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Task : GeoServer Common Query Language (CQL) (Google Code In)

  1. First Install the GeoServer From This Link http://geoserver.org/release/2.16.x/ and also Use any open data file (e.g. from your cities open data portal or the World Bank portal

  1. After Successfully Installation Open GeoServer.

This tutorial assumes that GeoServer is running at http://localhost:8080/geoserver/web/

  1. Now the login Interface will be open. Login With Usernmae : admin and Password : geoserver

And Now GeoServer Screen Will be Open.

  1. Now Create a New WorkSpace by navigating to Data >> WorkSpaces.

  1. Click on Add new workspace.

  2. You will be prompted to enter a workspace Name and Namespace URI

  3. Enter the Name and URI according to your project based work. Here I am using Name : Russia and URI : geoserver.org/Russia and choose default workspace. and it's done.

Note : A workspace name is a identifier describing your project. It must not exceed ten characters or contain spaces. A Namespace URI (Uniform Resource Identifier) can usually be a URL associated with your project with an added trailing identifier indicating the workspace. The Namespace URI filed does not need to resolve to an actual valid web address.

  1. Now Navigate to Store and Add a New Store. It will be redirected and you have to choose the type of data source you wish to configure.

Note : Note that the data sources are extensible, so your list may look slightly different.

9.Under Vector Data Source Select Shapefile.The New Vector Data Source page will be displaed.

  1. Under Basic Store Info Choose Workspace that you have previous created In my case It is Russia. Enter Data Source as Russia_Map. You can write a description. or leave it blank.

  2. Under Connection Parameter Choose the ShapeFile Location (In which directory is present ) choose the required files.

  1. Click Save You will be redirected to the New Layer page in order to configure the Asia_Russia layer

Adding New Layer

  1. Navigate to the New Layer page, click Publish beside the Asia_Russia layer name. then it will redirected to edit layer page which defines the data and publishing parameters for a layer.

  1. Generate the layer’s bounding boxes by clicking the Compute from data and then Compute from native bounds links.

  1. Click On Save.

  2. Now Navigate to Layer Preview and at top your layer Asia_Russia will be there. then choose OpenLayer Under Common Formats

  1. An OpenLayers map will load in a new tab and display the shapefile data with the default line style. You can use this preview map to zoom and pan around the dataset, as well as display the attributes of features.

Let's Implement CQL queries

CQL(Common Query Language) : created by the OGC for the Catalogue Web Services specification. Unlike the XML-based Filter Encoding language, CQL is written using a familiar text-based syntax. It is thus more readable and better-suited for manual authoring.

As Our OpenMap has been loaded through openlayers and you can see the respective map. Just zoom in and zoom out for more clearly to be shown.

Click on the Options button at the top of the map preview to open the advanced options toolbar. The example filters can be entered in the Filter: CQL box.

1st Query : Like we want to show the only the region of Russia and India so the command for filter will be NAME IN ('INDIA', 'RUSSIA') It will show only the Russia and India region. And to show only one region like India just use the query REGION='INDIA'

2nd Query : Now If we want to show the (Top level of domain) of India only just use the filter 'tld='.in' It will show the top level domain for India only fromt tehe whole map.

3nd Query : Like Now I want to show that display only the states that intersect the (-90,40,-60,45) bounding box. The filter will be BBOX(the_geom, -90, 40, -60, 45)

Note : The full list of geometric predicates is: EQUALS, DISJOINT, INTERSECTS, TOUCHES, CROSSES, WITHIN, CONTAINS, OVERLAPS, RELATE, DWITHIN, BEYOND.

4th Query : Now I want to show that the value of iso_num (iso = country_code) will be greater than 500 then the required filter will be iso_num > 350

5th Query : Now I want to show that the value of iso_num will be between 200 and 800 so the required filter is iso_num BETWEEN 200 AND 800

Installation of Open Layers

OpenLayers is a high-performance, feature-packed library for creating interactive maps on the web. It can display map tiles, vector data and markers loaded from any source on any web page. OpenLayers has been developed to further the use of geographic information of all kinds. It is completely free, Open Source JavaScript, released under the BSD 2-Clause License.

  1. First Install the ol package by npm install ol

  2. Create the bundle for the browser by npm run build

  3. Download any IDE (Integrated Development Environment) like Visual Code.

  4. You Can Install Visual Code Plugins (For not getting any error) Optional

  5. Now Create a New HTML file.

  6. Open the html file through Web Browser and see the map.

  7. Now Create an html document that will display the OpenLayers to display the added layer.

WMS REFLECTOR

This is a great way to preview options in GeoServer without coding a long URL. The reflector will output PNG (the default), JPEG, PNG 8, and GIF. Also, in cases where you don't want to use GeoWebCache, this is quite useful.

Standard WMS requests can be quite long and verbose. For instance the following, which returns an OpenLayers application with an 800x600 image set to display the feature topp:states, with bounds set to the northwestern hemisphere by providing the appropriate bounding box

Using the reflector you can make the request very short and display the Web Map. http://localhost:8080/geoserver/wms/reflect?format=application/openlayers&layers=topp:states&width=800 And to create the OUTPUT image. <img src="http://localhost:8080/geoserver/wms/reflect?layers=topp:states&width=400" height="169" width="400"/>

Also It creates an open layers or just reflect the image file.

WMS REFLECTOR ADVANTAGE

Wms Reflector >> small and simple code .With ease understand

WMS reflector has a great advantage in some occasions., as Standard WMS requests can be quite long and verbose. Typing into a browser, or HTML editor, can be quite cumbersome and error prone. The WMS Reflector solves this problem nicely by using good default values for the options that you do not specify. For instance the following, which returns an OpenLayers application with an 800x600 image set to display the feature for Russia:Asia_Russia

Note : WMS reflector is not as standard as OGC web services as OGC web services has many functionalities, and is used in Project in wider range. where as WMS reflector could only be used in previewing the WMS layer.

Also It creates an open layers or just reflect the image file.

Now Create an html document that will display the OpenLayers to display the added layer.

Image of the layer

Thank You !