MESSAGING API OVER HTTP PROTOCOL TO ESTABLISH CONTEXT FOR DATA EXCHANGE

Technologies are provided for a protocol for retrieving data from a remote server at a local client and establishing a context for the client at the server. A client may execute an application enabling users to receive data such as emails stored at the server. The client may employ a messaging-over hypertext transfer protocol (HTTP) to request the data from the server. An HTTP POST request may incorporate specialized headers with instructions for data retrieval, and may enable the client to establish a context with the server to identify the client for subsequent data requests. After receipt of the POST request, the server may send a receipt response and chunked intermediary responses while the request is being processed. The server may also send a cookie to the client representing the context of the client, and the client may return the cookies with subsequent data requests to the server.