1. A computer-implemented method for classifying messages, comprising: obtaining a particular string from a particular message sent to an application, the particular message includes a request for the application to perform a transaction, and the application executes in response to the request; obtaining runtime data regarding execution of the application based on the request, and associating the runtime data with the particular string; calculating a distance between the particular string and a representative string of each group of a plurality of groups using a message distance algorithm, one of the distances is a minimum distance; in response to determining that the minimum distance exceeds a threshold, creating a new group and grouping the particular string into the new group as a sole member of the new group initially; subsequently obtaining an additional string from an additional message sent to the application, the additional message includes an additional request for the application to perform a transaction, and the application executes in response to the additional request; obtaining additional runtime data, regarding execution of the application based on the additional request, and associating the additional runtime data with the additional string; calculating an additional distance, using the message distance algorithm, between the additional string and: (a) the representative string of each group of the plurality of groups, and (b) the particular string in the new group as the sole member of the new group, one of the additional distances is a minimum additional distance; and grouping the additional string into one group of the plurality of groups and the new group which is associated with the minimum additional distance.