Web Services at IRIS DMC

Joanna Muench

Linus Kamb

Outline

Web service development process at DMC

Demos SOSA seismogram processing UPDS product handling DHI database access

Developing a web service

Interface creation with a wsdl Code generation Building the backend Client side development Deployment Testing and logging Reports from the field

Creating an interface WSDL (web service definition

language) is public interface to service

Best practice - define wsdl first Avoids language specific

constructs Guarantees* interface intent

But - complicated, easy to make mistakes

<?xml version="1.0" encoding="UTF-8"?><wsdl:definitions name="dhi_webservice" targetNamespace="http://dhiWS.dmc.iris.edu/wsdl" xmlns:mime="http://schemas.xmlsoap.org/wsdl/mime/" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:tns="http://dhiWS.dmc.iris.edu/wsdl" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsd1="http://dhiWS.dmc.iris.edu/types"> <wsdl:documentation xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/">Created using

Cape Clear Studio SOA Editor> <wsdl:types> <xsd:schema targetNamespace="http://dhiWS.dmc.iris.edu/types" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsd1="http://dhiWS.dmc.iris.edu/types"> <xsd:import namespace="http://schemas.xmlsoap.org/wsdl/"/> <xsd:import namespace="http://schemas.xmlsoap.org/soap/encoding/"/> <xsd:element name="TimeSpan"> <xsd:annotation> <xsd:documentation>Defines a time span with start and end

times.</xsd:documentation> </xsd:annotation> <xsd:complexType> <xsd:sequence> <xsd:element maxOccurs="1" minOccurs="1" name="startTime"

type="xsd:dateTime"/> <xsd:element maxOccurs="1" minOccurs="1" name="endTime"

type="xsd:dateTime"/> </xsd:sequence> </xsd:complexType> </xsd:element>

Tools for WSDL creation Cape Clear SOA Editor

Graphic interface WSDL validator Great manual (and free!)

Other editors: Altova XMLSpy Sonic Software or, XML Editor + WSDL

validator

Code generation Tools that translate wsdl into a web service

engine in your favorite language Provide stubs and bindings, making server

and/or client generation easier Available in many languages

Java: Axis, GLUE, JibxSOAP Perl: SOAPLite C#: .NET C++: gSOAP, Axis

Building the backend Implement desired functionality

Various architectures possible Maintain flexibility through interfaces

Test Fill in stub methods in generated code,

calling your implementation You’re ready to deploy!

Building the client Deployment is more

interesting with a client Client skeleton can be

generated from wsdl Could be command line

driven, web application or full application

Common practice to have a client internal to server project, for testing new ideas

Server Deployment Most web service development environments

have deployment tools Automation is essential - useful tools like ant Three levels of deployment

Environment Function Updated

Local Development Every 5 min

Test Load test, etc. Daily (or less)

Production Public service New release only

Testing and logging Testing at all levels

Unit tests in dev Functional tests Performance tests

Automate and run frequently

Logging Debugging Performance

monitoring Usage monitoring

Reports from the Field

Can be easy but… Setting up deployment, classpaths, etc

can be tricky Tools aren’t foolproof (at least not the free

ones) Attachment specification still vague

IRIS DMC web services

SeismoProcess - component of SOSA (Synthetic and Observed Seismogram Analysis)

UPDS (Uniform Product Distribution Service) revolves around web service

DHI (Data Handling Interface) web service

SeismoProcess Service Provides additional processing capabilities for

SOSA, a Java GUI application Part of SCEC CME

Motivation: Update and expand processing capabilities without

re-installing application Prototype for possible more general seismogram

processing service Released as part of SOSA 1.0, but not yet

running on production server

SeismoProcess Service

SeismoProcess Service

Implementation details Attachment style SOAP with Attachments

(SwA) Seismograms sent as SAC files

Issues Attachment configuration Performance

UPDS - Motivation

Uniform Product Distribution System Submit, archive, query, and access Handles XML “Data Products” Many different types of products Unknown future products Extensible products, product list

UPDS - Design

Submission service Query/Access service Unstructured XML Application and Web interfaces Flexible interfaces

UPDS - Overview

DATAPRODUCT

PRODUCER

PRODUCTARCHIVE

SUBMISSIONWEB SERVICE

ProductHandlerModule

ProductHandlerModule

ProductHandlerModule

ProductHandlerModules

<XML><PRODUCT></XML>

SUBMIT CLIENT

WebAccess

QUERY / ACCESSWEB SERVICES

CLIENTPROGRAM

UPDS - Overview

DATAPRODUCT

PRODUCER

PRODUCTARCHIVE

SUBMISSIONWEB SERVICE

ProductHandlerModule

ProductHandlerModule

ProductHandlerModule

ProductHandlerModules

<XML><PRODUCT></XML>

WebAccess

QUERY / ACCESSWEB SERVICES

CLIENTPROGRAM

SERVLET

Q/A WEB SERVICES

Q/A LIB

Q/A LIB

UPDS - Issues

“Pure” XML vs binary products Large products

“Pure” WS vs multi-protocol approach Large result sets Attachment handling Performance

DHI web service Web service to CORBA-based DHI SCEC CME in conjunction with USArray Provides subset of full DHI capabilities Motivation:

Language agnostic service Available over port 80 Provide most commonly accessed DHI functions,

simplified data types Not yet beta release

DHI web service

DHI web service

Implementation details Attachment style Seismograms sent as mSeed, SAC or link to

URL for download Issues

Attachment configuration problems in Axis Performance of underlying CORBA service

Recap

Can be easy but… hard to do right Setting up deployment, etc can be tricky Tools aren’t foolproof (at least not the free

ones) Attachment specifications still vague