.. _geomesa-process: GeoMesa Processes ================= The following analytic processes are available and optimized on GeoMesa data stores, found in the ``geomesa-process`` module: - :ref:`arrow_conversion_process` - encodes simple features in the `Apache Arrow `_ format - :ref:`bin_conversion_process` - encodes simple features in a minimized 16-byte format - :ref:`density_process` - computes a density heatmap for a CQL query - :ref:`date_offset_process` - modifies the specified date field in a feature collection by an input time period. - :ref:`hash_process`/:ref:`hash_color_process` - computes an additional 'hash' attribute which is useful for styling. - :ref:`join_process` - merges features from two different schemas using a common attribute field - :ref:`knn_process` - performs a KNN search - :ref:`point2point_process` - aggregates a collection of points into a collection of line segments - :ref:`proximity_process` - searches near a set input features - :ref:`query_process` - performs a Geomesa query, useful as input for nested requests - :ref:`routesearch_process` - matches features traveling along a given route - :ref:`sampling_process` - uses statistical sampling to reduces the features returned by a query - :ref:`statsiterator_process` - returns various stats for a CQL query - :ref:`tracklabel_process` - selects the last feature in a track based on a common attribute, useful for styling - :ref:`tubeselect_process` - performs a correlated search across time and space - :ref:`unique_process` - identifies unique values for an attribute Where possible, the calculations are pushed out to a distributed system for faster performance. Currently this has been implemented in the Accumulo data store and partially in the HBase data store. Other back-ends can still be used, but local processing will be used. Installation ------------ While they can be used independently, the common use case is to use them with GeoServer. To deploy them in GeoServer requires: 1. a GeoMesa datastore plugin 2. the GeoServer WPS extension .. note:: Some processes also require custom output formats, available separately in the GPL licensed `GeoMesa GeoServer WFS module `__ The GeoMesa datastore plugin is available in the binary distribution in the gs-plugins directory. Documentation about the GeoServer WPS Extension (including download instructions) is available `here `__. To verify the install, start GeoServer, and you should see a line like ``INFO [geoserver.wps] - Found 15 bindable processes in GeoMesa Process Factory``. In the GeoServer web UI, click 'Demos' and then 'WPS request builder'. From the request builder, under 'Choose Process', click on any of the 'geomesa:' options to build up example requests and in some cases see results. Processors ---------- .. _arrow_conversion_process: ArrowConversionProcess ^^^^^^^^^^^^^^^^^^^^^^ The ``ArrowConversionProcess`` converts an input feature collection to arrow format. ===================== =========== Parameters Description ===================== =========== features Input feature collection to encode includeFids Include feature IDs in arrow file proxyFids Proxy feature IDs to integers instead of strings formatVersion Arrow IPC format version dictionaryFields Attributes to dictionary encode useCachedDictionaries Use cached top-k stats (if available), or run a dynamic stats query to build dictionaries sortField Attribute to sort by sortReverse Reverse the default sort order batchSize Number of features to include in each record batch doublePass Build dictionaries first, then query results in a separate scan ===================== =========== .. _bin_conversion_process: BinConversionProcess ^^^^^^^^^^^^^^^^^^^^^^ The ``BinConversionProcess`` converts an input feature collection to BIN format. ========== =========== Parameters Description ========== =========== features Input feature collection to query track Track field to use for BIN records geom Geometry field to use for BIN records dtg Use cached top-k stats (if available), or run a dynamic stats query to build dictionaries label Attribute to sort by axisOrder Reverse the default sort order ========== =========== .. _density_process: DensityProcess ^^^^^^^^^^^^^^ The ``DensityProcess`` computes a density map over a set of features stored in GeoMesa. A raster image