Web Services

"Web Services" is the name that has been given to the concept of exposing core functionality of a specific web application, website or web page for the purpose of allowing that service to be packaged up and utilized by other web services, web applications, websites or web pages either by making requests and pulling down data, or running entire interfaces from the site within their own interface.

The reputation of the Web Services term being used more in an enterprise setting than in a small business or startup setting (which favors the simple yet overloaded term "API"), has earned Web Services the title of: "the business side of APIs"

What are Web Services?

Web Services are:

   * Small units of code
   * Designed to handle a limited set of tasks or functionality
   * Programs which use XML based communicating protocols (or JSON, which has become more common for the average simplistic/consumer API)
   * Independent of Operating Systems
   * Independent of Programming Languages
   * Connect people, systems and devices through Endpoints
   * May use a description language such as WSDL, WADL or OpenAPI (Swagger) to describe their functionality

Benefits of Web Services

   * Easier to communicate between applications
   * Easier to reuse existing services
   * Easier to distribute information to more consumers
   * Rapid development

Web services make it easier to communicate between different applications. They also make it possible for developers to reuse existing web services instead of writing new ones.

Web services can create new possibilities for many businesses because it provides an easy way to distribute information to a large number of consumers. One example could be flight schedules and ticket reservation systems.

Use a web development platform that will help you save a lot of time and bring excitement to your daily development work. It will also create professional best-practices around your code development and team collaboration.

Approaches

Web Services typically make use of either WSDL or SOAP protocols for exposing their functionality, but may also alternatively rely on one of the following standard web protocols as well HTTP, REST, DIG, XML, and UDDI.

Monolith

Monolithic architectures are tightly-coupled applications or services where all code (front-end & back-end, APIs, SDKs, integration/glue code, custom business logic, etc) lives in a single project and repository, deployed to a single Web Server and/or Container which needs to be "scaled horizontally" when usage begins to outpace throughput/capacity.

See section: Architecture

SOA

Service-Oriented Architecture (SOA) begins the move away from Monoliths by breaking up logically related parts of the monolith into individual applications/systems deployed separately as Web Services which expose some or all of their functionality via APIs. There is a potential (when each separate Web Service and the integrations between them are architected correctly) to realize "loose coupling" using SOA.

See section: SOA

Microservices

Microservices takes the SOA approach to the next level of granularity where complex applications are decomposed into the smallest possible, independent processes, communicating with each other using language-agnostic APIs. These services are specialized, "highly decoupled", with each focused on doing a small task at a time, rather than many complex background operations, calls, or evaluations.

Any good Microservices architecture should have:

1. services which are easy to replace
2. services which are highly modularized (small set of functionality per service)
3. services must then be organized around their capabilities (similar services are grouped together in API structure)
4. lend itself to a Continuous Delivery software development process
5. is distinct from SOA in that the latter aims at integrating various (Business) applications, whereas several Microservices belong to one domain/application

• wikipedia: Microservices
• Martin Fowler - Microservices: https://martinfowler.com/articles/microservices.html
• The 12-Factor App: https://12factor.net/ (design patterns for Microservices)
• Microservices Architecture Design Pattern: http://microservices.io/patterns/microservices.html (links to examples of usage at large companies and real demos)
• Microservices explained: http://martinfowler.com/articles/microservices.html (first major article on Microservices, and the most-quoted)
• What Are Microservices and Why Are They Important: http://www.brunton-spall.co.uk/post/2014/05/21/what-is-a-microservice-and-why-does-it-matter/
• Apache Camel for Micro­service Architectures: http://java.dzone.com/articles/apache-camel-micro%C2%ADservice
• Microsoft Azure - Service Fabric: http://azure.microsoft.com/en-us/services/service-fabric
• Mulesoft’s “guide to Contiuous Innovation” via Microservices best practices: https://www.mulesoft.com/sites/default/files/resource-assets/MuleSoft%20%20-%20Best%20Practices%20for%20Microservices.pdf
• Micro­service Websites -- Building consumer-facing websites with multiple teams: https://gustafnk.github.io/microservice-websites/

CQRS

Command Query Responsibility Segregation (CQRS) is an architectural pattern for overcoming Microservice and Database separation to enable joining disparate data from several data sources.

