The Esri Web Map tag is used within the Geo Map tag to present content from an ArcGIS web map hosted with Esri or on premises.

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Usage

If the web map is hosted with Esri, you can add the web map without a portal URL by specifying the web map ID. (For example, http://www.arcgis.com/home/webmap/viewer.html?webmap=de87749b005346d59e1cd34275154c96) 
<geo:map provider="esri" response="response" address-field="customer_address" label-field="name" height="700px">
   <esri:webmap id="de87749b005346d59e1cd34275154c96"></esri:webmap>
</geo:map>
If the web map is hosted on your own servers, simply specify the web map ID and the URL of the server; for example: 
<geo:map provider="esri" response="response" address-field="customer_address" label-field="name" height="700px">
   <esri:webmap id="de87749b005346d59e1cd34275154c96" url="http://yourportalurl.com/sharing/rest/content/items"></esri:webmap>
</geo:map>
To see all related attributes, see the esri:webmap tag documentation.