is returned. ============ =========== Parameters Description ============ =========== data Input Simple Feature Collection to run the density process over radiusPixels Radius of the density kernel in pixels. Controls the "fuzziness" of the density map weightAttr Name of the attribute to use for data point weights outputBBOX Bounding box and CRS of the output raster outputWidth Width of the output raster in pixels outputHeight Height of the output raster in pixels ============ =========== .. _date_offset_process: DateOffsetProcess ^^^^^^^^^^^^^^^^^ The ``DateOffsetProcess`` modifies the specified date field in a feature collection by an input time period. ============ =========== Parameters Description ============ =========== data Input features dateField The date attribute to modify timeOffset Time offset (e.g. P1D) ============ =========== .. _hash_process: HashAttributeProcess ^^^^^^^^^^^^^^^^^^^^ The ``HashAttributeProcess`` adds an attribute to each SimpleFeature that hashes the configured attribute modulo the configured param. ============ =========== Parameters Description ============ =========== data Input Simple Feature Collection to run the hash process over attribute The attribute to hash on modulo The divisor ============ =========== .. _hashExampleXML: Hash example (XML) """"""""""""""""""" :download:`HashAttributeProcess_wps.xml ` is a geoserver WPS call to the GeoMesa HashAttributeProcess. It can be run with the following curl call: .. code-block:: bash curl -v -u admin:geoserver -H "Content-Type: text/xml" -d@HashAttributeProcess_wps.xml localhost:8080/geoserver/wps The query should generate results that look like :download:`this `: .. code-block:: json { "id" : "d0971735-f8fe-47ed-a7cd-2e12280e8ac1", "geometry" : { "coordinates" : [ 151.1554, 18.2014 ], "type" : "Point" }, "type" : "Feature", "properties" : { "Vitesse" : 614, "Heading" : 244, "Date" : "2016-05-02T18:00:44.030+0000", "hash" : 237, "CabId" : 150002, } } .. _hash_color_process: HashAttributeColorProcess ^^^^^^^^^^^^^^^^^^^^^^^^^ The ``HashAttributeColorProcess`` adds an attribute to each SimpleFeature that hashes the configured attribute modulo the configured param and emit a color. ============ =========== Parameters Description ============ =========== data Input Simple Feature Collection to run the hash process over attribute The attribute to hash on modulo The divisor ============ =========== .. _join_process: JoinProcess ^^^^^^^^^^^ The ``JoinProcess`` queries a feature type based on attributes from a second feature type. ============= =========== Parameters Description ============= =========== primary Primary feature collection being queried secondary Secondary feature collection to be joined joinAttribute Attribute field to join on joinFilter Additional filter to apply to joined features attributes Attributes to return. Attribute names should be qualified with the schema name, e.g. foo.bar ============= =========== .. _knn_process: KNearestNeighborSearchProcess ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The ``KNearestNeighborSearchProcess`` performs a K-nearest-neighbor search on a feature collection using a second feature collection as input. It returns ``k`` neighbors for each point in the input data set. Note that if a feature is the nearest neighbor of multiple points in the input data set, it is returned only once. ================= =================================================================================================== Parameter Description ================= =================================================================================================== inputFeatures Input feature collection. The geometries of the features defines the KNN search dataFeatures The data set to query for neighbors numDesired ``k``, number of nearest neighbors to return estimatedDistance Estimate of the distance in meters for the ``k``-th nearest neighbor, used for the initial query window maxSearchDistance Maximum search distance in meters, used to prevent runaway queries of the entire data set ================= =================================================================================================== .. _knnExampleXML: K-Nearest-Neighbor Example (XML) """""""""""""""""""""""""""""""" :download:`KNNProcess_wps.xml ` is a geoserver