XML Lookup Utility
Vinaya Mayya
The Ed-Fi Data Standard allows two alternative values for reference types: lookup types and identity types. The Ed-Fi Bulk Load Client requires that identity type references always be used. The XML Lookup Utility is a command-line application that resolves lookup references to identity references in Ed-Fi XML documents. The utility is suitable for interactive or scripted use as part of a larger data-ingestion process.
The utility uses Ed-Fi Standard XSD files (with extensions) combined with a functional Ed-Fi ODS / API to add identity type information to reference types that only contain lookup types, thus allowing the Bulk Load Client to ingest the files. It does not need to be recompiled when the Ed-Fi Data Standard or extensions are changed, as it dynamically maps the Ed-Fi Standard XSD elements to the Ed-Fi REST API endpoints documented in the Swagger metadata.
When the utility is run against one or more XML documents, copies of the the original XML documents with the resolved identity types are created. The original XML documents are left unchanged by the utility.
The utility source code can be found in the Ed-Fi-ODS repository in the \Utilities\DataLoading\EdFi.XmlLookup.Console directory. It is part of the LoadTools solution (\Utilities\DataLoading).
Command-Line and Configuration Parameters
The utility accepts command-line parameters as well as values in the EdFi.XmlLookup.Console.config file, the following command line parameters
| Parameter | .config Setting | Description | Default | Example Parameter Value | |
|---|---|---|---|---|---|
/? | Help | Displays help information |
| ||
/b | Base URL | OdsApi:Url | The base url used to derive api, metadata, oauth, and dependency urls (e.g., http://server). If provided, apiurl, metadataurl and oauthurl parameters can be skipped. | /b "http://server" | |
/d | Data Folder | Folders:Data | The location of the XML files | Working directory of the utility | /d "c:\data" |
/y | School Year | OdsApi:SchoolYear | The school year for the ODS API (Appended to API URL) | /y "2018" | |
/p | Profile | OdsApi:Profile | If provided, the profile to use when calling the API | /p read_only_profile | |
/k | OAuth Key | OdsApi:Key | The application key for the session | /k myKey | |
/s | OAuth Secret | OdsApi:Secret | The secret associated with the key for the session | /s mySecret | |
/f | Force Metadata Reload | ForceMetadata | If provided, it forces a reload of the metadata | Do not force reload | /f |
/w | Working Folder | Folders:Working | A read/write directory to store the metadata information | Working directory of the utility | /w "c:\temp\lookup" |
/x | XSD Folder | Folders:Xsd | The directory containing the Ed-Fi Standard XSD files | the /Schema directory under the Working Folder | /x "c:\ed-fi\standard" |
/a | API URL | OdsApi:ApiUrl | The Ed-Fi ODS API URL (deprecated) | /a "http://server/data/v3" | |
/o | OAuth URL | OdsApi:OAuthUrl | The OAuth URL for retrieving a session token (deprecated) | /o "http://server/" | |
/m | OpenAPI Metadata URL | OdsApi:MetadataUrl | The OpenAPI (Swagger) base URL (deprecated) | /m "http://server/metadata" |
Operation
The XML Lookup Utility requires values for all the configuration values (except for /p and /f) to be present either in the .config file or as command-line parameters.
Existing identity type values are never overwritten. Where identity types can be inferred directly from lookup types, that conversion happens first. Identical lookup type values within a document are resolved against the API call only once. Lookup type values may be reused several and possibly hundreds of times instead of being resolved from the API every time. Memory use is kept at a minimum by scanning XML documents rather than loading the entire document into memory. A session token is only retrieved once when the utility runs.
Processing Overview
When the XML Lookup Utility is run, the following actions occur:
- The Ed-Fi Standard XML files are read and checked for errors.
- The OpenAPI data is read from the cache, or a cache built from the provided OpenAPI URL.
- Mappings are created for:
- Lookup to Identity XML Types.
- Incoming XML Lookup types and GetByExample query parameters.
- GetByExample resources and Identity XML Types.
- For each XML file in the data directory:
- The file is scanned for reference types.
- If the reference type contains an identity type, it is ignored.
- If the lookup type contains all the fields required for the identity type, an identity type is created without calling the ODS / API.
- If the lookup type has not been resolved, the appropriate GetByExample API call is invoked and an identity type is created.
- The file is then read again and a copy of the file is written with identity types being injected.
Troubleshooting
Because the data model of the ODS and the associated REST API is dynamic and extensible, and because security is highly configurable, there are no guarantees that the utility can successfully create every possible lookup-to-identity mapping. However, troubleshooting information is available after the utility runs to assist in resolving some of these issues.
The most typical issues are related to security configuration for the client application associated with the key/secret pair, missing resources, and incomplete or ambiguous lookup elements. A successful lookup returns exactly one resource. Missing or multiple resources are an error.
Security issues can be resolved by changing the settings for the client application in the security administration tools. Lookup failures may also be the result of ambiguous or non-existent data in the ODS / API platform.
Comments in Generated XML Documents
The generated XML documents contain XML comments identifying values that were generated. These comments show which identity values were created and which lookup values were used to create them, which can be useful in tracing issues in the results.
Logging Messages
As configured by default, the Utility displays logging information on the screen and captures more detailed information in a log file for each run. Generally speaking, all ERROR- and CRITICAL-level issues found in the log file should be resolved before submitting the resolved XML documents for loading.
Logging configuration may be changed by adjusting the .config file appropriately. Refer to the excellent log4net documentation for detailed instructions on how to configure application logging to suit your exact needs.
Developers' Guide Contents
Find out more about how to develop platforms based on the Ed-Fi ODS / API v7.1: