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Restful Fundamentals
10 de Feb de 2017•0 recomendaciones•170 vistas
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The objective of this presentation to understand basic concept of REST and how to apply HTTP Methods with REST.
Suresh MadhraSeguir
Asst Manager - Custom Delivery en DXC TechnologyPublicidad
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Restful Fundamentals
- REST Fundamentals – Applying HTTP Methods
- REST Representational State Transfer
- REST HTTP + Resource-Oriented Architecture
- AGENDA - HTTP HTTP RESOURCE STATIC DYNAMIC URL RESOURCE LOCATOR RESOUCRE IDENTIFER VERBS GET POST PUT DELETE CONTENT TYPE MESSAGE HTTP REQUEST HTTP RESPONSE STATUS CODE 1xx - INFORMATIONAL 2xx - SUCCESSFUL 3xx - REDIRECTION 4xx – CLIENT ERROR 5xx – SERVER ERROR WWW HTML
- WHAT IS THE WEB? An information system of interlinked hypertext documents and resources accessed via the Internet
- HYPERTEXT DOCUMENTS
- HYPERTEXT MARKUP LANGUAGE
- AGENDA - HTTP HTTP RESOURCE STATIC DYNAMIC URL RESOURCE LOCATOR RESOUCRE IDENTIFER VERBS GET POST PUT DELETE CONTENT TYPE MESSAGE HTTP REQUEST HTTP RESPONSE STATUS CODE 1xx - INFORMATIONAL 2xx - SUCCESSFUL 3xx - REDIRECTION 4xx – CLIENT ERROR 5xx – SERVER ERROR WWW HTML
- RESOURCES Anything that can be identified, named, addressed or handled on the Web
- RESOURCE ▫ Can be concrete things: • Web Pages • Video files • Articles • Blogs • Image file
- RESOURCE ▫ Can be static and dynamic
- RESOURCE ▫ Can also represent abstract concepts • Employee or Product or Order • Time • Money Transfer • Calendar • User Accounts
- AGENDA HTTP HTTP RESOURCE STATIC DYNAMIC URL RESOURCE LOCATOR RESOUCRE IDENTIFER VERBS GET POST PUT DELETE CONTENT TYPE MESSAGE HTTP REQUEST HTTP RESPONSE STATUS CODE 1xx - INFORMATIONAL 2xx - SUCCESSFUL 3xx - REDIRECTION 4xx – CLIENT ERROR 5xx – SERVER ERROR WWW HTML
- URL Uniform Resource Locator A URL is a specialization of URI that defines the network location of resource URL defines how the resource can be obtained eg. http://some.domain.com/orderinfo?id=123
- URL ANOTOMY UR I - Uniform Resource I d e n t i f i e r UR L - Uniform Resource L o c a t o r
- RESOURCE IDENTFIERS A resource only exists on the Webif it has an identifier (URI)
- RESOURCE NAMES ▫ URN - Uniform Resource Name • products/54321 • about-us • articles/web.html • posts/2015-01-12 • podcasts/rest.mp3 • products/9595
- AGENDA HTTP RESOURCE STATIC DYNAMIC URL RESOURCE LOCATOR RESOUCRE IDENTIFER CONTENT TYPE VERBS GET POST PUT DELETE MESSAGE HTTP REQUEST HTTP RESPONSE STATUS CODE 1xx - INFORMATIONAL 2xx - SUCCESSFUL 3xx - REDIRECTION 4xx – CLIENT ERROR 5xx – SERVER ERROR WWW HTML
- HTTP can transfer any kind of information between clients and servers E.g. Text files, PDF, e-documents, images, videos, etc. In any case, the data is streamed over TCP/IP and browser knows how to interpret the binary streams because of the HTTP protocol response header Content-Type CONTENT-TYPES
- AGENDA HTTP RESOURCE STATIC DYNAMIC URL RESOURCE LOCATOR RESOUCRE IDENTIFER CONTENT TYPE VERBS GET POST PUT DELETE MESSAGE HTTP REQUEST HTTP RESPONSE STATUS CODE 1xx - INFORMATIONAL 2xx - SUCCESSFUL 3xx - REDIRECTION 4xx – CLIENT ERROR 5xx – SERVER ERROR WWW HTML
- HTTP VERBS
- AGENDA HTTP RESOURCE STATIC DYNAMIC URL RESOURCE LOCATOR RESOUCRE IDENTIFER CONTENT TYPE VERBS GET POST PUT DELETE MESSAGE HTTP REQUEST HTTP RESPONSE STATUS CODE 1xx - INFORMATION 2xx - SUCCESSFUL 3xx - REDIRECTION 4xx – CLIENT ERROR 5xx – SERVER ERROR WWW HTML
- HTTP STATUS CODE Ser ver ’s processed status corresponding to a request Combination of numerical code & short description
- AGENDA HTTP RESOURCE STATIC DYNAMIC URL RESOURCE LOCATOR RESOUCRE IDENTIFER CONTENT TYPE VERBS GET POST PUT DELETE MESSAGE HTTP REQUEST HTTP RESPONSE STATUS CODE 1xx - INFORMATIONAL 2xx - SUCCESSFUL 3xx - REDIRECTION 4xx – CLIENT ERROR 5xx – SERVER ERROR WWW HTML
- HYPERTEXT TRANSFER PROTOCOL Server Client Yahoo.comMozilla Firefox
- HTTP COMMUNICATION
- HTTP MESSAGE - REQUEST Server Client Yahoo.comMozilla Firefox HTTP Request GET /HTTP/1.1 User-Agent: Mozilla Firefox Host: example.com Accept: */*
- HYPERTEXT TRANSFER PROTOCOL ServerClient Yahoo.comMozilla Firefox HTTP Response HTTP/1.1 200 OK Content-Type: text/html Content-Length: 1270 <!doctype html> <html> <head> <title>Example Domain</title> </head> <body> … </body> </html>
