Visa process for participation in a seminar/workshop

For the purpose of travelling to China on an invitation to participate in a seminar/workshop/review exercise in an organisation ( International non profit development organisation) which has a sister office in Sri Lanka, will the production of following documents for visa be sufficient?
(a)an invitation letter from the organisation in China,declaring that all travel related costs including accommodation and food will be met by the inviting company
(b) an introduction letter of the traveller (who works for the Sri lanka office) from the sri lanka office of the same organisation and
(c) a copy of the business registration with Sri Lanka government .
The duration will be about 3 to 4 weeks. Sri lankan passport holder.