transaction
Management
SPI (service provider
interface)
Security
Management
Resource
Adapter
EIS-specific interface
EIS
25
IMS TM Resource Adapter …
 Supports the development of J2EE applications, Web services, and
business processes that can interface with IMS Connect
 Development component
– Rational Developer for System z – RDz
 Runtime component
– Must be installed into an application server, e.g., WebSphere
PLI
C
IMPORT
IMS
SERVICE
COBOL
IMS
RESOURCE
ADAPTER
Export
Installed
Applications
Appl.EAR
DEPLOY
& TEST
Unit Test
Environment
RDz
J2C
Connection
Factory
IMS
RESOURCE
ADAPTER
imsico.RAR
WebSphere
Java
Applet
BROWS
ER
IMS
TCP/IP
(supplied with
IMS Connect) WebSphere Application Server
IMS
Connect
Toolkits that generate web services, EJBs, JSP, etc. for IMS, CICS, DB2
26
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© Copyright IBM Corporation 2010. All rights reserved. The information contained in these materials is provided for informational purposes only, and is provided AS IS without warranty of any kind,
express or implied. IBM shall not be responsible for any damages arising out of the use of, or otherwise related to, these materials. Nothing contained in these materials is intended to, nor shall have
the effect of, creating any warranties or representations from IBM or its suppliers or licensors, or altering the terms and conditions of the applicable license agreement governing the use of IBM
software. References in these materials to IBM products, programs, or services do not imply that they will be available in all countries in which IBM operates. Product release dates and/or capabilities
referenced in these materials may change at any time at IBM’s sole discretion based on market opportunities or other factors, and are not intended to be a commitment to future product or feature
availability in any way. IBM, the IBM logo, Rational, the Rational logo, Telelogic, the Telelogic logo, and other IBM products and services are trademarks of the International Business Machines
Corporation, in the United States, other countries or both. Other company, product, or service names may be trademarks or service marks of others.
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