- HTTP request message is sent from the client (Brower) to HTTP Web-Server. Request message contain: location of a resource or resource URI HTTP method to use when accessing the resource. Optional request headers (name-value pairs) providing additional information Request body that identifies additional data to be uploaded to the server (e.g. form parameters, attachments, etc.) HTTP REQUEST MESSAGE
- HTTP response message is sent from HTTP Web-Server back to the client (Web-Browser). Response message contain: Carry status of processed request. Provide response headers (name-value pairs) providing additional information about the response Supplies optional response body that identifies additional data to be downloaded to the server (e.g. html, images, attachments etc. HTTP RESPONSE MESSAGE
- HTTP MESSAGE FORMAT
- Request Line HTTP MESSAGE FORMAT
- /fruits/list?category=fruits&limits= 20 Path to resource Query string HTTP /1.1 HTTP HEADER – REQUEST LINE
- Request/ Response General Header Carry information about the HTTP transaction Can be a part of request, as well as response General Headers HTTP HEADER – GENERAL
- Request Header Specific to an HTTP Request Carry information about the client, and the type of request Facilitates better understanding between client and server Request Headers HTTP HEADER – REQUEST
- Request/ Response Entity Header Carry information about the content Mainly part of HTTP Response Entity Headers HTTP HEADER – ENTITY
- HTTP REQUEST RESPONSE MESSAGE EXCHANGE
- REST Representational State Transfer
- REST HTTP + Resource-Oriented Architecture
- REST HTTP + Resource-Oriented Architecture RESTful
- What is REST? REST is not a technology, nor a framework REST is an architectural style - Set of principles & constraints Why constraints? Constraints help us in developing applications that are “easy” to maintain and extend. REST
- MAJOR PLAYERS
- REST ACTORS REST RESOURCES REPRESENTATION ACTIONS
- REST ACTORS REST RESOURCES REPRESENTATION ACTIONS
- In general, a RESTful resource is anything that is addressable over Web Addressable = anything that can be accessed and transferred between clients and servers Resource must have a unique address over the Web Under HTTP these are URIs RESOURCES
- In a RESTful web service, Resources are categorized as: Singleton resource is a single chunk of information, similar to a row in a database table. Collection resource is a set of resources with the same structure, similar to a selection of rows in a database table. RESOURCES MODEL
- Uniform Resource Identifier In a RESTful web service, It is a hyperlink to a resource Means for clients and servers to exchange representations of resources ex. .../orderinfo?id=123 Only means to locate a specific resource Used to negotiate representations of a given resource In the url you give certain parameters that define which information you want the server to return to you (just like giving GET variables to a page). Server will respond you with a resource representation containing the information you’ve asked URIs
- URIs are also used to link resources together. ex. URIs
- REST ACTORS REST RESOURCES REPRESENTATION ACTIONS
- Representation of resources is what is sent back and forth between clients & servers So, we never send or receive resources, only their representations REPRESENTATION
- Format of the representation is determined by the content- type Interaction of the representation on the resource is determined by the action (GET, POST etc.) REPRESENTATION
- Different clients are able to consume different representations of the same resource A representation can take various forms, such as: • image • a text file • an XML stream • a JSON stream Note: But its resource has to be available through the same URI REPRESENTATION FORMATS
- REPRESENTATION FORMATS For human-generated requests through a web browser, a representation is typically in the form of an HTML page For automated requests from other web services, readability is not as important and a more efficient representation can be used such as XML or JSON
- REST ACTORS REST RESOURCES REPRESENTATION ACTIONS
- ACTIONS Actions are used to operate on resources For example, they can be used for – getting info about a movie – adding a photo to Flickr – deleting a file from a folder Note: Data transmitted to and from the resource is a representation of it.
