0. do ineed to install the all-in-one SDK to create a custom workflow?
Yes but please consider that the Activiti engine will be removed from Alfresco Content Services in the future probably starting from ACS 8.x. The Workflow console for managing custom workflows in ACS was removed starting from ACS 7.3 as mentioned in the official documentation:
Since September 1st 2017, the Alfresco EULA forbids adding workflows to the workflow engine embedded in Alfresco Content Services. With the release of version 7.3, this will be enforced through a check on a flag in the license file.
Customers who bought Alfresco Content Services before September 1st 2017 will retain the ability to add and modify workflows for the embedded workflow engine.
I suggest to create your custom workflows using Activiti or APS externally from ACS with the related standalone platform totally focused on BPM.
1. do i need to download eclipse and install the activit plugin designer?
No it's not needed anymore starting from Activiti 6 because it includes a process modeler very similar to what is included in APS (the Enterprise edition of Activiti).
Please consider to use our Activiti SDK project in order to create your own custom Activiti project:
Or if you are a partner or an Enteprise customer you can use our APS SDK:
Both this project are supported by Zia Consulting.
2. i needs java knowlege to create a custom workflow in alfresco?
In general no, you only need to know the BPMN 2.0 specification in order to design your process using the correct elements / activities such as events, tasks and sequence flows.
But if you need to create integrations or adding some custom behaviors, you probably need Java knowledge in order to extend in the right way the Activiti engine with new listeners, service tasks or behaviors:
Consider that in general is a best practice to implement unit and integration tests using Java:
3. if i use eclipse to generate a custom workflow i need an AMP files to deploy in alfresco?
In order to install any type of extensions in ACS, you need to package your assets as an AMP or a JAR that you can deploy as a module:
4. if i use activiti cloud modeling and generate sampleworkflow.bpmn20.xml is enought run a custom workflow and deploy it in workflow admin console?
Unfortunately Activiti Cloud is based on Activiti 7 totally implemented as a microservices platform, in ACS we have an embedded instance of Activiti 5 where you can't deploy or change custom workflows (I mean anymore).
If your process is using basic BPMN 2.0 elements without specific usage of Activiti Cloud services, then probably you can deploy it in ACS or Activiti Community, otherwise not. It strongly depends on how you are decorating tasks and listeners and which services you are using durinig the process execution.
5. it requires alfresco enterprise to deploy a custom workflow?
No, also in Alfresco Content Services Enteprise you can't implement your custom workflows anymore. The Activiti engine is embedded in same way you see in the Community edition. I strongly suggest you to look at the Activiti SDK based on Activiti Community 6 or try to use Alfresco Process Services (APS) that is the Enterprise version of Activiti.
Activiti Cloud is an incomplete project dedicated to teams want to implement their own PaaS platform based on a BPM engine, so it is not platform or a product, you should see Activiti Cloud like a framework.
6. it requeire activiti enterprise to deploy a custom workflow?
No you can't deploy custom workflows in ACS, you should use APS or Activiti Community externally and arranging an integration between ACS and Activiti. If you use APS you have a native connector for interacting with ACS.
7. what are the simple and step by step idea and easy way in order to create a custom workflow and deploy it in alfresco 7.2 community version.
There is no solution here, you can't implement custom workflows anymore. The risk is to follow a tutorial and then when you will upgrade to ACS 7.3 you can't manage what you have done!
Hope this helps