|Abstract: |This TR provides an overview about the current status of querying and filtering in oneM2M, formulates new use cases, and provides an overview about relevant query languages. |
|Template Version: January 2020 (do not modify) | |
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@@ -131,6 +131,8 @@ It is possible to add multiple queries and to logical combine them with setting
In addition **_FILTER CRITERIA_***filter handling* attributes are used to limit the number of filter result, specifying an offset in the filter result, or limit the search depth in the resource tree.
TS-0004 [[1](#_ref_1)] , clause 7.3.3.17.16 "Conditions on labelsQuery attribute" defines a tiny query language to do add basic comparison operators to handle filtering on a resource's *label* attribute (which is a list and may contain multiple tags, or tokens). However, this filter query is defined only for the *labels* attribute, and not for other scalar or list-type attributes.
<mark>TODO: Example</mark>
## 5.2 Semantic Discovery and Query
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@@ -201,13 +203,13 @@ The first requirement implies a technical filter or query while the other requir
The following is a list of new use cases that are interesting for IoT application as well as for additional functionality for common services within the CSE.
### 6.2.1 Searching for an IMEI in the *label* Attribute
### 6.2.1 Searching for Specific Protocol Schemes in *pointOfAccess* Attribute
An application entity needs to store extra meta tags in a resource, e.g. the IMEI number of the hosting devices, and other tags. For this, the application entity uses the *label* attribute. Another application entity that wants to retrieve resources by the IMEI number wants to query for these resources by only the single tag in the *label* attribute.
A management system (Application Entity) needs to find out which other Application Entities are request reachable through a specific protocol, e.g. *MQTT*. For this, the Application Entity performs a query to search for the sub-string "mqtt://" in the entries of the *pointOfAccess* attribute of all resources with the *resourceType* "Application Entity".
**Requirement(s)**
- Filter on a single tag (string) in list attribute.
