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1 תוכנית יומית לכנס התכנסות וארוחת בוקר 08:00-09:00 הרצאה הפסקה ראשונה הרצאה ארוחת צהריים הרצאה הפסקה מתוקה -09:00-10:30-10:30-10:45-10:45-12:30-12:30-13:30-13:30-15:00-15:00-15:15 הרצאה 15:15-16:30 לפרטים נוספים: טל פקס ג'ון ברייס הדרכה, חומה ומגדל 29 תל אביב, מיקוד

3 Java Web-Services, Microservices with REST & Spring Cloud Tavor Haim 1

4 Topics Architecture REST based Web Services JAX-RS Spring MVC + Spring Boot Microservices SpringCloud 2

5 Web Services Web service is: A service available on the internet, that uses standard protocols for integration Service Internet [HTTP] Standard protocols 3

6 Architecture MVC client show data get data controller model dispatch view 1 view 2 view 3 View and model communicated through value objects Trivial server side code is embedded in views Views are still a mix of server & client code... 4

7 Architecture The problem with views Mixing server side code in view causes some serious problems: Value objects embedded in HTML It is never just HTML (CSS, Jscript ) What if client requires something else than HTML?? 5

8 Architecture The problem with views List of web frameworks that should help: Echo, Cocoon, Millstone, OXF, Struts, SOFIA, Tapestry, WebWork, RIFE, Spring MVC, Canyamo, Maverick, Jpublish, JATO, Folium, Jucas, Verge, Niggle, Bishop, Barracuda, Action Framework, Shocks, TeaServlet, wings, Expresso, Bento, jstatemachine, jzonic, OpenEmcee, Turbine, Scope, Warfare, JWAA, Jaffa, Jacquard, Macaw, Smile, MyFaces, Chiba, Jbanana, Jeenius, Jwarp, Genie, Melati, Dovetail, Cameleon, Jformular, Xoplon, Japple, Helma, Dinamica, WebOnSwing, Nacho, Cassandra, Baritus, Stripes, Click, GWT, Apache Wicket So many means that: none is really good enough maybe problems can t be solved with MVC 6

9 Architecture AJAX to the rescue View of classic architecture Web Server Browser HTML 1 HTTP Request HTML 2 HTTP Response CGI Engine 7

10 Architecture Moving to Single Page Applications (SPA) Using AJAX, web modules can focus on transferring data rather than view Client receives a single HTML loaded with Jscript functions & callbacks Jscript caller functions sends request data Jscript callback processes response and renders it to page Finally! Web modules input & output can be based on structured, self descriptive text formats Future non-html clients may use the same modules & data 8

11 Architecture Moving to single page applications MVC Model 2 Views are Generated on server side client show data controller dispatch get data model SERVER view 1 view 2 view 3 The new MVC Views are handled by the Client client. view Communication between client and server is data- based. SERVER request data controller model get data 9

12 Client MVC Client MVC frameworks View - <html> elements Model Javascript code that processes local and remote data On page load On event Controller Javascript infrastructure for synching data between Model and View 10

13 Client MVC Benefits Clear separation between UI and code views became very complex and modularity is needed Abstracted data liquidity Shortened AJAX code can be done in a single row! Leading frameworks AngularJS React 11

14 Client MVC Angular way: HTML Single Page Javasctipt ng-app HTML Fragment Javasctipt ng-controller HTML Fragment Javasctipt ng-controller HTML Fragment Javasctipt ng-controller HTML Fragment Javasctipt ng-controller Javasctipt ng-controller On page load On events 12

15 Architecture Future internet clients Phones & voice over IP networks Smart cards Chips Nanotechnology 13

16 Architecture Future internet clients The new MVC SERVER request view data controller model get data 14

17 RPC Architecture & Terms Remote Procedure Call Client invokes method on a Remote Object over a network Client obeys a contract which is the Remote Interface Remote object is a resource Remote method is a service In order to communicate both client & server uses sockets Socket communication is determined according to the remote interface Stub - Client side socket Skeleton server side socket that is used as a proxy to the remote object 15

