Revision as of 09:55, 23 September 2016

Overview

Libraries for access and storage of unstructured bytestreams, or files, can be provided through a standards-based, POSIX-like API which supports the organisation and operations normally associated with local file systems whilst offering scalable and fault-tolerant remote storage.

The StorageManager acts as facade to the service and allows clients to download, upload, remove, add and list files. Files have owners and owners may define access rights to files, allowing private, public, or group-based access.

Key features

The core of StorageManager is a java library named storage-manager-core that offers a interface for performing CRUD operation through a remote backend:

• Create blob
• Read blob
• Update existing blob
• Delete existing blob
• Move existing blob to a new location
• Copy existing blob to a new location

Design

Philosophy

This represents a unique endpoint for those clients or services which want to perform CRUD operation on a remote backend

Architecture

The storage-manager is composed by two libraries:

• storage-manager-wrapper : in charge to discover backend information from IS-Collector service;
• storage-manager-core : manage the interactions with remote backend.

Storage Manager Architecture

Access Mode

There are 3 ways to access remote files:

Private

Accessible only to the owner of the file

Public

Accessible to all users of the community

Shared

Accessible to all users of the same group of the owner

These types of access will be specified when instantiating the client. If the client is instantiated for example,with the private access mode, all the operations done with this client instance will be in private access mode.

VOLATILE area

Since 1.0.1 version of storage-manager there is a new storage area called VOLATILE. The files inserted on this special area are automatically removed after a period of 7 days from the first upload. The use of this area is intended for all clients that need to use storage for temporary data. The use of VOLATILE area is very simple and very similar to the standard usage of storage-manager. The only difference is that using the VOLATILE area the client must add an input parameter on the storage-manager client constructor. The new input parameter is an enumerated type and is called MemoryType, it can have only 2 values:

• VOLATILE: for storing in the VOLATILE area: the files are deleting automatically after 7 days
• PERMANENT: for storing in the standard area: the files are deleting only manually

The VOLATILE area is suggested to all clients that do not need to maintain data on the storage permanently. Through the use of this area the client doesn't need to perform the delete operation manually. It is strongly discouraged the usage of the VOLATILE storage area for storing data that will need to last more than seven days.

Operations

Inspired by Build Pattern, the StorageManger library implements many operations on remote files. The methods LFile and RFile refer to, respectively, Local File (if needed) and Remote File. The remote file could be identified by path or by id. The id is returned when the file is created. In the call's signature, these methods are preceded by a method that identify an operation, see examples below:

put(boolean replace)

put a local file in a remote directory. If replace is true then the remote file, if exists, will be replaced.

If the remote directory does not exist it will be automatically

put(true).LFile(“localPath”).RFile(“remotePath”);

put(true).LFile(“localPath”).RFile(id);

get()

downloads a file from a remote path to a local directory

get().LFile(“localPath”).RFile(“remotePath”);

get().LFile(“localPath”).RFile(id);

remove()

removes a remote file

remove().RFile(“remotePath”);

remove().RFile(id);

removeDir()

removes a remote directory and all files in it. This operation is recursive.

removeDir().RDir(“remoteDirPath”);

showDir()

shows the content of a directory

showDir.RFile(“remoteDirPath”);

lock()

locks a remote file to prevent multiple access. It returns an id string for unlock the file. Remember that every lock has a TTL associated (Default: 180000 ms).

lock().RFile(“remotePath”);

Otherwise: Download the file in "localFilePath" and Lock the remote file stored on backend server

lock().LFile("localFilePath").RFile("remotePath")

unlock(String key4Unlock)

if the file is locked, unlocks the remote file.

unlock(“key4Unlock”).RFile(“remotePath”);

Otherwise: Upload the new File stored in the local FileSystem at: "localFilePath" and unlock the file on the backend server

unlock("key4Unlock").LFile("localFilePath").RFile("remotePath")

getTTL()

returns the TimeToLive associated to a remote file if the file is currently locked

getTTL().RFile("remoteDirPath");

setTTL(int milliseconds)

resets the TimeToLive to a remote file that is currently locked. This operation is consented max 5 times for any file.

setTTL(180000).RFile("remoteDirPath");

getUrl()

returns the smp url of a file stored in the repository

this method is not compatible with private access mode

getUrl().RFile(“remotePath”);

getUrl().RFile(id);

getHttpUrl()

returns the http url of a file stored in the repository

this method is not compatible with private access mode

getUrl().RFile(“remotePath”);

getUrl().RFile(id);</code>

copy()

copies a remote file from a remote path to another remote path

return the id of the new file stored in the repository

this method is available only in version 2.0.0

copy().RFile(“remotePath1”).Rfile(“remotePath2”);

moveFile()

moves a remote file from a remote path to another remote path

return the id of the file stored in the repository

this method is available only in version 2.0.0 or later

moveFile().from(“remoteFilePath1”).to(“remoteFilePath2”);

moveDir()

moves a remote directory from a remote directory path to another remote directory path

this method is available only in version 2.0.0 or later

moveDir().from(“remoteDirPath1”).to(“remoteDirPath2”);

link()

links a remote file from a remote path to another remote path as an hard link in Unix system

return the id of the new file linked in the repository

this method is available only in version 2.0.0

link().RFile(“remotePath1”).Rfile(“remotePath2”);

