Hi Supun,
Please see my comments inline!
Synapse language is treated as a programming language at least for the out side
world. For example sequences can be attributed to functions. In any programming
language the order in which these symbols occur does not matter as long as the
symbols can be found by the caller.
Agreed.
So I have doubts in implementing an order for the synapse elements. By order I
meant something like all the sequences are at the top then the proxy services
etc.
I share these doubts, but you describe exactly the current implementation.
Please have a look at:
SynapseXMLConfigurationSerializer.serializeConfiguration(SynapseConfiguration
synCfg). It uses a fixed order of top level elements.
Specific element serializers are then using an order depending on the way the
configuration has been stored in memory. Mostly the XML information will be
transferred to strongly typed data structures. While deserializing those
values, currently a fixed order will be used. This might be different, from the
one originally read in. Some list like structures are stored to unordered
Map-Implementations for faster key-value access. While deserializing those
values you end up with a random order. I think that this part could be fixed
rather easily by using LinkedHashMap preserving the key order in which entries
have been added to the map.
When a user types in the synapse.xml, we should be able to preserve the order
in which they have entered the elements in the synapse.xml. If you meant this
one I'm +1 for implementing it.
I also agree this would be the most desirable option, although the current
implementation seems to be very far a way from that. Each factory/serializer
pair would need to be designed for this purpose (e.g. keep a list or list of
linked maps or any suitable structure of read elements/attributes, store it for
deserialization purposes only and use this to retrieve the values in the exact
order from structured object structures). I guess only something like this
could warrant a working round-trip serialization/deserialization where the user
may modify any part of the configuration, insert new stuff at any allowed place
and this exact order will be preserved during later deserializations.
So my concrete suggestion for a start was just to replace all class member
implementations of SynapseConfiguration which are currently of type HashMap
with LinkedHashMap. From my point of view this is at least an improvement. No
pain, big gain? ;-)
Regards,
Eric
