This piece is in continuous, simple binary form. The A section has three phrases. The first eight measures contain two phrases, the first ending with a half cadence and the second with a perfect authentic cadence. Together, they seem like a parallel period, though I'm not sure if I can call it a period within the A section when there is still another phrase. The next eight bars (mm. 9-16) form a phrase that modulates to the dominant (D), and ends with a perfect authentic cadence in that key.
The B section is a phrase group which includes two phrases of eight bars each (it is symmetric). The first phrase ends with a deceptive cadence which resolves to e minor (the relative minor). The second phrase could have been four bars long, but Bach extended the cadence with an extra IV-V-I in the last three measures.