I just created a Fedora Issue for this: Improve REST API responses https://jira.duraspace.org/browse/FCREPO-764
-- Scott Asger Askov Blekinge wrote: > +1 Seconded. The Rest api functions are well thought out, but the stuff > sent to the user is generated by appending strings, and error handling > is not to easy, if you do not use Java. > > > > On Wed, 2010-08-11 at 02:55 +0200, Scott Prater wrote: >> Below are some comments from one of my developer colleagues, who knows >> almost nothing about Fedora, but is working on an application to ingest >> objects. >> >> Perhaps the REST API error handling and responses could be improved in >> future releases? I could open a ticket for it, if others think it would >> be useful, too. >> >> -- Scott >> >> ################################################################### >> An Outsider's Notes on Working w/ the Fedora REST API >> >> In general: bravo >> >> The API is generally intuitive and makes it clear and easy how to >> interact with Fedora. I can create objects, datastreams, relationships >> as needed. I got up and running with it right away. >> >> The biggest sign that it is well-designed is that I was able to wire up >> a REST client library to it written by someone else (and in another >> programming language) and it worked as expected from that library's >> understanding of how a REST client should interact w/ a REST API. >> >> Where it needs improvement is in the area of API response messages, >> specifically on errors. From the point-of-view of the REST API >> consumer, Java stack traces are unhelpful. They are useful in logs, >> where developers and application maintainers can go to see them, but to >> Fedora users, it is mostly noise. >> >> A concise response is more helpful to application developers using the >> RESTful API. I need only three things: 1) an HTTP status code (which I >> can get from the headers); 2) a local fedora error code, whether it is >> your own numeric codes or other strings like "PIDNotFound" or >> "LabelTooLong"; and 3) a concise explanation. (1) and (2) allow me to >> gracefully handle the errors (and report them to my own logs) in a way >> that I can keep executing for the rest of the content I am trying to >> ingest. (3) provides me with some context for the error the first time I >> encounter it and lets me know what I should write into my error handling >> the next time I encounter the code from (2). >> >> By using the RESTful API, my application treats Fedora as a black box. >> Printing the Java stack trace reveals the inner workings of Fedora, >> which my application shouldn't see nor care about. >> >> Here's how my ideal response might look: >> >> <fedora-response type="action-failed"> >> <http-code>415</http-code> >> <fedora-error-code>LabelTooLong</fedora-error-code> >> <explanation> >> Object label must not exceed 255 characters >> (foxml:property NAME='info:fedora/fedora-system:def/model#label') >> </explanation> >> </fedora-response> >> >> This is what I currently get back, and what I don't even attempt to parse: >> >> javax.ws.rs.WebApplicationException: >> org.fcrepo.server.errors.ObjectValidityException: <?xml version="1.0" >> encoding="UTF-8"?> >> <RESULT xmlns:foxml="info:fedora/fedora-system:def/foxml#" >> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";> >> <foxml:property> >> <ASSERT>Object label must not exceed 255 characters >> (foxml:property NAME='info:fedora/fedora-system:def/model#label')</ASSERT> >> </foxml:property> >> </RESULT> >> at >> org.fcrepo.server.rest.BaseRestResource.handleException(BaseRestResource.java:168) >> at >> org.fcrepo.server.rest.FedoraObjectResource.createObject(FedoraObjectResource.java:298) >> at sun.reflect.GeneratedMethodAccessor72.invoke(Unknown Source) >> at >> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) >> at java.lang.reflect.Method.invoke(Method.java:597) >> at >> com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$ResponseOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:175) >> at >> com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:67) >> at >> com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:163) >> at >> com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:71) >> at >> com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:111) >> at >> com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:63) >> at >> com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:689) >> at >> com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:647) >> at >> com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:638) >> at >> com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:309) >> at >> com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:425) >> at >> com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:590) >> at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) >> at >> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) >> at >> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) >> at >> org.fcrepo.server.security.servletfilters.FilterRestApiFlash.doFilter(FilterRestApiFlash.java:79) >> at >> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) >> at >> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) >> at >> org.fcrepo.server.security.jaas.AuthFilterJAAS.doFilter(AuthFilterJAAS.java:287) >> at >> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) >> at >> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) >> at >> org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) >> at >> org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) >> at >> org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:525) >> at >> org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) >> at >> org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) >> at >> org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) >> at >> org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293) >> at >> org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849) >> at >> org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) >> at >> org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454) >> at java.lang.Thread.run(Thread.java:637) >> Caused by: org.fcrepo.server.errors.ObjectValidityException: <?xml >> version="1.0" encoding="UTF-8"?> >> <RESULT xmlns:foxml="info:fedora/fedora-system:def/foxml#" >> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";> >> <foxml:property> >> <ASSERT>Object label must not exceed 255 characters >> (foxml:property NAME='info:fedora/fedora-system:def/model#label')</ASSERT> >> </foxml:property> >> </RESULT> >> at >> org.fcrepo.server.validation.DOValidatorSchematron.validate(DOValidatorSchematron.java:132) >> at >> org.fcrepo.server.validation.DOValidatorSchematron.validate(DOValidatorSchematron.java:87) >> at >> org.fcrepo.server.validation.DOValidatorImpl.validateByRules(DOValidatorImpl.java:339) >> at >> org.fcrepo.server.validation.DOValidatorImpl.validate(DOValidatorImpl.java:252) >> at >> org.fcrepo.server.validation.DOValidatorModule.validate(DOValidatorModule.java:187) >> at >> org.fcrepo.server.storage.DefaultDOManager.getIngestWriter(DefaultDOManager.java:792) >> at >> org.fcrepo.server.management.DefaultManagement.ingest(DefaultManagement.java:107) >> at sun.reflect.GeneratedMethodAccessor73.invoke(Unknown Source) >> at >> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) >> at java.lang.reflect.Method.invoke(Method.java:597) >> at >> org.fcrepo.server.messaging.NotificationInvocationHandler.invoke(NotificationInvocationHandler.java:68) >> at $Proxy0.ingest(Unknown Source) >> at >> org.fcrepo.server.management.ManagementModule.ingest(ManagementModule.java:336) >> at >> org.fcrepo.server.rest.FedoraObjectResource.createObject(FedoraObjectResource.java:293) >> ... 35 more >> > > -- Scott Prater Library, Instructional, and Research Applications (LIRA) Division of Information Technology (DoIT) University of Wisconsin - Madison [email protected] ------------------------------------------------------------------------------ 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