Veebiteenused (kordamisküsimused ja vastused kontrolltööks) (0)

Veebiteenused. Kontrolltöö.

SOA

• A  service -oriented architecture  (SOA) is an architectural pattern in computer software design in which application components provide services to other components via a communications protocol , typically over a network . The principles of service-orientation are independent of any vendor, product or technology .
  
• Kasutab XMLi sõnumivahetuseks
  
• Võimalus integreeride süsteeme
  

Service-oriented architecture (SOA)

• Arhitektuur , mis kasutab
  
  • teenuseid organisatsiooni integrastiooni ehitusklotsidena
    
  • komponentide taaskasutust läbi nõrga seotuse.
    

SOA: On arhitektuur

• Mingi hulga teenuste tegemine ei anna meile SOA-d.
  
• Arhitektuur peab andma meile juhised teenuste loomiseks.
  

SOA: Ehitatakse teenustest

• Nagu objekt-orienteeritud maailmas on objekt/klass nii on SOA-s teenuses peamine komponent .
  
• Ilma teenusteta pole meil millestki ehitada, midagi jälgida (monitor) ega käivitada.
  

SOA: integratsioon

• SOA esindab ühte võimalust süsteemide integratsiooniks.
  
• Erinevate süsteemide kokkuühendamise võib lahendada mõne P2P lahendusega palju kiiremini.
  
• Samas võib minna alternatiivide puhul ka palju rohkem aega, kuna süsteemid räägivad erinevat keelt (sõnumite formaat).
  
• SOA kasutab sõnumivahetuses XML-i.
  

SOA: nõrk seotus

• SOA-s püütakse teha nõrgalt seotud komponente, ehk teenuseid, mis ei tea midagi klientidest, kes neid kasutama hakkavad.
  

SOA: taaskasutus

• Pole alati hädavajalik.
  
• Samas, kui ühegi komponendi taaskasutus võimalust pole ega näe ka tulemas, siis on tõenäoliselt tegu üle mõeldud lahendusega ja kindlasti mitte SOA-ga.
  

SOA müügijutt..

• Kattes oma süsteemi selgroo ( mission critical) veebiteenustega, mis opereerivad SOA raamistikul, saad sa kergesti
  
  • laiendatava,
    
  • taaskasutatava ja asendatava lahenduse
    

• SOA annab meile raamistiku , kus mitmed mittefunktsionaalsed nõuded on juba täidetud.
  
  • Näiteks turvalisus
    
  • Arendajad keskenduda äriprobleemidele.
    

VEEBITEENUS

• A Web service is a service offered by an electronic device to another electronic device, communicating with each other via the World wide web. In a web service, web technology such as the HTTP, originally designed for human-to- machine communication , is utilized for machine-to-machine communication, more specifically for transferring machine readable file formats such as XML and  JSON . In practice, the web service typically provides an  object -oriented web based interface to a database server , utilized for example by another web server, or by a mobile application, that provides a user interface to the end user. Another common application offered to the end user may be a mashup, where a web server consumes several web services at different machines , and compiles the content into one user interface.
  

Veebiteenus tähendab programmide omavahelist suhtlemist ja andmevahetust üle hariliku veebi.

• Veebiteenus on üle veebi (http) välja kutsutav (käivitatav) meetod (protseduur või funktsioon).
  
• Veebiteenust kutsutakse välja mingis kindlas formaadis sõnumiga (nt. SOAP ) ja vastus saadakse samuti selles formaadis.
  
• Sarnaselt tavaliste funktsioonidega saab ka veebiteenuse väljakutsel määrata sisendparameetreid.
  
• A software system designed to support interoperable machine-to-machine interaction over a network
  
• It has an interface described in a machine-processable format ( WSDL )
  
• Other systems interact with the Web service in a manner prescribed by its description using SOAP-messages, typically conveyed using HTTP with an XML serialization in conjunction with other Web- related standards
  

Veebiteenus

• Veebiteenus on üle veebi (http) välja kutsutav (käivitatav) meetod (protseduur või funktsioon).
  
• Veebiteenust kutsutakse välja mingis kindlas formaadis sõnumiga (nt. SOAP) ja vastus saadakse samuti selles formaadis.
  
• Sarnaselt tavaliste funktsioonidega saab ka veebiteenuse väljakutsel määrata sisendparameetreid.
  

