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OnEarth 2 WMS Time Service

This service passes through all requests to mapserver, except "getmap" requests should append each layer's <layer_name>_PREFIX and <layer_name>_SHAPEFILE variables to URL

Requirements

  • Lua 5.1
  • luarocks
  • mod_ahtse_lua
  • openssl-devel
  • libyaml-devel

Installation

First make sure that the mod_ahtse_lua module is installed.

Next, use luarocks to install the OnEarth 2 GetCapabilities service module and its dependencies:

luarocks make onearth_wms_time-0.1-1.rockspec

Using the service

Access any normal wms URI and it gets forwarded to the wms_time_service. Once there the service will redirect to a mapserver URL. If the request is getmap then it will append the PREFIX and SHAPEFILE variables for each input layer.

e.g. 1: Accessing: http://localhost/wms/epsg4326/best/wms.cgi?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetCapabilities Redirects to: http://localhost/mapserver/epsg4326/best/wms.cgi?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetCapabilities

e.g. 2: Accessing: http://localhost/wms/epsg4326/best/wms.cgi?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&FORMAT=image%2Fjpeg&TRANSPARENT=true&LAYERS=MODIS_Terra_CorrectedReflectance_TrueColor&CRS=EPSG%3A4326&STYLES=&WIDTH=1536&HEIGHT=768&BBOX=-90%2C-180%2C90%2C180&time=2019-02-10 Redirects to:
http://localhost/mapserver/epsg4326/best/wms.cgi?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&FORMAT=image%2Fjpeg&TRANSPARENT=true&LAYERS=MODIS_Terra_CorrectedReflectance_TrueColor&CRS=EPSG%3A4326&STYLES=&WIDTH=1536&HEIGHT=768&BBOX=-90%2C-180%2C90%2C180&time=2019-02-10&MODIS_Terra_CorrectedReflectance_TrueColor_PREFIX=MODIS_Terra_CorrectedReflectance_TrueColor_Day%2F2011%2F&MODIS_Terra_CorrectedReflectance_TrueColor_SHAPEFILE=MODIS_Terra_CorrectedReflectance_TrueColor_Day-2011244000000

The Configuration Tool

The WMS Time service can be fairly easily configured by hand, but a configuration tool has been provided to make it a bit easier. For more in-depth information about configuring the module, see the end of this document.

The syntax for running the configuration tool is:

lua make_wms_time_endpoint.lua endpoint_config

This tool requires a few different configuration files to work:

  • endpoint config -- contains information about how the WMS Time endpoint should be set up in Apache
  • layer config(s) -- contains information about each of the layers to be included in the WMS Time files.

Note that Apache must be restarted for new configurations to take effect. This command may need to be run as sudo depending on the permission settings for your Apache directories.

Endpoint Configuration

The endpoint configuration should be a YAML file in the following format:

time_service_uri: "http://localhost/time_service/time"
layer_config_source: "/etc/onearth/layers/layer_config.yaml"
apache_config_location: "/etc/httpd/conf.d"
mapserver:
  redirect_endpoint: "/var/www/html/mapserver/epsg3857/std"
  external_endpoint: "/wms/epsg3857/std"
  internal_endpoint: "/var/www/html/wms/epsg3857/std"
  config_prefix: "epsg3857_std_wms_time_service"
  ...
Configuration Options:

Note that all file paths must be accessible to Apache!

time_service_uri (required) -- If you are using dynamic layers, put the URL of the OnEarth 2 date service here.

layer_config_source (required) -- This can be a path either to a single layer configuration YAML file, or a directory containing multiple layer config files. In the case of a directory, the tool will parse all files in that directory with a .yaml extension. Note that the tool will not recurse the contents of subdirectories if they are present.

apache_config_location (optional) -- Location that the main Apache configuration files will be stored (this will need to be somewhere Apache is configured to read when it starts up). Defaults to /etc/httpd/conf.d

mapserver config options

redirect_endpoint -- location on disk for the mapserver files. Must be accessible by Apache.

internal_endpoint -- location on disk for the endpoint config for Apache.

external_endpoint -- relative URI under which the wms time service should be accessible.

config_prefix -- Filename prefix to be used for the WMS Time service Apache config that's generated.

Apache Configuration

The WMS Time service uses the mod_ahtse_lua module, which allows Lua scripts to be run from within Apache. Refer to that module's README for more information on how to set up that module and point it to a Lua script.

Service Configuration

Here's a sample Lua configuration script. This file should be what the AHTSE_lua_Script directive in your Apache configuration points to.

local onearth_wms_time = require "onearth_wms_time"
local config = {
    layer_config_source="config_location",
    time_service_uri="time_service_uri",
    time_service_keys="time_service_keys"
}
handler = onearth_wms_time.handler(config)