Franz Schubert (1797-1828), wrote for a Classical composer relatively few for the violin-piano repertoire, In total, he wrote 3 sonatinas, a 'Grand Duo', Fantasy and a Rondo. The name Sonatina is a bit misleading. If one compares the structure of those pieces and compares it with, for example, the sonatinas for piano-solo of Beethoven, one can see the clear difference between the two. The sonatinas of Beethoven are comparably much smaller. It is, therefore, right to say that the Sonatinas of Schubert could and should be seen as Sonatas.
Schubert's first instrument was the violin. His father, who had a Latin-school and was known for his qualities as an amateur musician, was his first teacher. It is known that his father often took part in chamber music in which he always took the role of the cellist. Schubert started at the age of 8, according to a note of his dad. After he knew how to play the basics his father brought him for singing lessons and Schubert himself went to a local piano-factory and tried to learn piano in the shop. Not long after, Schubert started to get his lessons from Michael Holzer which was a respected musician.
During his teenage years, it is known that Schubert played the viola in the house-concerts on Sundays that his father organized. During that period, around 1813, he had gotten more interested in chamber music which resulted in 4 string quartets.
In general, the style of Schubert is known for its lyricism. With the extensive amount of songs that he wrote in his short life, one can see the clear influence of the lyrical references in his music. The violin works, like the sonatinas, are a clear example of that. One can as well see, especially in the sonatinas that the accompaniment, in both instruments, are often with the typically repeated notes, which Schubert also wrote in, for example, his songs and his Arpeggione Sonata. One of the main aspects, when it comes to interpretation, is how to treat these repeating figures and how to make it in such a way that it sustains the melody.
Schubert also kept in the style of his time by writing national music. Most composers of the Romantic era, like Liszt, Brahms, Schumann etc were famous for putting nationalistic influences in their compositions. For the violin and piano music of Schubert, one can for example clearly hear in the Fantasy op.159 the Hungarian aspects in the Allegretto.