18 RPC Architecture & Terms public int sum (int x, int y); User input is : 5, +, 6 Result is : 11 Remote Interface CLIENT stub out.writeutf( sum ); out x=out.writeint(5); out y=out.writeint(6); int result=in.readint(); skeleton SERVER get data String action=in.readutf(); int x=in.readint(); int y=in.readint(); out.write(ro.invoke(action,x,y)); Remote Object public int sum (int x, int y){ return x+y; } 16

19 RPC 2-tier vs. 3-tier RPC Container stub stub stub stub skeleton skeleton skeleton get data skeleton Container stub stub stub stub Remote Object RO Pool skeleton RO skeleton skeleton skeleton RO RO Manager RO 17

20 RPC XML for RPC SOAP Web Services XML SERVER CLIENT XML Request stub skeleton XML Response get data Remote Object 18

21 XML based Web Services XML based RPC (SOAP) Server WSDL Describes Service Client Application SOAP SKEL Layer Proxies 19

22 XML based Web Services SOAP over HTTP Request example HTTP 1.0 POST Host: Content-Type: text/xml; charset="utf-8" Content-Length: nnnn SOAPAction: "Some-URI POST method - allows great amount of data upload SOAP Header that provides another checking mechanism <SOAP-ENV:Envelope xmlns:soap-env=" SOAP-ENV:encodingStyle=" <SOAP-ENV:Body> <m:getlasttradeprice xmlns:m="some-uri"> <symbol>dis</symbol> </m:getlasttradeprice> </SOAP-ENV:Body> </SOAP-ENV:Envelope> 20

23 Architecture XML vs. JSON What is JSON? Java Script Object Notation Also self-descriptive text based protocol Used for marshalling and un-marshalling Jscript objects { people : [ { name": David, age": 20 }, { name": Dana, age": 25 }, { name": Eve, age": 30 }, ] } 21

24 Architecture XML vs. JSON Why is it an alternative for XML? Better for small applications (like client side apps) No parsers are needed Contracts are less critical Light integration Jscript and Android developers prefers it Got popular APIs for binding, handling & presenting JSON based data 22

25 Architecture XML vs. JSON JAXB supports JSON as well Root class is denoted No schema is needed all adjustments are done with JAXB annotations JSON has no strong standards as XML (yet..) 23

26 Modern Integration Big data the challenge From single & concurrent to parallel & cloud computing Using NoSQL DB in addition to the classic relational DB Saving bandwidth & performance XML is a very inefficient protocol uses tags to wrap data XML forces the use of parsers HTTP Message SOAP is an additional protocol on top of HTTP HTTP headers HTTP body SOAP Message SOAP Envelope SOAP Header SOAP Body SOAP Elements SOAP Attachments 24

27 Just to get familiar with Java Web Modules Web app structure Static content Dynamic content WEB-INF & web.xml Servlets Life cycle Coding URL pattern Filters HttpServletRequest HttpSession ServletContext Main scopes Page Request Session Application WAR files 25

28 REST based Web Services REST REpresentational State Transfer is an HTTP based advanced RPC passing data in any format including XML, JSON and binary data REST can be counted as part of HTTP unlike SOAP which is a separate protocol 26

29 REST based Web Services HTTP for RPC Clients may use the following HTTP features in order to invoke a service: URI: Path can determine the endpoint class and even method Accept & Content-Type Headers: Used by the client to specify response MIME type service methods may result in different MIME types client call can be delegated to method that produces the MIME type it expects HTTP Method: GET, POST, DELETE, PUT, HEAD each method can be mapped to several HTTP-methods client call is delegated to the method matches client HTTP request method 27

30 REST based Web Services HTTP for RPC - RESTful Suggested way to implement business according to HTTP method HTTP Method Single element Collection GET Fetch an element from a collection Fetch the whole collection PUT Replace or create new element in a collection Override one collection with a new one POST Assign a value to an object Add new value to a collection DELETE Delete a specific element from a collection Delete the entire collection 28