- HTTP-BASED ACTIONS Note: RESTful web services can also execute logic at the server level, but remembering that every result must be a resource representation
- HTTP as Uninform Interface Note: RESTful web services can also execute logic at the server level, but remembering that every result must be a resource representation
- HTTP as Uninform Interface Restful Approach Traditional Approach Focus on resource names Focused on the actions to be performed on resources Four specific actions that we can take upon resources — Create, Retrieve, Update, and Delete (CRUD) Countless actions with no naming or implementation standards
- HTTP as Uninform Interface
- Artificial example of a web service handling students in some classroom Location of the service = http://restfuljava.com/ Resources are represented as XML streams CLASSROOM EXAMPLE
- Student (identified by name): http://restfuljava.com/students/{name} List of students: http://restfuljava.com/students CLASSROOM EXAMPLE - URIs
- Student Schema <student> <name>Jane</name> <age>10</age> <link>/students/Jane</link> </student> CLASSROOM EXAMPLE - REPRESENTATIONS
- Students List: <students> <student> <name>Jane</name> <age>10</age> <link>/students/Jane</link> </student> <student> <name>John</name> <age>11</age> <link>/students/John</link> </student> </students> CLASSROOM EXAMPLE - REPRESENTATIONS
- CLASSROOM EXAMPLE - REPRESENTATIONS GET POST PUT DELETE GET is used to RETRIEVE resources POST is used to CREATE resources PUT is used to UPDATE resources DELETE is used to DELETE resources No side effects Has side effects Has side effects Has side effects Can also return only parts of the resource The resource identity/URL is not known at creation time Return updated resource URL Used for Read operation and query
- GET EXAMPLE
- POST EXAMPLE
- Theinitial GETis omitted here PUT EXAMPLE
- DELETE EXAMPLE
- REST Constraints 1. Uniform Interfaces – Resource Model • Every resource has a unique id which uniquely identify. • Every resource has URI [Uniform Resource Identifier]. URI Syntax URI
- Resource URL Mapping with HTTP Method HTTP Methods Resource CRUD OperationsResource URI
- REST Constraints
- REST Constraints Uniform Interface
- REST Constraints 1. Uniform Interfaces
- REST Constraints 1. Uniform Interfaces - Resources
- REST Constraints 1. Uniform Interfaces - Resource • Resource is a chunk of related information of an entity. • Can be static and dynamic. • Resources words are ‘NOUNS’ such as Movies, Employees, Products, Photos
- REST Constraints 1. Uniform Interfaces – Resource Model • Singleton resource is a single chunk of information, similar to a row in a database table. • Collection resource is a set of resources with the same structure, similar to a selection of rows in a database table.
- REST Constraints 1. Uniform Interfaces – Resource Model • Every resource has a unique id which uniquely identify. • Every resource has URI [Uniform Resource Identifier]. URI Syntax URI
- REST Constraints 1. Uniform Interfaces – Resource Model Yahoo Social REST APIs Singleton resource : Following URI defines the profile resource for the user whose ID is 12345. https://social.yahooapis.com/v1/user/12345/profile The next URI specifies the connections (friends) for the user whose ID is 6677. https://social.yahooapis.com/v1/user/6677/connections Collection resource : Following URI accesses the collection of schools contained in the profile of the user of ID 98765. https://social.yahooapis.com/v1/user/98765/profile/schools
- REST Constraints 1. Uniform Interfaces - Methods
- Resource URL Mapping with HTTP Method HTTP Methods Resource CRUD OperationsResource URI REST Constraints
- HTTP Methods
- REST Constraints 1. Uniform Interfaces - Representations
- REST Constraints Stateless
- 2. Stateless Server Two types of State Application State Resource State REST Constraints
- 2. Stateless Server No client context is stored on the server between requests. Each request from any client contains all of the information necessary to service the request, and any state is held in the client. The server can be stateful, this constraint merely requires that server-side state be addressable by URL as a resource. REST Constraints
- REST Constraints Application State Exchange of Request Identify between Server and Client
- REST Constraints Resource State What is stored on the server (Beyond Session)
- REST Constraints 2. Stateless Server Each request contains ALL the information necessary to understand it Application (session) state is kept on the client
- REST Constraints 2. Stateless Server Visibility - Performance Reliability - Consistency Scalability
- REST Constraints Client Server
- 1. Client - Server Separation of Concerns: Client responsible for UI Server responsible for data storage REST Constraints
- 1. Client - Server REST Constraints + Scalability + Simplicity
- REST Constraints Cache
- REST Constraints 3. Cache Clients are able to cache responses. Responses must, implicitly or explicitly, define themselves as cacheable or not.
