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Exceptions Raised by MN and CN APIs

General

All exceptions raised by API methods in DataONE include three basic elements of information and an optional element traceInformation as detailed in Types.ErrorMessage, repeated here for convenience.

Element Cardinality Description
errorCode 1 The error code. This is the HTTP error code (i.e. 4xx). In all cases, the HTTP Status Code value in the response headers should match this value.
detailcode 1 A code that can be mapped to a specific location in the source code of the implementation. Implemented as a string with dot notation to indicate progressive levels of detail.
pid 0..1 Required for exceptions that include an identifier in the constructor signature (e.g. NotFound, IdentifierNotUnique, SynchronizationFailed).
nodeId 0..1 The node identifier of the machine that raised the exception
description 0..1 A human readable message describing what happened
traceInformation 0..1 Optional free text providing more information about the error condition. The intent of this element is to assist with debugging. Note that care should be taken to ensure senstive information is not accidentally exposed through error conditions.

Expressed in xml-schema:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <!-- A derived string type with at least length 1 and it must contain non-whitespace -->
    <xs:simpleType name="NonEmptyString">
        <xs:restriction base="xs:string">
            <xs:minLength value="1" />
            <xs:pattern value="[\s]*[\S][\s\S]*" />
        </xs:restriction>
    </xs:simpleType>

    <!-- Exception type for error serialization in DataONE -->
    <xs:complexType name="DataONEException">
        <xs:sequence>
            <xs:element name="description" minOccurs="0" maxOccurs="1" type="xs:string"></xs:element>
            <xs:element name="traceInformation" minOccurs="0" maxOccurs="1" type="xs:anyType"></xs:element>
        </xs:sequence>
        <xs:attribute name="name" type="NonEmptyString" use="required"></xs:attribute>
        <xs:attribute name="errorCode" type="xs:integer" use="required"></xs:attribute>
        <xs:attribute name="detailCode" type="NonEmptyString" use="required"></xs:attribute>
        <xs:attribute name='identifier' type="NonEmptyString" use="optional"></xs:attribute>
        <xs:attribute name='nodeId' type="NonEmptyString" use="optional"></xs:attribute>
    </xs:complexType>
</xs:schema>

HTTP Exception Handling Codes

HTTP error codes of relevance to the DataONE services are repeated here for convenience. Refer to the HTTP specification for a complete reference.

Code Meaning Description
400 Bad Request Bad request if the request REST operation is invalid, serialization is erroneous, mime type is not supported, or resource is not supported.
401 Unauthorized Authentication failure. Credentials are required or were invalid.
403 Forbidden The current user does not have the right to perform the requested action.
404 Not Found The requested resource does not exist.
405 Method not allowed The HTTP method used is not allowed on this resource. Response must include an Allow header indicating valid HTTP methods.
406 Not Acceptable The resource identified by the request is only capable of generating response entities which have content characteristics not acceptable according to the accept headers sent in the request.
408 Request Timeout The client did not produce a request within the time that the server was prepared to wait.
409 Conflict The request could not be completed due to a conflict with the current state of the resource.
410 Gone The resource is known to be permanently deleted (as opposed to 404 which indicates uncertainty about the state of the object).
413 Request Entity Too Large The server is refusing to process a request because the request entity is larger than the server is willing or able to process.
415 Unsupported Media Type The server is refusing to service the request because the entity of the request is in a format not supported by the requested resource for the requested method.
500 Internal Server Error The server encountered an unexpected condition which prevented it from fulfilling the request.
501 Not Implemented The server does not support the functionality required to fulfill the request. This is the appropriate response when the server does not recognize the request method and is not capable of supporting it for any resource.

Serializing Exceptions

All error messages in DataONE are serialized in XML. In the future, DataONE interfaces may support additional serialization formats such as HTML and JSON, and the serialization format will be selected through normal HTTP content negotiation procedures (RFC2616).

An example of an XML serialized error message:

<error name='NotFound'
       errorCode='404'
       detailCode='1020.1'
       pid='123XYZ'
       nodeId='urn:node:DEMO1'>
  <description>The specified object does not exist on this node.</description>
  <traceInformation>
    method: mn.get
    hint: http://cn.dataone.org/cn/resolve/123XYZ
  </traceInformation>
</error>

Note that the detailCode, pid, and nodeId attributes are optional. The description element is optional but strongly recommended, and traceInformation is optional though especially useful during development and testing.