• Pattern -- Command Query Responsibility Segregation (CQRS): http://microservices.io/patterns/data/cqrs.html
• Concepts of CQRS: https://dzone.com/articles/concepts-of-cqrs

Saga pattern

• Three Important Patterns for Building Microservices: https://dzone.com/articles/3-most-important-patterns-for-building-microservic

ServiceMesh

• Do I Need an API Gateway if I Use a Service Mesh?: https://blog.christianposta.com/microservices/do-i-need-an-api-gateway-if-i-have-a-service-mesh/

Istio

• Istio: https://istio.io/ | SRC
• OpenShift E-Learning -- Service Mesh (Istio-specific courses): https://learn.openshift.com/servicemesh/

WS-*

WS-* is a prefix used to indicate specifications associated with Web Services and there exist many WS-* standards including:

1. WS-Addressing
2. WS-Discovery
3. WS-Federation
4. WS-Policy
5. WS-Security
6. WS-Trust.

• wikipedia: WS-*
• PHP XML Signature: https://www.phpclasses.org/package/11426-PHP-Parse-and-create-XML-documents-signed-digitally.html (Parse and create XML documents signed digitally)

WSSE

Number 5 in the list above, Web Service Security (WSSE) is one of the fundamental technologies of WS-* that offer greater levels of authentication and authorization capabilities than regular HTTP/S used by REST.

Vendors

Apache

CXF

• Apache CXF: http://cxf.apache.org
• Java Web services -- Introducing CXF: http://www.ibm.com/developerworks/java/library/j-jws12.html

Axis

• Axis2: http://ws.apache.org/axis2

Sun

Sun's Java has been a leading purveyor of Web Services development and real-world business cases.

IBM

IBM targets small and mid-sized Enterprises with their Managed Web Services platforms.  In addition, IBM has launched a new project under the
AlphaWorks program for making Web Services much easier and more accessible to the average developer. 

• OpenLibery: https://openliberty.io/ (IBM's OSS Microservices project)

Oracle

Oracle allows Web Services to interface with their database technology, and even permits the customized creation of unique Web Services from within
the Database Adminstration console. 

Microsoft

Farbeit for Microsoft to miss out on the action, and they also have their own sweet of .NET Web Service solutions.

Google

Google has been a leader in creating unique Web Services of their own, which could then be used by developers, however of these efforts few have been
truly open in nature, though the company ironically enjoys an ora of openness, thanks mainly to its great comminucation streams with developers and
projects like "Google Summer of Code" where Google hires several hundred student developers over the summer to work on various open source projects.
Their latest announcement for the Google AppEngine is another major initiative towards empowering smaller, independent software developers through
free and low-cost alternatives for application hosting, plus access to the Google distributed computing cloud..

Yahoo!

Yahoo! has recently stated that it would take an Open approach and strategy for all future Web Services, at is at the same time attempting to open up its existing Web services. This was the strategy for 2006-2011, unfortunately after that period the focus shifted to monetization and those Yahoo! Web Services not making substantial profits/returns were discontinued or deprecated over the next few years. The only remaining substantial services were the [ Yahoo! Weather], [ Yahoo! Finance (Stock Quotes)], [ Yahoo! News] and [ YQL] service. Many considered this the most logical way for Yahoo! to avoid a hostile takeover by Microsoft, but ironically enough (or perhaps predictably) their attempt to bring in "big-money enterprise monetization-minded" executives ended up resulting in further Yahoo! property sell-offs, firings, layoffs, service discontinuations and an eventual sale to Verizon and re-branding of Yahoo! to Altaba.

Service Directories

• Backstage (Web Service catalog): https://backstage.io/ | SRC | DOCS
• WebServiceX: http://www.webservicex.net/ | CurrencyWS | Stocks | ValidateCreditCard | GeoIP
• XMethods: https://web.archive.org/web/20070217165335/http://www.xmethods.net/ (full list)
• CDYNE: http://cdyne.com/ | PhoneNumberVerification | Phone-Notify | SMS-Notify | IP2GEO
• Informatica -- Data-as-a-Service: https://www.informatica.com/products/data-quality/data-as-a-service/free-trials.html (formerly StrikeIron WebServices) | AddressVerification | Sales Tax Calculation | Do Not Call List Verification
• seekda: http://webservices.seekda.com/ (was once the world's largest XML-RPC & SOAP Web Services search engine, now defunct)

EXAMPLES

• REDDIT - Experimental API - Add ID parameter to "info" API call: http://code.reddit.com/ticket/154
• Reddit’s Secret API: http://blog.programmableweb.com/2008/11/25/reddits-secret-api/

NDFD

• NDFD - WSDL: http://www.weather.gov/forecasts/xml/DWMLgen/wsdl/ndfdXML.wsdl | http://www.weather.gov/forecasts/xml/SOAP_server/ndfdXMLserver.php
• NDFD - SOAP request builder: http://www.weather.gov/forecasts/xml/SOAP_server/ndfdXML.htm
• More Examples with Parsing NDFD Data in PHP: http://phpstarter.net/2009/03/more-examples-with-parsing-ndfd-data-in-php/

Other

• WebServiceX - Stock Lookup: http://www.webservicex.net/stockquote.asmx | EXAMPLE - Apple stock price
• WebServiceX - Currency Convertor: http://www.webservicex.net/CurrencyConvertor.asmx | EXAMPLE - Canadian to American exchange rate

auth-token=jcCZ66ljo2gWPgOjuX3M7TubmV+hzWWs2cGEYSZM4t06CJWVGZf2DqzlYAjjjxNmKrVv74XiTILVNkYOZ5YlhA== EXAMPLE]

• SmartyStreets (formerly QualifiedAddress) - LiveAddress validation API: http://smartystreets.com/products/liveaddress-api | [https://api.qualifiedaddress.com/street-address/?street=1600+Amphitheatre+Parkway&city=Mountain+View&state=CA&zipcode=94043&candidates=5&
• USPS ZipCode Lookup/Validation: EXAMPLE
• Movie Information: http://www.ignyte.com/webservices/ignyte.whatsshowing.webservice/moviefunctions.asmx
• Lottery Feed: http://www.lotteryfeed.com/xml_formats.html
• Chicago Transit Authority (CTA) -- Bus Tracker APIs: https://www.transitchicago.com/developers/bustracker/ | DOCS
• Affirmations API: https://www.affirmations.dev/
• They Said So - Quotes API: https://quotes.rest/ (OpenAPI 3.x)
• I can haz "Dad Jokes" API: https://icanhazdadjoke.com/api
• Chuck Norris jokes API: https://api.chucknorris.io/
• Star Wars API: https://swapi.dev/
• LOTR - "The One ring" API: https://the-one-api.dev/
• PokeAPI: https://pokeapi.co/ | - Pokedex (Pokemon characters/data)
• REST countries: https://restcountries.eu/
• RandomUser API: https://randomuser.me/documentation | EXAMPLE - fields to include | EXAMPLE - limit results | EXAMPLE-set field constraints
• Simpsons quotes API: https://thesimpsonsquoteapi.glitch.me/quotes