Pilt veebiteenuste abil integreerimisest

• Erinevad platvormid ja programmeerimiskeeled
  
• Erinevad kasutajaliidesed ühel kesksüsteemil
  
• Erinevad organisatsioonid
  
• Varjatud realisatsioon
  
• Kliendi ja teenusepakkuja sõltumatu arendus
  

Veebiteenuste eelised..
Veebiteenuste puudused…

• Erinevate platvormide rakenduste koostöö võimaldamine
  
• Teksti põhised ja avatud standardid on arendajale arusaadavad
  
• Annavad võimaluse erinevate ettevõtete erinevas kohas asuvaid rakendusi ja teenuseid integreerida üheks uueks teenuseks
  
• Veebiteenuste taaskasutamise võimalus
  

• Suurem keerukus
  
• Väiksem jõudlus
  
• ...
  

• Kasutusvõimalused - Web services can be published, found, and used on the Web. SOA arhitektuur kasutab teenuseid.
  

XSD

• Mõiste
  
• An XML Schema describes the structure of an XML document .
  
• The XML Schema language is also referred to as XML Schema Definition (XSD).
  
• XSD põhjal tekkib XML
  

STANDARDID XSD

• SOAP
  
• WSDL - SOA nurgakivi !
  
• XSD
  

XSD - XML Schema Definition

• XSD kirjeldab XML dokumendi struktuuri
  
  • Elemendid ( Elements )
    
  • Atribuudid (Attributes)
    
  • Nende tüübid
    
    • Tavatüübid ( Simple types )
      
    • Komplekstüübid ( Complex types)
      
    • Piirangud (Restrictions)
      

XSD võrdlused andmebaasi tabelite ja java klassidega

• XSD – Document structure
  
• Table structure
  
• Class definition
  

• XML – Document instance
  
• Record in a Table
  
• Object instance
  

XSD määrab..

• Millised elemendid ja atribuudid tohivad olla dokumendis
  
• Millised elemendid on alamelemendid
  
• Alamelementide järjestuse ja arvu
  
• Kas element on tühi või sisaldab teksti
  
• Andmetüübid elementide ja atribuutide jaoks
  
• Vaikimisi ja fikseeritud väärtused elementidele ja atribuutidele
  
• Piirangud
  

The purpose of an XML Schema is to define the legal building blocks of an XML document:

• the elements and attributes that can appear in a document
  
• the number of (and order of) child elements
  
• data types for elements and attributes
  
• default and fixed values for elements and attributes
  

• Mida saab XSD-ga XML dokumendis määrata?
  
  • Elemendid
    

XML Schemas define the elements of your XML files.
A simple element is an XML element that contains only text. It cannot contain any other elements or attributes.

What is a Simple Element?

A simple element is an XML element that can contain only text. It cannot contain any other elements or attributes.
However , the "only text" restriction is quite misleading. The text can be of many different types. It can be one of the types included in the XML Schema definition (boolean, string , date , etc.), or it can be a custom type that you can define yourself.
You can also add restrictions (facets) to a data type in order to limit its content, or you can require the data to match a specific pattern.

Defining a Simple Element

The syntax for defining a simple element is:
where xxx is the name of the element and yyy is the data type of the element.
XML Schema has a lot of built -in data types. The most common types are:

• xs:string, decimal, integer , Boolean, date, time
  

Example

Here are some XML elements:
Refsnes
36
1970-03-27

• Atribuudid
  

All attributes are declared as simple types.
Simple elements cannot have attributes. If an element has attributes, it is considered to be of a complex type. But the attribute itself is always declared as a simple type.

How to Define an Attribute?

The syntax for defining an attribute is:
where xxx is the name of the attribute and yyy specifies the data type of the attribute.

• Nende tüübid
  

XML Schema has a lot of built-in data types. The most common types are:

• xs:string, decimal, integer, Boolean, date, time
  

• Tavatüübid
  

The simpleType element defines a simple type and specifies the constraints and information about the values of attributes or text-only elements.

Element Information

Ei ole alamelemente
Siia sisse lähevad restrictionid

• Parent elements: attribute, element, list, restriction, schema, union
  

  
    
      
      
    
  

• Komplekstüübid
  

Võivad olla alamelemendid
The complexType element defines a complex type. A complex type element is an XML element that contains other elements and/or attributes.

