WebServices Notes by Sekhar Sir JavabynataraJ

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Web Services

Transcript of WebServices Notes by Sekhar Sir JavabynataraJ

  • Web Services

  • ~- ~ ~.~ -- .. . . ...

    WEB-SERVICES [Intro) By Mr. SekharReddy ., i ; Q.) What is distributed technology?

    I ' I

    A technology is said to be distributed i f it's business objects are geographically dispersed i I (across multiple JVM's) and st111 communicating one another. ' I

    Q.) Why distributed technology?

    I-) Load balancing

    I High Availability

    I-:, High Processing

    Q.) What are different distributed technologies?

    I > There are so many distributed technologies o CORBA o RMI o EJB o WEB SERVICES ... etc.

    .&

    CORBA > More complexity in the implementation

    I - > Heavy weight Language dependent

    I > Commercial I :, Plat from independent

    RMI I > Lack of Enterprise services/Middle ware services I > Open source I IVo acknowledgement , # I > Language dependent I > Plat from independent

    E3 B I-> Supports Enterprise services/Middle ware services in the declarative manner

    Having multiple flavors of APIs t o handle different requirements o Session beans

    Stateless Stateful

    o Entity beans(not using now) = JPA

    o Message Driven Beans -- !

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  • . . - ~ - ~ .. - - ...p-p.p....p-.pp-

    WEB-SERVICES (Intro) By Mr. ~ e k h a r ~ e d d v ~ ~ . ~ ~ ! I > Managed by Application server

    Robust I Heavy weight c> Language Dependent G Plat from independent

    WEB SERVICES I-? Supports Enterprise services I > Interoperable (Language independent & Plat from independent)

    So, Web services is interoperable distributed technology I ! 1

    Q.) What we require if two persons need to communicate?

    1 .) Two persons @ I I 2.) Medium

    3.) Language 4.) RuIes(protocoI)

    I

    Web services architecture I f two applications needs to communicate

    a Both the applications should be connected (network) e Both application needs to communicate by following some rules(protocols)

    o H r r P o FTP o SMTP ... etc.

    r:, To communicate language is required(Neutra1 language) o XML

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    WEB-SERVICES (Introl Bv Mr. ~ e k h a r ~ F d x F T I 1

    SMTP

    I In the internet world we prefer t o use H-TTP protocol, and we have so many technologies ,, which supports HlTP protocol. I

    X I

    I > Lets assume that we are sending employee information form "Consumer" to "Provider" in the XML format as follows. i

    I

    ysreddy +.-..- - __.__.L.---'

    Authentication Data * * * * * *

  • ,,,'

    ,.,;,- Authentication Data ,,,,,, ,,.. ,,, ,,'

    ,,I'

    ,.,.,'' ,,.,

    ysreddy:::-. . ,, ,,,... ,,,, ,,,,, I, ,111 ..__> ,,,, , 1

    ,,,' ,,,"

    **** **

  • .- ~~ - ~ - - -

    WEB-SERVICES (Intro) Bv Mr. SekharReddv-- 1

    .;t, "WSDL" is the document which explains the services information. But how can I "Consumer" get that WSDL document, from where "Consumer" get? i

    L-:, So "WSDL" documents has to be placed in some location from where "Consumer" can access them, that location is nothing but "UDDI"

    I I

    ~2 UDDI stands for Universal Description Discovery and Integration I UDDI is the Registry where all the WSDL documents are registered ' I , ' I UDDI should be interoperable, so it is also developed in XPIL \ I r2 UDDI registry also called XlYL registry I

    -

    I

    i i ~.

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  • 2. ) What is WS-I? The WS-I (Web Services Interoperability) Organization is an association of I T industry compa~iies, including IBM and Microsoft, that aim to create Web services specifications that all companies can use.

    4.) What are the different standards given by WS-I to implement Web services ? r3 WS-I has given

    o Basic Profile 1.0 (BP 1.0) o Basic Profile 1.1 (BP 1 .l) o Basic Profile 2.0 (BP 2.0)

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    WEB-SERVICES (Intro) By Mr. S e k h a r R e d d v . ,

    I Q.) What are Web services? I

    I-:, Web services is a software application that confirms the WS-1's given speicifiations( BP -.I

    l.O/BP l . l / B P 2.0) is said t o be web services. I I I I 13 Any program that is distributed in nature, language independent and plat form neutral is \ said to be web services.

