modified dataman doc to address latest changes

docs/user_guide/source/engines/dataman.rst

@@ -1,6 +1,6 @@
-***************
-DataMan for WAN
-***************
+******************************************
+DataMan for Wide Area Network Data Staging
+******************************************
 
 The DataMan engine is designed for data transfers over the wide area network. To use this engine, you can either specify it in your xml config file, with tag ``<engine type=DataMan>`` or set it in your application code:
 
@@ -21,23 +21,33 @@ On the reader side you need to do instead:
 .. note::
  The DataMan engine currently does not support data staging within a cluster.
 
-The DataMan engine does not accept any parameters. However, users are allowed to specify the following transport parameters:
-
-1. **Library**: the underlying network / socket library used for data transfer.
-
-2. **IPAddress**: the IP address of the host where the writer application runs.
-
-3. **Port**: the port on the writer host that will be used for data transfers.
-
-4. **Timeout**: the timeout in seconds to wait for every send / receive.
-
-============= ================= ================================================
- **Key**       **Value Format**  **Default** and Examples
-============= ================= ================================================
- Library           string        **ZMQ**
- IPAddress         string        **127.0.0.1**, 22.195.18.29
- Port              integer       **12306**, 22000, 33000
- Timeout           integer       **5**, 10, 30
-============= ================= ================================================
+The DataMan engine takes the following parameters:
+
+1. ``IPAddress``: No default value. The IP address of the host where the writer application runs.
+   This parameter is compulsory in wide area network data staging.
+
+2. ``Port``: Default **50001**. The port number on the writer host that will be used for data transfers.
+
+3. ``Timeout``: Default **5**. Timeout in seconds to wait for every send / receive operation.
+   Packages not sent or received within this time are considered lost.
+
+4. ``AlwaysProvideLatestTimestep``: Default **TRUE**.
+AlwaysProvideLatestTimestep is a boolean parameter that affects what
+of the available timesteps will be provided to the reader engine.  If
+AlwaysProvideLatestTimestep is **TRUE**, then if there are multiple
+timesteps available to the reader, older timesteps will be skipped and
+the reader will see only the newest available upon BeginStep.
+This value is interpreted by only by the DataMan Reader engine.
+If AlwaysProvideLatestTimestep is **FALSE**, then the reader engine
+will be provided with the oldest step that has not been processed.
+
+=============================== ================== ================================================
+ **Key**                         **Value Format**   **Default** and Examples
+=============================== ================== ================================================
+ IPAddress                       string             **N/A**, 22.195.18.29
+ Port                            integer            **50001**, 22000, 33000
+ Timeout                         integer            **5**, 10, 30
+ AlwaysProvideLatestTimestep     boolean            **TRUE**, false
+=============================== ================== ================================================
 
 

examples/hello/datamanReader/helloDataManReader.cpp

@@ -16,12 +16,12 @@
 #include <thread>
 #include <vector>
 
-int rank, size;
+int mpiRank, mpiSize;
 
 template <class T>
 void PrintData(std::vector<T> &data, size_t step)
 {
-    std::cout << "Rank: " << rank << " Step: " << step << " [";
+    std::cout << "Rank: " << mpiRank << " Step: " << step << " [";
     for (size_t i = 0; i < data.size(); ++i)
     {
         std::cout << data[i] << " ";
@@ -33,8 +33,8 @@ int main(int argc, char *argv[])
 {
     // initialize MPI
     MPI_Init(&argc, &argv);
-    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
-    MPI_Comm_size(MPI_COMM_WORLD, &size);
+    MPI_Comm_rank(MPI_COMM_WORLD, &mpiRank);
+    MPI_Comm_size(MPI_COMM_WORLD, &mpiSize);
 
     // initialize adios2
     adios2::ADIOS adios(MPI_COMM_WORLD, adios2::DebugON);

examples/hello/datamanWriter/helloDataManWriter.cpp

@@ -22,12 +22,12 @@ adios2::Dims shape;
 adios2::Dims start;
 adios2::Dims count;
 
-int rank, size;
+int mpiRank, mpiSize;
 
 template <class T>
 void PrintData(std::vector<T> &data, const size_t step)
 {
-    std::cout << "Rank: " << rank << " Step: " << step << " [";
+    std::cout << "Rank: " << mpiRank << " Step: " << step << " [";
     for (const auto i : data)
     {
         std::cout << i << " ";
@@ -43,7 +43,7 @@ std::vector<T> GenerateData(const size_t step)
     std::vector<T> myVec(datasize);
     for (size_t i = 0; i < datasize; ++i)
     {
-        myVec[i] = i + rank * 10000 + step;
+        myVec[i] = i + mpiRank * 10000 + step;
     }
     return myVec;
 }
@@ -52,13 +52,13 @@ int main(int argc, char *argv[])
 {
     // initialize MPI
     MPI_Init(&argc, &argv);
-    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
-    MPI_Comm_size(MPI_COMM_WORLD, &size);
+    MPI_Comm_rank(MPI_COMM_WORLD, &mpiRank);
+    MPI_Comm_size(MPI_COMM_WORLD, &mpiSize);
 
     // initialize data dimensions
     count = {Nx, Ny};
-    start = {rank * Nx, 0};
-    shape = {size * Nx, Ny};
+    start = {mpiRank * Nx, 0};
+    shape = {mpiSize * Nx, Ny};
 
     // initialize adios2
     adios2::ADIOS adios(MPI_COMM_WORLD, adios2::DebugON);