Element Information

• Parent elements: element, redefine, schema
  

  
    
  
  
  
  
    
  

• Piirangud
  

Restrictions are used to define acceptable values for XML elements or attributes. Restrictions on XML elements are called facets.
  
    
      
      
    
  

• Lokaalsed elemendid ja tüübid on sisemise elemendi sees
  
• Globaalsed elemendid ja tüübid on ruutelemendi sees
  

WSDL
WSDL on keel, mis kirjeldab veebiteenuseid

• WSDL stands for Web Services Description Language
  
• WSDL is used to describe web services
  
• WSDL is written in XML
  

An WSDL document describes a web service. It specifies the location of the service, and the methods of the service, using these major elements:

• Mida ta kirjedab?
  

Operatsioonid

• The  operation  element defines each operation that the portType exposes.
  

Sõnumid

• Defines the data elements for each operation
  

Andmetüübid

• Defines the (XML Schema) data types used by the web service
  

Defines the (XML Schema) data types used by the web service
Defines the data elements for each operation
Describes the operations that can be performed and the messages involved.kirjeldab operatsioone ja nende sisend -väljund sõnumeid
Defines the protocol and data format for each port type - määratakse sõnumivahetuse transport iga operatsiooni kohta (document+literal recommended)
– nimi ja asukoht

• Alamosad ja nende ülesanded
  
  • types
    
  • message
    
  • portType
    
  • binding
    
  • service
    

WSDL’i elemendid
...
...
...
...
...
WSDL’i elemendid

• Types – siin saame XSD importida või kohapeal deklareerida
  
• Messages – iga requesti ja response jaoks on siin üks sõnum
  
• PortType – kirjeldab operatsioonid ja nende sisend ning väljund sõnumid.
  
• Binding - määratakse sõnumivahetuse transport iga operatsiooni kohta (document+literal recommended)
  
• Service – nimi ja asukoht
  

Näide :
WSDL asukoht - Tüüpiliselt asub WSDL aadressil:

• endpoint?wsdl
  

Näiteks http://localhost:9999/hello?wsdl
SOAP

• SOAP stands for Simple Object  Access  Protocol
  
• SOAP is an application communication protocol
  
• SOAP is a format for sending and receiving messages
  
• SOAP is platform independent
  
• SOAP is based on XML
  

It is important for web applications to be able to communicate over the Internet .
The best way to communicate between applications is over HTTP, because HTTP is supported by all Internet browsers and servers. SOAP was created to accomplish this.
SOAP provides a way to communicate between applications running on different operating systems, with different technologies and programming languages .

• Ülesanded
  
• It is important for web applications to be able to communicate over the Internet.
  
• The best way to communicate between applications is over HTTP, because HTTP is supported by all Internet browsers and servers. SOAP was created to accomplish this.
  
• SOAP provides a way to communicate between applications running on different operating systems, with different technologies and programming languages.
  
  • Komponendid
    

• Envelope - ruutelement
  

The required SOAP Envelope element is the root element of a SOAP message. This element defines the XML document as a SOAP message.
  ...
  Message information goes here
  ...

• Header
  

• The optional SOAP Header element contains application-specific information (like authentication, payment , etc) about the SOAP message.
  
• If the Header element is present , it must be the first child element of the Envelope element.
  
• Note : All immediate child elements of the Header element must be namespace-qualified.
  

  234
  

• The example above contains a header with a "Trans" element, a "mustUnderstand" attribute with a value of 1, and a value of 234.
  

• Body
  

• The required SOAP Body element contains the actual SOAP message intended for the ultimate endpoint of the message.
  
• Immediate child elements of the SOAP Body element may be namespace-qualified.
  

• Example

  
    Apples
  

• The example above requests the price of apples. Note that the m: GetPrice and the Item elements above are application-specific elements. They are not a part of the SOAP namespace.
  
• A SOAP response could look something like this:
  

  
    1.90
  
NIMERUUM

• Nimeruum (namespace) on lihtsalt loogiline (elementide ja tüüpide) nimede grupeering
  
• Nimeruumis peavad nimed olema unikaalsed
  
• Ühes XSD failis defineeritakse üks nimeruum
  

Selleks, et vältida elementide nimede konflikte.