31 REST based Web Services JAX-RS main Maps to URL pattern Mandatory on class level Optional on method level Maps to HTTP request method Used for RESTful Produces sets MIME type client requested to accept as part of the response Consumes sets MIME type client should sent as part of the request 29

32 REST based Web Services Building and publishing RESTful public class greet public String greet() public void addperson(person p) { } 30

33 REST based Web Services JAX-RS main annotations Sending simple parameters are passed as part of the URL Cannot be optional Support multiple params on each Parameters are passed as part of the request In GET parameters are part of the query string In POST parameters are placed in the request body Are optional to inject values when not sent by client 31

34 REST based Web Services Building and publishing RESTful public class greet public String greet(@defaultvalue( David user ) String name) sum/{num1}/{num2} ) public void sum((@pathparam( num1 ) int x, (@PathParam( num2 ) int y) { } 32

35 REST based Web Services Marshalling & public class MediaType.APPLICATION_JSON}) public Entry editentry(entry toedit) edit Clients may assign JSON/XML // entry public class Entry{ return e; private String name; } private String phone; private String cellphone; } public Entry(){} } 33

36 Configuring web.xml <?xml version="1.0" encoding="utf-8"?> WEB-INF\web.xml <web-app > <display-name>hello In Different Formats</display-name> <servlet> <servlet-name>jersey REST Service</servlet-name> <servlet-class>com.sun.jersey.spi.container.servlet.servletcontainer</servlet-class> <init-param> <param-name>com.sun.jersey.config.property.packages</param-name> <param-value>your.service.package.name</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>jersey REST Service</servlet-name> <url-pattern>/rest/*</url-pattern> </servlet-mapping> </web-app> 34

37 REST based Web Services Invoking via HTTP requests: Root Context, usually your project name The URL pattern to call Jersey servlet The name of the resource (service) 35

38 REST based Web Services Creating RESTful client Jersey offers simple client API get(..) / post(..) public class Test { / put(..) / delete(..) public static void main(string[] args) { ClientConfig config = new DefaultClientConfig(); Client client = Client.create(config); URI baseuri = UriBuilder.fromUri(" WebResource service = client.resource(baseuri ); // Get plain text System.out.println(service.path("rest").path("hello").accept(MediaType.TEXT_PLAIN).get(String.class)); // Get XML System.out.println(service.path("rest").path("hello").accept(MediaType.TEXT_XML).get(String.class)); // The HTML System.out.println(service.path("rest").path("hello").accept(MediaType.TEXT_HTML).get(String.class)); } 36

39 REST based Web Services Creating RESTful client Jersey client JAR Not part of JAX-RS standard (!) Can be easily used for unit testing via Junit or any other framework 37

40 REST based Web Services JAX-RS main annotations Lifecycle and CGI Services uses request scope by default Use Singleton annotation in order to set it to application Injects CJI objects: HttpServletRequest ServletContext 38

41 REST based Web Services Building and publishing public class Hello private HttpServletRequest private ServletContext ctx;. } 39

42 REST based Web Services Session management On server side simply inject HttpServletRequest Use req.getsession(..) in order to Obtain HttpSession instance Embed a session cookie Use session s attributes to hold user session state On client side you need to plant the session cookie on each request To do that we obtain all response cookies Then we place all cookies (including session cookie) on your request via builders 40

43 REST based Web Services Session management Server side Client public class StoreCart private HttpServletRequest req; public void startsession(){ HttpSession session = req.getsession(true); } ClientResponse resp = service.path( somepath").accept( ).get(clientresponse.class); WebResource wr=service.path( someotherpath"); WebResource.Builder builder=wr.getrequestbuilder(); for(cookie c:resp.getcookies()){ builder.cookie(c); } builder.accept( ); get response with session cookie build a request (WebResource) obtain Builder in order to update request load all cookies from response onto builder submit request via builder 41

