The Data-stream is an abstraction of the flow of data between entities and individuals. Its nodes range from corporations to governmental institutions - from charities to black market businesses as well as perfectly legal and ethical enterprise etc. It is not to be confused with the Information-stream.
Differences from the Information stream
As opposed to The Information-stream, which is the open flow if information within a society, The Data-stream would be the more private and secretive transfers of data between companies/corporations and governmental agencies. An important distinction to make between the Data and Information streams is that unlike the Information-stream, the Data-stream is encrypted and private. Not open to observation by the public eye like the Information stream is. The datastream can only be accessed at privileged points of entry such as certain protected servers at a company or network. The only people capable of seeing into the datastream would either be permitted members of that node; insiders involved in their corporate workings, or skilled hackers/hacktivists who could break into those servers to snag certain datapoints of interest.
If two friends were messaging each other through an encrypted medium such as Signal messenger, the messages are sent from one recipient to the other, but once they arrive in the recipient's inbox, the messages are decrypted. The difference between encrypted messages among friends and private emails between intelligence contracting agencies seeking to disrupt democracy, is that usually a conversation between friends does not bear such an impactful and truth-revealing on as mass a scale, effect on reality. The distinction here that keeps personal communications to the Information-stream rather than the Data-stream is that when the information is brought to light and extracted from its private stream, decrypted into known reality (if you will), the private emails of intelligence contractors reveal a hidden reality that potentially impacts on a mass scale. It's a conversation among global players. The encrypted confessions of teenagers to one another in an instant messaging app is unlikely to hold that same level of potential for mass revelation.
Real world examples of the Data-stream being breached
The hacks of HBGary & Stratfor and the glorious 50 days of lulz all serve fine examples of outers, externals, breachers etc. (anyone who gains access to somewhere they shouldn't be granted access) gaining access to points in the Data-stream and extracting important data which when given the context of being extracted from its private network, is in a way, decrypted from the void of the unknown (yes officer, I have my poetic license here somewhere *rummages around*) and turned into useful, important information that helps shed more light onto reality than were it never extracted. (Like how Team Themis were planning on smearing numerous journalists and undermining activist movements in secret while being employed by the US government).