• XML Namespaces provide a method to avoid element name conflicts.
  
• 
  

• Name Conflicts

• In XML, element names are defined by the developer . This often results in a conflict when trying to mix XML documents from different XML applications.
  

• Ülesanded
  
  • Grupeerib
    
  • Tagab elemendi unikaalsuse
    
• Kasutamine
  

Namespaces in Real Use

XSLT is a language that can be used to transform XML documents into other formats.
The XML document below , is a document used to transform XML into HTML.
Järgnevad mustrid erinevad ühe asja poolest

• Nende elemendid ja tüübid on kas lokaalselt või globaalselt defineeritud.
  
• Globaalne element või tüüp on schema alamelement.
  
• Lokaalne element või tüüp on defineeritud mõne teise elemendi või tüübi sees.
  
• Lokaalseid elemente ei saa taaskasutada.
  

Muster “Russian Doll”
Muster “Salami Slice”
Muster “Venetian Blind”

• Üks juurelement on globaalne
  
• Kõik tüübid on lokaalsed
  

• Kõik elemendid on globaalsed
  
• Kõik tüübid on lokaalsed
  

• Üks juurelement on globaalne
  
• Kõik tüübid on globaalsed
  

• TargetNamespace
  

XML
Mõiste
XML is a software- and hardware-independent tool for storing and transporting data.
XML stands for EXtensible Markup Language. XML was designed to store and transport data. XML was designed to be both human- and machine-readable.
Komponendid

• Viitamine
  

• Elemendid ja nende väärtused
  

An XML element is everything from ( including ) the element's start tag to (including) the element's end tag.
29.99
An element can contain:text, attributes, other elements, or a mix of the above
  
     Harry Potter
    J K. Rowling
    2005
    29.99
  
  
    Learning XML
    Erik T. Ray
    2003
    39.95
  
In the example above:
, , , and have text content because they contain text (like 29.99).
and have element contents, because they contain elements.
has an attribute (category=" children ").
XML elements must follow these naming rules :

• Element names are case -sensitive
  
• Element names must start with a letter or underscore
  
• Element names cannot start with the letters xml (or XML, or Xml, etc)
  
• Element names can contain letters, digits, hyphens, underscores, and periods
  
• Element names cannot contain spaces
  

Atribuudid ja nende väärtused

• XML elements can have attributes, just like HTML.
  
• Attributes are designed to contain data related to a specific element.
  
• Attribute values must always be quoted. Either single or double quotes can be used.
  
• For a person 's gender , the element can be written like this:
  
• 
  
• or like this:
  
• 
  
• If the attribute value itself contains double quotes you can use single quotes, like in this example:
  
• 
  

XML Elements vs. Attributes

Take a look at these examples :
  Anna
  Smith
   female
  Anna
  Smith
In the first example gender is an attribute. In the last, gender is an element. Both examples provide the same information.
There are no rules about when to use attributes or when to use elements in XML.

• Nimeruumid
  

XML Namespaces provide a method to avoid element name conflicts.

Name Conflicts

In XML, element names are defined by the developer. This often results in a conflict when trying to mix XML documents from different XML applications.
This XML carries HTML table information:
  
    Apples
    Bananas
  
This XML carries information about a table (a piece of furniture):
  African Coffee Table
  80
  120
If these XML fragments were added together, there would be a name conflict. Both contain a element, but the elements have different content and meaning .A user or an XML application will not know how to handle these differences .

Solving the Name Conflict Using a Prefix

Name conflicts in XML can easily be avoided using a name prefix.
This XML carries information about an HTML table, and a piece of furniture:
  
    Apples
    Bananas
  
  African Coffee Table
  80
  120
In the example above, there will be no conflict because the two elements have different names.

XML Namespaces - The xmlns Attribute

When using prefixes in XML, a namespace for the prefix must be defined.
The namespace can be defined by an xmlns attribute in the start tag of an element.
The namespace declaration has the following syntax. xmlns:prefix="URI".
  
    Apples
    Bananas
  
  African Coffee Table
  80
  120

• Viited (näiteks XSD-le)
  

Süntaks -The syntax rules of XML are very simple and logical . The rules are easy to learn, and easy to use. XML documents must contain one root element that is the parent of all other elements:

XML Documents Must Have a Root Element

  
    .....
  
