SSA v1.1 Erratum 1: Base URL trailing separator clarification

Author: James Dempsey

Date last changed: 2021-11-02

Date accepted: 2022-01-26

Issue: SSA Issue #4

Rationale

There is confusion between the examples and the normative text of the standard as to whether the trailing separator should be included in the registered base URL for an SSA service. The last character of the base URL could be either a question mark '?' or an ampersand '&' depending on whether the service is defined with extra query parameters. It has been common practice to include the trailing separator in the registered base URL. However, clients should be prepared for missing delimiters as this has been ambiguous in the document for some time.

This erratum requires the trailing separator to be included in the registered URL and updates all text and examples to include it.

Erratum Content

This erratum makes the following changes:

Section 3.2 Methods & Protocols

change the example SSA query from

<Service.BaseURL>?VERSION=1.0&REQUEST=queryData<&param=value…>

to

<Service.BaseURL>VERSION=1.0&REQUEST=queryData<&param=value…>

Section 8.3.3 HTTP GET

In table 2, change the URL component in the BaseURL from

http://host:port]/path[?[name[=value]{&name=[value]}]]

to

http://host[:port]/path?{name=[value]&}

This also fixes some unrelated errors in the original example.

Section 8.10 Error Response and Other Unsuccessful Results

In the example, change the baseURL from

<INFO name="baseUrl" value="http://webtest.aoc.nrao.edu/ivoa-dal"/>

to

<INFO name="baseUrl" value="http://webtest.aoc.nrao.edu/ivoa-dal?"/>

Impact Assessment

Currently, all but one registered SSA service include a trailing separator in their registered base URL. However, clients should still expect some services to omit the trailing separator and we recommend they inspect the URL to determine if it is required. Likewise, validators should handle missing separators by reporting their absence but continuing validation.