Resources

• Web Services Architecture Usage Scenarios: https://www.w3.org/TR/ws-arch-scenarios/
• Useful Lesser Known Websites & Web Services: https://www.pinterest.ca/pin/68726038084/
• Free-Web-Services: http://free-web-services.com/ (directory of both REST & SOAP web services to add to your website or application)
• PHP Web services: SOAP, REST, WS-*, SOA and WOA with PHP.: http://phpwebservices.blogspot.com/2008/12/rest-vs-soap.html
• SOAP and REST Protocols for CALAIS - Source Code Examples: http://www.opencalais.com/taxonomy/term/44
• WSO2 Tools: http://wso2.org/tools
• Transforming SOAP-Messages with XSLT: http://blog.jdevelop.eu/?p=74
• ZooKeeper for Microservice Registration and Discovery: http://dzone.com/articles/connect-the-unconnected-how-to-succeed-at-digital
• GCP -- Microservices demo: https://github.com/GoogleCloudPlatform/microservices-demo (for an Online Boutique shop with Ads, Recommendations, Email, Shopping Cart, Shipping Calculator, Currency Converter, Payment facilitation, Checkout)

Tutorials

• Web Services - REST .vs. SOAP: https://blogs.oracle.com/milan/entry/web_services_rest_vs_soap
• JAVA -- Working with Web Services in JAX-WS (SOAP) and JAX-RS (REST): http://docs.oracle.com/javaee/6/tutorial/doc/bnayk.html
• JAX-RS .vs. Spring for REST Endpoints: https://dzone.com/articles/lets-compare-jax-rs-vs-spring-for-rest-endpoints
• NetBeans - Web Services Learning Trail: http://netbeans.org/kb/trails/web.html
• Three Minutes to a Web Service -- Write a Web service in 15 lines of code with JAX-RPC: http://www.artima.com/lejava/articles/threeminutes.html
• Java Web Services Tutorial: http://java.sun.com/blueprints/webservices/using/webservbp.html
• Service layer and DAO architecture: http://biese.wordpress.com/2007/10/08/service-layer-and-dao-architecture/
• Getting Started with JAX-WS Web Services (in NetBeans): http://netbeans.org/kb/docs/websvc/jax-ws.html?intcmp=925655
• Creating a JAX-WS Web Service and Clients with EJB 3.1 Singleton Bean (JAVA): http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/EJBSingletonWebServices/SingletonWebServices.html
• Customising JAX-WS prefix of a SOAP response: https://stackoverflow.com/questions/12889943/customising-jax-ws-prefix-of-a-soap-response

• What’s package-info.java for?: https://www.intertech.com/Blog/whats-package-info-java-for/

• Web Service Interoperability (consume a .NET Web Service in Java): http://www.dzone.com/links/r/web_service_interoperability_2.html
• Parse Weather Forecast Data (from the NOAA's NDFD web service) in PHP: http://phpstarter.net/2009/02/parse-weather-forecast-data-from-the-ndfd-in-php/
• Reading Security Header in JAX-WS web service: https://forums.oracle.com/thread/2337032?tstart=15
• Why REST + JSON is preferred over SOAP for mobile web services: http://www.bamboorocketapps.com/rest-json-vs-soap-xml/
• SOAP Web Service Security Example: http://www.mulesoft.org/documentation/display/current/SOAP+Web+Service+Security+Example
• Using Message Security with Java WSDP: http://docs.oracle.com/cd/E17802_01/webservices/webservices/docs/2.0/tutorial/doc/Security-WebSvcs7.html
• Application Authentication with JAX-WS: http://www.mkyong.com/webservices/jax-ws/application-authentication-with-jax-ws/
• Web services using Apache Axis2 - How to build, invoke, reverse-engineer a Web Service using Apache Axis2: http://www.ibm.com/developerworks/webservices/library/ws-apacheaxis/section2.html
• Developing a web service (in J2EE) and consuming it with J2ME Client: http://www.ibm.com/developerworks/webservices/library/ws-devwsconsum/section3.html
• Understanding SOAP and REST Basics: http://blog.smartbear.com/apis/understanding-soap-and-rest-basics/
• Microservices with Spring: http://dzone.com/articles/microservices-with-spring

