add salesforce source docs

Author: odacremolbap

docs/images/salesforce-source/connected-app-policies.png

@@ -9,6 +9,7 @@ The following is a list of Triggermesh event Sources, some available as open sou
 * [AWS CodeCommit](./awscodecommit.md): Capture notifications from an AWS CodeCommit repository.
 * [AWS DynamoDB](./awsdynamodb.md): Capture activity from an AWS DynamoDB table.
 * [AWS Kinesis](./awskinesis.md): Forward messages from an AWS Kinesis Data Stream.
+* [Salesforce](./salesforce.md): Consume messages from Salesforce Streaming API.
 
 <!--
 * [Azure Storage](./azurestorage.md):

docs/images/salesforce-source/file-upload-secret.png

@@ -0,0 +1,106 @@
+# Event source for Salesforce
+
+This event source acts as a consumer of the [Salesforce stream API][salesforce-stream-api-docs] and forwards all messages it receives
+after wrapping them in a [CloudEvent][ce] envelope.
+
+## Prerequisites
+
+### Salesforce account
+
+Salesforce source uses [OAuth JWT credentials][salesforce-oauth-jwt] for service authentication.
+
+1. First you will need to generate a X509 certificate for signing and verifying requests.
+We will be using `openssl` but any other certificate generation tool should work.
+
+```sh
+openssl req -x509 -sha256 -nodes -days 36500 -newkey rsa:2048 -keyout tm-sf.key -out tm-sf.crt
+```
+
+2. At Salesforce site select `Setup > Apps > App Manager`, click on `New Connected App`.
+
+    - Fill in mandatory fields, then click `Enable OAuth Settings`.
+    - Callback URL is mandatory but can be filled with any HTTPS data.
+    - Enable `Use digital signatures` and upload the public cert (`tm-sf.crt` in the example above).
+    - Add Scopes for `api` and `refresh_token, offline_access`.
+    - Save.
+
+    ![Salesforce connected app](../images/salesforce-source/salesforce-connected-app.png)
+
+    - Select the Connected App from the list and at the click on `Manage`.
+    - Click `Edit policies`.
+    - Set Permitted users to `Admin approved users are pre-authorized`.
+    - Save.
+
+    ![Connected app policies](../images/salesforce-source/connected-app-policies.png)
+
+    - Select the Connected App from the list and at the click on `Manage`.
+    - Click `Manage Profiles`.
+    - Add permissions on the data this user will have access to.
+    - Save.
+
+3. Retrieve OAuth data to configure Triggermesh Source.
+
+   - Select the Connected App from the list and at the click on `View`.
+   - Copy `Consumer Key`
+   - Reveal and copy `Consumer Secret`
+
+### Salesforce stream channel
+
+Refer to [Salesforce stream API][salesforce-stream-api-docs] on how to create stream channels:
+
+   - Change Data Capture events: `/data/ChangeEvents`
+   - PushTopics for streams based on single entity SOQL querys: `/topic/TicketsSold`
+   - Standard Platform Events for Salesforce event monitoring: `/event/LoginEventStream`
+   - Custom Platform Events for your SOQL plaform events: `/event/MyCustom__e`
+
+Each Streaming event type has a distinct [set of features][salesroce-event-features]
+
+### Certificate Key Secret
+
+The TriggerMesh Salesforce integration needs the certificate key to sign authentication requests with the Salesforce API.
+A [secret needs to be created at Triggermesh][tm-secret] that contains that certificate key.
+The file name containing the key will need to be renamed to `certKey`, then select `Secrets` > `+ ADD SECRET`, `File Upload`
+
+![Upload secret](../images/salesforce-source/file-upload-secret.png)
+
+## Deploying an instance of the Source
+
+Open the Bridge creation screen and add a source of type `Salesforce`.
+
+![Adding Salesforce source](../images/salesforce-source/salesforce-source.png)
+
+In the Source creation form, give a name to the event source and add the following information:
+
+* **Broker** to send the events to.
+* **Client ID** as retrieved from Salesforce Connected App.
+* **Server** for authentication at Salesforce.
+* **User** for the Salesforce account.
+* **Channel** as configured at the Salesforce stream.
+
+![Salesforce source form](../images/salesforce-source/salesforce-source-form.png)
+
+After clicking the `Save` at the source you will be taken back to the Bridge editor. Proceed to adding the remaining
+components to the Bridge, then submit it.
+
+Wait a few seconds for all components to become ready, the green `Status` indicator for the bridge indicates that the event source is ready to forward messages from the Salesforce event Stream.
+
+![Bridge status](../images/salesforce-source/salesforce-bridge-ready.png)
+
+## Event types
+
+The Salesforce event source emits events of the following types:
+
+* `com.salesforce.stream.message`
+
+
+
+
+
+[salesforce-stream-api-docs]: https://developer.salesforce.com/docs/atlas.en-us.api_streaming.meta/api_streaming/
+[salesforce-oauth-jwt]: https://help.salesforce.com/articleView?id=remoteaccess_oauth_jwt_flow.htm
+[salesroce-event-features]: https://developer.salesforce.com/docs/atlas.en-us.api_streaming.meta/api_streaming/event_comparison.htm
+[ce]: https://cloudevents.io/
+
+[tm-secret]: ../guides/secrets.md
+
+