WPS call to the GeoMesa KNearestNeighborSearchProcess. In this example, it is chained with a Query process (see :ref:`chaining_processes`), in order to avoid returning the query features as data. It can be run with the following curl call: .. code-block:: bash curl -v -u admin:geoserver -H "Content-Type: text/xml" -d@KNNProcess_wps.xml localhost:8080/geoserver/wps .. _point2point_process: Point2PointProcess ^^^^^^^^^^^^^^^^^^ The ``Point2PointProcess`` aggregates a collection of points into a collection of line segments. ===================== =========== Parameters Description ===================== =========== data Input feature collection groupingField Field on which to group sortField Field on which to sort (must be Date type) minimumNumberOfPoints Minimum number of points breakOnDay Break connections on day marks filterSingularPoints Filter out segments that fall on the same point ===================== =========== .. _point2pointExampleXML: Point2Point example (XML) """"""""""""""""""""""""" :download:`Point2PointProcess_wps.xml ` is a geoserver WPS call to the GeoMesa Point2PointProcess. It can be run with the following curl call: .. code-block:: bash curl -v -u admin:geoserver -H "Content-Type: text/xml" -d@Point2PointProcess_wps.xml localhost:8080/geoserver/wps .. _point2pointExampleResults: The query should generate results that look like :download:`this `: .. code-block:: json { "id" : "367152240-4", "geometry" : { "coordinates" : [ [ -13.4041, 37.8067 ], [ -13.4041, 37.8068 ] ], "type" : "LineString" }, "type" : "Feature", "properties" : { "Date_end" : "2018-02-05T14:54:36.598+0000", "CabId" : 367152240, "Date_start" : "2018-02-05T14:53:58.078+0000" } } .. _proximity_process: ProximitySearchProcess ^^^^^^^^^^^^^^^^^^^^^^ The ``ProximitySearchProcess`` performs a proximity search on a Geomesa feature collection using another feature collection as input. ===================== =========== Parameters Description ===================== =========== inputFeatures Input feature collection that defines the proximity search dataFeatures The data set to query for matching features bufferDistance Buffer size in meters ===================== =========== .. _proximityExampleXML: Proximity search example (XML) """""""""""""""""""""""""""""" :download:`ProximitySearchProcess_wps.xml ` is a geoserver WPS call to the GeoMesa ProximitySearchProcess. It can be run with the following curl call: .. code-block:: bash curl -v -u admin:geoserver -H "Content-Type: text/xml" -d@ProximitySearchProcess_wps.xml localhost:8080/geoserver/wps .. _routesearch_process: RouteSearchProcess ^^^^^^^^^^^^^^^^^^ The ``RouteSearchProcess`` finds features around a route that are heading along the route and not just crossing over it. ================ =========== Parameters Description ================ =========== features Input feature collection to query routes Routes to search along. Features must have a geometry of LineString bufferSize Buffer size (in meters) to search around the route headingThreshold Threshold for comparing headings, in degrees routeGeomField Attribute that will be examined for routes to match. Must be a LineString geomField Attribute that will be examined for route matching bidirectional Consider the direction of the route or just the path of the route headingField Attribute that will be examined for heading in the input features. If not provided, input features geometries must be LineStrings ================ =========== .. _routeSearchExampleXML: Route search example (XML) """""""""""""""""""""""""" :download:`RouteSearchProcess_wps.xml ` is a geoserver WPS call to the GeoMesa RouteSearchProcess. It can be run with the following curl call: .. code-block:: bash curl -v -u admin:geoserver -H "Content-Type: text/xml" -d@RouteSearchProcess_wps.xml localhost:8080/geoserver/wps .. _sampling_process: SamplingProcess ^^^^^^^^^^^^^^^ The ``SamplingProcess`` uses statistical sampling to reduces the features returned by a query. ============= =========== Parameters Description ============= =========== data Input features. samplePercent Percent of features to return, between 0 and 1. threadBy Attribute field to link associated features for sampling. ============= =========== .. _samplingExampleXML: Sampling example (XML) """""""""""""""""""""" :download:`SamplingProcess_wps.xml ` is a geoserver WPS call to the GeoMesa SamplingProcess. It can be run with the following curl call: .. code-block:: bash curl -v -u admin:geoserver -H "Content-Type: text/xml" -d@SamplingProcess_wps.xml localhost:8080/geoserver/wps .. _statsiterator_process: StatsProcess ^^^^^^^^^^^^ The ``StatsProcess`` allows the running of statistics on a given feature set. ========== =========== Parameters Description ========== =========== features The feature set on which to query. Can be a raw text input, reference to a remote URL, a subquery or a vector layer statString Stat string indicating which stats to instantiate - see below encode Return the values encoded as json. Must be ``true`` or ``false``; empty values will not work properties The properties / transforms to apply before gathering stats ========== =========== Stat Strings """""""""""" Stat strings are a GeoMesa domain specific language (DSL) that allows the specification of stats for the iterators to collect. See :ref:`statistical_queries` for an explanation of the available stats. .. _tracklabel_process: TrackLabelProcess ^^^^^^^^^^^^^^^^^ The ``TrackLabelProcess`` returns a single feature that is the head of a track of related simple features. ========== =========== Parameters Description ========== =========== data Input features track Track attribute to use for grouping features dtg Date attribute to use for ordering tracks ========== =========== .. _trackLabelExampleXML: TrackLabel example (XML) """""""""""""""""""""""" :download:`TrackLabelProcess_wps.xml ` is a geoserver WPS call to the GeoMesa TrackLabelProcess. It can be run with the following curl call: .. code-block:: bash curl -v -u admin:geoserver -H "Content-Type: text/xml" -d@TrackLabelProcess_wps.xml localhost:8080/geoserver/wps .. _tubeselect_process: TubeSelectProcess ^^^^^^^^^^^^^^^^^ The ``TubeSelectProcess`` performs a tube select on a Geomesa feature collection based on another feature collection. To get more informations on ``TubeSelectProcess`` and how to use it, you can read `this tutorial `__. ================= =========== Parameters Description ================= =========== tubeFeatures Input feature collection (must have geometry and datetime) featureCollection The data set to query for matching features filter The filter to apply to the featureCollection maxSpeed Max speed of the object in m/s for nofill & line gapfill methods maxTime Time as seconds for nofill & line gapfill methods bufferSize Buffer size in meters to use instead of maxSpeed/maxTime calculation maxBins Number of bins to use for breaking up query into individual queries gapFill Method of filling gap (nofill, line) ================= =========== .. _tubeSelectExampleXML: TubeSelect example (XML) """""""""""""""""""""""" :download:`TubeSelectProcess_wps.xml ` is a geoserver WPS call to the GeoMesa TubeSelectProcess. It can be run with the following curl call: .. code-block:: bash curl -v -u admin:geoserver -H "Content-Type: text/xml" -d@TubeSelectProcess_wps.xml localhost:8080/geoserver/wps .. _query_process: QueryProcess ^^^^^^^^^^^^ The ``QueryProcess`` takes an (E)CQL query/filter for a given feature set as a text object and returns the result as a json object. ========== =========== Parameters Description ========== =========== features The data source feature collection to query. Reference as ``store:layername``. For an XML file enter ```` For interactive WPS request builder select ``VECTOR_LAYER`` & choose ``store:layername`` filter The filter to apply to the feature collection. For an XML file enter: .. code-block:: xml For interactive WPS request builder select TEXT & choose ``"text/plain; subtype=cql"`` enter the query text in the text box output Specify how the output feature collection will be presented. For an XML file enter: .. code-block:: xml result For interactive WPS request builder check the Generate box and choose "application/json" properties The properties / transforms to apply before gathering stats. ========== =========== .. _queryExampleXML: Query example (XML) """"""""""""""""""" :download:`QueryProcess_wps.xml ` is a geoserver WPS call to the GeoMesa QueryProcess that performs the same query shown in the `Accumulo-quickstart `_. It can be run with the following curl call: .. code-block:: bash curl -v -u admin:geoserver -H "Content-Type: text/xml" -d@QueryProcess_wps.xml localhost:8080/geoserver/wps The query should generate results that look like :download:`this `: .. code-block:: json { "type": "FeatureCollection", "features": [ { "type": "Feature", "geometry": { "type": "Point", "coordinates": [ -76.513, -37.4941 ] }, "properties": { "Who": "Bierce", "What": 931, "When": "2014-07-04T22:25:38.000+0000" }, "id": "Observation.931" } ] } .. _unique_process: UniqueProcess ^^^^^^^^^^^^^ The ``UniqueProcess`` class is optimized for GeoMesa to find unique attributes values for a feature collection, which are returned as a json object. =========== =========== Parameters Description =========== =========== features The data source feature collection to query. Reference as ``store:layername``. For an XML file enter ```` For interactive WPS request builder select ``VECTOR_LAYER`` & choose ``store:layername`` attribute The attribute for which unique values will be extracted. Attributes are expressed as a string. For an XML file enter ``attribute-name`` filter The filter to apply to the feature collection. For an XML file enter: .. code-block:: xml For interactive WPS request builder select TEXT & choose ``"text/plain; subtype=cql"`` enter the query text in the text box. histogram Create a histogram of attribute values. Expressed as a boolean (true/false). For an XML file enter ``true/false`` sort Sort the results. Expressed as a string; allowed values are ASC or DESC. For an XML file enter ``ASC/DESC`` sortByCount Sort by histogram counts instead of attribute values. Expressed as a boolean (true/false). For an XML file enter ``true/false`` output Specify how the output feature collection will be presented. For an XML file enter: .. code-block:: xml result For interactive WPS request builder check the Generate box and choose "application/json" =========== =========== .. _uniqueExampleXML: Unique example (XML) """""""""""""""""""" :download:`UniqueProcess_wps.xml ` is a geoserver WPS call to the GeoMesa UniqueProcess that reports the unique names in in the 'Who' field of the Accumulo quickstart data for a restricted bounding box (-77.5, -37.5, -76.5, -36.5)). It can be run with the following curl call: .. code-block:: bash curl -v -u admin:geoserver -H "Content-Type: text/xml" -d@UniqueProcess_wps.xml localhost:8080/geoserver/wps .. _uniqueExampleResults: The query should generate results that look like this: .. code-block:: json { "type": "FeatureCollection", "features": [ { "type": "Feature", "properties": { "value": "Addams", "count": 37 }, "id": "fid--21d4eb0_15b68e0e8ca_-7fd6" }, { "type": "Feature", "properties": { "value": "Bierce", "count": 43 }, "id": "fid--21d4eb0_15b68e0e8ca_-7fd5" }, { "type": "Feature", "properties": { "value": "Clemens", "count": 48 }, "id": "fid--21d4eb0_15b68e0e8ca_-7fd4" } ] } .. _chaining_processes: Chaining Processes ^^^^^^^^^^^^^^^^^^ WPS processes can be chained, using the result of one process as the input for another. For example, a bounding box in a GeoMesa :ref:`query_process` can be used to restrict data sent to :ref:`statsiterator_process`. :download:`GeoMesa_WPS_chain_example.xml ` will get all points from the AccumuloQuickStart table that are within a specified bounding box (-77.5, -37.5, -76.5, -36.5), and calculate descriptive statistics on the 'What' attribute of the results. The query should generate results that look like this: .. code-block:: json { "type": "FeatureCollection", "features": [ { "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 0, 0 ] }, "properties": { "stats": "{\"count\":128,\"minimum\":[29.0],\"maximum\":[991.0],\"mean\":[508.5781249999999],\"population_variance\":[85116.25952148438],\"population_standard_deviation\":[291.74691004616375],\"population_skewness\":[-0.11170819256679464],\"population_kurtosis\":[1.7823482287566166],\"population_excess_kurtosis\":[-1.2176517712433834],\"sample_variance\":[85786.46628937007],\"sample_standard_deviation\":[292.893267743337],\"sample_skewness\":[-0.11303718280959842],\"sample_kurtosis\":[1.8519712064424219],\"sample_excess_kurtosis\":[-1.1480287935575781],\"population_covariance\":[85116.25952148438],\"population_correlation\":[1.0],\"sample_covariance\":[85786.46628937007],\"sample_correlation\":[1.0]}" }, "id": "stat" } ] }