Usage/Examples

Usage

The following code explains how to instatiate a client for performing remote operations on the storage repository: GCUBEScope scope = GCUBEScope.getScope("/gcube");

// The Access type can be private | shared | public

IClient client=new StorageClient("ServiceClass", "ServiceName", "owner", AccessType.SHARED, scope).getClient();

The following code explains how to upload a new file in the storage repository: String id=client.put(true).LFile("/home/rcirillo/FilePerTest/pippo.jpg").RFile("/img/pippo.jpg");

The following code explains how to download a file from the storage repository: client.get().LFile("/home/rcirillo/FilePerTest/pippo.jpg").RFile("/img/pippo.jpg");

or alternatively, download the file by Id client.get().LFile("/home/rcirillo/FilePerTest/pippo.jpg").RFile(id);

or alternatively, download the file by stream InputStream is = client.get().RFileAStream("/img/pippo.jpg");

The following code explains how to show the contents of a remote directory on the storage repository: List<StorageObject> list=client.showDir().RDir("img");

The following code explains how to lock a file on the storage repository: String id=client.lock().RFile("/img/pluto.jpg");

The following code explains how to unlock a file on the storage repository: client.unlock(id).RFile("/img/pluto.jpg");

The following code explains how to remove a file on the storage repository: client.remove().RFile("/img/pluto.jpg");

or alternatively, remove a file by Id client.remove()..RFile(id);

The following code explains how to remove a dir on the storage repository: client.removeDir().RDir("/img");

The following code explains how to move a dir on the storage repository from a remote path to another remote path: client.moveDir().from("/img/test1").to("/img/test2");

The following code explains how to move a file from a remote path to another remote path: client.moveFile().from("/img/test1.xml").to("/img/test2.xml");

Example

Scenario 1

In this example a GCUBE service s1 (identify by: ServiceClass: sc, ServiceName: sn), running in the sScope /gcube upload the file: /home/xxx/FilePerTest/test.jpg in shared mode in the VOLATILE area. Another instance of the same service, s2 (identify by: ServiceClass: sc2, ServiceName: sn2) running in the same scope but on another node, download it.

The following code shows the upload operation:

String scope="/gcube";

ScopeProvider.instance.set(scope);

IClient client=new StorageClient("sc", "sn", "s1", AccessType.SHARED, MemoryType.VOLATILE).getClient();

String id=client.put(true).LFile("/home/xxx/FilePerTest/test.jpg").RFile("/img/test.jpg");

The following code shows the download operation:

String scope="/gcube";

ScopeProvider.instance.set(scope);

IClient client=new StorageClient("sc2", "sn2", "s2", AccessType.SHARED, MemoryType.VOLATILE).getClient();

String id=client.get().LFile("/home/yyy/FilePerTest/test.jpg").RFile("/img/test.jpg");

The file is downloaded in the local directory: /home/yyy/FilePerTest/ where s2 is running and the file name is test.jpg

Scenario 2

In this example a GCUBE service s1 (identify by: ServiceClass: sc, ServiceName: sn), running in the scope /gcube uploads the file: /home/xxx/FilePerTest/test1.jpg in shared mode in VOLATILE area. It then retrieves the url of the file uploaded by the method getUrl and passes it to another service s2 that is in running on another node. The s2 service retrieves the inputStream of the file that the service s1 had uploaded by the url. Remember, getUrl() method is not compatible with private access mode:

String scope="/gcube";

ScopeProvider.instance.set(scope);

IClient client=new StorageClient("sc", "sn", "s1", AccessType.SHARED, MemoryType.VOLATILE).getClient();

String id=client.put(true).LFile("/home/xxx/FilePerTest/test1.jpg").RFile("/img/test1.jpg");

String url=client.getUrl().RFile("/img/test1.jpg");

The s2 service retrieves the inputStream of the file by the url stored in the "url" variable:

Handler.activateProtocol();

URL smsHome = new URL("smp://img/test1.jpg5ezvFfBOLqbElsh5xYVgBTxt8lwt4fl");

URLConnection uc = null;

uc = ( URLConnection ) smsHome.openConnection();

InputStream is=uc.getInputStream();

Scenario 3

In this example a GCUBE service s1 (identify by: ServiceClass: sc, ServiceName: sn), running in the scope /gcube uploads the file: /home/xxx/FilePerTest/test2.jpg in shared mode in VOLATILE area. It then retrieves the url of the file uploaded by the method getHttpUrl and passes it to another service s2 that is in running on another node. The s2 service retrieves the inputStream of the file that the service s1 had uploaded by the url.

