Update FAQ.md

docs/FAQ.md

@@ -15,6 +15,76 @@
     ##### last change 2023-03-13 by Michael Baudis [:fontawesome-brands-github:](https://github.com/mbaudis)
 
 
+??? question "How do I emulate Beacon v1 while supporting the v2 protocol?<a id="v1-emulation"> </a>" 
+
+    The [Beacon Framework](/framework) describes the overall structure of the API
+    requests, responses, parameters etc. One can implement e.g. a Boolean beacon (_cf._ the
+    original protocol) without any use of the model, just by providing a well-formed
+    JSON response upon a request [very similar to the (pre-)v1 allele request](/variant-queries/#beacon-sequence-queries).
+
+
+    ##### Minimal Example Request
+
+    This example is for a minimal SNV-type variant query.
+
+    ```
+    /beacon/g_variants/?referenceName=refseq:NC_000017.11&start=7577120&referenceBases=G&alternateBases=A
+    ```
+
+    ##### Example Boolean Response
+
+    In this minimal response to the query above the beacon indicates that its default
+    response is Boolean and that it could interpreted it against the `genomicVariant` entity and in the context of the same Beacon version.
+
+    In principle one could launch a Beacon instance using the example response document as a template
+    in whatever server environment one has at hand. However, a proper Beacon v2
+    installation also has to provide informational endpoints (`/info`, `/map` ...)
+    to allow it's integration through [aggregators](/networks/).
+
+    ```json
+    {
+      "meta": {
+        "apiVersion": "v2.0.0",
+        "beaconId": "org.progenetix.beacon",
+        "receivedRequestSummary": {
+          "apiVersion": "v2.0.0",
+          "pagination": {
+            "limit": 2000,
+            "skip": 0
+          },
+          "requestedGranularity": "boolean",
+          "requestedSchemas": [
+            {
+              "entityType": "genomicVariant",
+              "schema": "https://progenetix.org/services/schemas/genomicVariant/"
+            }
+          ],
+          "requestParameters": {
+            "alternateBases": "A",
+            "referenceBases": "G",
+            "referenceName": "refseq:NC_000017.11",
+            "start": [
+              7577120
+            ]
+          }
+        },
+        "returnedGranularity": "boolean",
+        "returnedSchemas": [
+          {
+            "entityType": "genomicVariant",
+            "schema": "https://progenetix.org/services/schemas/genomicVariant/"
+          }
+        ]
+      },
+      "responseSummary": {
+        "exists": true
+      }
+    }
+    ```
+
+    ###### last change 2023-02-17 @mbaudis
+
+
 ??? security "What are the general security principles for Beacon?"
 
     An implementation of a Beacon must implement the Global Alliance for Genomics and Health ([GA4GH](https://www.ga4gh.org)) Beacon standard. The V2 standard has been approved by both the Regulatory and Ethics, and Data Security foundational workstreams.
@@ -39,4 +109,86 @@
 
 ??? security "How do I test a Beacon without having to go through complex security matters (yet)?"
 
