It's a big but connected world with huge number of entities communicating by different languages and different protocols. In a service oriented architecture there is a set of such entities/components providing and consuming different services.
For these heterogeneous entities to communicate there need be a person in the middle who can speak with all of them regardless of the languages they speak and protocols they follow. Also, in order to deliver a useful service for a consumer there need to be a person to orchestrate the services provided from different entities. This person better be fast and able to handle concurrency pretty well.
Abstractly speaking Enterprise Service Bus(ESB) is that person and WSO2 ESB is the best opensource option out there if you need one!
Following are the main functionalities WSO2 ESB provides [2]
1. Service mediation
2. Message routing
3. Data transformation
4. Data transportation
5. Service hosting
Even though ESB could cover most of the integration use cases that you might need to implement, there are many extension points you could use in case you are unable to implement your use case with built-in capabilities.
You can download WSO2 ESB at [1] and play with it! [2] is a great article that you must read that would quickly walk you through what WSO2 ESB has to offer!
[1] http://wso2.com/products/enterprise-service-bus/
[2] http://wso2.com/library/articles/2017/07/what-is-wso2-esb/
Showing posts with label ESB. Show all posts
Showing posts with label ESB. Show all posts
SFTP protocol over VFS transport in WSO2 ESB 5.0.0
The Virtual File System (VFS) transport is used by WSO2 ESB to process files in the specified source directory. After processing the files, it moves them to a specified location or deletes them.
Let's look at a sample scenario how we can use this functionality of WSO2 ESB.
Let's say you need to periodically check a file system location on a given remote server and if a file is available you need to send an email attaching that file and move that file to some other file system location. This can be achieved as follows.
1. Let's first configure your remote server so that ESB could securely communicate with it over SFTP.
First create a public-private key pair with ssh.
run ssh-keygen command.
eg:
manurip@manurip-ThinkPad-T540p:~/Documents/Work/Learning/blogstuff$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/manurip/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/manurip/.ssh/id_rsa.
Your public key has been saved in /home/manurip/.ssh/id_rsa.pub.
The key fingerprint is:
c3:57:b2:82:ee:d3:b3:74:55:bf:9c:93:b7:7a:2e:df manurip@manurip-ThinkPad-T540p
The key's randomart image is:
+--[ RSA 2048]----+
| |
| |
| . . . |
| o + . . |
| . S o . .|
| . + . . +|
| ... . *.|
| ...o. . .=|
| ...o .*+E|
+-----------------+
Now open your .ssh folder which is located at /home/user in linux and open the file id_rsa.pub which contains the public key. Copy that and log in to your remote server and copy that and paste it in ~/.ssh/authorized_keys file.
2. Now, let's configure ESB.
First we need to enable VFS transport receiver so that we can monitor and receive the files from our remote server. To do that uncomment the following line in ESB-home/repository/conf/axis2/axis2.xml
<transportReceiver name="vfs" class="org.apache.synapse.transport.vfs.VFSTransportListener"/>
Also, we need to be able to send a mail. For that, uncomment the following line as well from the same file. Also fill in the configuration. In case you will be using a gmail address to send mail, the configuration would be as following.
<transportSender name="mailto" class="org.apache.axis2.transport.mail.MailTransportSender">
<parameter name="mail.smtp.host">smtp.gmail.com</parameter>
<parameter name="mail.smtp.port">587</parameter>
<parameter name="mail.smtp.starttls.enable">true</parameter>
<parameter name="mail.smtp.auth">true</parameter>
<parameter name="mail.smtp.user">test@gmail.com</parameter>
<parameter name="mail.smtp.password">password</parameter>
<parameter name="mail.smtp.from">test@gmail.com</parameter>
</transportSender>
3. Now, create the following proxy service and sequence and save them in ESB-home/repository/dpeloyment/server/synapse-configs/default/proxy-services and ESB-home/repository/dpeloyment/server/synapse-configs/default/sequences respectively.
Here is the proxy service
Here, if your private key is in a different location(means its not at ~/.ssh/) or the name is different(i.e. name is not id_rsa) you will need to provide it as a parameter as follows.
<parameter name="transport.vfs.SFTPIdentities">/path/id_rsa_custom_name</parameter>
Here you can see that we have referred to sendMailSequence in our proxy service via the sequence mediator. The sendMailSequence will be as follows.
5. Now we are good to go! Go ahead and start WSO2 ESB. And log in to your remote server and create an xml file(say test.xml) in /home/user/test/source which the location we gave as the value for transport.vfs.FileURI property. Soon after doing that you will see that it gets moved to /home/user/dest which the location we gave as the value for transport.vfs.MoveAfterProcess property. Also an email with test.xml attached will be sent to the email address you specified in your sendMailSequence.xml.
Also if you added the log mediators I have put in the proxy service and sendMailSequence you should see the similar logs as follows in the wso2carbon.log.
[2016-12-13 22:04:28,510] INFO - LogMediator log = ====VFS Proxy====
[2016-12-13 22:04:28,511] INFO - LogMediator sequence = sendMailSequence
References
[1] https://docs.wso2.com/display/ESB500/VFS+Transport
[2] http://uthaiyashankar.blogspot.com/2013/07/wso2-esb-usecases-reading-file-from.html
WSO2 ESB Foreach mediator example
Say you have a payload. For example,
Here, you have an array with the root elemet "data". And you need to perform some processing for each of these objects in the array and send the resulting payload to an endpoint. I'm going to use foreach mediator to achieve this.
Lets say following is the resulting payload you want.
This payload contains, a root element "info" under which there is an array of objects having,
1. id element which is created using value of "name" element from original payload, converted to uppercase , value of "id" element from original payload, and the string "ID"
2. classid element which is the value of "id" element from the original payload
3. The "name" from original payload in uppercase.
4. university element which is hard-coded
5. department element which is also hard-coded
And you need to send this resulting payload to some endpoint in JSON format.
Inside foreach mediator I use script mediator to convert the name to uppercase. Then using payload factory mediator I create the payload. And outside the foreach mediator I use send mediator to send the resulting payload to the endpoint.
Here is the sequence.
Let's use the following API to call my-in-seq.
Add both above API and sequence to synapse config. We can send a curl request as follows and see how it works.
References
[1] https://docs.wso2.com/display/ESB490/ForEach+Mediator
Here, you have an array with the root elemet "data". And you need to perform some processing for each of these objects in the array and send the resulting payload to an endpoint. I'm going to use foreach mediator to achieve this.
Lets say following is the resulting payload you want.
This payload contains, a root element "info" under which there is an array of objects having,
1. id element which is created using value of "name" element from original payload, converted to uppercase , value of "id" element from original payload, and the string "ID"
2. classid element which is the value of "id" element from the original payload
3. The "name" from original payload in uppercase.
4. university element which is hard-coded
5. department element which is also hard-coded
And you need to send this resulting payload to some endpoint in JSON format.
Inside foreach mediator I use script mediator to convert the name to uppercase. Then using payload factory mediator I create the payload. And outside the foreach mediator I use send mediator to send the resulting payload to the endpoint.
Here is the sequence.
Let's use the following API to call my-in-seq.
Add both above API and sequence to synapse config. We can send a curl request as follows and see how it works.
References
[1] https://docs.wso2.com/display/ESB490/ForEach+Mediator
Subscribe to:
Posts (Atom)