44 REST Based Web Services Another popular implementation is SpringMVC Same architecture Different controller Similar annotations for REST mapping (not JAX-RS compliant) SpringBoot Allows to rapidly create Spring projects (based on Maven/Gradle) Provides SpringMVC with embedded Tomcat/Jetty configuration 42

45 REST Based Web Services Creating SpringMVC project with SpringBoot Just download Maven/Gradle project & import it to your working IDE 43

46 REST Based Web Services SpringBoot public class SampleController{ public static void main(string[] args) { SpringApplication.run(SampleController.class, args); { { Running this application will Start embedded Tomcat/Jetty Deploy all included services 44

47 REST Based Web Services Creating REST services wit SpringBoot : Main SpringMVC value means URLpatter method - GET/POST produces MediaType consumes @RequestBody 45

48 REST Based Web Services Creating REST services with SpringBoot public class greet/{user} ) public String greet(@pathvariable( user ) String name){ return Hello +name; } public static void main(string[] args) { SpringApplication.run(SampleController.class, args); { { Calling the service: 46

49 REST Based Web Services SpringBoot is very relevant for Microservices Most configuration is transparent Custom configuration: resources\application.properties resources\application.yml resources\bootstrap.yml Can be packed as standalone executable jar Maven install 47

50 Microservices Definition: Microservices is a variant of the service-oriented architecture (SOA) architectural style that structures an application as a collection of loosely coupled services (wiki) 48

51 Microservices Break application into small, fine-grained, standalone services Each services has its contract (interface) its own deployment settings Its own container / server instance(s) For new developments design for service For existing application - decompose 49

52 Microservices Hotels Domain Example: Hotel System & Storage roomav.war RoomAvailabilityService members customers members.war MembershipService payment.war PaymentService 50

53 Microservices Benefits: Each business component maintained separately Business flow based on services may use both internal and external business logic transparently Intensive releases and continuous developments are easier Integration mechanism is a non-issue Service may count on multiple alternative services for failover Service deployment, availability and maintainability can be automated via DevOps tools 51

54 Microservices Drawbacks: Intensive HTTP communication (still text based ) Going stateless? Not always and then what? 2-phase commit is not supported in any microservice so can t be used Higher costs each microservice comes with its infrastructure. When microservices span over different systems or divisions few challenges emerges: Team communication Need in good documentation Testing is hard when more than single service is involved 52

55 Microservices Best practices: Create separate data-store per microservice Provide global data management system Runs in the backgrounds Fixes data inconsistencies Update code by creating a new microservice Combine with version control Use separate builds for each service Run services in containers. Container is NOT a services Keep server configuration plain when administrating microservices Any complex configuration should be set internally by the server 53

56 Microservices Microservice Ecosystem minimal requirements Configuration server Loads the configuration information for all services Usually obtains info from a GIT repository Service discovery Responsible for maintaining a map of all active services Checks heartbeat every few seconds API Gateway Entry façade to the Microservice domain Proxies requests to actual services Circuit breaker Provides cross-service invocation tracking Supports failover executions Monitoring 54

57 55

58 Spring Cloud Written by Rony Keren John Bryce Training Center 56

Introduction provides tools for out-of-the-box Microservice platform solutions Built on Spring-boot & Spring MVC Provides both abstractions & implementations Allows rapidly wrap a

59 Introduction provides tools for out-of-the-box Microservice platform solutions Built on Spring-boot & Spring MVC Provides both abstractions & implementations Allows rapidly wrap a micro-service with all / most important capabilities in order to integrate into Microservice ecosystems Done mostly via annotations Spring Cloud provides Cloud Native application style 57

60 Features Distributed/versioned configuration Service registration and discovery Routing Service-to-service calls Load balancing Circuit Breakers Global locks Leadership election and cluster state Distributed messaging 58

61 Projects Configuration server with GIT Netflix (Eureka, Hystrix, Zuul ) Cloud Bus Cloud Foundry (SSH & oauth2 support) Cloud Cluster (Zookeeper, Redis, Hazelcast, Consul) Cloud Data Flow (data composing) Cloud Stream (external resources Kafka & RabbitMQ) Cloud Zookeeper (service discovery) Cloud Gateway (based on Project Reactor programmatic routing) Load balancing - Ribbon 59