-    As a Beacon is designed to support data discoverability of controlled access datasets, it is recommended that synthetic or artificial data is used for testing and initial deployment of Beacon instances. The use of synthetic data for testing is important in that it ensures that the full functionality of a Beacon can be tested and / or demonstrated without risk of exposing data from individuals. In addition to testing or demonstrating a deployment, synthetic data should be used for development, for example adding new features. Additionally, these data can also be used to demonstrate the access levels and data governance procedures for loading data to a Beacon to build trust with data controllers or data access committees who may be considering loading data to a Beacon. An example dataset that contains chromosome specific vcf files is hosted at EGA under dataset accession EGAD00001006673. While this dataset requires a user to log in to get access, the EGA test user can access this dataset.
+    As a Beacon is designed to support data discoverability of controlled access datasets, it is recommended that synthetic or artificial data is used for testing and initial deployment of Beacon instances. The use of synthetic data for testing is important in that it ensures that the full functionality of a Beacon can be tested and / or demonstrated without risk of exposing data from individuals. In addition to testing or demonstrating a deployment, synthetic data should be used for development, for example adding new features. Additionally, these data can also be used to demonstrate the access levels and data governance procedures for loading data to a Beacon to build trust with data controllers or data access committees who may be considering loading data to a Beacon. An example dataset that contains chromosome specific vcf files is hosted at EGA under dataset accession EGAD00001006673. While this dataset requires a user to log in to get access, the EGA test user can access this dataset.
+
+??? question "What types of genomic variants are supported in Beacon queries?"
+
+    Beacon v2.0 does not provide a mechanism to detect what types of genomic variant
+    queries are supported by a given instance.
+
+    Beacon had been originally designed to handle the "simplest" type of genomic
+    variant queries in which a `position`, `alternateBases` (_i.e._ one or more base
+    sequence of the variant at the position) and - sometimes optional - the reference
+    sequence at this position (necessary e.g. for small deletions).
+
+    Beacon v1.1 in principle supported "bracketed" queries and a `variantType` parameter
+    (pointing to the VCF use) - see the [current documentation](https://docs.genomebeacons.org/variant-queries/#beacon-bracket-queries) for details. However, the support & interpretation was - and still is (2022-12-13) -
+    left to implementers. Similar for [Beacon Range Queries](https://docs.genomebeacons.org/variant-queries/#beacon-range-queries).
+
+    However, the [Beacon documentation](https://docs.genomebeacons.org/variant-queries/#varianttype-parameter-interpretation)
+    provides information about use and expected interpretation of `variantType` values, specifically
+    for copy number variations.
+
+    ###### last change 2022-12-14 @mbaudis
+
+
+??? question "How can I add e.g. an age limit to a query for a disease?"
+
+    Ages are queried as [ISO8601 durations](https://genomestandards.org/standards/dates-times/#durations)
+    such as `P65Y` (_i.e._ 65 years) with a comparator (`=`, `<=`, `>` ...). However,
+    the value needs an indication of _what_ the duration refers to and resources
+    may provide different ways to indicate this (as then shown in their `/filtering_terms`)
+    endpoint).
+
+    We recommend that all Beacon instances that support age queries support at
+    minimum the syntax of `age:<=P65Y` and map such values to the internal datapoint
+    most relevant for the resource's context (in most cases probably corresponding
+    to "age at diagniosis").
+
+    However, different scenarios may be supported (e.g. `EFO_0005056:<=P1Y6M` for
+    an "age at death" scenario).
+
+    ###### last change 2023-05-31 by @mbaudis
+
+??? question "How can I handle haplotype queries & representation in Beacon v2?<a id="haplotypes"> </a>"
+
+    #### Queries
+
+    The Beacon framework currently (_v2.0_ and earlier) considers genomic
+    variants to be _allelic_ and does not support the query for multiple alleles
+    or "haplotype shorthand expressions" (e.g. `C,T`).
+
+    **Workarounds** In case of a specific need for haplotype queries implementers
+    of a given beacon with control of its data content in principle can extend their
+    query model to support shorthand haploype expressions, as long as they support
+    the standard format, too. However, such an approach may be superseeded or in conflict
+    with future direct protocol support.
+
+    An approach in line with the current protocol would be to query for one allelic
+    variant with a record-level `genomicVariation` response, and then query the
+    retrieved variants individually by their `id` in combination with the second
+    allele.
+
+    #### Variant representation
+
+    As with queries the Beacon "legacy" format does not support haplotype representation
+    but would represent each allelic variation separately. The same is true for the
+    VRSified variant representation which for v2.0 corresponds to VRS v1.2.
+    However, draft versions of the VRS standard (will) address haplotype and genotype
+    representations and will be adopted by Beacon v2.n after reaching a release state.
+
+
+??? question "Does the Beacon protocol support Boolean expressions?<a id="boolean-logic"> </a>"
+
+    No (...but). Beacon queries as of v2 always assume a logical **AND** between query parameters
+    and individual filters, _i.e._ all conditions have to be met. There is currently
+    no support for Boolean expressions.
+    However, a logical exception is the use of multiple filters for the same parameter which
+    a Beacon implementation should treat as a logical **OR** since they otherwise
+    would fail in most instances. E.g. the query using `NCIT:C3493` and `NCIT:C2926`
+    (mapped against `biosample.histological_diagnosis.id`) would match both
+    _Lung Non-Small Cell Carcinoma_ (NCIT:C2926) and _Lung Squamous Cell Carcinoma_
+    (NCIT:C3493) which are exclusive diagnoses. 
+
+
+