Although SharePoint 2013 doesn't allow publishing content directly into its index, it does provide a way to create connectors that it can use to crawl non-native content based on the SharePoint Business Data Connectivity (BDC) model. In previous versions, we offered a Windows Communication Foundation (WCF)-based BDC connector to index content into SharePoint Search. This component used a file system-based intermediate repository, which wrought a series of inconveniences regarding performance, security and scalability. With the creation of StageR (a mongodb and node.js-based staging repository), it's now possible to create a more compact solution when indexing content into SharePoint Search that also leverages all of the capabilities of StageR .
Read more about our components:
Welcome to Publish to SharePoint 2013 for Aspire. Information for publishing, pushing documents acquired and processed by Aspire Publish to SharePoint 2013.
...
About the Publish to SharePoint 2013 publisher for Aspire, how it works, features,
Supported Publish to SharePoint 2013 versions, user access requirements, other requirements
Step by step tutorial to crawl your first Publish to SharePoint 2013
Questions and answers, including troubleshooting techniques
Questions and answers, components and troubleshooting techniques for developers
Publish to SharePoint 2013 concerning information
...