62 Spring Cloud Contexts Bootstrap application context o Is the absolute root context o Is the parent of the main application o Populates and shares environmental information (Environment) Bootstrap properties cannot be overridden by application Holds configuration info Configuration files: bootstrap.properties / bootstrap.yml (instead of application ) o Usually, loads remote configurations from Configuration Server ApplicationContext o Usually a direct sibling of Bootstrap Application Context Use parent() to obtain bootstrap from application context o By default, application configuration is used when not found in bootstrap 60

63 Spring Cloud Contexts Generally, client Microservices use bootstrap.yml / bootstrap.properties o Bootstrap configuration allows getting conf. info from a remote repository o Bootstrap context will help in generating service application context Bootstrap configuration holds local configuration as well o Used in a case where remote configuration is unavailable The process: Client-Microservice configuration-server GIT if config server not available: Client-Microservice local configuration 61

64 Spring Cloud + Netflix Common out-of-the-box solutions: Configuration server Service discovery - Eureka API gateway - Zuul Circuit breaker (load-balancing) Hystrix Monitoring Hystrix oauth2 support Zuul Client-side Load balancing - Ribbon 62

65 Configuration Server Serves externalized configuration in a distributed system Provides server and client-side support Default implementation uses GIT to download configuration info Config Server 63

66 Configuration Server Config Server Maven dependencies: dependency management takes care for the jar dependency chain pom.xml <dependencies> <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-config-server</artifactid> </dependency> </dependencies> <dependencymanagement> <dependencies> <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-dependencies</artifactid> <version>edgware.sr2</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencymanagement> 64

67 Configuration Server public class ConfigServer } public static void main(string[] args) } SpringApplication.run(ConfigServer.class, args); } } spring: cloud: config: server: git : uri: server: port: 9999 service-a.yml service-b.yml gateway-service.yml 9999 Config Server 65

68 Configuration Server Any service that uses Config-server will: Try to get *.yml / *.properties loaded from GIT If fails to connect to the Config-Server, uses its own local configuration service-a.yml service-b.yml gateway-service.yml service-a 9999 Config Server 66

69 Configuration Server Microservices are set to connect to config server or use local configuration 8001/7001 service-a bootstrap.yml spring: application: name: service-a cloud: config: uri: server: host: localhost port: MicroserviceA.java public class MicroserviceA } public static void main(string[] args) } SpringApplication.run(MicroserviceA.class, args); } } service-a.yml (port:8001) 9999 Config Server 67

70 Configuration Server Running multiple Microservice instances Assign zero value to port Configuration server randomizes values 9999 service-b.yml (port: 0 ) Config Server 68

71 Configuration Server Client Microservice Maven devendencies: pom.xml <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-config</artifactid> </dependency> 69

72 Configuration Server Config Server test server configuration: Information is returned in JSON format 70

73 Service Discovery - Eureka Service discovery receives notifications from other services Maintains health & state service-b 8002 service-a.yml (port:8001) service-b.yml (port: 8002) service-a Config Server 2000 Discovery service 71

74 Service Discovery - Eureka Enabling Eureka discovery service in Spring Boot Discovery public class DiscoverServerApplication { public static void main(string[] args) { SpringApplication.run(DiscoverServerApplication.class, args); } } application.yml server: port:

75 Service Discovery - Eureka Eureka clients are o Our Microservices o Eureka client embedded client (requires URL configuration) Discovery server may be configured as: o Instance & Client default Runs continues intensive checks with embedded client o Instance maintains available Microservices client list 2000 Discovery service application.yml eureka: client: registerwitheureka: false fetchregistry: false service-url: defaultzone: server: port: 2000 Configuration: 73

76 Service Discovery - Eureka Discovery server Maven dependencies: pom.xml <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-netflix-eureka-server</artifactid> </dependency> 74

