[suggestion] Seperate Constants.java into some SubConstants Class

[cvictory]

Currently we manage out constants values in org.apache.dubbo.common.Constants.java.

This class is very bloated and this structure is not well enough. Maybe we should categorize such constants into groups. In this way , we can add some XxxConstants, such as RegistryConstants,ConfigCenterConstants etc. It'd be better if it is split by module of dubbo-core.

[CrazyHZM]

@cvictory
Is there a plan for this suggestion? If there is no plan, I plan to start doing this in the near future.

[beiwei30]

@CrazyHZM pls. take a look at #4017. I've finished step1.

• step2, we need to create multiple Constants in dubbo-common module.
• step3, start to reference new Constatns one by one.
• step4, delete old Constants
• step5, examine each new Constants and evaluate if they are more suitable to move out from dubbo-common into its delegated module, say: org.apache.dubbo.common.serialize.Constants to dubbo-serialization-api

Let me know if it's reasonable, and which part will you claim for step2. I will start from common:

    // BEGIN common
    public static final String DUBBO = "dubbo";
   ...
   public static final int MAX_PROXY_COUNT = 65535;
    // END common

[CrazyHZM]

@beiwei30
I think this step is good, I am responsible for doing the remoting, rpc, config parts, I will start with remoting

[beiwei30]

will you do it based on the current pull request, or wait until it's merged?

[CrazyHZM]

Wait until after being merged

[beiwei30]

@CrazyHZM #4017 is merged. pls. start to move constants into constants sub package first. In this step, let's don't touch org.apache.dubbo.common.Constants untouched.

[beiwei30]

FYI, the first new constant class I created is: org.apache.dubbo.common.constants.CommonConstants

[CrazyHZM]

I created
org.apache.dubbo.common.constants.RemotingConstants、
org.apache.dubbo.common.constants.RpcConstants and org.apache.dubbo.common.constants.ConfigConstants.

[beiwei30]

@CrazyHZM see #4020

[CrazyHZM]

@beiwei30
step2 #4021

[beiwei30]

@beiwei30
step2 #4021

I left my comment. Would you mind to review mine too?

[CrazyHZM]

@CrazyHZM see #4020

I will merge it when I pass ci

[beiwei30]

I think we can now move to step3.

[CrazyHZM]

I will start modifying the remoting later.

[beiwei30]

so, now we should move to step4, start to review any constants suitable to move back to its own module.

for example, in RPCConstants:

    // BEGIN dubbo-rpc-rest
    String KEEP_ALIVE_KEY = "keepalive";

    boolean DEFAULT_KEEP_ALIVE = true;

    String EXTENSION_KEY = "extension";
    // END dubbo-rpc-rest

[CrazyHZM]

Add comments first or move directly?

[beiwei30]

if you are pretty sure it should be move into individual module, just do it, and let's review :)

[CrazyHZM]

ok,I will start to review remoting part.

[beiwei30]

@CrazyHZM FYI, I am on remoting.

[CrazyHZM]

@beiwei30
I will start the fourth step of config.

[cvictory]

You can continue to work at this in dubbo-2.7.3