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2. What is a Web Service?
A web service is a software application identified by a URI, whose interface and bindings are capable of being identified, described and discovered by XML artifacts and supports direct interactions with other software application using XML based messages via Internet-based protocols. (World Wide Web Consortium)
3. Intent of Web Services
A language and platform independent method to implement Service Oriented Architecture (SOA) using standard internet technologies For application-to-application communication Has little to do with HTML Not limited to someone adding a hook into their web site. A web service can live anywhere on the network (Inter or Intra). Entities choose to use web services for ease of implementation, conciseness of the standard, and low cost
4. Examples of Web Services
Southwest Airlines accesses Budget Rent-a-Car to make car reservations after making airline reservations Amazon allows other companies to search and purchase items via Web Services. If you are a nutritionist you can purchase nutrition books from Amazon without leaving your nutrition web site There are stock-quote services, traffic-report services, and a weather services available Ideal for any Service Oriented Architecture (SOA) deployment
5. What makes up a Web Service
All components are based on theXMLstandard SOAP:Simple Object Access Protocol WSDL:Web Service Description Language UDDI:Universal Description, Discovery, Integration
SOAP is the service messaging layer of a web service. The messages are XML based. The protocol consists of three parts: An envelope that defines a framework for describing what is in a message and how to process it A set of encoding rules for expressing instances of application-defined datatypes A convention for representing remote procedure calls and responses A transport or protocol binding
A WSDL is an XML document that describes the functional characteristics of the services offered. The operations the service has available The messages the service will accept The protocol of the service
8. Where Web Services exist in the Standards World
WSDL Definition Specifications Web Services Architecture and Interoperability (WS-I) Profiles Introduced in 2000, and gaining momentum. Many companies are in 2 ndand 3 rdgeneration deployments De-facto Standard for SOA over XML Anyone who needs interoperability between applications Software and Hardware industry giants such as IBM, Sun, Dell, Microsoft, Intel are behind the standard
9. Why Web Services for ESNet?
Can be done in a faster and cheaper manner WSDL gives widely recognized definition language to define the service messages between the GWs and the CSCEs Platform and Technology neutral Insulates TF-34 from the intricate underlying details of defining a protocol Ease of adding new services ComCARE messages are being defined as web services NENA 4 Generation 1 has already developed schemas for the ALI Type Lib. The schemas are 2 weeks away from final approval http://www.nena.org/xml%5Fschemas/Current%20Release/Version%204.X.X.list.html
Leverage existing technologies such Clustering and Load Balancing to transparently manage reliability Techniques have been established to ensure that the messages get to their endpoints Heartbeat mechanism can still be implemented
Security concerns are the same as connection oriented architecture Web Service over HTTP or HTTPS can be as secure as any website SSL, Basic Auth, NTLM, Passport, custom Relies on security capabilities of the transport layer Security best practices are being recommended. People who specialize have put an a great amount of effort in developing the best practices documents.
12. Pros and Cons of Web services for ESNet
Faster definition and deployment. Reduced deployment cost for PSAPs, service providers, and ESMI intergrades Ease of implementation with off the shelf technologies Can use Microsofts .NET or Javas J2EE (IBM Web Spear, BEA Web Logic, etc.) Leverage Application Server Technology Leverage Load Balancer Technology A number of runtime management and support tools available A number of production/development tools available (many more than SIP). In the .NET development environment, development of web services is completely wizard driven Allows for extensibility in protocol Allows for a more scalable architecture Seamless fail-over with the use of Load Balancers and Clustering- Connections are acquiesced on every call to a service Leverage existing NENA XML schemas Ease of integration of ComCARE work Allows for easy market entryfor new data service providers Affords PSAPs highest degree of flexibility for adding new services Supports distributed Service Registry's which dynamically show which services are available for use
13. Pros and Cons of Web services for ESNet (Continued)
SOA supports the creation ofSecurity Services which incorporates authentication, certification, andencryption through std.PKI and other security practices Supports 'Virtual Security Gateways' which model a physical security gateway, but are more flexible to extend, consolidate, and upgrade Each endpoint can be both a 'Client' and a 'Server' - this allows PSAPs to not only ask for information, but to also provide information easily Web-Services can be added as extensions to existing hub-and-spoke system design toenable service-enabled applications to interoperate Connectionless model only connects when datais needed - allows for messaging efficiency Overall message overhead is reduced Presence services can be implemented to ensure the application is available when needed (Heartbeats can still be implemented) Web-based connectionsare fast - since these areno different thanany otherIP-based connection (on the order of milliseconds) The web services standards may evolve Overhead in initiating a connection Matching requirements - individual customer requirements are possible but need to be carefully managed among all customers Availability - no architecture is perfect - many of the same dedicated 'guaranteed' data delivery infrastructure can be leveraged to assure increased availability in a Web-Services model
14. Pros and Cons of Hub and Spoke/Connection Oriented Architecture
Few connection establishments means less overhead Software exception is thrown if there is a problem with a TCP/IP socket Hub-and-spoke Enterprise Integration Architecture(EAI) is the most popular of traditional EAI models - been around for a while Hub-and-spoke EAI's provide physical congestion control points to the PSAPs Hub-and-spoke EAI's provide physical congestion control points to the PSAPs Affords CESE client a certain amount of autonomy by virtue of RG hiding rem