• Create microservices with .NET and ASP.NET Core: https://docs.microsoft.com/en-us/learn/paths/create-microservices-with-dotnet/
• Securing Microservices - The API gateway, authentication and authorization: https://sdtimes.com/apis/securing-microservices-the-api-gateway-authentication-and-authorization/
• GraphQL is (rather "could become") the New API Gateway: https://levelup.gitconnected.com/graphql-is-the-new-api-gateway-383edeed4bcd

External Links

• Apache CXF vs. Apache AXIS vs. Spring WS: http://architects.dzone.com/articles/apache-cxf-vs-apache-axis-vs
• W3C Talk on SOAP .vs. REST Web Services: http://www.w3.org/2005/Talks/1115-hh-k-ecows/
• SOAP and REST a Perspective (video): http://channel9.msdn.com/posts/rojacobs/endpointtv-SOAP-and-REST-a-Perspective/
• Compare RESTful vs SOAP Web Services: http://java.dzone.com/articles/compare-restful-vs-soap-web
• How To Make Your Web Service More Developer Friendly: http://blog.programmableweb.com/2009/01/13/how-to-make-your-web-service-more-developer-friendly/
• Making Your Webservice More Developer Friendly: http://www.callingshotgun.net/geekery/making-your-webservice-more-developer-friendly/
• Google AppEngine: http://code.google.com/appengine/
• February 07, 2007Screencast #WS1: Web services development using NetBeans IDE and GlassFish: http://blogs.sun.com/arungupta/entry/screencast_ws1_web_services_development
• Web Services are Not Slow: http://wso2.org/library/588
• How to call a web service from a browser: http://devdaily.com/blog/post/java/how-to-call-web-service-from-browser/
• Netbeans - Introduction to Web Services: http://netbeans.org/kb/docs/websvc/intro-ws.html
• Web Services discussion worth watching: http://www.advogato.org/article/464.html
• Web Service performance benchmarks (REST is in, SOAP is out... but JSON not great for large datasets): http://www.jamesward.com/census/
• XML Binding Frameworks in the Context of Service-Oriented Architecture: http://soa.sys-con.com/node/114130
• DEMO on a SOAP and REST Client with PHP: http://www.dimuthu.org/blog/2008/10/17/demo-on-a-soap-and-rest-client-with-php/
• NetBeans to Generate Simpler RESTful Web Services: http://netbeans.dzone.com/nb-generate-simpler-rest
• Three steps toward the glory of REST: http://martinfowler.com/articles/richardsonMaturityModel.html
• RESTful Web Services (in Java): http://www.oracle.com/technetwork/articles/javase/index-137171.html
• Richardson Maturity Model for RESTful Web Services: http://martinfowler.com/articles/richardsonMaturityModel.html
• How we ended up with microservices (at SoundCloud): http://philcalcado.com/2015/09/08/how_we_ended_up_with_microservices.html
• Building Microservices -- Inter-Process Communication in a Microservices Architecture: http://dzone.com/articles/building-microservices-inter-process-communication-1
• Introducing frock - Easy fake services for a Microservices environment: http://www.urbanairship.com/blog/introducing-frock-easy-fake-services-for-a-microservices-environment
• Service Delivery Review -- The Missing DevOps Feedback Loop?: https://www.infoq.com/articles/service-delivery-review-missing-devops-feedback-loop
• Introduction to Service Oriented Architectures, SOAP/WSDL Web Services and RESTful Web Services: https://www.slideshare.net/ecosio/presentation-slideshare-34325282
• Applying MVC Pattern to Web Services: http://navveenbalani.com/index.php/articles/applying-mvc-pattern-to-web-services/
• We went Monorepo (even with Microservices): https://medium.com/invisible-reports/report-we-went-monorepo-c0aadd144fb
• What is a "Service" banner?: https://blog.shodan.io/what-is-a-banner/
• Microservice Architecture and its 10 Most Important Design Patterns: https://towardsdatascience.com/microservice-architecture-and-its-10-most-important-design-patterns-824952d7fa41

References

See Also

EAI | API | REST | SOAP | WebApp | DesktopApp