77 Service Discovery - Eureka Microservices register to Discovery service o Configuration (local and/or on GIT): service-a.yml & service-b.yml service-b 8002 service-a Discovery service server: port:. eureka: client: serviceurl: public class MicroserviceA } public static void main(string[] args) } SpringApplication.run(MicroserviceA.class, args); } } is more generic and supported by does the same but is supported only by Eureka 75

78 Service Discovery - Eureka Client Microservice discovery enabling Maven dependencies: pom.xml <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-eureka</artifactid> </dependency> 76

79 Service Discovery - Eureka After starting discovery server we can monitor running services MICROSERVICE-A Admin-PC Microservice-A7001 MICROSERVICE-B Admin-PC Microservice-B:

80 API Gateway - Zuul Spring Cloud provides an Embedded Zuul proxy o Acts as API Gateway 78

81 API Gateway - Zuul Gateway server Zuul Maven dependencies: pom.xml <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-zuul</artifactid> </dependency> <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-eureka</artifactid> </dependency> <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-config</artifactid> </dependency> 79

82 API Gateway - Zuul Spring Cloud provides an Embedded Zuul proxy o Acts as API Gateway 80

83 API Gateway - Zuul When starting Gateway server it: o downloads configuration from Config Server (port 8080) Port (8080) Note: discovery server registration info Zuul uses LOWER-CASE proxy names regardless o Queries Discovery Server for all running services actual application name as specified in bootstrap.yml o Before running Gateway: e.g: service-a is tracked via service-a o After running Gateway services also available on: service-a.yml service-b.yml 81

84 API Gateway - Zuul Zuul uses Ribbon implementation o Ribbon is used for load-balancing when multiple Microservice instances exists o Default load-balance algorithm is Round-Robin Currently, we can run multiple instance but only one will be discovered by Eureka o This is because our instances registers to Eureka with the same instance Id o Eureka keeps track of the last instance and ignores all others. o Later we will solve this issue by assigning different instance Id to Eureka 82

85 Circuit Breaker Hystrix Hystrix implements Circuit breaker DP o Tracks requests o Cancel policy (5 failures in 20 sec.) In cases a running Microservice has slow responses o Failover to another Microservice X to alternative callback X 83

86 Circuit Breaker Hystrix Circuit Breaker is configured on @EnableCircuitBreaker public class MicroserviceA { public static void main(string[] args) } SpringApplication.run(MicroserviceA.class, args); } class public RestTemplate testtemplate(){ return new RestTemplate(); } } Circuit Breaker service-a puts all resource activity on a Ribbon Circuit Breaker works on load balanced resources only (but not vice versa) 84

87 Circuit Breaker Hystrix Client Microservice Hystrix circuit breaker Maven dependencies: pom.xml <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-hystrix</artifactid> </dependency> 85

Circuit Breaker Hystrix Using load-balanced resources: o @HystrixCommand defines failover callback & meta data o URL is resolved by Gateway Server ( /service-b/ ) @Autowired private RestTemplate

88 Circuit Breaker Hystrix Using load-balanced resources: defines failover callback & meta data o URL is resolved by Gateway Server ( /service-b/ private RestTemplate = "fallback", groupkey = srva", commandkey = srva", threadpoolkey = public String method() { String url = " return resttemplate.getforobject(url, String.class); { public String fallback(throwable hystrixcommand) { return "Fall Back Message"; { X Note: Pay attention to the fact that we use a URL without mentioning its host:port Hystrix counts on information taken from Config & Discovery and maintains a valid server-list 86

89 Monitoring Hystrix Dashboard Hystrix commands are gathered Command can be monitored via Hystrix Dashboard In most cases Dashboard is enabled on Gateway Server Denote service to enable Tracks all endpoints in a Microservice o Success, failure, short-circuited, timed-out o Execution time o @SpringBootApplication public class GatewayApplication } public static void main(string[] args) } SpringApplication.run(GatewayAplication.class, args); } } 87

