Thanks Amit for reply,
I am developing a plugin for Adobe Illustrator with some XMP functionality. So I have clubbed Adobe Illustrator SDK and XMP-SDK. I am adding information about some of the texts present in the art-board in metadata as XMP. There was situation where provisions in AI SDK were not sufficient to implement the requirements. So I had to consider XMPMeta and XMPFiles components.
As you have mentioned about no-limit for size to be added with the metadata, I looked for other possible factors that are creating problems in adding metadata after certain point of time and I found that certain spacial characters like ©,{,} etc. are also creating problems for XMPMeta object. Also, there is not much explanation available about reasons for CanPutXMP to fail.
As the situation is not producing helpful error message, I am finding it difficult to reach to root cause of unsuccessful metadata modification.