The Exceptions

Summary of exceptions defined in the DataONE APIs
Exception errorCode Description
Exceptions.AuthenticationTimeout 408 The authentication request timed out.
Exceptions.IdentifierNotUnique 409 The provided identifier conflicts with an existing identifier in the DataONE system. When serializing, the identifier in conflict should be rendered in traceInformation as the value of an identifier key.
Exceptions.InsufficientResources 413 There are insufficient resources at the node to support the requested operation.
Exceptions.InvalidCredentials 401 Indicates that the credentials supplied (to CN_crud.login() for example) are invalid for some reason.
Exceptions.InvalidRequest 400 The parameters provided in the call were invalid. The names and values of parameters should included in traceInformation.
Exceptions.InvalidSystemMetadata 400 The supplied system metadata is invalid. This could be because some required field is not set, the metadata document is malformed, or the value of some field is not valid. The content of traceInformation should contain additional information about the error encountered (e.g. name of the field with bad value, if the document is malformed).
Exceptions.InvalidToken 401 The supplied authentication token (Session) could not be verified as being valid.
Exceptions.NotAuthorized 401 The supplied identity information is not authorized for the requested operation.
Exceptions.NotFound 404 Used to indicate that an object is not present on the node where the exception was raised. The error message should include a reference to the CN_crud.resolve() method URL for the object.
Exceptions.NotImplemented 501 A method is not implemented, or alternatively, features of a particular method are not implemented.
Exceptions.ServiceFailure 500 Some sort of system failure occurred that is preventing the requested operation from completing successfully. This error can be raised by any method in the DataONE API.
Exceptions.UnsupportedMetadataType 400 The science metadata document submitted is not of a type that is recognized by the DataONE system.
Exceptions.UnsupportedType 400 The information presented appears to be unsupported. This error might be encountered when attempting to register unrecognized science metadata for example.
Exceptions.SynchronizationFailed 0 Sent to a Member Node from a Coordinating Node when an attempt to synchronize some object fails.
Exceptions.VersionMismatch 409 The serialVersion of the system metadata being updated differs from the serialVersion supplied with the change request.
exception Exceptions.AuthenticationTimeout(detailCode, description, traceInformation)

The authentication request timed out.

ErrorCode:

408
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining
  • traceInformation (dictionary) – Optional set of key-value pairs that can include the name of the method that raised the error plus other details such as parameters used in the call that can be helpful for debugging. Sensitive information such as passwords must never be logged or recorded in error messages.
exception Exceptions.IdentifierNotUnique(detailCode, description, pid[, traceInformation])

The provided identifier conflicts with an existing identifier in the DataONE system. When serializing, the identifier in conflict should be rendered in traceInformation as the value of an identifier key.

ErrorCode:

409
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining how to avoid the problem.
  • pid (Types.Identifier) – The identifier value that is in conflict
  • traceInformation (dictionary) – Optional additional information to assist with debugging.
exception Exceptions.InsufficientResources(detailCode, description[, traceInformation])

There are insufficient resources at the node to support the requested operation.

ErrorCode:

413
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining how to avoid the problem.
  • traceInformation (dictionary) – Optional set of key-value pairs that can include the name of the method that raised the error plus other details such as parameters used in the call that can be helpful for debugging.
exception Exceptions.InvalidCredentials(detailCode, description[, traceInformation])

Indicates that the credentials supplied (to CN_crud.login() for example) are invalid for some reason.

ErrorCode:

401
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining how to avoid the problem.
  • traceInformation (dictionary) – Can include the name of the method that raised the error and perhaps the username. Obviously, the supplied password or other sensitive information should not be included.
exception Exceptions.InvalidRequest(detailCode, description[, traceInformation])

The parameters provided in the call were invalid. The names and values of parameters should included in traceInformation.

ErrorCode:

400
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining how to avoid the problem.
  • traceInformation (dictionary) – Can include the name of the method that raised the error and perhaps the username. Obviously, the supplied password or other sensitive information should not be included.
exception Exceptions.InvalidSystemMetadata(detailCode, description[, traceInformation])

The supplied system metadata is invalid. This could be because some required field is not set, the metadata document is malformed, or the value of some field is not valid. The content of traceInformation should contain additional information about the error encountered (e.g. name of the field with bad value, if the document is malformed).