90 Monitoring Hystrix Dashboard Gateway / client Microservice Hystrix dashboard Maven dependencies: pom.xml <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-hystrixdashboard</artifactid> </dependency> 88

91 Monitoring Hystrix Dashboard Logging to Hystrix Dashboard on running service o On Gateway Server : 89

92 Monitoring Hystrix Dashboard In order to monitor all Microservice endpoints specify its location and press Start Monitor o Location ends with /hystrix.stream o (Gateway URL) 90

93 Client Side Load Balancing Spring Cloud Ribbon o Ribbon maintains load-balancing for domain-intra-communication Tracks living instances & ignores failed instances Maintains valid available server list Can be fully configured both programmatically & via configuration files Can be easily wrap any RestTemplate activity done from one Microservice to another Round-robin is used by default Dashboard Load Balancer service-a 8001 service-b 0 91

94 Client Side Load Balancing For load-balancing multiple service-b instances should be running o Random ports by assigning zero value allows multiple instances on the same host o Problem is that Eureka uses <application-name>:<port> as default instance ID These values are the same for every service-b instance: service-b:0 o In order to provide each instance a unique name edit service-b.yml on GIT: service-b.yml server: port:. eureka: instance: instanceid: ${spring.application.name}:${spring.application.instance_id:${random.valu e}} service-b 0 client: serviceurl: defaultzone: 92

95 Client Side Load Balancing Monitoring instances in Eureka: 93

96 Client Side Load Balancing Spring Cloud Ribbon Load Balancer & Hystrix Circuit Breaker o Ribbon is for load balancing o Hystrix is for circuit breaker Gateway & client load balancing uses ribbon Any load balanced call may use circuit breaker as well How this combination behaves? 94

97 Client Side Load Balancing We can already enjoy load-balancing by denoting resttemplate A much cleaner & rapid way is to use Feign Clients which load-balance natively declarative rest client generation Generates RestTemplate based implementation Wraps RestTemplate with client load-balancing ribbon Uses URL or logical (proxy) names as base client URL o Feign Clients can be reused by different Microservices o Note: Zuul already uses ribbon. in addition to ribbon-load-balancer for adding Circuit-breaking capabilities 95

98 Client Side Load Balancing Client Microservice Ribbon Feign Starter Maven dependencies: pom.xml <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-feign</artifactid> </dependency> 96

Client Side Load Balancing Spring Cloud Ribbon @FeignClient(name="service-B") public interface ServiceBFeignClient { @GetMapping("/some/url") String method(); } @RestController public class

99 Client Side Load Balancing Spring Cloud public interface ServiceBFeignClient String method(); public class private ServiceBFeignClient client; } When calling microservice-b calls ( are public String callserviceb(){ return public class MicroserviceA{ 97

100 Client Side Load Balancing Ribbon can be totally configured by creating RibbonConfigurations What can be set? Bean Type Bean Name Class Name IClientConfig ribbonclientconfig DefaultClientConfigImpl IRule ribbonrule ZoneAvoidanceRule IPing ribbonping DummyPing ServerList<Server> ribbonserverlist ConfigurationBasedServerList ServerListFilter<Server> ribbonserverlistfilter ZonePreferenceServerListFilter ILoadBalancer ribbonloadbalancer ZoneAwareLoadBalancer ServerListUpdater ribbonserverlistupdater PollingServerListUpdater 98

101 Client Side Load Balancing Creating Ribbon protected static class FooConfiguration public ZonePreferenceServerListFilter serverlistfilter() { ZonePreferenceServerListFilter filter = new ZonePreferenceServerListFilter(); filter.setzone(."); return filter; } public IPing ribbonping() { return new CustomPingUrl(); } 99

102 Spring Cloud Microservice Ecosystem 100

103 101

Java - Web-Services and REST

Java - Web-Services and REST Rony Keren rkeren@johnbryce.co.il Topics Definition Architecture SPA Single Page Applications RPC Remote Procedure Call REST Based Web Services HTTP based RPC JAX-RS Jersey