WSI allows complete access to your store database, which may include sensitive data. Adherence to proper security practices defined here are mandatory for proper deployment and usage.
Turn off all protocols except SOAP
Make sure you are running the web service over HTTPS protocol in a production environment. Running over HTTP is ok in dev/test setup, but you must use SSL encryption for production data transfers.
WSI is not really designed to import massive amounts of products, entities, or customers in a single 'pass'. While this import option can handle more at once than the standard Excel product import, we still recommend that imports be done & reviewed incrementally, and that transactions be used. See this page for more information on Transaction nodes.
Excel Bulk Import Tool
While the Excel tool is easier for a non-technical user, we highly recommend that store owners work with a developer to use the WSI feature for imports instead. Though more complicated to set up, it is far more flexible, can import every field rather than the limited data set supported by the Excel import, and supports larger imports.
WSI processes and imports XML nodes at the data level, bypassing the 'application layer' of AspDotNetStorefront, including the cache. Because of this, if front-end caching is enabled on your store, products & entities imported through WSI may not be reflected immediately on the front end. You can either wait for the cache to update (determined by the CacheDurationMinutes AppConfig), or restart the site to force an update.
There is also a ResetCache processing node element in WSI that you can include in your XML import document that can also do this automatically. Do not execute that action too often via WSI however, or it may negatively affect your store performance by clearing the cache too frequently.
Invalid security header on WSI calls
This means that you are not using time synchronization (a Windows function) on your client and web site servers. Time sync MUST be used on both machines, or SOAP calls will not work. Please see your host or IT manager for assistance with enabling time sync.