Web Services: An Introduction Al Kassam Briyante Software Corp

What is a web service? Many Definitions Many Definitions At a minimum, a Web Service is a piece of self- contained software that works over the Internet and uses a standardized XML-based messaging system At a minimum, a Web Service is a piece of self- contained software that works over the Internet and uses a standardized XML-based messaging system In simpler terms, it’s a program (which exists on an unrelated computer on the Internet) which can be run there on demand by a program on your computer In simpler terms, it’s a program (which exists on an unrelated computer on the Internet) which can be run there on demand by a program on your computer

How does it work? Web Service Client Application Application Server Internet In its most basic form, it is a Web-based Remote Procedure Call (RPC) mechanism. In its most basic form, it is a Web-based Remote Procedure Call (RPC) mechanism. XML is used to encode all communications XML is used to encode all communications XML-RPC and Simple Object Access Protocol (SOAP) are currently the most common protocols in use for conducting the RPC XML-RPC and Simple Object Access Protocol (SOAP) are currently the most common protocols in use for conducting the RPC

Web Services interaction GetTemperature( “92010” )GetTemperature( “90210” ) Return( “65” ) Process returned Value Client ApplicationApplication Server

What’s good about WS ? Shares many similarities with existing web based interaction (http/s, firewalls, etc) Shares many similarities with existing web based interaction (http/s, firewalls, etc) Clients and servers can be created using unrelated technologies Clients and servers can be created using unrelated technologies Supports all web site security models (http/s, certificates, LDAP etc.) Supports all web site security models (http/s, certificates, LDAP etc.) Offers additional security features beyond that of web sites (WS Security). Offers additional security features beyond that of web sites (WS Security).

Pitfalls Massively distributed, therefore no standards for error management Massively distributed, therefore no standards for error management Far greater need for security Far greater need for security Response time cannot be guaranteed Response time cannot be guaranteed

Two aspects to Web Services Use Web Services that others have created (consumption) Use Web Services that others have created (consumption) Create your own Web Services for others to use (publishing) Create your own Web Services for others to use (publishing)

Consuming Web Services Universal Description, Discovery and Integration (UDDI) registries are used to catalogue available Web Services Universal Description, Discovery and Integration (UDDI) registries are used to catalogue available Web Services Use an XML-RPC or SOAP toolkit for your platform and your preferred programming language Use an XML-RPC or SOAP toolkit for your platform and your preferred programming language Build your application logic around data retrieved from many different organizations through their published Web Services Build your application logic around data retrieved from many different organizations through their published Web Services

Publishing Web Services Create your Web Service using your preferred programming language and either the XML-RPC or SOAP toolkit for your platform Create your Web Service using your preferred programming language and either the XML-RPC or SOAP toolkit for your platform Use the Web Service Description Language (WSDL) to describe your Web Service to other software systems Use the Web Service Description Language (WSDL) to describe your Web Service to other software systems Allow others to discover your Web Service by publishing to a UDDI server Allow others to discover your Web Service by publishing to a UDDI server

How do they help me? Provide access to a wider range of information and services than a web site. Provide access to a wider range of information and services than a web site. No need to copy data locally as it is always available across the internet. No need to copy data locally as it is always available across the internet. Software systems can reap the same benefits as web client users. Software systems can reap the same benefits as web client users. Facilitates electronic collaboration between (disparate) systems. Facilitates electronic collaboration between (disparate) systems.

How does this help Justice? Existing agencies already form the hubs for justice related information. Large amounts of useful information already exist, but in disparate systems.

Where can an officer look for information? Existing systems provide access to information stored locally within an agency.

Some agencies offer information services via a web portal of some kind. Some agencies offer information services via a web portal of some kind.

Web Services can help create a new “face” for an agency Web Services can help create a new “face” for an agency

Web Services in Justice An ideal platform for data sharing without the need to gather data in one place An ideal platform for data sharing without the need to gather data in one place Information obtained from multiple agencies can be presented in a unified view Information obtained from multiple agencies can be presented in a unified view Elegantly solves integration of disparate island of data throughout Justice Elegantly solves integration of disparate island of data throughout Justice Can be real time Can be real time Available 24 hours a day Available 24 hours a day

Dig Deeper MS Web Services Enhancements 1.0/2.0 provides for much broader use of Web Services (WS-Security, WS-Addressing, etc) MS Web Services Enhancements 1.0/2.0 provides for much broader use of Web Services (WS-Security, WS-Addressing, etc) “Web Services Essentials”, Ethan Cerami “Web Services Essentials”, Ethan Cerami