In this example  is the root element:
  Tove
  Jani
  Reminder
  Don't forget me this weekend !
This line is called the XML  prolog :
The XML prolog is optional. If it exists, it must come first in the document.
XML documents can contain international characters , like Norwegian øæå or French êèé.
To avoid errors, you should specify the encoding used, or save your XML files as UTF-8.
UTF-8 is the default character encoding for XML documents.

All XML Elements Must Have a Closing Tag

XML tags are case sensitive. The tag is different from the tag .
Opening and closing tags must be written with the same case:
This is incorrect
This is correct
In XML, all elements must be properly nested within each other:
This text is bold and italic
JSON
JSON on süntaks andmete salvestamiseks ja vahetamiseks.
JSON ( JavaScript Object Notation) - Nimi-väärtus paaride kollektsioon

• XMLi alternatiid
  
• JSON: JavaScript Object Notation.
  
• JSON is a syntax for storing and exchanging data.
  
• JSON is an easier -to-use alternative to XML.
  
• The following JSON example defines an employees object, with an array of 3 employee records:
  

• JSON Example

<,
   ,
   

• 
   
  

• Süntaks
  
• The JSON syntax is a subset of the JavaScript syntax.
  

JSON syntax is derived from JavaScript object notation syntax:

• Data is in name/value pairs
  
• Data is separated by commas
  
• Curly braces hold objects
  
• Square brackets hold arrays
  

JSON eelised:
Saab parsida standard JS funktsiooniga, parsimine lihtsam

Simplicity

XML is simpler than SGML, but JSON is much simpler than XML. JSON has a much smaller grammar and maps more directly onto the data structures used in modern programming languages.

Extensibility

JSON is not extensible because it does not need to be. JSON is not a document markup language, so it is not necessary to define new tags or attributes to represent data in it.

Interoperability

JSON has the same interoperability potential as XML.

Openness

JSON is at least as open as XML, perhaps more so because it is not in the center of corporate/ political standardization struggles.
XML eelised:

XML is human readable 

JSON is much easier for human to read than XML. It is easier to write, too. It is also easier for machines to read and write.

XML can be used as an exchange format to enable users to move their data between similar applications

The same is true for JSON.

XML provides a structure to data so that it is richer in information

The same is true for JSON.

XML is easily processed because the structure of the data is simple and standard

JSON is processed more easily because its structure is simpler.

There is a wide range of reusable software available to programmers to handle XML so they don't have to re-invent code

JSON, being a simpler notation, needs much less specialized software. In the languages JavaScript and Python , the JSON notation is built into the programming language; no additional software is needed at all. In other languages, only a small amount of JSON-specific code is necessary. For example, a package of three simple classes that makes JSON available to Java is available for free from JSON.org.

XML separates the presentation of data from the structure of that data.

XML requires translating the structure of the data into a document structure. This mapping can be complicated. JSON structures are based on arrays and records. That is what data is made of. XML structures are based on elements (which can be nested), attributes (which cannot), raw content text, entities, DTDs, and other meta structures.

A common exchange format

JSON is a better data exchange format. XML is a better document exchange format. Use the right tool for the right job.

Many views of the one data

JSON does not provide any display capabilities because it is not a document markup language.
XPath
XPATH on päringukeel XML dokumentidest informatsiooni otsimisest nagu SQL on päringukeel andmebaasi tabelitest otsimiseks.
Pärime välja kõik title’d

• /CATALOG/CD/TITLE
  
• //TITLE
  

Pärime välja kõik cd’d, mille hind on suurem kui 10

• /CATALOG/CD[PRICE>10]
  
• XPath is used to navigate through elements and attributes in an XML document.j
  

• Süntaks
  
• XPath uses path expressions to select nodes in an XML document. The node is selected by following a path or steps. The most useful path expressions are listed below:
  

Expression
Description
nodename Selects all nodes with the name "nodename"
/ Selects from the root node
// Selects nodes in the document from the current node that match the selection no matter where they are
. Selects the current node
.. Selects the parent of the current node
@ Selects attributes

Relative vs. Absolute paths

In HTML, you can specify an Absolute Path for the hyperlink, describing where another page is with the server name, folders, and filename all in the URL. Or, if you are referring to another file on the same site, you need not enter the server name or all of the path information. This is called a Relative Path. The concept can be applied similarly in XPath.
If location path starts with the node that we've selected then it is an relative path. If location path starts with root node or with '/' then it is an absolute path.