- REST Constraints 3. Cache Efficiency Scalability UP Performance
- REST Constraints Layered System
- AN EXMAPLE HTTP server: example.com
- READING A TEXT RESOURCE http://example.com/hello-world.txt GET /hello-world.txt HTTP/1.1 Host: example.com HTTP Request
- READING A TEXT RESOURCE http://example.com/hello-world.txt HTTP Response HTTP/1.1 200 OK Content-Type: text/plain Content-Length: 13 Hello, World!
- CREATING A TEXT RESOURCE POST / HTTP/1.1 Host: example.com Content-type: text/plan Hello Mars HTTP Request
- CREATING A TEXT RESOURCE HTTP/1.1 201 Created Location: /hello-mars.txt HTTP Response
- RESOURCE DOES NOT EXIST http://example.com/hello-world.txt GET /hello-world.txt HTTP/1.1 Host: example.com HTTP Request
- RESOURCE DOES NOT EXIST HTTP/1.1 404 Not Found HTTP Response
- EMPLOYEE RESOURCE Name Gender Role
- XML REPRESENTATION <employee> <name>Alice</name> <role>Developer</role> <gender>female</gender> </employee>
- JSON REPRESENTATION { "name": "Alice", "role": "Developer", "gender": "female" }
- HTML REPRESENTATION <h1>Alice</h1> <dl> <dt>Role:</dt> <dd>Developer</dd> <dt>Gender:</dt> <dd>Female</dd> </dl>
- EMPLOYEE RESOURCE /employees/alice /employees/bob /employees/eve
- RESOURCE OPERATIONS
- LIST EMPLOYEE RESOURCES GET /employees HTTP/1.1 Host: example.com Accept: application/xml HTTP Request
- LIST EMPLOYEE RESOURCES HTTP Response HTTP/1.1 200 OK Content-Type: application/xml <employees> <employee href="/employees/alice"/> <employee href="/employees/bob"/> <employee href="/employees/eve"/> </employee>
- LIST EMPLOYEE RESOURCES HTTP Response HTTP/1.1 200 OK Content-Type: application/xml <employees> <employee href="/employees/alice"/> <employee href="/employees/bob"/> <employee href="/employees/eve"/> </employee>
- READ EMPLOYEE RESOURCE GET /employees/alice HTTP/1.1 Host: example.com Accept: application/xml HTTP Request
- READ EMPLOYEE RESOURCE HTTP Response HTTP/1.1 200 OK Content-Type: application/xml <employees> <name>Alice</name> <role>Developer</role> <gender>Female</gender> </employee>
- CREATE EMPLOYEE RESOURCE HTTP Request POST /employees HTTP/1.1 Host: example.com Content-Type: application/xml <employee> <name>John</name> <role>QA</role> <gender>male</gender> </employee>
- CREATE EMPLOYEE RESOURCE HTTP Response HTTP/1.1 200 OK
- UPDATE EMPLOYEE RESOURCE HTTP Request PUT /employees/alice HTTP/1.1 Host: example.com Content-Type: application/xml <employee> <name>Alice</name> <role>Manager</role> <gender>female</gender> </employee>
- UPDATE EMPLOYEE RESOURCE HTTP Response HTTP/1.1 201 Created Location: /employees/john
- DELETE EMPLOYEE RESOURCE HTTP Request DELETE /employees/alice HTTP/1.1 Host: example.com Content-Type: application/xml
- DELETE EMPLOYEE RESOURCE HTTP Response HTTP/1.1 204 NO Content
- RESOURCE ORIENTED ARCHITECTURE Addressability Statelessness Connectedness Uniform Interface
- ADDRESSSABILITY Every interesting piece of information the server can provide should be exposed as a resource, and given its own URI http://example.com/employees/alice
- STATELESSNESS Every HTTP request should happen in complete isolation http://google.com/search?q=jellyfish
- STATELESSNESS
- STATELESSNESS http://google.com/search?q=jellyfish&start=10
- STATELESSNESS Application State vs. Resource State
- CONNECTEDNESS Documents should contain not just data, but links to other resources
- CONNECTEDNESS
- CONNECTEDNESS
- CONNECTEDNESS
- CONNECTEDNESS { "employees": [ "/employees/alice", "/employees/bob", "/employees/eve", ... ] "next_page": "/employees?start=10", "create_employee": "/employees" }
- HATEOS Hypermedia As The Engine of Application State
- REST Constraints
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