ErrorCode:

400
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining how to avoid the problem.
  • traceInformation (dictionary) – Key-value pairs that should include additional information about the error that was encountered while processing the SystemMetadata document.
exception Exceptions.InvalidToken(detailCode, description[, traceInformation])

The supplied authentication token (Session) could not be verified as being valid.

ErrorCode:

401
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining how to avoid the problem.
  • traceInformation (dictionary) – Optional set of key-value pairs that can include the name of the method that raised the error plus other details such as parameters used in the call that can be helpful for debugging.
exception Exceptions.NotAuthorized(detailCode, description[, traceInformation])

The supplied identity information is not authorized for the requested operation.

ErrorCode:

401
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining how to avoid the problem.
  • traceInformation (dictionary) – Optional set of key-value pairs that can include the name of the method that raised the error plus other details such as parameters used in the call that can be helpful for debugging.
exception Exceptions.NotFound(detailCode, description, pid[, traceInformation])

Used to indicate that an object is not present on the node where the exception was raised. The error message should include a reference to the CN_crud.resolve() method URL for the object.

ErrorCode:

404
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining how to avoid the problem.
  • pid (Types.Identifier) – The identifier of the object that can not be located.
  • traceInformation (dictionary) – Optional set of key-value pairs that can include the name of the method that raised the error plus other details such as parameters used in the call that can be helpful for debugging.
exception Exceptions.NotImplemented(detailCode, description[, traceInformation])

A method is not implemented, or alternatively, features of a particular method are not implemented.

ErrorCode:

501
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining how to avoid the problem.
  • traceInformation (dictionary) – Optional set of key-value pairs that can include the name of the method that raised the error plus other details such as parameters used in the call that can be helpful for debugging.
exception Exceptions.ServiceFailure(detailCode, description[, traceInformation])

Some sort of system failure occurred that is preventing the requested operation from completing successfully. This error can be raised by any method in the DataONE API.

ErrorCode:

500
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining how to avoid the problem.
  • traceInformation (dictionary) – Optional set of key-value pairs that can include the name of the method that raised the error plus other details such as parameters used in the call that can be helpful for debugging.
exception Exceptions.UnsupportedMetadataType(detailCode, description[, traceInformation])

The science metadata document submitted is not of a type that is recognized by the DataONE system.

ErrorCode:

400
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining how to avoid the problem.
  • traceInformation (dictionary) – Optional set of key-value pairs that can include the name of the method that raised the error plus other details such as parameters used in the call that can be helpful for debugging.
exception Exceptions.UnsupportedType(detailCode, description[, traceInformation])

The information presented appears to be unsupported. This error might be encountered when attempting to register unrecognized science metadata for example.

ErrorCode:

400
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description that can assist the caller in determining how to avoid the problem.
  • traceInformation (dictionary) – Optional set of key-value pairs that can include the name of the method that raised the error plus other details such as parameters used in the call that can be helpful for debugging.
exception Exceptions.SynchronizationFailed(detailCode, description, pid[, traceInformation])

Sent to a Member Node from a Coordinating Node when an attempt to synchronize some object fails.

ErrorCode:

0
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description of the problem which can be forwarded to an administrator for further action.
  • pid (Types.Identifier) – Identifier of the object that could not be synchronized.
  • traceInformation (dictionary) – Optional set of key-value pairs that can include the name of the method that raised the error plus other details such as parameters used in the call that can be helpful for debugging.
exception Exceptions.VersionMismatch(detailCode, description, pid[, traceInformation])

The serialVersion of the system metadata being updated differs from the serialVersion supplied with the change request.

ErrorCode:

409
Parameters:
  • detailCode (string) – Set by the method raising the exception.
  • description (string) – Human readable description of the problem which can be forwarded to an administrator for further action.
  • pid (Types.Identifier) – Identifier of the system metadata for the object being updated.
  • traceInformation (dictionary) – Optional set of key-value pairs that can include the name of the method that raised the error plus other details such as parameters used in the call that can be helpful for debugging.

This material is based upon work supported by the National Science Foundation under Grant Numbers 083094 and 1430508.

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.