String scope="/gcube";

ScopeProvider.instance.set(scope);

IClient client=new StorageClient("sc", "sn", "s1", AccessType.SHARED, MemoryType.VOLATILE).getClient();

String id=client.put(true).LFile("/home/xxx/FilePerTest/test2.jpg").RFile("/img/test2.jpg");

String httpUrl=client.getHttpUrl().RFile("/img/test2.jpg");

The s2 service retrieves the inputStream of the file by the url stored in the "url" variable:

URL smsHome = new URL(httpUrl);

URLConnection uc = null;

uc = ( URLConnection ) smsHome.openConnection();

InputStream is=uc.getInputStream();

Alternatively, the httpUrl could be also resolved by a browser. This is an example of the httpUrl generated by getHttpUrl method:

http://data-d.d4science.org/T1VWSC9Kc0Q2ZlJzbHA0d1kvWjZFdmRjbkE1M1pLT09HbWJQNStIS0N6Yz0

Deployment

To release the library at a particular gcube scope you need to create only a runtime resource that specifies the address of the server used for storing data. This is an example of runtime resource used.

<Resource version="0.4.x">
   <ID>46083b40-a5e3-11e2-a210-9a433747c17a</ID>
   <Type>RuntimeResource</Type>
   <Scopes>
      <Scope>/gcube/devsec</Scope>
      <Scope>/gcube</Scope>
      <Scope>/gcube/devsec/devVRE</Scope>
   </Scopes>
   <Profile>
      <Category>DataStorage</Category>
      <Name>StorageManager</Name>
      <Description>Backend description  for StorageManager library</Description>
      <Platform>
         <Name>storage-manager</Name>         <Version>2</Version>         <MinorVersion>0</MinorVersion>         <RevisionVersion>0</RevisionVersion>         <BuildVersion>0</BuildVersion>      </Platform>
      <RunTime>
         <HostedOn>d4science.org</HostedOn>
         <GHN UniqueID="" />
         <Status>READY</Status>
      </RunTime>
      <AccessPoint>
         <Description>MongoDB server</Description>
         <Interface>
            <Endpoint EntryName="server1">146.48.123.01</Endpoint>
         </Interface>
         <AccessData>
            <Username />
            <Password>6vW1u92cpdgHzYAgIurn9w==</Password>
         </AccessData>
         <Properties>
            <Property>
               <Name>host</Name>
               <Value encrypted="false">nodeXX.d.d4science.research-infrastructures.eu</Value>
            </Property>
            <Property>
               <Name>priority</Name>
               <Value encrypted="false">default</Value>
            </Property>
            <Property>
               <Name>type</Name>
               <Value encrypted="false">MongoDB</Value>
            </Property>
         </Properties>
      </AccessPoint>
      <AccessPoint>
         <Description>MongoDB server</Description>
         <Interface>
            <Endpoint EntryName="server2">146.48.123.02</Endpoint>
         </Interface>
         <AccessData>
            <Username />
            <Password>6vW1u92cpdgHzYAgIurn9w==</Password>
         </AccessData>
         <Properties>
            <Property>
               <Name>host</Name>
               <Value encrypted="false">nodeYY.d.d4science.research-infrastructures.eu</Value>
            </Property>
            <Property>
               <Name>priority</Name>
               <Value encrypted="false">default</Value>
            </Property>
            <Property>
               <Name>type</Name>
               <Value encrypted="false">MongoDB</Value>
            </Property>
         </Properties>
      </AccessPoint>
   </Profile>
</Resource>

The "endpoint" tag specifies the ip of server. The resource can specify one or more servers. In this case there are three servers. If the servers are more than one then the second server has attribute value: "server2" and so on. The values of entryName attributes of endpoint tag, in this case, are: server1, server2, server3. The property named "type", specifies what kind of backend, in this case is a MongoDB server.

Maven Coordinates

If a client want to use storage-manager libraries, it should import in the pom the following dependencies:

   <dependency>
     <groupId>org.gcube.contentmanagement</groupId>
     <artifactId>storage-manager-core</artifactId>
     <version>[2.0.0, 3.0.0)</version>
   </dependency>
   <dependency>
     <groupId>org.gcube.contentmanagement</groupId>
     <artifactId>storage-manager-wrapper</artifactId>
     <version>[2.0.0, 3.0.0)</version>
   </dependency>

Alternatively, if a client want to use the storage-manager out of the D4Science infrastructure, it's need only the storage-manager-core dependency:

   <dependency>
     <groupId>org.gcube.contentmanagement</groupId>
     <artifactId>storage-manager-core</artifactId>
     <version>[2.0.0, 3.0.0)</version>
   </dependency>

Media:Example.ogg