    I I -

    I I There so many API's, Implementations for the WS-I given standards 1

    ~3 Sun has released "JAX-RPC" API that follows BP 1.0 standard Sun has released "JAX-WS" API that follows BP 1 . 1 standard

    JAX-RPC -4 ,AX-ws I

    JAX-RPC : Java APIs for XML-based Remote Procedure Call

    JAX-WS : Java API fo r XPlL Web Services

    JAX-P : Java API for XML Processing

    JAX-B : Java Architecture for XML Binding I i -

    JAX-R : Java API for XML Registries 1 SAAJ : SOAP with Attachments API for Java 1

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    Implementation (from different companies)

    -- -- . -- --

    Specification (froni WS-I)

    API (from Sun microsystem)

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    . WEB-SERVICES [Intro) By Mr. ~ekharkeddf

    JAX-WS RI(from Sun) BP 1.1 JAX-WS Apache-Axis2(from ASF)

    Metro(from Sun) CXF(from ASF) ... etc.

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    BP 1.0

    NOTE: JAX-WS RI(Reference Implementation) was fa~led to access by .Net, means fa~led in interoperability. Sun then released "metro" implementation of JAX-WS, which resolved interoperab~lity problem and also added some more features.

    i i NOTE: Apache CXF internally uses spring.

    - --

    JAX-RPC

    ! Web Services Development

    -- ----

    JAX-RPC-SI(from sun) ... Apache-Axis(from ASF) etc

    I I Web services development can done in two ways

    1. Contract first(top-down) approach 2. Contract last(bottom-up) approach

    -

    I , Contract first A ~ ~ r o a c h -

    ! WSDL + Services ! - I

    Contract last Amroach 1 I

    I ' Services + WSDL I I , NOTE:

    ~3 Services can be developed with any technology like .Net, Java, Php ... etc ...

    ' d I n java, Services can be developed using any API like JAX-RPC, JAX-WS, RESTFUL etc.. ... I ~3 I n java, Services can be developed using any implementations like sun, apache etc..

    I I But WSDL development is unique, it's not plat form specific, not language specific, not technology specific, not API specific, not implementation specific.

    , So, we can say we are developing web services using I > JAX-RPC, Contract first approach

    I I 3 JAX-RPC , Contract last approach I I

    I NOTE: I n the internet world w& prefer to use HlTP protocol, and we have so many technologies I

    / which supports HlTP protocol. - I ! Q.) What are the HTTP protocols implemented API's? ( 1. Servlet API

    2. EJB API i I I

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    WEB-SERVICES (lntro'l--- Bv Mr. ~ e k h a r ~ e d T l t 7

    ' Q.) W h a t is e n d p o i n t ? 1 I, A component which receives "Consumer" request

    I, I n general we use either servlet or ejb as an End Po~nt. So, we can say we are developing web services using

    I > JAX-RPC, Servlet end point url, Contract first approach 1 > JAX-RPC, EJB end point url, Contract last approach

    I

    i MEP 1 MEP stands for ~ e s s a g d ~ x c h a n g i n g Patterns

    1

    r3 " C o n s ~ ~ r n e r ~ ~ can communicate with "Provider" in three ways o Synchronous request-reply o Asynchronous request-reply

    I I o Fire and forget

    I I Synchronous reques t - rep ly I 0 I n this "Consumer" sends the request t o "Provider", and "Consumer" blocks until response I

    comes back from the "Provider", Until response comes back "Consumer" can't proceed. I

    After Response Received, continues i ts process ......

    Asvnch ronous reauest-re~ly 1 I I

    e In this "Consumer" sends the.request t o "Provider", and "Consumer" will not wait until it ' gets the response. I

    I > After request sent t o the "Provider" it continues its flow of execution I "Consumer" will have "Response L is tener " which listens the response from the

    "Provider". - i

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