• Päringute tulemuse ennustamine -Ise panen midagi ja ennustan mis tuleb
  

XSLT

• Mõiste – andmete teisendamiseks XMList
  
• Selle sees oli kasutatud XPath
  
• XSLT on XML-põhine keel XML dokumentide mingisse teise formaati teisendamiseks.
  
• XSLT kirjeldab reeglid, millega lähtepuu (source tree) transformeeritakse tulemuspuuks ( result tree).
  
• Lähtepuust päritakse andmeid kasutades XPATH-i.
  

Milleks kasutatakse?

• Andmete konverteerimiseks erinevate XML Schema-de vahel (meie kasutame samuti).
  
• XML andmete HTML-ks või XHTML -ks konverteerimiseks (näide 1).
  
• XML andmete tavaliseks tekstiks või PDF-ks või mõneks muuks dokumendiks konverteerimiseks.
  

XSLT protsessorid

• XSLT protsessorid võivad olla kliendi- või serveripoolsed.
  
• Mitmetesse JAVA ja .NET-i jt raamistikesse on XSLT protsessorid juba sisse ehitatud.
  

• XSL stands for EXtensible Stylesheet Language, and is a style sheet language for XML documents.
  
• XSLT stands for XSL Transformations. In this tutorial you will learn how to use XSLT to transform XML documents into other formats, like XHTML.
  
  • Ülesanne
    

XSLT is a language for transforming XML documents into XHTML documents or to other XML documents.

• Süntaks – W3S
  

REST
REST is an architecture style for designing networked applications. The idea is that, rather than using complex mechanisms such as CORBA, RPC or SOAP to connect between machines, simple HTTP is used to make calls between machines
In computing, representational state transfer (REST) is the software architectural style of the World Wide Web.

• Põhimõtted – igal teenusel on oma URL. IGALE TEENUSELE OMA URI
  

REST (querying a phonebook)

• Hea näide:
  
  • http://www.acme.com/phonebook/UserDetails/12345
    
• Halb näide
  
  • http://www.acme.com/phonebook/getUserDetails?id=12345
    
• Veel halvem näide
  
  • http://www.acme.com/phonebook/user12345.xml
    

• REST provides a lighter weight alternative. Instead of using XML to make a request, REST relies on a simple URL in many cases. In some situations you must provide additional information in special ways, but most Web services using REST rely exclusively on obtaining the needed information using the URL approach . REST can use four different HTTP 1.1 verbs (GET, POST, PUT, and DELETE ) to perform tasks.
  
• REST doesn’t have to use XML to provide the response. You can find REST-based Web services that output the data in Command Separated Value (CSV), JavaScript Object Notation (JSON) and Really Simple Syndication (RSS). The point is that you can obtain the output you need in a form that’s easy to parse within the language you need for your application.
  
  • Ressurss - Kõik asjad, mille poole on vaja pöörduda, on ressurssid. Toimub eraldi URIga.
    
• Resources are the key abstractions in REST.
  
• They are the remote accessible objects of the application.
  
• A resource is a unit of identification.
  
• Everything that might be accessed or be manipulated remotely could be a resource.
  
  • URI paths
    

Uniform Resource Identifier, is a string of characters used to identify a resource
ühtne ressursi-indikaator Internetis leiduvail tarkvaralistel võrguressurssidel (HTML dokumendid, pildid, videoklipid, programmid , muusika jne) on igaühel oma unikaalne URI, mis määrab kindlaks ressursi nime (URN) ja aadressi (URL), mis näita ära, kust ja kuidas võib seda ressurssi kätte saada

• REST teenuse kirjeldamise vahendid
  
  • Loetelu
    
  • Turvalisus
    
• SOAP ja REST teenuste turvalisus. RESTil pole spetsiifilist turvalisust
  

Ligipääsu piiramine

• http/s autentimise kasutamine
  
• access_token
  
  • teenusepakkuja lahendus (kasutaja küsib teenusepakkujalt access tokeni)
    
  • kolmanda osapoole kaudu ( kasutades OAuth, OpenID vms lahendust )
    

Järgnevad REST ja WS-* näited